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

Compared Performance of the 2023 Duke-International Society for Cardiovascular Infectious Diseases, 2000 Modified Duke, and 2015 European Society of Cardiology Criteria for the Diagnosis of Infective Endocarditis in a French Multicenter Prospective Cohort

BACKGROUND

The 2023 Duke-International Society for Cardiovascular Diseases (ISCVID) criteria for infective endocarditis (IE) were proposed as an updated diagnostic classification of IE. Using an open prospective multicenter cohort of patients treated for IE, we compared the performance of these new criteria to that of the 2000 Modified Duke and 2015 European Society of Cardiology (ESC) criteria.

METHODS

Cases of patients treated for IE between January 2017 and October 2022 were adjudicated as certain IE or not. Each case was also categorized as either definite or possible/rejected within each classification. Sensitivity, specificity, and accuracy were estimated with 95% confidence intervals.

RESULTS

Of the 1194 patients analyzed (mean age, 66.1 years; 71.2% males), 414 (34.7%) had a prosthetic valve and 284 (23.8%) had a cardiac implanted electronic device (CIED); 946 (79.2%) were adjudicated as certain IE; 978 (81.9%), 997 (83.5%), and 1057 (88.5%) were classified as definite IE in the 2000 modified Duke, 2015 ESC, and 2023 Duke-ISCVID criteria, respectively. The sensitivity of each set of criteria was 93.2% (95% confidence interval [CI], 91.6-94.8), 95.0% (95% CI, 93.7-96.4), and 97.6% (95% CI, 96.6-98.6), respectively (P < .001 for all 2-by-2 comparisons). Corresponding specificity rates were 61.3% (95% CI, 55.2-67.4), 60.5% (95% CI, 54.4-66.6), and 46.0% (95% CI, 39.8-52.2), respectively. In patients without CIED, sensitivity rates were 94.8% (95% CI, 93.2-96.4), 96.5% (95% CI, 95.1-97.8), and 97.7% (95% CI, 96.6-98.8); specificity rates were 59.0% (95% CI, 51.6-66.3), 56.6% (95% CI, 49.3-64.0), and 53.8% (95% CI, 46.3-61.2), respectively.

CONCLUSIONS

Overall, the 2023 Duke-ISCVID criteria had a significantly higher sensitivity but a significantly lower specificity compared with older criteria. This decreased specificity was mainly attributable to patients with CIED.

External Validation of the 2023 Duke-International Society for Cardiovascular Infectious Diseases Diagnostic Criteria for Infective Endocarditis

BACKGROUND

The 2023 Duke-International Society of Cardiovascular Infectious Diseases (ISCVID) criteria for infective endocarditis (IE) were introduced to improve classification of IE for research and clinical purposes. External validation studies are required.

METHODS

We studied consecutive patients with suspected IE referred to the IE team of Amsterdam University Medical Center (from October 2016 to March 2021). An international expert panel independently reviewed case summaries and assigned a final diagnosis of "IE" or "not IE," which served as the reference standard, to which the "definite" Duke-ISCVID classifications were compared. We also evaluated accuracy when excluding cardiac surgical and pathologic data ("clinical" criteria). Finally, we compared the 2023 Duke-ISCVID with the 2000 modified Duke criteria and the 2015 and 2023 European Society of Cardiology (ESC) criteria.

RESULTS

A total of 595 consecutive patients with suspected IE were included: 399 (67%) were adjudicated as having IE; 111 (19%) had prosthetic valve IE, and 48 (8%) had a cardiac implantable electronic device IE. The 2023 Duke-ISCVID criteria were more sensitive than either the modified Duke or 2015 ESC criteria (84.2% vs 74.9% and 80%, respectively; P < .001) without significant loss of specificity. The 2023 Duke-ISCVID criteria were similarly sensitive but more specific than the 2023 ESC criteria (94% vs 82%; P < .001). The same pattern was seen for the clinical criteria (excluding surgical/pathologic results). New modifications in the 2023 Duke-ISCVID criteria related to "major microbiological" and "imaging" criteria had the most impact.

CONCLUSIONS

The 2023 Duke-ISCVID criteria represent a significant advance in the diagnostic classification of patients with suspected IE.

Candida endocarditis: Update on management considerations

The rise in incidence rates of invasive candidiasis warrants an increase in attention and efforts toward preventing and treating this virulent infection. Cardiac involvement is one of the most feared sequelae and has a poor prognosis. Despite the introduction of several novel antifungal agents over the past quarter century, complications and mortality rates due to Candida endocarditis have remained high. Although fungal endocarditis has a mechanism similar to bacterial endocarditis, no specific diagnostic criteria or algorithm exists to help guide its management. Furthermore, recent data has questioned the current guidelines recommending a combined approach of antifungal agents with surgical valve or indwelling prostheses removal. With the emergence of multidrug-resistant Candida auris, a focus on improved prophylactic measures and management strategies is necessary.

