Infective Endocarditis

Background

Infective endocarditis (IE) occur when microorganisms adhere to endocardial surface of the heart. This most commonly occurs in the setting of prior trauma or damage to the heart valve. This is why intravenous drug abusers and children with congenital heart valvular anomalies are at increased risk. Until recently, the disease was classified as acute or subacute based upon the progression of the untreated disease. However, it is now recognized that there is significant clinical and etiological overlap between the two stages of the disease. Modern classifications tend to classify the disease based upon the infecting agent, which will appropriately guide antibiotic treatment.

OUTLINE

Epidemiology

Disease Associations

Pathogenesis

Laboratory/Radiologic/Other Diagnostic Testing

Gross Appearance and Clinical Variants

Prognosis and Treatment

Commonly Used Terms

Internet Links

EPIDEMIOLOGY CHARACTERIZATION

Infective endocarditis: an epidemiological review of 128 episodes.

Dyson C, Barnes RA, Harrison GA.

Department of Medical Microbiology, University Hospital of Wales, Health Park, Cardiff, UK.
J Infect 1999 Mar;38(2):87-93 Abstract quote
OBJECTIVES: The objective was to determine the current epidemiology of infective endocarditis.

PATIENTS AND METHODS: All microbiologically positive episodes of infective endocarditis treated at The University Hospital of Wales over a 9-year period from March 1987 to March 1996 was reviewed. Patients originated from the catchment area of The University Hospital of Wales or were referred from other hospitals in Wales. Data extraction was from records held in the Microbiology Department and, whenever possible, from patients' casenotes. The epidemiological parameters were: (1) age and sex of patients; (2) distribution of affected sites; (3) frequency of predisposing risk factors (cardiac and extracardiac); (4) incidence of early prosthetic valve endocarditis; and (5) mortality rates.

RESULTS: There were 128 microbiologically positive episodes of endocarditis in 125 patients. The mean age of the population was 53.1 years and the aortic valve was the most frequently involved site of infection (51.6%). A presumed source of infection was identified in 20% if episodes. The commonest predisposing cardiac risk factor in native valve episodes was bicuspid aortic valve (16.7%) but there was no identifiable cardiac risk factor in a much larger proportion (37.7%) of native valve episodes. There was a low incidence (0.6%) of culture positive early prosthetic valve episodes and low mortality rates for both native and prosthetic valve endocarditis (12.3% and 24.5%) in this study. Viridans streptococci were the predominant organisms. In prosthetic valve episodes with onset after the 60th postoperative day but within one postoperative year the identity of the isolate suggested, in most cases, perioperative valve contamination.

CONCLUSIONS: The epidemiology of infective endocarditis has undergone significant change. Inability to detect clinically common predisposing lesions, and the frequent absence of any identifiable predisposing cardiac risk factor mean that initial diagnosis is often difficult and demands a high index of suspicion. There was a low incidence of culture positive early prosthetic valve episodes and there were low mortality rates for both native and prosthetic valve endocarditis; these figures suggest improvements in cardiac care. The microbiological evidence indicates that the duration of the postoperative time period used for classifying prosthetic valve endocarditis into 'early' and 'late' episodes should be extended from 60 days to 1 year.

GEOGRAPHY

DENMARK

Native valve infective endocarditis in the general population: a 10-year survey of the clinical picture during the 1980s.

Nissen H, Nielsen PF, Frederiksen M, Helleberg C, Nielsen JS.

Cardiology Department, Odense University Hospital, Denmark.

Eur Heart J 1992 Jul;13(7):872-7 Abstract quote
In a population of 930,000 inhabitants all records of native valve infective endocarditis diagnosed in the decade 1980-89 were reviewed.

Using strict case definitions 132 clinically well-defined or post-mortem diagnosed cases were found. Included were cases referred to the local department of cardiology, as well as cases treated in non-specialized departments. Of 132 cases found 23 were only diagnosed post mortem. The male/female ratio was 71/61. The median prehospital duration of symptoms was 20 days (range 0-180 days) and the median in-hospital diagnostic delay was 5 days (range 0-54 days). Known cardiac disease was found in 42% of cases, a possible portal of entry was found in 33%, but in 36% there were no predisposing factors. Remarkably, only two patients had known rheumatic heart disease and none had a known dental focus. During the clinical course 55% experienced cardiac failure and 17% embolic episodes. In 19 patients surgery was required. Of 111 culture-positive cases streptococci were found in 61 and staphylococci in 45 cases. Echocardiography was performed in 95 cases with echocardiographic signs of endocarditis in 65 patients.

Overall mortality was 33% with a mortality in clinically diagnosed cases of 18%. Of 14 cases needing immediate surgical intervention, two died.

NETHERLANDS

Epidemiology of bacterial endocarditis in The Netherlands. I. Patient characteristics.

van der Meer JT, Thompson J, Valkenburg HA, Michel MF.

Department of Clinical Microbiology, Erasmus University, Rotterdam, The Netherlands.
Arch Intern Med 1992 Sep;152(9):1863-8 Abstract quote
BACKGROUND--Studies of the epidemiology of bacterial endocarditis are usually based on a retrospective review of medical records from referral centers serving diverse patient populations. These studies are therefore likely to suffer from selection bias. We conducted a nationwide prospective epidemiologic study of endocarditis in the Netherlands.

METHODS--During a 2-year period, all cases of consecutively hospitalized patients with suspected endocarditis in the Netherlands were reported to us. While hospitalized, patients were visited for an in-person interview and a review of the medical record.

RESULTS--Of 559 episodes, 438 met the criteria for endocarditis; these included 89 episodes of prosthetic valve endocarditis and 349 episodes of native valve endocarditis. Adjusted for age- and sex-specific population figures, the incidence was 19 per million person-years. The incidence increased significantly with age, and men were more often affected than women (266 and 172 cases, respectively). Rheumatic and congenital cardiac lesions formed most of the underlying heart diseases. Mitral valve prolapse was present in only 29 patients with native valve endocarditis (8.3%). A history of intravenous drug abuse was present in 32 patients (7.3%). Viridans streptococci, staphylococci, and enterococci together constituted 86% of the isolated bacterial strains. Only 1.1% of the patients had culture-negative endocarditis. Overall case fatality was 19.7% and varied widely according to causative microorganism.

CONCLUSION--The distribution of causal microorganisms, the case fatality rate, and the incidence rate of endocarditis are age related. Therefore, a meaningful comparison of data is only possible between population-based cohorts of patients with endocarditis.

SWEEDEN

Epidemiologic aspects of infective endocarditis in an urban population. A 5-year prospective study.

Hogevik H, Olaison L, Andersson R, Lindberg J, Alestig K.

Department of Infectious Diseases, Goteborg University, Sweden.
Medicine (Baltimore) 1995 Nov;74(6):324-39 Abstract quote
A prospective study of the epidemiology of infective endocarditis (IE) in a well-defined urban population of 428,000 inhabitants during a 5-year period was carried out. All patients were treated in the same institution, and history, diagnostic procedures, and treatment were standardized. Of 233 consecutive suspected episodes of IE, 127 fulfilled the modified von Reyn criteria.

After patients not living in the defined area were excluded, 99 episodes in 90 patients were analyzed in the epidemiologic part of the study. Of these, 33 episodes were definite endocarditis, verified by surgery or autopsy; 35 probable; and 31 possible endocarditis episodes. Another 34 episodes were found retrospectively and are included in the incidence calculation. The crude incidence was calculated to be 6.2/100,000 inhabitants per year, which is high compared to earlier studies. Adjusted to the population of Sweden, the incidence was 5.9/100,000 inhabitants per year. The annual incidence was higher for women, 6.6/100,000, than for men, 5.8/100,000. In the oldest age-group (80-89 years) the annual incidence was 22/100,000 in the prospective study and 30/100,000 if retrospective cases were included. Contrary to almost all other studies, we did not find a male predominance among our cases. Only 7% of patients were intravenous drug abusers, and 15% had a prosthetic valve.

The most common bacteria were methicillin-susceptible Staphylococcus aureus (31%) and alpha-streptococci (28%); 12% of episodes were culture negative. The mortality from IE in the population was 1.4/100,000 inhabitants per year. A higher-than-expected incidence of IE was found, especially among older patients and women.

DISEASE ASSOCIATIONS CHARACTERIZATION

BICUSPID AORTIC VALVE

Bicuspid aortic valve--A silent danger: analysis of 50 cases of infective endocarditis.

Lamas CC, Eykyn SJ.

St. Thomas' Hospital, London, SE1 7EH, London, United Kingdom.
Clin Infect Dis 2000 Feb;30(2):336-41 Abstract quote
We analyzed 50 cases of bicuspid aortic valve endocarditis in patients who presented to St. Thomas' Hospital from 1970 through 1998.

These represented 12.3% of the 408 cases of native valve endocarditis (NVE). All patients were male, and their mean age was 39 years. Forty-five of the 50 cases were pathologically proven; 47 were clinically definite according to the Duke criteria and 49 according to our modifications of the Duke criteria. Viridans streptococci and staphylococci accounted for 72% of cases. The prevalences of clinical features were similar to those seen in NVE: fever (temperature >/=38 degrees C, 74%) and malaise (70%), although dyspnea was more frequent (36%). There was a high incidence of serious complications (72% heart failure; 30% periannular abscesses). Surgery was required during the initial admission in 82% of cases.

Overall mortality was 14%, and surgical mortality was 9%. Few patients knew they had a "heart condition," and a bicuspid aortic valve was detected in only 35% of echocardiograms performed before surgery.