A New Clinical Prediction Rule for Infective Endocarditis in Emergency Department Patients With Fever: Definition and First Validation of the CREED Score

Background Infective endocarditis (IE) could be suspected in any febrile patients admitted to the emergency department (ED). This study was aimed at assessing clinical criteria predictive of IE and identifying and prospectively validating a sensible and easy-to-use clinical prediction score for the diagnosis of IE in the ED. Methods and Results We conducted a retrospective observational study, enrolling consecutive patients with fever admitted to the ED between January 2015 and December 2019 and subsequently hospitalized. Several clinical and anamnestic standardized variables were collected and evaluated for the association with IE diagnosis. We derived a multivariate prediction model by logistic regression analysis. The identified predictors were assigned a score point value to obtain the Clinical Rule for Infective Endocarditis in the Emergency Department (CREED) score. To validate the CREED score we conducted a prospective observational study between January 2020 and December 2021, enrolling consecutive febrile patients hospitalized after the ED visit, and evaluating the association between the CREED score values and the IE diagnosis. A total of 15 689 patients (median age, 71 [56-81] years; 54.1% men) were enrolled in the retrospective cohort, and IE was diagnosed in 267 (1.7%). The CREED score included 12 variables: male sex, anemia, dialysis, pacemaker, recent hospitalization, recent stroke, chest pain, specific infective diagnosis, valvular heart disease, valvular prosthesis, previous endocarditis, and clinical signs of suspect endocarditis. The CREED score identified 4 risk groups for IE diagnosis, with an area under the receiver operating characteristic curve of 0.874 (0.849-0.899). The prospective cohort included 13 163 patients, with 130 (1.0%) IE diagnoses. The CREED score had an area under the receiver operating characteristic curve of 0.881 (0.848-0.913) in the validation cohort, not significantly different from the one calculated in the retrospective cohort (P=0.578). Conclusions In this study, we propose and prospectively validate the CREED score, a clinical prediction rule for the diagnosis of IE in patients with fever admitted to the ED. Our data reflect the difficulty of creating a meaningful tool able to identify patients with IE among this general and heterogeneous population because of the complexity of the disease and its low prevalence in the ED setting.

Diagnostic accuracy of splinter haemorrhages in patients referred for suspected infective endocarditis

OBJECTIVE

Splinter haemorrhages are an examination finding that has classically been associated with infective endocarditis (IE), but are not included in current diagnostic algorithms. Splinter haemorrhages have not been evaluated as a diagnostic tool using modern definitions of IE. We determined their sensitivity and specificity in patients with suspected IE and investigated their inclusion in the Duke criteria.

METHODS

This is a retrospective diagnostic accuracy study using data from 1119 patients with suspected IE referred to the IE service. Patients were categorised according to the Duke criteria, the current diagnostic gold standard, into Duke 'rejected', 'possible' or 'definite' groups. Definite cases (n=451) served as the true positives and rejected cases (n=486) as the true negatives against which splinter haemorrhages were compared. Duke possible cases (n=182) were used the assess the clinical impact of adding splinter haemorrhages to the Duke criteria.

RESULTS

In clinically suspected cases of IE and using the Duke criteria as the gold standard comparator, splinter haemorrhages had a sensitivity of 26% (95% CI 22 to 31) (119 out of 451) and a specificity of 83% (95% CI 79 to 86) (403 out of 486). Inclusion of splinter haemorrhages as a minor vascular phenomenon in the Duke criteria would result in a reclassification of 12% of cases from Duke rejected to possible and 13% from Duke possible to definite.

CONCLUSION

Splinter haemorrhages are an insensitive tool in the diagnosis of IE, but their high specificity indicates they do have clinical value in patients with suspected infection. Their inclusion in the Duke criteria as a minor vascular criterion reduces diagnostic uncertainty for some Duke possible cases, while increasing it for a similar proportion of Duke rejected cases.

STratification risk analysis in OPerative management (STOP score) for drug-induced endocarditis

BACKGROUND

The opioid epidemic has seen a drastic increase in the incidence of drug-associated infective endocarditis (IE). No clinical tool exists to predict operative morbidity and mortality in patients undergoing surgery.

METHODS

A multi-institutional database was reviewed between 2011 and 2018. Multivariate logistic regression was fitted in an automated stepwise fashion. The STratification risk analysis in OPerative management of drug-associated IE (STOP) score was constructed. Morbidity was defined as reintubation, prolonged ventilation, pneumonia, renal failure, dialysis, stroke, reoperation for bleeding, and a permanent pacemaker. Cross-validation provided an unbiased estimate of out-of-sample performance.