INTRAVENOUS DRUG ABUSE

Clinical features, site of involvement, bacteriologic findings, and outcome of infective endocarditis in intravenous drug users.

Mathew J, Addai T, Anand A, Morrobel A, Maheshwari P, Freels S.

Department of Medicine, Cook County Hospital, Chicago, IL, USA.
Arch Intern Med 1995 Aug 7-21;155(15):1641-8 Abstract quote
BACKGROUND: Intravenous drug use is an increasingly common condition predisposing to infective endocarditis. Data on infective endocarditis in intravenous drug users are limited.

OBJECTIVE: To determine the clinical features, bacteriologic findings, site of involvement, complications, and mortality associated with infective endocarditis in intravenous drug users.

METHODS: Cohort study of intravenous drug users with native valve infective endocarditis.

RESULTS: A total of 125 cases of infective endocarditis occurred in 114 patients (84 cases [67%] in men and 41 cases [32%] in women) with a mean (+/- SD) age of 37 +/- 7 years. The tricuspid valve was involved in 58 cases (46%), the mitral valve in 40 cases (32%), and the aortic valve in 24 cases (19%). The microorganisms identified included Staphylococcus in 82 cases (65.6%) and Streptococcus in 32 cases (25.6%). Twenty-three patients (18%) underwent surgery, and two (9%) of them died. One hundred two patients (82%) were treated medically, and nine (9%) of them died. Fifteen patients (63%) with aortic valve involvement vs 17 patients (17%) without aortic valve involvement underwent surgery or died without surgery (odds ratio, 8.24; 95% confidence interval, 3.1 to 21.8). Among the survivors, at least one major cardiovascular complication occurred in 79 cases (69.3%).

CONCLUSIONS: Infective endocarditis in intravenous drug users affects the right and left sides of the heart with approximately equal frequency. At present, more than 90% of cases of infective endocarditis in intravenous drug users in Chicago are caused by staphylococci or streptococci. Involvement of the aortic valve is predictive of increased morbidity and mortality in intravenous drug users with infective endocarditis. With medical treatment, and surgery when medical treatment fails, intravenous drug users with infective endocarditis have an in-hospital survival rate of 91%

PATHOGENESIS CHARACTERIZATION

STREPTOCOCCUS AGALACTIAE

Streptococcus agalactiae infective endocarditis: analysis of 30 cases and review of the literature, 1962-1998.

Sambola A, Miro JM, Tornos MP, Almirante B, Moreno-Torrico A, Gurgui M, Martinez E, Del Rio A, Azqueta M, Marco F, Gatell JM.

Hospital Clinic-Institut d'Investigacions Biomediques August Pi i Sunyer, University of Barcelona, E-08036-Barcelona, Spain.
Clin Infect Dis 2002 Jun 15;34(12):1576-84 Abstract quote
We describe 30 cases (1.7%) of community-acquired penicillin-susceptible Streptococcus agalactiae endocarditis among 1771 episodes of endocarditis diagnosed in 4 Spanish hospitals from 1975 through 1998.

Endocarditis affected a native valve (most often the mitral valve) in 25 cases (83%). Surgical valve replacement was performed for 12 patients (40%). Fourteen patients (47%) died. Mortality rates for patients with native and prosthetic valve endocarditis were 36% and 100%, respectively (P=.01). The mortality rate for native valve endocarditis decreased during the last 6 years of the study (from 61% in 1975-1992 to 8% in 1993-1998; P<.05). Additionally, 115 cases in the literature from 1962-1998 were reviewed. During 1980-1998, the percentage of patients who underwent cardiac surgery increased from 24% (in the previous period, 1962-1979) to 43% (P=.05) and the mortality rate decreased from 45% to 34% (P=NS).

S. agalactiae is an uncommon cause of endocarditis with a high mortality rate, although the prognosis of native valve endocarditis has improved in recent years, probably because of an increased use of cardiac surgery.

LABORATORY/RADIOLOGIC/
OTHER TESTS
CHARACTERIZATION

RADIOLOGIC

Clinical outcome and echocardiographic findings of native and prosthetic valve endocarditis in the 1990's.

Schulz R, Werner GS, Fuchs JB, Andreas S, Prange H, Ruschewski W, Kreuzer H.

Department of Cardiology, Georg-August-University, Gottingen, Germany.

Eur Heart J 1996 Feb;17(2):281-8 Abstract quote
Prosthetic valve endocarditis is considered to be associated with a more severe prognosis than native valve endocarditis. Among other factors, inappropriate visualization of vegetations in prosthetic valve endocarditis by transthoracic echocardiography is responsible for this observation. Since the introduction of transoesophageal echocardiography into clinical practice the diagnostic sensitivity and specificity of the detection of vegetations located on prosthetic valves have been enhanced.

Therefore we aimed to determine and compare the prognosis of prosthetic valve endocarditis and native valve endocarditis in the era of this improved diagnostic approach. One hundred and six episodes of infective endocarditis in 104 patients were seen at our institution between 1989 and 1993. Eighty patients (77%) had native valve endocarditis and 24 (23%) had late prosthetic valve endocarditis. In the latter group two patients had recurrent infective endocarditis. Patients with prosthetic valve endocarditis were older (mean age 64 vs 54 years in native valve endocarditis; P < 0.001) and the majority was female (62% vs 38% in native valve endocarditis; P < 0.05). In prosthetic valve endocarditis, infection of a valve in the mitral position predominated (65% vs 30% in native valve endocarditis; P < 0.01), whereas in native valve endocarditis more than half the cases had isolated aortic valve endocarditis (51% vs 27% in prosthetic valve endocarditis; P < 0.01). In prosthetic valve endocarditis more cases were caused by Staphylococcus aureus (31% vs 14% in native valve endocarditis; P = 0.08), whereas in native valve endocarditis the most frequent organisms were streptococci (29% vs 19% in prosthetic valve endocarditis; P = 0.12). Differences in the clinical features of native valve endocarditis and prosthetic valve endocarditis could not be found except for a higher rate of embolism in native valve endocarditis (40% vs 19% in prosthetic valve endocarditis; P < 0.05). Vegetations could be detected by transthoracic echocardiography more frequently in native valve endocarditis (71% vs 15% in prosthetic valve endocarditis; P < 0.0001). Transoesophageal echocardiography visualized vegetations in 95% of the episodes of native valve endocarditis and in 80% of the episodes of prosthetic valve endocarditis (P = 0.09). Thus, the diagnostic gain by transoesophageal echocardiography was greatest in prosthetic valve endocarditis. Patients with native valve endocarditis had significantly larger vegetations than patients with prosthetic valve endocarditis (P < 0.05 for length, P < 0.001 for width). The median time to diagnosis was similar in native valve endocarditis and prosthetic valve endocarditis (31 vs 28 days). Surgery was performed in 74% of patients with native valve endocarditis and in 58% of those with prosthetic valve endocarditis; the median time delay between the diagnosis of infective endocarditis and surgery tended to be shorter in prosthetic valve endocarditis than in native valve endocarditis (45 vs 60 days). The in-hospital mortality and the mortality during a follow-up of 22 +/- 10 months did not significantly differ between native valve endocarditis and prosthetic valve endocarditis (21% vs 17%; 28% vs 25%).

In summary in the era of transoesophageal echocardiography, late prosthetic valve endocarditis does not seem to carry a worse prognosis than native valve endocarditis. This can be attributed in part to the improved diagnostic accuracy achieved by transoesophageal echocardiography leading to comparable diagnostic latency periods in both patient groups. Finally, better characterization of vegetations on prosthetic valves by transoesophageal echocardiography allows early lifesaving surgery in patients with prosthetic valve endocarditis.

LABORATORY MARKERS

BLOOD CULTURES

Are blood and valve cultures predictive for long-term outcome following surgery for infective endocarditis?

Renzulli A, Carozza A, Marra C, Romano GP, Ismeno G, De Feo M, Della Corte A, Cotrufo M.

Institute of Cardiac Surgery, Second University of Naples, V. Monaldi Hospital, Via L. Bianchi, Naples, Italy.
Eur J Cardiothorac Surg 2000 Mar;17(3):228-33 Abstract quote
OBJECTIVE: To evaluate whether perioperative bacteria identification in blood and/or in valve cultures can predict early and late outcome of surgery for infective endocarditis, a retrospective study was performed.

METHODS: Between January 1978 and December 1998, 232 patients, 79 (34.1%) female and 153 (65.9%) male with mean age of 44. 95+/-1.03 years (range 8-79) underwent surgery for infective endocarditis on a native (162 cases) or prosthetic (70 cases) valve. Patients were divided into three groups according to the perioperative x of microbiological tests: Group A: patients with preoperative positive blood cultures (83 cases); Group B: patients with positive valve cultures (35 cases); Group C: patients with negative blood and valve cultures (114 cases). Categorical values were compared by chi(2) analysis, whereas continuous data were compared by ANOVA and Bonferroni correction for post hoc comparisons. Analysis of late survival and complications was performed with Kaplan-Meier and Log Rank test. Late mortality, reoperation, perivalvular leak, recurrence of infection were considered as treatment failure. All data were presented as mean+/-standard error. RESULTS: Hospital mortality was 10.8% (9/83) in Group A, 8.6% (3/35) in Group B, and 14.9% (17/114) in Group C (P=0.52; not significant (NS)). Ten-year survival was 62.7+/-8% in Group A, 43.9+/-19% in Group B and 62.7+/-7% in Group C (P=0.38; NS). Ten-year freedom from reoperation was 85.2+/-6% in Group A, 37.9+/-20% in Group B and 80+/-6% in Group C (P=0.0034). Ten-year freedom from treatment failure was 56.3+/-8% in Group A, 31.6+/-16% in Group B and 55. 3+/-7% in Group C (P=0.46; NS).

CONCLUSIONS: Positive blood and tissue cultures are not predictive for hospital mortality and late treatment failure in patients with infective endocarditis. Positive valve cultures, a common finding in patients with staphylococcal endocarditis, are predictive for a higher risk of reoperation.

BLOOD CULTURE NEGATIVE

Infective endocarditis in patients with negative blood cultures: analysis of 88 cases from a one-year nationwide survey in France.

Hoen B, Selton-Suty C, Lacassin F, Etienne J, Briancon S, Leport C, Canton P.

Department of Infectious and Tropical Diseases, Centre Hospitalier Universitaire de Nancy, France.
Clin Infect Dis 1995 Mar;20(3):501-6 Abstract quote
Blood cultures were negative in 88 (14%) of 620 cases of infective endocarditis (IE) documented in France during a 1-year nationwide survey.

In 15 of these 88 cases, the causative microorganism was identified: seven cases of Q fever endocarditis and two cases of chlamydial endocarditis were diagnosed by serological and/or immunohistologic techniques, and a pathogen was cultured from five surgically removed valves and one arterial septic embolus. Forty-two (48%) of the 88 cases involved patients who had received antibiotics before the first blood sample was taken for culture. Mortality was lower in this group than among patients who had not previously received antibiotics (7% vs. 22%, P = .05). Comparison of blood culture-negative cases of IE with blood culture-positive cases revealed that the former tended to occur more often on prosthetic valves (32% vs. 22%, P = .16), were more often left-sided (97% vs. 83%, P = .0009), less often included extracardiac symptoms at presentation (52% vs. 63%, P = .06), and were more often surgically treated (53% vs. 34%, P = .001). Mortality was similar regardless of the results of blood culture (15% vs. 21%, P = .18).

This study showed that more than 10% of all cases of IE in France are still associated with negative blood cultures and confirmed that a search for pathogens such as Coxiella burnetii and Chlamydia species is worthwhile in this situation.

GROSS APPEARANCE/
CLINICAL VARIANTS CHARACTERIZATION

GENERAL

VARIANTS

ELDERLY

Clinical and bacteriological characteristics of infective endocarditis in the elderly.

Selton-Suty C, Hoen B, Grentzinger A, Houplon P, Maignan M, Juilliere Y, Danchin N, Canton P, Cherrier F.

Department of Cardiology, CHU Brabois, Nancy, France.
Heart 1997 Mar;77(3):260-3 Abstract quote
OBJECTIVE: To determine the clinical and bacteriological features of infective endocarditis in the elderly.

DESIGN: Prospective case series.

SETTING: A university hospital that is both a referral and a primary care centre.

PATIENTS: 114 consecutive patients treated for infective endocarditis from November 1990 to December 1993: 25 were > 70 years of age (group 1) and 89 were < 70 years old (group 2).

RESULTS: Location of infective endocarditis, clinical signs, and symptoms were similar in the two groups, except for a lower occurrence of embolic episodes in the elderly (group 1:8%, group 2: 28%; P < 0.04). A higher rate of infective endocarditis on intracardiac prosthetic devices was noted in group 1 (group 1: 52%, group 2: 25%; P < 0.05). The distribution of causative micro-organisms showed a higher proportion of bacteria from the gastrointestinal tract in the elderly (group D streptococci and enterococci: 48% in group 1 v 20% in group 2) and the presumed portal of entry was more often digestive (group 1: 50%, group 2: 17%; P = 0.01). Elderly patients were less often operated on (group 1: 24%, group 2: 43%; P = 0.07) and their mortality rate was higher (group 1: 28%, group 2: 13%; P = 0.08).

CONCLUSIONS: Infective endocarditis in patients over 70 often occurs in those with intracardiac prosthetic devices and is more often due to bacteria from the gastrointestinal tract. Its prognosis appears to be worse than in younger subjects.

INFECTIVE

Changing profile of infective endocarditis: results of a 1-year survey in france.

Hoen B, Alla F, Selton-Suty C, Beguinot I, Bouvet A, Briancon S, Casalta JP, Danchin N, Delahaye F, Etienne J, Le Moing V, Leport C, Mainardi JL, Ruimy R, Vandenesch F.

Service de Maladies Infectieuses et Tropicales, University of Besancon Medical Center, F-25030 Besancon Cedex, France.
JAMA 2002 Jul 3;288(1):75-81 Abstract quote
CONTEXT: Since the first modern clinical description of infective endocarditis (IE) at the end of the 19th century, the profile of the disease has evolved continuously, as highlighted in epidemiological studies including a French survey performed in 1991.

OBJECTIVE: To update information gained from the 1991 study on the epidemiology of IE in France.

DESIGN AND SETTING: Population-based survey conducted from January through December 1999 in all hospitals in 6 French regions representing 26% of the population (16 million inhabitants).

PATIENTS: Three hundred ninety adult inpatients diagnosed with IE according to Duke criteria.

MAIN OUTCOME MEASURES: Incidence of IE; proportion of patients with underlying heart disease; clinical characteristics; causative microorganisms; surgical and mortality outcomes.

RESULTS: The annual age- and sex-standardized incidence was 31 (95% confidence interval [CI], 28-35) cases per million, not including the region of New Caledonia, which had 161 (95% CI, 117-216) cases per million. There was no previously known heart disease in 47% of the cases. The proportion of prosthetic-valve IE was 16%. Causative microorganisms were: streptococci, 48% (group D streptococci, 25%; oral streptococci, 17%, pyogenic streptococci, 6%); enterococci, 8%; Abiotrophia species, 2%; staphylococci, 29%; and other or multiple pathogens, 8%. Blood cultures were negative in 9% and no microorganism was identified in 5% of the cases. Early valve surgery was performed in 49% of the patients. In-hospital mortality was 16%. Compared with 1991, this study showed a decreased incidence of IE in patients with previously known underlying heart disease (20.6 cases per million vs 15.1 cases per million; P<.001); a smaller incidence of oral streptococcal IE (7.8 cases per million vs 5.1 cases per million; P<.001), compensated by a larger proportion of IE due to group D streptococci (5.3 cases per million vs 6.2 cases per million; P =.67) and staphylococci (4.9 cases per million vs 5.7 cases per million; P =.97); an increased rate of early valve surgery (31.2% vs 49.7%; P<.001); and a decreased in-hospital mortality rate (21.6% vs 16.6%; P =.08).

CONCLUSION: Although the incidence of IE has not changed, important changes in disease characteristics, treatment, and outcomes were noted.

PEDIATRIC

Infective endocarditis in children--incidence, pattern, diagnosis and management in a developing country.
Sadiq M, Nazir M, Sheikh SA.

Department of Paediatric Cardiology, Punjab Institute of Cardiology, Lahore, Pakistan.
Int J Cardiol 2001 Apr;78(2):175-82 Abstract quote
BACKGROUND: In developing countries, patients with infective endocarditis are referred late, there is low yield of blood cultures and incidence of rheumatic heart disease is still high. Objective: Evaluate clinical pattern, assess diagnostic criteria in our settings and determine outcome. Setting: A tertiary referral center for paediatric and adult cardiology.

PATIENTS AND METHODS: All children with infective endocarditis admitted to a single center from April 1997 to March 2000 were analysed. The diagnosis was based on Duke's criteria, which proposed two major and six minor criteria. Minor criteria were expanded to include raised acute phase reactants and presence of newly diagnosed or increasing splenomegally. The patients were stratified as definite, possible and rejected cases.

RESULTS: Of 1402 hospital admissions, 45 patients fulfilled the diagnostic criteria for infective endocarditis giving an incidence of 32 per 1000 hospital admissions. The mean age was 7.9 +/- 4 years (4 months to 16 years) with only two patients under 1 year of age. Rheumatic heart disease was the underlying lesion in 24 patients (53%) while congenital heart lesions occurred in 20 patients (45%). Previous antibiotic treatment was given in 26 patients (58%) definitely. Blood cultures were positive in 21 patients (47%); Streptococcus Viridans being the most common organism, while vegetations on echocardiography were present in 32 patients (71%). Surgery was undertaken in four patients and five patients left against medical advise. Of 10 patients with aortic valve involvement, there were three deaths (30%) and overall mortality was 13% (six patients).

CONCLUSIONS: The incidence of infective endocarditis is 32 per 1000 (3.2%) hospital admissions in a tertiary paediatric cardiology referral center. Rheumatic heart disease is still the most common underlying heart lesion. Blood cultures are positive in less than 50% of cases and echocardiography in expert hands is a more sensitive tool in our set up. Mortality is still high and aortic valve involvement in particular, carried poor prognosis.

Changing Risk Factors for Pediatric Infective Endocarditis.

Fisher MC.

Department of Pediatrics, Monmouth Medical Center, 300 Second Avenue, Long Branch, NJ 07740, USA.
Curr Infect Dis Rep 2001 Aug;3(4):333-336 Abstract quote
Infective endocarditis in children is an uncommon infection. Three major groups of children are at risk: 1) those with underlying congenital heart disease, 2) those with central vascular catheters, and 3) children infected with certain virulent organisms. Although the overall incidence of infective endocarditis has increased, the population of children involved has changed.

Children with corrected congenital heart disease are at risk during the early postoperative period. Children in whom vascular shunts or grafts are employed remain at the highest risk for endocarditis. Use of central vascular catheters increases risk in children with underlying heart disease and those with normal hearts. Finally, certain pathogens attack the heart valves and cause high morbidity and mortality.