RESULTS

A total of 1181 patients underwent surgery for drug-associated IE (median age, 39; interquartile range [IQR], 30-54, 386 women [32.7%], 341 reoperations for prosthetic valve endocarditis [28.9%], 316 patients with multivalve disease [26.8%]). Operative morbidity and mortality were 41.1% and 5.9%, respectively. Predictors of morbidity were dialysis (95% confidence interval [CI], 1.16-2.82), emergent intervention (1.83-4.73), multivalve procedure (1.01-1.98), causative organisms other than Streptococcus (1.09-2.02), and type of valve procedure performed [aortic valve procedure (1.07-2.15), mitral valve replacement (1.03-2.05), tricuspid valve replacement (1.21-2.60)]. Predictors of mortality were dialysis (1.29-5.74), active endocarditis (1.32-83), lung disease (1.25-5.43), emergent intervention (1.69-6.60), prosthetic valve endocarditis (1.24-3.69), aortic valve procedure (1.49-5.92) and multivalve disease (1.00-2.95). Variables maximizing explanatory power were translated into a scoring system. Each point increased odds of morbidity and mortality by 22.0% and 22.4% with an accuracy of 94.0% and 94.1%, respectively.

CONCLUSION

Drug-related IE is associated with significant morbidity and mortality. An easily-applied risk stratification score may aid in clinical decision-making.

Differentiating Takotsubo cardiomyopathy from ST-segment elevation myocardial infarction

Background:

Takotsubo cardiomyopathy affects between 1.7% and 2.2% of patients hospitalized with suspected acute coronary syndromes. Characterized by chest pain, electrocardiogram changes, and transient left ventricular apical wall motion abnormality, it is under-recognized and often misdiagnosed.

Objectives:

In order to better differentiate between St-segment myocardial infarction and Takotsubo cardiomyopathy, we developed a scoring system.

Methods:

Of the 82 patients enrolled with Takotsubo cardiomyopathy, 67 had ST-segment elevation on electrocardiogram and were compared with 79 ST-elevation myocardial infarction patients. A multi-variant logistic regression model was used to find factors independently associated with Takotsubo cardiomyopathy. The Platelets and Thrombosis in Sheba (PLATIS)-Takotsubo cardiomyopathy is based on a 10-point scoring system: stressful events (3), females (2), no history of diabetes mellitus (2), estimated left ventricular ejection fraction ≤ 40% on admission echo (1), positive troponin on admission (1), and no smoking (1). Patients with Takotsubo cardiomyopathy were older (66 ± 11 vs 60 ± 11 years, p < 0.001), predominantly female (90% vs 15%, p < 0.001), with a lower incidence of diabetes mellitus, dyslipidemia, and smoking. Nevertheless, in-hospital mortality was similar in both groups.

Results:

In a multivariate logistic regression analysis, the average Platelets and Thrombosis in Sheba-Takotsubo cardiomyopathy scoring was significantly higher in Takotsubo cardiomyopathy compared with ST-elevation myocardial infarction patients (8.35 ± 1.7 vs 3.42 ± 1.6, p < 0.001). With an overall score of ≥7, the receiver-operating characteristic curve was 0.82 with a sensitivity of 75% and a specificity of 89% (positive predictive value = 85% and negative predictive value = 80%).

Conclusion:

The Takotsubo cardiomyopathy scoring system is a simple, reliable tool that can assist in diagnosing and differentiating between patients with Takotsubo cardiomyopathy and those with ST-elevation myocardial infarction.

Infective endocarditis

Infective endocarditis (IE) is a rare, life-threatening disease that has long-lasting effects even among patients who survive and are cured. IE disproportionately affects those with underlying structural heart disease and is increasingly associated with health care contact, particularly in patients who have intravascular prosthetic material. In the setting of bacteraemia with a pathogenic organism, an infected vegetation may form as the end result of complex interactions between invading microorganisms and the host immune system. Once established, IE can involve almost any organ system in the body. The diagnosis of IE may be difficult to establish and a strategy that combines clinical, microbiological and echocardiography results has been codified in the modified Duke criteria. In cases of blood culture-negative IE, the diagnosis may be especially challenging, and novel microbiological and imaging techniques have been developed to establish its presence. Once diagnosed, IE is best managed by a multidisciplinary team with expertise in infectious diseases, cardiology and cardiac surgery. Antibiotic prophylaxis for the prevention of IE remains controversial. Efforts to develop a vaccine that targets common bacterial causes of IE are ongoing, but have not yet yielded a commercially available product.

Mitral Valve Perforation in Libman-Sacks Endocarditis: A Heart-Wrenching Case of Lupus

Libman-Sacks (LS) endocarditis is one of the most common cardiac manifestations of systemic lupus erythematosus. Rarely, however, it can lead to serious complications, including severe valvular regurgitation or superimposed bacterial endocarditis. We describe the initial diagnostic challenges, clinical course, imaging studies and histopathological findings of a patient who presented with life-threatening lupus complicated by hemoptysis and respiratory failure secondary to a rare complication of LS endocarditis, acute mitral valve perforation. We review the current literature on valve perforation in the setting of LS endocarditis. In conclusion, although the disease is often asymptomatic and hemodynamically insignificant, it can result in serious and potentially fatal complications secondary to valve perforation, which may demand emergency surgical management.

Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications: A Scientific Statement for Healthcare Professionals From the American Heart Association

BACKGROUND

Infective endocarditis is a potentially lethal disease that has undergone major changes in both host and pathogen. The epidemiology of infective endocarditis has become more complex with today's myriad healthcare-associated factors that predispose to infection. Moreover, changes in pathogen prevalence, in particular a more common staphylococcal origin, have affected outcomes, which have not improved despite medical and surgical advances.