PROGNOSIS AND TREATMENT CHARACTERIZATION

PROGNOSTIC FACTORS

DUKE'S CRITERIA

Evaluation of the Duke criteria versus the Beth Israel criteria for the diagnosis of infective endocarditis.

Hoen B, Selton-Suty C, Danchin N, Weber M, Villemot JP, Mathieu P, Floquet J, Canton P.

Department of Infectious Diseases, Nancy University Medical Center, France.
Clin Infect Dis 1995 Oct;21(4):905-9 Abstract quote
New diagnostic criteria for infective endocarditis (IE) have been proposed by the Duke University Endocarditis Service (Durham, NC) to update the widely used Beth Israel (Boston) criteria.

We compared the Duke criteria with the Beth Israel criteria in a series of 115 consecutive patients with suspected IE who were hospitalized in a referral center. The diagnosis of IE was histologically and/or bacteriologically confirmed for 27 operated patients. If surgery had not been performed on these 27 patients, 22 vs. 12 would have been classified as having inverted question markclinically definite inverted question mark and inverted question markprobable inverted question mark IE by the Duke vs. the Beth Israel criteria, respectively, whereas 0 vs. 5 would have been inverted question markrejected inverted question mark by the Duke vs. the Beth Israel criteria, respectively. The improvement in sensitivity of the criteria from 44% (Beth Israel) to 82% (Duke) was statistically significant (P < .01).

We confirm that the Duke criteria improve the sensitivity of diagnosis of IE. The specificity of these criteria should be further evaluated.

An assessment of the usefulness of the Duke criteria for diagnosing active infective endocarditis.

Sekeres MA, Abrutyn E, Berlin JA, Kaye D, Kinman JL, Korzeniowski OM, Levison ME, Feldman RS, Strom BL.

Division of Infectious Diseases, Medical College of Pennsylvania, Philadelphia, USA.
Clin Infect Dis 1997 Jun;24(6):1185-90 Abstract quote
We evaluated the usefulness of the Duke criteria for diagnosing cases of active infective endocarditis (IE). Patients were identified prospectively over a 3-year period at 54 hospitals in the Philadelphia metropolitan area.

Three of us independently reviewed abstracted hospital records and classified 410 patients as definite, probable, or possible cases of IE or as probable noncases. We then applied the Duke criteria to this sample to assess the degree of agreement between our diagnoses and the diagnoses based on these new criteria. Agreement was good to excellent, ranging from 72% to 90%, depending on the case definition used. The sensitivity of the Duke criteria was also good to excellent, varying from 71% to 99%, again depending on case definition used. Specificity was lower (0-89%).

We conclude that use of the Duke criteria will result in little underdiagnosis of IE but that it may result in overdiagnosis of IE; therefore, these criteria should be applied prospectively to determine their clinical usefulness.

New diagnostic criteria for infective endocarditis. A study of sensitivity and specificity.

Cecchi E, Parrini I, Chinaglia A, Pomari F, Brusasco G, Bobbio M, Trinchero R, Brusca A.

Divisione di Cardiologia, Maria Vittoria Hospital, U.S.L. 3, Torino, Italy.
Eur Heart J 1997 Jul;18(7):1149-56 Abstract quote
OBJECTIVE: The purpose of this study was to determine the sensitivity and specificity of new criteria proposed by Duke University for case definition of infective endocarditis as compared to the previously accepted Von Reyn criteria.

PATIENTS: A total of 143 consecutive suspected cases of infective endocarditis in 137 febrile patients were included. Of these, 69 had infective endocarditis, pathologically proven in 28, but with only a clinical diagnosis in 41. In the remaining 74 cases, the diagnosis of infective endocarditis was rejected after a follow-up of at least 3 months.

RESULTS: The sensitivity of Duke's criteria was significantly higher, both when patients with possible infective endocarditis were considered as true-positive (definition 1; 100% vs 69%, P < 0.001) and when possible cases were considered as rejected (definition 2; 76% vs 51%, P < 0.01). Specificity was very high with both criteria: 92% Von Reyn vs 88% Duke (ns) with definition 1 and 99% Von Reyn vs 97% Duke (ns) with definition 2. The overall accuracy of the Duke criteria in the entire population was significantly higher with both definitions (0.94 vs 0.81 definition 1, P < 0.001; 0.87 vs 0.75, P = 0.015 definition 2).

CONCLUSION: Duke's criteria for defining infective endocarditis has been shown to be more sensitive than previously adopted criteria, while maintaining a high degree of specificity. Therefore, they must be accepted as a substitute for previous criteria.

Diagnosis of infective endocarditis. Sensitivity of the Duke vs von Reyn criteria.

Heiro M, Nikoskelainen J, Hartiala JJ, Saraste MK, Kotilainen PM.

Department of Medicine, Turku University Central Hospital, Finland.
Arch Intern Med 1998 Jan 12;158(1):18-24 Abstract quote
BACKGROUND: Because of the highly variable clinical manifestations of infective endocarditis (IE), different sets of diagnostic criteria have been used to standardize case definitions of IE. We evaluated the validity of the recently proposed Duke criteria, as compared with the older von Reyn criteria, in patients with no history of injecting drug abuse.

METHODS: A total of 243 consecutive episodes of suspected IE in 222 patients treated during the years 1980 through 1995 in a Finnish teaching hospital were retrospectively evaluated for the likelihood of IE by means of these 2 classification schemes.

RESULTS: Of all disease episodes, 114 were designated as definite IE by the Duke criteria, as compared with 64 episodes so classified by the von Reyn criteria (P < .001; Fisher exact test). Moreover, as many as 115 disease episodes were rejected by the von Reyn criteria, whereas only 37 episodes were rejected by the Duke criteria (P < .001). Of the cases rejected by the von Reyn criteria, the Duke clinical criteria designated 6 (5%) as definite IE and 72 (63%) as possible IE. Among histopathologically verified episodes, 46 were designated as definite IE by the Duke clinical criteria, as compared with a diagnosis of probable IE by the von Reyn criteria in 33 episodes (P = .02). Moreover, 26 pathologically proved cases would have been rejected by the von Reyn criteria had surgery not been performed, as compared with none being rejected by the Duke criteria (P < .001).

CONCLUSIONS: Corroborating earlier findings, the higher sensitivity of the Duke criteria, as compared with the von Reyn criteria, was demonstrated in this study. These results confirm the validity of the Duke criteria in diagnosing IE in a non-drug-addict patient population.

Native valve infective endocarditis in elderly and younger adult patients: comparison of clinical features and outcomes with use of the Duke criteria and the Duke Endocarditis Database.

Gagliardi JP, Nettles RE, McCarty DE, Sanders LL, Corey GR, Sexton DJ.

Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
Clin Infect Dis 1998 May;26(5):1165-8 Abstract quote
The effect of age on the presentation and outcome of infective endocarditis (IE) is unclear. Many of the available data are based on analyses of mixed populations of patients including intravenous drug users or those with prosthetic valve endocarditis or native valve IE.

We used the Duke criteria to compare the characteristics of 44 episodes of definite native valve IE in elderly patients (> 64 years old) with the characteristics of 64 similarly defined episodes of native valve IE in younger, nonintravenous-drug-using adult patients (> 29 years and < 60 years old). Our data suggest that the clinical presentation, characteristics, and outcome of native valve IE are similar for elderly patients and younger adult patients, although elderly patients were hospitalized an average of 12 days longer.

Although we found that the occurrence of renal failure and cerebral embolism during an episode of IE was associated with higher rates of death (odds ratios, 4.8 and 4.0, respectively), age was not a significant contributor to mortality.

Are the Duke criteria superior to the Beth Israel criteria for the diagnosis of infective endocarditis in children?

Stockheim JA, Chadwick EG, Kessler S, Amer M, Abdel-Haq N, Dajani AS, Shulman ST.

Department of Pediatrics, Children's Memorial Hospital, Northwestern University Medical School, Chicago, Illinois, USA.
Clin Infect Dis 1998 Dec;27(6):1451-6 Abstract quote
Accurate diagnosis of infective endocarditis may be difficult. The Beth Israel criteria and the newer Duke criteria assign probability to the diagnosis of infective endocarditis on the basis of the presence of common features and manifestations.

We reviewed 111 cases of pediatric infective endocarditis diagnosed and treated over 19 years. Each case was classified by the two criteria, and the results were compared. Of 111 cases, 73 (66%) and 18 (16%) were classified as definite by the Duke criteria and the Beth Israel criteria, respectively. No cases were rejected by the Duke criteria, while 21 (19%) of 111 were rejected by the Beth Israel criteria. In 18 pathologically proven cases, reanalysis without pathological data showed that the Duke criteria had significantly greater sensitivity (83%) than the Beth Israel criteria (67%) (P < .03). Echocardiographic evidence was required in 22 cases for definite classification by the Duke criteria; none were rejected, however, when echocardiographic findings were ignored.

Our results suggest that the Duke criteria are superior to the Beth Israel criteria for the diagnosis of pediatric infective endocarditis.

GENERAL

Determinants of prognosis in 300 episodes of infective endocarditis.

Mansur AJ, Grinberg M, Cardoso RH, da Luz PL, Bellotti G, Pileggi F.

Heart Institute, Sao Paulo University Medical School, Brazil.
Thorac Cardiovasc Surg 1996 Feb;44(1):2-10 Abstract quote
We studied 300 episodes of infective endocarditis in 287 patients to evaluate clinical and laboratory determinants of prognosis by estimating the probability of in-hospital death.