METHODS AND RESULTS

This statement updates the 2005 iteration, both of which were developed by the American Heart Association under the auspices of the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease, Council on Cardiovascular Disease of the Young. It includes an evidence-based system for diagnostic and treatment recommendations used by the American College of Cardiology and the American Heart Association for treatment recommendations.

CONCLUSIONS

Infective endocarditis is a complex disease, and patients with this disease generally require management by a team of physicians and allied health providers with a variety of areas of expertise. The recommendations provided in this document are intended to assist in the management of this uncommon but potentially deadly infection. The clinical variability and complexity in infective endocarditis, however, dictate that these recommendations be used to support and not supplant decisions in individual patient management.

Role of echocardiogram in decision making for surgery in endocarditis

Infective endocarditis is a serious disease that carries significant morbidity and mortality. Adequate treatment is based on a high degree of clinical suspicion, accurate microbiologic diagnosis, and high-quality imaging. Echocardiography has been shown to be a fundamental tool for diagnosis and management. Currently accepted Duke criteria include blood cultures and echocardiography. Transthoracic and transesophageal echocardiography play a critical role in the decision-making process, especially when surgical treatment is contemplated. Because infective endocarditis is considered a medical and surgical disease, and considering that the current rate of surgery is about 50%, echocardiography has definite value in preoperative diagnosis and surgical planning, intraoperative confirmation of lesions and quality of repair or replacement before and after cardiopulmonary bypass, and postoperative assessment.

The changing face of prosthetic valve endocarditis at a tertiary-care hospital: 1986-2005

INTRODUCTION AND OBJECTIVES

To investigate changes in the clinical characteristics, etiology and prognosis of prosthetic valve endocarditis at a tertiary-care hospital.

METHODS

Retrospective cohort study of all patients diagnosed with prosthetic valve endocarditis using modified Duke criteria between 1986 and 2005. The analysis covered two time periods: January 1986 to December 1995 (P1) and January 1996 to December 2005 (P2).

RESULTS

In total, 133 episodes of endocarditis occurred in 122 patients. Of these, 73 (54.9%) were diagnosed in P1 and 60 (45.1%) in P2, with incidences of 2.19% and 2.18%, respectively. The patients' mean age (SD) was 52.6+/-16.6 years in P1 and 66.2+/-11.5 years in P2 (P=.0001). Clinical characteristics were similar in the two study periods. The increase in Enterococcus infection was remarkable (12.5% in P2 vs. 4.9% in P1; relative risk [RR]=2.5; 95% confidence interval [CI], 0.7-9.6), as was the decrease in viridans group Streptococcus infection (12.5% in P2 vs. 31.1% in P1; RR=0.4; 95% CI, 0.2-0.9). Some 90.4% of patients (63/73) underwent surgery in P1, while 68.3% (41/60) underwent surgery in P2. The difference was significant (RR=0.8; 95% CI, 0.6-0.9). The in-hospital mortality rate was 28.8% in P1 and 30% in P2 (RR=1; 95% CI, 0.6-1.7).

CONCLUSIONS

Changes in the epidemiology and microbiological etiology of prosthetic valve endocarditis were observed over the 20-year study period. Diagnostic and therapeutic approaches also changed, but mortality remained high.

Acute infective endocarditis

Acute infective endocarditis is a complex disease with changing epidemiology and a rapidly evolving knowledge base. To consistently achieve optimal outcomes in the management of infective endocarditis, the clinical team must have an understanding of the epidemiology, microbiology, and natural history of infective endocarditis, as well as a grasp of guiding principles of diagnosis and medical and surgical management. The focus of this review is acute infective endocarditis, though many studies of diagnosis and treatment do not differentiate between acute and subacute disease, and indeed many principles of diagnosis and management of infective endocarditis for acute and subacute disease are identical.

Infective endocarditis in drug addicts: role of HIV infection and the diagnostic accuracy of Duke criteria

BACKGROUND

Intravenous drug users (IVDUs) are at increased risk of infective endocarditis. Moreover, HIV infection is common in IVDUs, with a reported prevalence of 40-90%. The clinical features of IVDUs with infective endocarditis and HIV infection may be peculiar. Few data have been reported on the diagnostic accuracy of Duke criteria in IVDUs with or without HIV infection, and a comparison of these two populations is lacking.

METHODS

The present study aimed to compare prospectively the clinical features of patients with infective endocarditis with or without HIV infection and to evaluate the diagnostic accuracy of Duke criteria in these patients. The study population consisted of 201 consecutive adult IVDUs with a suspected infective endocarditis (102 patients with HIV infection and 99 patients without HIV infection).