The patients' ages ranged from 2 months to 78 (mean 30.76 +/- 16.06) years; 185 (62%) episodes occurred in male and 115 (38%) in female patients. A total of 386 complications occurred in 223 (74%) episodes of endocarditis. The infecting microorganisms were streptococci in 147 episodes, Staphylococcus aureus in 59, Staphylococcus epidermidis in 14, gram-negative bacteria in 16, other gram-positive bacteria in 8, fungi in 4. The causative microorganism was not identified in 52 episodes (negative blood cultures). The underlying cardiac disease was valvular in 119 episodes, congenital in 37, prosthetic heart valve in 69, and others in 6. No previous heart disease was identified in 69 episodes. Surgical treatment was carried out in 102 (34%) patients.

Overall, 78 (26%) patients died. The probability of death was estimated with a logistic regression model (stepwise procedure). The model with best prediction included the cardiac status previous to the endocarditis, the causative microorganism, the occurrence of complications, and the blood leukocyte count.

The most important variable in predicting in-hospital death was the occurrence of complications, followed by cardiac status (prosthetic valve endocarditis), the infecting microorganism, and leukocyte count. The model underestimated the severity of the disease in patients with acute endocarditis and overestimated in patients with prosthetic valve endocarditis submitted to surgical treatment.

Infective endocarditis: review of 135 cases over 9 years.

Sandre RM, Shafran SD.

Department of Medicine, University of Alberta, Edmonton, Canada.
Clin Infect Dis 1996 Feb;22(2):276-86 Abstract quote
One hundred thirty-five cases of infective endocarditis in adults at the University of Alberta Hospital from 1985 to 1993 were reviewed and the von Reyn and Duke criteria were compared.

There were 80 cases of native valve endocarditis, 15 cases of endocarditis in intravenous drug users, 7 cases of early prosthetic valve endocarditis, and 33 cases of late prosthetic valve endocarditis. Valve replacement or repair was performed in 33% of all cases. The overall mortality was 19%. The mortality among patients treated surgically was significantly lower than that among those treated medically (9% vs. 24%, respectively; P = .037). However, when patients who were too medically unstable for surgery or who refused surgery were excluded, the mortality among the medically treated group decreased to 15%, which was not significantly different from that among the surgically treated group. The 33 patients transferred from other hospitals were infected with similar pathogens; however, the rate of surgical intervention among these patients was much higher than that among other patients (64% vs. 24%, respectively; P < .0001), and the mortality was slightly lower (12.1% vs. 21.6%, respectively; P = .31).

The 54 surgical and autopsy-proven cases were classified by the von Reyn and the Duke criteria without knowledge of the operative and autopsy results: 15% of these cases were rejected by the von Reyn criteria, and none were rejected by the Duke criteria.

Infective endocarditis, 1984 through 1993: a clinical and microbiological survey.

Benn M, Hagelskjaer LH, Tvede M.

Medical Department, Viborg Hospital, Denmark.

ortance of early case detection and treatment.

J Intern Med 1997 Jul;242(1):15-22 Abstract quote
OBJECTIVES: To characterize the epidemiology and the clinical and microbiological spectrum of infective endocarditis in a Danish population.

DESIGN: A retrospective review.

SETTING: All episodes hospitalized of infective endocarditis from 1984 to 1993 in Viborg County were reviewed. The county is served by one general and four local hospitals.

SUBJECTS: One hundred and nine episodes of suspected infective endocarditis with 62 episodes in 59 patients fulfilling the diagnostic criteria by von Reyn.

RESULTS: An overall incidence of 27 episodes per million per year was found. The incidence was 17.4 episodes per million per year in the first part of the decade and 36.5 episodes per million per year in the second part (P < 0.001). Microscopic haematuria was found in 70.2% of the patients with infective endocarditis, compared to 16.7% of the patients in whom the diagnosis was rejected (P < 0.01). Staphylococcus aureus was found in 38.9%, non-beta-haemolytic streptococci in 24.1% and Enterococcus faecalis in 16.7%. The overall mortality was 35.5%. The mortality decreased significantly from 50.0% in the first part of the decade to 28.6% in the second part (P < 0.01). The mortality was 23.1% in patients in whom the diagnosis was established whilst they were alive. This finding was significantly lower than the overall mortality (P < 0.05).

CONCLUSION: The incidence of infective endocarditis increased during the decade. The frequency of non-beta-haemolytic streptococci was lower than normally reported. Mortality is still high, with the main mortality within the first week in hospital, which stresses the importance of early case detection and treatment.

Long term outcome of infective endocarditis in patients who were not drug addicts: a 10 year study.

Castillo JC, Anguita MP, Ramirez A, Siles JR, Torres F, Mesa D, Franco M, Munoz I, Concha M, Valles F.

Servicio de Cardiologia, Hospital Universitario Reina Sofia, Cordoba, Avda Menendez Pidal, s/n 14004 Cordoba, Spain.
Heart 2000 May;83(5):525-30 Abstract quote
OBJECTIVE: To determine the clinical features and long term prognosis of infective endocarditis in patients who were not drug addicts.

DESIGN: Prospective case series.

SETTING: A university hospital that is both a referral and a primary care centre.

PATIENTS: 138 consecutive cases of infective endocarditis diagnosed and treated from January 1987 to March 1997.

RESULTS: Mean patient age was 44 (20) years old. 95 patients (69%) had native valve endocarditis and 43 (31%) had prosthetic valve endocarditis. Staphylococci were the causal microorganisms in 34% of cases and streptococci in 33%. Severe complications occurred in 83% of patients and 51% of patients underwent surgery during the active phase (22% was emergency surgery). Inpatient mortality was 21%. During a follow up of 56 (44) months, 10 patients (9%) needed late cardiac surgery and seven (5% of the whole series) died. Overall 10 year survival was 71%. There were no significant differences in survival depending on the type of treatment received during the hospital stay (medical or combined medical-surgical).

CONCLUSIONS: A high early surgery rate is related to good long term results and does not increase in-hospital mortality. Medical treatment, however, also offers favourable long term results in cases of responsive infective endocarditis where poor prognostic factors are absent.

Infective endocarditis: clinical spectrum, presentation and outcome. An analysis of 212 cases 1980-1995.

Netzer RO, Zollinger E, Seiler C, Cerny A.

Division of Cardiology, University Hospital, Inselspital Bern, Freiburgstrasse, 3013 Bern, Switzerland.
Heart 2000 Jul;84(1):25-30 Abstract quote
OBJECTIVE: To evaluate recent changes in the spectrum and clinical presentation of infective endocarditis and to determine predictors of outcome.

DESIGN: A retrospective case study.

METHODS: Demographic, clinical, and echocardiographic characteristics were examined in 212 patients who fulfilled the Duke criteria for infective endocarditis between January 1980 and December 1995 to assess changes in clinical presentation and survival.

RESULTS: Clinical presentation and course did not change significantly during the study period despite the concurrent introduction of new diagnostic tools (for example, transoesophageal echocardiography). In-hospital mortality was 15% and remained unchanged. Neurological symptoms on admission, arthralgia, and weight loss were all independent risk factors for adverse outcome (odds ratios 26.1, 6.2, and 4.2, respectively). Age, prosthetic valve disease, previous antibiotic treatment, renal insufficiency, surgical treatment, and the type of valve involved were not predictive of mortality. In contrast to all other major reports, Streptococcus viridans was the most common causative organism in intravenous drug users (52%).

CONCLUSIONS: Despite the introduction of new diagnostic tools, the course of infective endocarditis has remained unchanged over a period of 16 years. Evidence of early dissemination of the disease to other sites was associated with adverse outcome. Even in elderly patients, early aggressive treatment seems to be effective.

Mortality from infective endocarditis: clinical predictors of outcome.

Wallace SM, Walton BI, Kharbanda RK, Hardy R, Wilson AP, Swanton RH.

Department of Cardiology, The Middlesex Hospital, University College London Hospitals NHS Trust, London, UK.
Heart 2002 Jul;88(1):53-60 Abstract quote
OBJECTIVE: To identify clinical markers available within the first 48 hours of admission that are associated with poor outcome in infective endocarditis.

DESIGNS: Retrospective cohort study.

SETTING: Teaching hospital.

PATIENTS: 208 of 220 patients with infective endocarditis.

METHODS: Consecutive patients with infective endocarditis presenting between 1981 and 1999 to a tertiary centre were studied. Clinical, echocardiographic, and haematological data recorded within 48 hours of admission were obtained. Data were analysed using logistic regression models. Main outcomes measures: Mortality at discharge and at six months.

RESULTS: Data were obtained for 93% of patients who were eligible for inclusion. 194 (93%) were positive for Duke criteria. Mean age was 52 (1.2) years, and 138 (66%) were men. 82 (39%) were transferred from other hospitals. 181 (87%) were blood culture positive, and 47 (23%) infections were Staphylococcus aureus. The infection was located on aortic (n = 85, 41%), mitral (n = 77, 37%), tricuspid (n = 18, 9%), and multiple valves (n = 20, 10%). 67 (32%) had prosthetic valve endocarditis. 48% of the cohort were managed with antibiotics alone. Mortality at discharge was 18% and at six months 27%. Duration of illness before admission, age, sex, valve infected, infecting organism, and left ventricular function were not predictors of adverse mortality. However, abnormal white cell count, serum albumin concentration, serum creatinine concentration, or cardiac rhythm, the presence of two major Duke criteria, or visible vegetation conferred a poor prognosis.

CONCLUSIONS: Conventional prognostic factors in this study did not appear to predict outcome early during hospital admission. However, simple clinical indices, which are readily available, are reliable, cheap, and potentially powerful predictors of poor outcome.

Infective endocarditis: determinants of long term outcome.

Netzer RO, Altwegg SC, Zollinger E, Tauber M, Carrel T, Seiler C.

Swiss Cardiovascular Centre Bern, University Hospital, Bern, Switzerland Institute for Infectious Diseases, University Hospital, Bern, Switzerland.
Heart 2002 Jul;88(1):61-6 Abstract quote
OBJECTIVE: To evaluate predictors of long term prognosis in infective endocarditis.

DESIGN: Retrospective cohort study.

SETTING: Tertiary care centre.

PATIENTS: 212 consecutive patients with infective endocarditis between 1980 and 1995

MAIN OUTCOME MEASURES: Overall and cardiac mortality; event-free survival; and the following events: recurrence, need for late valve surgery, bleeding and embolic complications, cerebral dysfunction, congestive heart failure.

RESULTS: During a mean follow up period of 89 months (range 1-244 months), 56% of patients died. In 180 hospital survivors, overall and cardiac mortality amounted to 45% and 24%, respectively. By multivariate analysis, early surgical treatment, infection by streptococci, age < 55 years, absence of congestive heart failure, and > 6 symptoms or signs of endocarditis during active infection were predictive of improved overall long term survival. Independent determinants of event-free survival were infection by streptococci and age < 55 years. Event-free survival was 17% at the end of follow up both in medically-surgically treated patients and in medically treated patients.

CONCLUSIONS: Long term survival following infective endocarditis is 50% after 10 years and is predicted by early surgical treatment, age < 55 years, lack of congestive heart failure, and the initial presence of more symptoms of endocarditis.

Henry JB. Clinical Diagnosis and Management by Laboratory Methods. Twentieth Edition. WB Saunders. 2001.
Rosai J. Ackerman's Surgical Pathology. Eight Edition. Mosby 1996.
Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.
Robbins Pathologic Basis of Disease. Sixth Edition. WB Saunders 1999.

Commonly Used Terms

Heart

Internet Links

Last Updated 7/5/2002

Send mail to psdermpath@earthlink.net with questions or comments about this web site.
Copyright � 2002 The Doctor's Doctor

EPIDEMIOLOGY	CHARACTERIZATION
Infective endocarditis: an epidemiological review of 128 episodes. Dyson C, Barnes RA, Harrison GA. Department of Medical Microbiology, University Hospital of Wales, Health Park, Cardiff, UK.	J Infect 1999 Mar;38(2):87-93 Abstract quote OBJECTIVES: The objective was to determine the current epidemiology of infective endocarditis. PATIENTS AND METHODS: All microbiologically positive episodes of infective endocarditis treated at The University Hospital of Wales over a 9-year period from March 1987 to March 1996 was reviewed. Patients originated from the catchment area of The University Hospital of Wales or were referred from other hospitals in Wales. Data extraction was from records held in the Microbiology Department and, whenever possible, from patients' casenotes. The epidemiological parameters were: (1) age and sex of patients; (2) distribution of affected sites; (3) frequency of predisposing risk factors (cardiac and extracardiac); (4) incidence of early prosthetic valve endocarditis; and (5) mortality rates. RESULTS: There were 128 microbiologically positive episodes of endocarditis in 125 patients. The mean age of the population was 53.1 years and the aortic valve was the most frequently involved site of infection (51.6%). A presumed source of infection was identified in 20% if episodes. The commonest predisposing cardiac risk factor in native valve episodes was bicuspid aortic valve (16.7%) but there was no identifiable cardiac risk factor in a much larger proportion (37.7%) of native valve episodes. There was a low incidence (0.6%) of culture positive early prosthetic valve episodes and low mortality rates for both native and prosthetic valve endocarditis (12.3% and 24.5%) in this study. Viridans streptococci were the predominant organisms. In prosthetic valve episodes with onset after the 60th postoperative day but within one postoperative year the identity of the isolate suggested, in most cases, perioperative valve contamination. CONCLUSIONS: The epidemiology of infective endocarditis has undergone significant change. Inability to detect clinically common predisposing lesions, and the frequent absence of any identifiable predisposing cardiac risk factor mean that initial diagnosis is often difficult and demands a high index of suspicion. There was a low incidence of culture positive early prosthetic valve episodes and there were low mortality rates for both native and prosthetic valve endocarditis; these figures suggest improvements in cardiac care. The microbiological evidence indicates that the duration of the postoperative time period used for classifying prosthetic valve endocarditis into 'early' and 'late' episodes should be extended from 60 days to 1 year.
GEOGRAPHY
DENMARK
Native valve infective endocarditis in the general population: a 10-year survey of the clinical picture during the 1980s. Nissen H, Nielsen PF, Frederiksen M, Helleberg C, Nielsen JS. Cardiology Department, Odense University Hospital, Denmark.	Eur Heart J 1992 Jul;13(7):872-7 Abstract quote In a population of 930,000 inhabitants all records of native valve infective endocarditis diagnosed in the decade 1980-89 were reviewed. Using strict case definitions 132 clinically well-defined or post-mortem diagnosed cases were found. Included were cases referred to the local department of cardiology, as well as cases treated in non-specialized departments. Of 132 cases found 23 were only diagnosed post mortem. The male/female ratio was 71/61. The median prehospital duration of symptoms was 20 days (range 0-180 days) and the median in-hospital diagnostic delay was 5 days (range 0-54 days). Known cardiac disease was found in 42% of cases, a possible portal of entry was found in 33%, but in 36% there were no predisposing factors. Remarkably, only two patients had known rheumatic heart disease and none had a known dental focus. During the clinical course 55% experienced cardiac failure and 17% embolic episodes. In 19 patients surgery was required. Of 111 culture-positive cases streptococci were found in 61 and staphylococci in 45 cases. Echocardiography was performed in 95 cases with echocardiographic signs of endocarditis in 65 patients. Overall mortality was 33% with a mortality in clinically diagnosed cases of 18%. Of 14 cases needing immediate surgical intervention, two died.
NETHERLANDS
Epidemiology of bacterial endocarditis in The Netherlands. I. Patient characteristics. van der Meer JT, Thompson J, Valkenburg HA, Michel MF. Department of Clinical Microbiology, Erasmus University, Rotterdam, The Netherlands.	Arch Intern Med 1992 Sep;152(9):1863-8 Abstract quote BACKGROUND--Studies of the epidemiology of bacterial endocarditis are usually based on a retrospective review of medical records from referral centers serving diverse patient populations. These studies are therefore likely to suffer from selection bias. We conducted a nationwide prospective epidemiologic study of endocarditis in the Netherlands. METHODS--During a 2-year period, all cases of consecutively hospitalized patients with suspected endocarditis in the Netherlands were reported to us. While hospitalized, patients were visited for an in-person interview and a review of the medical record. RESULTS--Of 559 episodes, 438 met the criteria for endocarditis; these included 89 episodes of prosthetic valve endocarditis and 349 episodes of native valve endocarditis. Adjusted for age- and sex-specific population figures, the incidence was 19 per million person-years. The incidence increased significantly with age, and men were more often affected than women (266 and 172 cases, respectively). Rheumatic and congenital cardiac lesions formed most of the underlying heart diseases. Mitral valve prolapse was present in only 29 patients with native valve endocarditis (8.3%). A history of intravenous drug abuse was present in 32 patients (7.3%). Viridans streptococci, staphylococci, and enterococci together constituted 86% of the isolated bacterial strains. Only 1.1% of the patients had culture-negative endocarditis. Overall case fatality was 19.7% and varied widely according to causative microorganism. CONCLUSION--The distribution of causal microorganisms, the case fatality rate, and the incidence rate of endocarditis are age related. Therefore, a meaningful comparison of data is only possible between population-based cohorts of patients with endocarditis.
SWEEDEN
Epidemiologic aspects of infective endocarditis in an urban population. A 5-year prospective study. Hogevik H, Olaison L, Andersson R, Lindberg J, Alestig K. Department of Infectious Diseases, Goteborg University, Sweden.	Medicine (Baltimore) 1995 Nov;74(6):324-39 Abstract quote A prospective study of the epidemiology of infective endocarditis (IE) in a well-defined urban population of 428,000 inhabitants during a 5-year period was carried out. All patients were treated in the same institution, and history, diagnostic procedures, and treatment were standardized. Of 233 consecutive suspected episodes of IE, 127 fulfilled the modified von Reyn criteria. After patients not living in the defined area were excluded, 99 episodes in 90 patients were analyzed in the epidemiologic part of the study. Of these, 33 episodes were definite endocarditis, verified by surgery or autopsy; 35 probable; and 31 possible endocarditis episodes. Another 34 episodes were found retrospectively and are included in the incidence calculation. The crude incidence was calculated to be 6.2/100,000 inhabitants per year, which is high compared to earlier studies. Adjusted to the population of Sweden, the incidence was 5.9/100,000 inhabitants per year. The annual incidence was higher for women, 6.6/100,000, than for men, 5.8/100,000. In the oldest age-group (80-89 years) the annual incidence was 22/100,000 in the prospective study and 30/100,000 if retrospective cases were included. Contrary to almost all other studies, we did not find a male predominance among our cases. Only 7% of patients were intravenous drug abusers, and 15% had a prosthetic valve. The most common bacteria were methicillin-susceptible Staphylococcus aureus (31%) and alpha-streptococci (28%); 12% of episodes were culture negative. The mortality from IE in the population was 1.4/100,000 inhabitants per year. A higher-than-expected incidence of IE was found, especially among older patients and women.