RESULTS

Infective endocarditis was the final diagnosis in 40 of 102 patients (38.2%) with HIV infection and in 55 of 99 HIV-negative patients (55.6%). Despite similar baseline features, longer vegetations were recorded in infective endocarditis without HIV infection (23.7 +/- 7.1 mm versus 13.6 +/- 6.8 mm; P = 0.001). Patients with infective endocarditis and HIV infection had a higher total mortality at 2 months (respectively 12.5% versus 1.8%; P = 0.09); almost all the deaths were recorded in patients with AIDS or a CD4 cell count below 200 per microl, and no deaths were recorded in patients with HIV infection and a CD4 cell count > 500 per microl.

CONCLUSIONS

Despite no identical clinical features, Duke criteria had a similar sensitivity, specificity and diagnostic accuracy in IVDUs with and without HIV infection.

Infective endocarditis: diagnosis, antimicrobial therapy, and management of complications: a statement for healthcare professionals from the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease, Council on Cardiovascular Disease in the Young, and the Councils on Clinical Cardiology, Stroke, and Cardiovascular Surgery and Anesthesia, American Heart Association: endorsed by the Infectious Diseases Society of America

BACKGROUND

Despite advances in medical, surgical, and critical care interventions, infective endocarditis remains a disease that is associated with considerable morbidity and mortality. The continuing evolution of antimicrobial resistance among common pathogens that cause infective endocarditis creates additional therapeutic issues for physicians to manage in this potentially life-threatening illness.

METHODS AND RESULTS

This work represents the third iteration of an infective endocarditis "treatment" document developed by the American Heart Association under the auspices of the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease, Council on Cardiovascular Disease of the Young. It updates recommendations for diagnosis, treatment, and management of complications of infective endocarditis. A multidisciplinary committee of experts drafted this document to assist physicians in the evolving care of patients with infective endocarditis in the new millennium. This extensive document is accompanied by an executive summary that covers the key points of the diagnosis, antimicrobial therapy, and management of infective endocarditis. For the first time, an evidence-based scoring system that is used by the American College of Cardiology and the American Heart Association was applied to treatment recommendations. Tables also have been included that provide input on the use of echocardiography during diagnosis and treatment of infective endocarditis, evaluation and treatment of culture-negative endocarditis, and short-term and long-term management of patients during and after completion of antimicrobial treatment. To assist physicians who care for children, pediatric dosing was added to each treatment regimen.

CONCLUSIONS

The recommendations outlined in this update should assist physicians in all aspects of patient care in the diagnosis, medical and surgical treatment, and follow-up of infective endocarditis, as well as management of associated complications. Clinical variability and complexity in infective endocarditis, however, dictate that these guidelines be used to support and not supplant physician-directed decisions in individual patient management.

Endocarditis after valve replacement surgery. Early recognition and treatment are essential to averting deadly complications

The incidence of infective endocarditis, an inflammation of the heart valves, the endocardium, or both that's caused by bacterial, viral, or fungal agents, continues to rise despite advances in treatment. People with prosthetic valves are among those at highest risk, and mortality rates can be extremely high, especially in cases of early onset. Diagnosis is challenging, in part because signs and symptoms associated with systemic infections can mask signs of the underlying endocarditis. This article outlines the causes and effects of prosthetic valve-related endocarditis (PVE), describes its signs and symptoms, discusses the leading diagnostic tests and criteria, and addresses prevention and treatment, as well as nursing implications.

Evolving trends in infective endocarditis

Infective endocarditis is a microbial infection of the endocardial surface and, despite improvements in diagnostic accuracy, medical therapy and surgical techniques, mortality remains high. This review focuses on changes in epidemiology, microbiology and diagnosis, as well as changes in medical and surgical management of infective endocarditis affecting native and prosthetic valves in adults, that have evolved during the past two decades. Significant changes have included an increasing involvement of prosthetic valves and nosocomially-acquired disease, an increased involvement of staphylococci as the causative agents, and a recognition that elderly individuals with degenerative valvular disease are the most vulnerable population. Topics still requiring study include whether and when valve replacement should be performed, and how to predict perivalvular complications or embolisation based on echocardiography findings. Optimisation of antimicrobial treatment schemes (choice of the antibiotic, dose and duration) also requires further investigation.

Contribution of systematic serological testing in diagnosis of infective endocarditis

Despite progress with diagnostic criteria, the type and timing of laboratory tests used to diagnose infective endocarditis (IE) have not been standardized. This is especially true with serological testing. Patients with suspected IE were evaluated by a standard diagnostic protocol. This protocol mandated an evaluation of the patients according to the modified Duke criteria and used a battery of laboratory investigations, including three sets of blood cultures and systematic serological testing for Coxiella burnetii, Bartonella spp., Aspergillus spp., Legionella pneumophila, and rheumatoid factor. In addition, cardiac valvular materials obtained at surgery were subjected to a comprehensive diagnostic evaluation, including PCR aimed at documenting the presence of fastidious organisms. The study included 1,998 suspected cases of IE seen over a 9-year period from April 1994 to December 2004 in Marseilles, France. They were evaluated prospectively. A total of 427 (21.4%) patients were diagnosed as having definite endocarditis. Possible endocarditis was diagnosed in 261 (13%) cases. The etiologic diagnosis was established in 397 (93%) cases by blood cultures, serological tests, and examination of the materials obtained from cardiac valves, respectively, in 348 (81.5%), 34 (8%), and 15 (3.5%) definite cases of IE. Concomitant infection with streptococci and C. burnetii was seen in two cases. The results of serological and rheumatoid factor evaluation reclassified 38 (8.9%) possible cases of IE as definite cases. Systematic serological testing improved the performance of the modified Duke criteria and was instrumental in establishing the etiologic diagnosis in 8% (34/427) cases of IE.