LABORATORY/RADIOLOGIC/ OTHER TESTS	CHARACTERIZATION
RADIOLOGIC
Clinical outcome and echocardiographic findings of native and prosthetic valve endocarditis in the 1990's. Schulz R, Werner GS, Fuchs JB, Andreas S, Prange H, Ruschewski W, Kreuzer H. Department of Cardiology, Georg-August-University, Gottingen, Germany.	Eur Heart J 1996 Feb;17(2):281-8 Abstract quote Prosthetic valve endocarditis is considered to be associated with a more severe prognosis than native valve endocarditis. Among other factors, inappropriate visualization of vegetations in prosthetic valve endocarditis by transthoracic echocardiography is responsible for this observation. Since the introduction of transoesophageal echocardiography into clinical practice the diagnostic sensitivity and specificity of the detection of vegetations located on prosthetic valves have been enhanced. Therefore we aimed to determine and compare the prognosis of prosthetic valve endocarditis and native valve endocarditis in the era of this improved diagnostic approach. One hundred and six episodes of infective endocarditis in 104 patients were seen at our institution between 1989 and 1993. Eighty patients (77%) had native valve endocarditis and 24 (23%) had late prosthetic valve endocarditis. In the latter group two patients had recurrent infective endocarditis. Patients with prosthetic valve endocarditis were older (mean age 64 vs 54 years in native valve endocarditis; P < 0.001) and the majority was female (62% vs 38% in native valve endocarditis; P < 0.05). In prosthetic valve endocarditis, infection of a valve in the mitral position predominated (65% vs 30% in native valve endocarditis; P < 0.01), whereas in native valve endocarditis more than half the cases had isolated aortic valve endocarditis (51% vs 27% in prosthetic valve endocarditis; P < 0.01). In prosthetic valve endocarditis more cases were caused by Staphylococcus aureus (31% vs 14% in native valve endocarditis; P = 0.08), whereas in native valve endocarditis the most frequent organisms were streptococci (29% vs 19% in prosthetic valve endocarditis; P = 0.12). Differences in the clinical features of native valve endocarditis and prosthetic valve endocarditis could not be found except for a higher rate of embolism in native valve endocarditis (40% vs 19% in prosthetic valve endocarditis; P < 0.05). Vegetations could be detected by transthoracic echocardiography more frequently in native valve endocarditis (71% vs 15% in prosthetic valve endocarditis; P < 0.0001). Transoesophageal echocardiography visualized vegetations in 95% of the episodes of native valve endocarditis and in 80% of the episodes of prosthetic valve endocarditis (P = 0.09). Thus, the diagnostic gain by transoesophageal echocardiography was greatest in prosthetic valve endocarditis. Patients with native valve endocarditis had significantly larger vegetations than patients with prosthetic valve endocarditis (P < 0.05 for length, P < 0.001 for width). The median time to diagnosis was similar in native valve endocarditis and prosthetic valve endocarditis (31 vs 28 days). Surgery was performed in 74% of patients with native valve endocarditis and in 58% of those with prosthetic valve endocarditis; the median time delay between the diagnosis of infective endocarditis and surgery tended to be shorter in prosthetic valve endocarditis than in native valve endocarditis (45 vs 60 days). The in-hospital mortality and the mortality during a follow-up of 22 +/- 10 months did not significantly differ between native valve endocarditis and prosthetic valve endocarditis (21% vs 17%; 28% vs 25%). In summary in the era of transoesophageal echocardiography, late prosthetic valve endocarditis does not seem to carry a worse prognosis than native valve endocarditis. This can be attributed in part to the improved diagnostic accuracy achieved by transoesophageal echocardiography leading to comparable diagnostic latency periods in both patient groups. Finally, better characterization of vegetations on prosthetic valves by transoesophageal echocardiography allows early lifesaving surgery in patients with prosthetic valve endocarditis.
LABORATORY MARKERS
BLOOD CULTURES
Are blood and valve cultures predictive for long-term outcome following surgery for infective endocarditis? Renzulli A, Carozza A, Marra C, Romano GP, Ismeno G, De Feo M, Della Corte A, Cotrufo M. Institute of Cardiac Surgery, Second University of Naples, V. Monaldi Hospital, Via L. Bianchi, Naples, Italy.	Eur J Cardiothorac Surg 2000 Mar;17(3):228-33 Abstract quote OBJECTIVE: To evaluate whether perioperative bacteria identification in blood and/or in valve cultures can predict early and late outcome of surgery for infective endocarditis, a retrospective study was performed. METHODS: Between January 1978 and December 1998, 232 patients, 79 (34.1%) female and 153 (65.9%) male with mean age of 44. 95+/-1.03 years (range 8-79) underwent surgery for infective endocarditis on a native (162 cases) or prosthetic (70 cases) valve. Patients were divided into three groups according to the perioperative x of microbiological tests: Group A: patients with preoperative positive blood cultures (83 cases); Group B: patients with positive valve cultures (35 cases); Group C: patients with negative blood and valve cultures (114 cases). Categorical values were compared by chi(2) analysis, whereas continuous data were compared by ANOVA and Bonferroni correction for post hoc comparisons. Analysis of late survival and complications was performed with Kaplan-Meier and Log Rank test. Late mortality, reoperation, perivalvular leak, recurrence of infection were considered as treatment failure. All data were presented as mean+/-standard error. RESULTS: Hospital mortality was 10.8% (9/83) in Group A, 8.6% (3/35) in Group B, and 14.9% (17/114) in Group C (P=0.52; not significant (NS)). Ten-year survival was 62.7+/-8% in Group A, 43.9+/-19% in Group B and 62.7+/-7% in Group C (P=0.38; NS). Ten-year freedom from reoperation was 85.2+/-6% in Group A, 37.9+/-20% in Group B and 80+/-6% in Group C (P=0.0034). Ten-year freedom from treatment failure was 56.3+/-8% in Group A, 31.6+/-16% in Group B and 55. 3+/-7% in Group C (P=0.46; NS). CONCLUSIONS: Positive blood and tissue cultures are not predictive for hospital mortality and late treatment failure in patients with infective endocarditis. Positive valve cultures, a common finding in patients with staphylococcal endocarditis, are predictive for a higher risk of reoperation.
BLOOD CULTURE NEGATIVE
Infective endocarditis in patients with negative blood cultures: analysis of 88 cases from a one-year nationwide survey in France. Hoen B, Selton-Suty C, Lacassin F, Etienne J, Briancon S, Leport C, Canton P. Department of Infectious and Tropical Diseases, Centre Hospitalier Universitaire de Nancy, France.	Clin Infect Dis 1995 Mar;20(3):501-6 Abstract quote Blood cultures were negative in 88 (14%) of 620 cases of infective endocarditis (IE) documented in France during a 1-year nationwide survey. In 15 of these 88 cases, the causative microorganism was identified: seven cases of Q fever endocarditis and two cases of chlamydial endocarditis were diagnosed by serological and/or immunohistologic techniques, and a pathogen was cultured from five surgically removed valves and one arterial septic embolus. Forty-two (48%) of the 88 cases involved patients who had received antibiotics before the first blood sample was taken for culture. Mortality was lower in this group than among patients who had not previously received antibiotics (7% vs. 22%, P = .05). Comparison of blood culture-negative cases of IE with blood culture-positive cases revealed that the former tended to occur more often on prosthetic valves (32% vs. 22%, P = .16), were more often left-sided (97% vs. 83%, P = .0009), less often included extracardiac symptoms at presentation (52% vs. 63%, P = .06), and were more often surgically treated (53% vs. 34%, P = .001). Mortality was similar regardless of the results of blood culture (15% vs. 21%, P = .18). This study showed that more than 10% of all cases of IE in France are still associated with negative blood cultures and confirmed that a search for pathogens such as Coxiella burnetii and Chlamydia species is worthwhile in this situation.