Use of surgery in patients with native valve infective endocarditis: results from the International Collaboration on Endocarditis Merged Database

BACKGROUND

Early surgery has been shown to be beneficial for patients with infective endocarditis (IE), yet surgery is not used in most patients. Evidence of the uncertainty around the use of surgery can be found in the wide variations in the use of cardiac surgery in IE with few precise indications for cardiac surgery yet defined. The aim of the study was to characterize patients with native valve IE relative to surgery and to determine if patients who benefit from an early surgical intervention can be identified.

METHODS

The International Collaboration on Endocarditis Merged Database was used to quantify the differences between patients with IE receiving medical and surgical intervention in 1516 patients with definite native valve IE. Propensity models were built to identify a group of patients that benefit from early surgery.

RESULTS

Patients in the early surgical group were more likely to be male, younger, and with less comorbidities compared with the early medical group (P < .001 for all) and were less likely to have infection with Staphylococcus aureus or viridans group streptococci (P < .05 for all). Intracardiac abscess and heart failure were much more common in the surgical group (P < .001 for all). In an unadjusted comparison, there was no statistically significant survival advantage in the surgical group. However, in the propensity analysis, in the subgroup of patients with the most indications for surgery, there was a significant decrease in mortality associated with early surgery (11.2% vs 38.0%, P < .001).

CONCLUSIONS

The benefits of surgery are not seen uniformly in all patients with native valve IE, but are most realized in a targeted population. This observation requires confirmation in other populations of patients with definite IE.

Blood culture-negative endocarditis in a reference center: etiologic diagnosis of 348 cases

To identify the current etiologies of blood culture-negative infective endocarditis and to describe the epidemiologic, clinical, laboratory, and echocardiographic characteristics associated with each etiology, as well as with unexplained cases, we tested samples from 348 patients suspected of having blood culture-negative infective endocarditis in our diagnostic center, the French National Reference Center for Rickettsial Diseases, between 1983 and 2001. Serology tests for Coxiella burnettii, Bartonella species, Chlamydia species, Legionella species, and Aspergillus species; blood culture on shell vial; and, when available, analysis of valve specimens through culture, microscopic examination, and direct PCR amplification were performed. Physicians were asked to complete a questionnaire, which was computerized. Only cases of definite infective endocarditis, as defined by the modified Duke criteria, were included. A total of 348 cases were recorded-to our knowledge, the largest series reported to date. Of those, 167 cases (48%) were associated with C. burnetii, 99 (28%) with Bartonella species, and 5 (1%) with rare, fastidious bacterial agents of endocarditis (Tropheryma whipplei, Abiotrophia elegans, Mycoplasma hominis, Legionella pneumophila). Among 73 cases without etiology, 58 received antibiotic drugs before the blood cultures. Six cases were right-sided endocarditis and 4 occurred in patients who had a permanent pacemaker. Finally, no explanatory factor was found for 5 remaining cases (1%), despite all investigations.Q fever endocarditis affected males in 75% of cases, between 40 and 70 years of age. Ninety-one percent of patients had a previous valvulopathy, 32% were immunocompromised, and 70% had been exposed to animals. Our study confirms the improved clinical presentation and prognosis of the disease observed during the last decades. Such an evolution could be related to earlier diagnosis due to better physician awareness and more sensitive diagnostic techniques. As for Bartonella species, B. quintana was recorded more frequently than B. henselae (53 vs 17 cases). For 18 patients with Bartonella endocarditis, the responsible species was not identified. Species determination was achieved through culture and/or PCR in 49 cases and through Western immunoblotting in 22. Comparison of B. quintana and B. henselae endocarditis revealed distinct epidemiologic patterns. The 2 cases due to T. whipplei reflect the emerging role of this agent as a cause of infective endocarditis. Because identification of the bacterium was possible only through analysis of excised valves by histologic examination, PCR, and culture on shell vial, the prevalence of the disease might be underestimated. Among patients who received antibiotic drugs before blood cultures, 4 cases (7%) were found to be associated with Streptococcus species (2 S. bovis and 2 S. mutans) through 16S rDNA gene amplification directly from the valve, which shows the usefulness of this technique in overcoming the limitations of previous antibiotic treatment. Right-sided endocarditis occurred classically in young patients (mean age, 36 yr), intravenous drug users in 50% of cases, and suffering more often from embolic complications. Finally, 5 cases without etiology or explaining factors were all immunocompetent male patients with previous aortic valvular lesions, and 3 of the 5 presented with an aortic abscess. Further investigations should be focused on this group to identify new agents of infective endocarditis.

Early predictors of in-hospital death in infective endocarditis

BACKGROUND

Data on early determinants of outcome in infective endocarditis (IE) are limited. We evaluated the prognostic significance of early clinical characteristics in a large, prospective cohort of patients with IE.

METHODS AND RESULTS

Two hundred sixty-seven consecutive patients with definite or possible IE by modified Duke criteria and echocardiography performed within 7 days of presentation were evaluated. Acute physiology was assessed by the Acute Physiology, Age, Chronic Health Evaluation II (APACHE II) score at the time of presentation, and early heart failure was diagnosed by Framingham criteria. In-hospital mortality rate in the cohort was 19% and similar for patients with definite or possible IE (20% versus 16%, respectively; P=0.464). Independent predictors of death determined by logistic regression modeling were diabetes mellitus (OR 2.48; 95% CI, 1.24 to 4.96), Staphylococcus aureus as causative organism (OR, 2.06; 95% CI, 1.01 to 4.20), APACHE II score (OR, 1.07; 95% CI, 1.01 to 1.12), and embolic event (OR, 2.79; 95% CI, 1.15 to 6.80). Early echocardiographic findings of the Duke criteria were not predictive of death.

CONCLUSIONS

Early in the course of IE, readily available clinical characteristics that reflect the host-pathogen interaction are predictive of in-hospital death. These factors may identify those patients with IE for more aggressive treatment.

Staphylococcus aureus bacteremia and endocarditis

Staphylococcus aureus is a leading cause of bacteremia and endocarditis. Over the past several years, the frequency of S aureus bacteremia (SAB) has increased dramatically. This increasing frequency, coupled with increasing rates of antibiotic resistance, has renewed interest in this serious, common infection. S aureus is a unique pathogen because of its virulent properties, its protean manifestations, and its ability to cause endocarditis on architecturally normal cardiac valves. Although the possibility of underlying endocarditis arises in virtually every patient with SAB, only a minority of bacteremic patients will actually have cardiac involvement. Distinguishing patients with S aureus infective endocarditis (IE) from those with uncomplicated SAB is essential, but often difficult. In this review, the authors summarize recent changes in the epidemiology of SAB and IE, discuss the challenges in distinguishing SAB from IE, and discuss current trends in the management of patients with SAB and IE.

Infective endocarditis in the elderly: diagnosis and management

Infective endocarditis is seen with increasing frequency in older patients. This increase is due to the general aging of the population, improved survival of patients with congenital and valvular heart disease, and the increasing use of catheters and other prosthetic devices with resulting higher incidence of nosocomial endocarditis. In older patients, infective endocarditis frequently develops in the absence of underlying structural heart disease; atheromatous deposits and mitral annular calcification are two important risk factors in this population. Infective organisms in older patients are frequently enterococci and other gastrointestinal tract bacteria. A marked febrile response is uncommon whereas central nervous system symptoms are more common in older patients. Transesophageal echocardiography can be performed safely and is a major diagnostic tool with sensitivity of more than 90% in detecting vegetations as small as 2-5 mm. Appropriately drawn blood cultures provide bacteriologic diagnosis in 80%-99% of patients. Prolonged antibiotic therapy may be required in many instances depending on the infective organism. Early surgical therapy is advisable for patients who develop heart failure as a result of severe acute aortic valvular regurgitation. Valve replacement surgery can be performed with acceptable mortality and morbidity even in very elderly patients.

Imaging techniques for diagnosis of infective endocarditis

Cardiac imaging, specifically echocardiography, has greatly enhanced the ability of clinicians to effectively diagnose and manage IE. Echocardiograms should generally be obtained in all patients suspected of having IE, both to establish the diagnosis and to identify complicated cardiac involvement that may warrant surgical intervention. Transesophageal imaging is more sensitive and specific than the transthoracic approach and currently represents the optimal approach to echocardiographic imaging. Manifestations of endocardial involvement include vegetations, abscesses, aneurysms, fistulae, leaflet perforations, and valvular dehiscence. The roles of other imaging modalities including CT, MRI, and nuclear imaging have yet to be fully established.

Progress toward a global understanding of infective endocarditis. Lessons from the International Collaboration on Endocarditis

In the century and a quarter since William Osler delivered his famed Gulstonian lectures on endocarditis, continual advancements have been made in understanding and treating this disease. Here we have reviewed some key aspects of current knowledge in the areas of population epidemiology, host factors, microorganisms, and diagnosis. The advent of the ICE investigation provides the opportunity to further expand our understanding of IE by developing a very large, global database of IE patients whose clinical, echocardiographic, and microbiologic findings have been characterized with standard methodology. Further, ICE may serve as a rich source of material for investigators seeking to perform specific studies. Finally, the ICE infrastructure creates the opportunity for performing randomized trials to test therapeutic strategies. Although many obstacles remain to be overcome, ICE has created the opportunity for a quantum leap in our knowledge of IE over the next 25 years.