GROSS APPEARANCE/ CLINICAL VARIANTS	CHARACTERIZATION
GENERAL
VARIANTS
ELDERLY
Clinical and bacteriological characteristics of infective endocarditis in the elderly. Selton-Suty C, Hoen B, Grentzinger A, Houplon P, Maignan M, Juilliere Y, Danchin N, Canton P, Cherrier F. Department of Cardiology, CHU Brabois, Nancy, France.	Heart 1997 Mar;77(3):260-3 Abstract quote OBJECTIVE: To determine the clinical and bacteriological features of infective endocarditis in the elderly. DESIGN: Prospective case series. SETTING: A university hospital that is both a referral and a primary care centre. PATIENTS: 114 consecutive patients treated for infective endocarditis from November 1990 to December 1993: 25 were > 70 years of age (group 1) and 89 were < 70 years old (group 2). RESULTS: Location of infective endocarditis, clinical signs, and symptoms were similar in the two groups, except for a lower occurrence of embolic episodes in the elderly (group 1:8%, group 2: 28%; P < 0.04). A higher rate of infective endocarditis on intracardiac prosthetic devices was noted in group 1 (group 1: 52%, group 2: 25%; P < 0.05). The distribution of causative micro-organisms showed a higher proportion of bacteria from the gastrointestinal tract in the elderly (group D streptococci and enterococci: 48% in group 1 v 20% in group 2) and the presumed portal of entry was more often digestive (group 1: 50%, group 2: 17%; P = 0.01). Elderly patients were less often operated on (group 1: 24%, group 2: 43%; P = 0.07) and their mortality rate was higher (group 1: 28%, group 2: 13%; P = 0.08). CONCLUSIONS: Infective endocarditis in patients over 70 often occurs in those with intracardiac prosthetic devices and is more often due to bacteria from the gastrointestinal tract. Its prognosis appears to be worse than in younger subjects.
INFECTIVE
Changing profile of infective endocarditis: results of a 1-year survey in france. Hoen B, Alla F, Selton-Suty C, Beguinot I, Bouvet A, Briancon S, Casalta JP, Danchin N, Delahaye F, Etienne J, Le Moing V, Leport C, Mainardi JL, Ruimy R, Vandenesch F. Service de Maladies Infectieuses et Tropicales, University of Besancon Medical Center, F-25030 Besancon Cedex, France.	JAMA 2002 Jul 3;288(1):75-81 Abstract quote CONTEXT: Since the first modern clinical description of infective endocarditis (IE) at the end of the 19th century, the profile of the disease has evolved continuously, as highlighted in epidemiological studies including a French survey performed in 1991. OBJECTIVE: To update information gained from the 1991 study on the epidemiology of IE in France. DESIGN AND SETTING: Population-based survey conducted from January through December 1999 in all hospitals in 6 French regions representing 26% of the population (16 million inhabitants). PATIENTS: Three hundred ninety adult inpatients diagnosed with IE according to Duke criteria. MAIN OUTCOME MEASURES: Incidence of IE; proportion of patients with underlying heart disease; clinical characteristics; causative microorganisms; surgical and mortality outcomes. RESULTS: The annual age- and sex-standardized incidence was 31 (95% confidence interval [CI], 28-35) cases per million, not including the region of New Caledonia, which had 161 (95% CI, 117-216) cases per million. There was no previously known heart disease in 47% of the cases. The proportion of prosthetic-valve IE was 16%. Causative microorganisms were: streptococci, 48% (group D streptococci, 25%; oral streptococci, 17%, pyogenic streptococci, 6%); enterococci, 8%; Abiotrophia species, 2%; staphylococci, 29%; and other or multiple pathogens, 8%. Blood cultures were negative in 9% and no microorganism was identified in 5% of the cases. Early valve surgery was performed in 49% of the patients. In-hospital mortality was 16%. Compared with 1991, this study showed a decreased incidence of IE in patients with previously known underlying heart disease (20.6 cases per million vs 15.1 cases per million; P<.001); a smaller incidence of oral streptococcal IE (7.8 cases per million vs 5.1 cases per million; P<.001), compensated by a larger proportion of IE due to group D streptococci (5.3 cases per million vs 6.2 cases per million; P =.67) and staphylococci (4.9 cases per million vs 5.7 cases per million; P =.97); an increased rate of early valve surgery (31.2% vs 49.7%; P<.001); and a decreased in-hospital mortality rate (21.6% vs 16.6%; P =.08). CONCLUSION: Although the incidence of IE has not changed, important changes in disease characteristics, treatment, and outcomes were noted.
PEDIATRIC
Infective endocarditis in children--incidence, pattern, diagnosis and management in a developing country. Sadiq M, Nazir M, Sheikh SA. Department of Paediatric Cardiology, Punjab Institute of Cardiology, Lahore, Pakistan.	Int J Cardiol 2001 Apr;78(2):175-82 Abstract quote BACKGROUND: In developing countries, patients with infective endocarditis are referred late, there is low yield of blood cultures and incidence of rheumatic heart disease is still high. Objective: Evaluate clinical pattern, assess diagnostic criteria in our settings and determine outcome. Setting: A tertiary referral center for paediatric and adult cardiology. PATIENTS AND METHODS: All children with infective endocarditis admitted to a single center from April 1997 to March 2000 were analysed. The diagnosis was based on Duke's criteria, which proposed two major and six minor criteria. Minor criteria were expanded to include raised acute phase reactants and presence of newly diagnosed or increasing splenomegally. The patients were stratified as definite, possible and rejected cases. RESULTS: Of 1402 hospital admissions, 45 patients fulfilled the diagnostic criteria for infective endocarditis giving an incidence of 32 per 1000 hospital admissions. The mean age was 7.9 +/- 4 years (4 months to 16 years) with only two patients under 1 year of age. Rheumatic heart disease was the underlying lesion in 24 patients (53%) while congenital heart lesions occurred in 20 patients (45%). Previous antibiotic treatment was given in 26 patients (58%) definitely. Blood cultures were positive in 21 patients (47%); Streptococcus Viridans being the most common organism, while vegetations on echocardiography were present in 32 patients (71%). Surgery was undertaken in four patients and five patients left against medical advise. Of 10 patients with aortic valve involvement, there were three deaths (30%) and overall mortality was 13% (six patients). CONCLUSIONS: The incidence of infective endocarditis is 32 per 1000 (3.2%) hospital admissions in a tertiary paediatric cardiology referral center. Rheumatic heart disease is still the most common underlying heart lesion. Blood cultures are positive in less than 50% of cases and echocardiography in expert hands is a more sensitive tool in our set up. Mortality is still high and aortic valve involvement in particular, carried poor prognosis.
Changing Risk Factors for Pediatric Infective Endocarditis. Fisher MC. Department of Pediatrics, Monmouth Medical Center, 300 Second Avenue, Long Branch, NJ 07740, USA.	Curr Infect Dis Rep 2001 Aug;3(4):333-336 Abstract quote Infective endocarditis in children is an uncommon infection. Three major groups of children are at risk: 1) those with underlying congenital heart disease, 2) those with central vascular catheters, and 3) children infected with certain virulent organisms. Although the overall incidence of infective endocarditis has increased, the population of children involved has changed. Children with corrected congenital heart disease are at risk during the early postoperative period. Children in whom vascular shunts or grafts are employed remain at the highest risk for endocarditis. Use of central vascular catheters increases risk in children with underlying heart disease and those with normal hearts. Finally, certain pathogens attack the heart valves and cause high morbidity and mortality.

Epidemiology
Disease Associations
Pathogenesis
Laboratory/Radiologic/Other Diagnostic Testing
Gross Appearance and Clinical Variants
Prognosis and Treatment
Commonly Used Terms
Internet Links

DISEASE ASSOCIATIONS	CHARACTERIZATION
BICUSPID AORTIC VALVE
Bicuspid aortic valve--A silent danger: analysis of 50 cases of infective endocarditis. Lamas CC, Eykyn SJ. St. Thomas' Hospital, London, SE1 7EH, London, United Kingdom.	Clin Infect Dis 2000 Feb;30(2):336-41 Abstract quote We analyzed 50 cases of bicuspid aortic valve endocarditis in patients who presented to St. Thomas' Hospital from 1970 through 1998. These represented 12.3% of the 408 cases of native valve endocarditis (NVE). All patients were male, and their mean age was 39 years. Forty-five of the 50 cases were pathologically proven; 47 were clinically definite according to the Duke criteria and 49 according to our modifications of the Duke criteria. Viridans streptococci and staphylococci accounted for 72% of cases. The prevalences of clinical features were similar to those seen in NVE: fever (temperature >/=38 degrees C, 74%) and malaise (70%), although dyspnea was more frequent (36%). There was a high incidence of serious complications (72% heart failure; 30% periannular abscesses). Surgery was required during the initial admission in 82% of cases. Overall mortality was 14%, and surgical mortality was 9%. Few patients knew they had a "heart condition," and a bicuspid aortic valve was detected in only 35% of echocardiograms performed before surgery.
INTRAVENOUS DRUG ABUSE
Clinical features, site of involvement, bacteriologic findings, and outcome of infective endocarditis in intravenous drug users. Mathew J, Addai T, Anand A, Morrobel A, Maheshwari P, Freels S. Department of Medicine, Cook County Hospital, Chicago, IL, USA.	Arch Intern Med 1995 Aug 7-21;155(15):1641-8 Abstract quote BACKGROUND: Intravenous drug use is an increasingly common condition predisposing to infective endocarditis. Data on infective endocarditis in intravenous drug users are limited. OBJECTIVE: To determine the clinical features, bacteriologic findings, site of involvement, complications, and mortality associated with infective endocarditis in intravenous drug users. METHODS: Cohort study of intravenous drug users with native valve infective endocarditis. RESULTS: A total of 125 cases of infective endocarditis occurred in 114 patients (84 cases [67%] in men and 41 cases [32%] in women) with a mean (+/- SD) age of 37 +/- 7 years. The tricuspid valve was involved in 58 cases (46%), the mitral valve in 40 cases (32%), and the aortic valve in 24 cases (19%). The microorganisms identified included Staphylococcus in 82 cases (65.6%) and Streptococcus in 32 cases (25.6%). Twenty-three patients (18%) underwent surgery, and two (9%) of them died. One hundred two patients (82%) were treated medically, and nine (9%) of them died. Fifteen patients (63%) with aortic valve involvement vs 17 patients (17%) without aortic valve involvement underwent surgery or died without surgery (odds ratio, 8.24; 95% confidence interval, 3.1 to 21.8). Among the survivors, at least one major cardiovascular complication occurred in 79 cases (69.3%). CONCLUSIONS: Infective endocarditis in intravenous drug users affects the right and left sides of the heart with approximately equal frequency. At present, more than 90% of cases of infective endocarditis in intravenous drug users in Chicago are caused by staphylococci or streptococci. Involvement of the aortic valve is predictive of increased morbidity and mortality in intravenous drug users with infective endocarditis. With medical treatment, and surgery when medical treatment fails, intravenous drug users with infective endocarditis have an in-hospital survival rate of 91%