Clinical presentation of infective endocarditis

Despite the decline in rheumatic heart disease worldwide and the use of antibiotic prophylaxis, there is no evidence that the incidence of infective endocarditis is decreasing. In fact, some data suggest it may be increasing. The classical fever of unknown origin presentation represents a minority of infective endocarditis cases today; thus, clinicians need to be vigilant about keeping infective endocarditis in mind with some of these more unusual presentations. This article focuses on the various presentations of infective endocarditis, which are organized into three groups of presenting symptoms and signs: nonspecific, cardiac, and embolic.

Infective endocarditis in the injection drug user

Although infective endocarditis is certainly not the most common infection seen in injecting drug users, it is the infection that clinicians most commonly think of when they consider infectious complications of injected drug use. The microbiology of infective endocarditis in injection drug users has remained relatively stable over the last several decades. Tricuspid valve endocarditis has been associated most frequently with injection drug use, but recent reports have suggested that involvement of left-sided valves is seen more often now than in the past. The use of transesophageal echocardiography has greatly advanced the ability to diagnose infective endocarditis and the cardiac complications of valvular infection.

Staphylococcus aureus bacteremia and endocarditis

Staphylococcus aureus is a leading cause of bacteremia and endocarditis. Over the past several years, the frequency of S. aureus bacteremia (SAB) has increased dramatically. This increasing frequency, coupled with increasing rates of antibiotic resistance, has renewed interest in this serious, common infection. S. aureus is a unique pathogen because of its virulent properties, its protean manifestations, and its ability to cause endocarditis on architecturally normal cardiac valves. Although the possibility of underlying endocarditis arises in virtually every patient with SAB, only a minority of bacteremic patients will actually have cardiac involvement. Distinguishing patients with S. aureus infective endocarditis (IE) from those with uncomplicated SAB is essential, but often difficult. In this review, the authors summarize recent changes in the epidemiology of SAB and IE, discuss the challenges in distinguishing SAB from IE, and discuss current trends in the management of patients with SAB and IE.

Imaging techniques for diagnosis of infective endocarditis

With the ability to structurally characterize cardiac manifestations, echocardiography is used for the diagnosis and management of infective endocarditis. In establishing the diagnosis according to the Duke criteria, the findings of endocardial involvement (vegetation, abscess, prosthetic valve dehiscence) or new valvular regurgitation represent "major" diagnostic criteria. As echocardiography cannot reliably differentiate noninfective from infective lesions, however, proper diagnosis lies in correlating echocardiography with clinical findings. The more invasive transesophageal approach provides substantially greater image resolution; this approach should be considered first in the evaluation of patients with higher prior probabilities of endocarditis and those with potential endocardial complications.

Progress toward a global understanding of infective endocarditis. Early lessons from the International Collaboration on Endocarditis investigation

In the century and a quarter since William Osler delivered his framed lectures on endocarditis substantial advancements have occurred in the understanding and treatment of this disease. This article summarizes current understanding of endocarditis in the areas of population epidemiology, host factors, microorganisms, diagnosis, and therapy. In addition, the authors discuss possible directions for investigation in the future, including a new multinational consortium, the International Collaboration on Endocarditis (ICE). This collaboration aims to provide a mechanism to advance the understanding of endocarditis in areas difficult to study without an established network. The multinational nature of the collaboration may also permit a more global view of IE and provide opportunities for studies such as randomized trials of therapeutic treatment strategies.

Diagnosis of culture-negative endocarditis: the role of the Duke criteria and the impact of transesophageal echocardiography

BACKGROUND

The Duke criteria have been shown to be more sensitive than the von Reyn criteria in the diagnosis of culture-positive endocarditis but to date have not been fully validated for culture-negative endocarditis (CNE). The aim of this study was (1) to compare the diagnostic accuracy of the Duke criteria versus clinical judgment and the von Reyn criteria in CNE and (2) to assess the diagnostic impact of transesophageal echocardiography (TEE) on the Duke criteria in CNE.

METHODS

The study group consisted of 49 patients with suspected CNE in whom the presence (n = 32) or absence (n = 17) of endocarditis was confirmed by surgery, autopsy, or both. All patients underwent transthoracic echocardiography (TTE) and TEE. They were classified into a Duke category initially with TTE data only, and then the Duke categories were reevaluated with the additional TEE data.

RESULTS

The Duke criteria demonstrated a significantly higher sensitivity (72%) than the von Reyn criteria (28%; P =.0008) and a higher specificity (100%) than clinical judgment (76%; P =.02). No major differences were noted between sensitivities of the Duke criteria and clinical judgement. TEE significantly augmented the capacity to diagnose CNE by Duke criteria versus TTE (P <.05).

CONCLUSIONS

The Duke criteria are of high diagnostic validity for the conduction of clinical studies on CNE. They have the potential to affect clinical decision-making, based on the higher specificity versus clinical judgment. TEE appears to be crucial for the diagnosis of CNE when the Duke criteria are applied. The diagnostic differentiation between CNE, sclerotic valve degeneration, and nonbacterial thrombotic endocarditis remains a challenge.

Endocarditis due to rare and fastidious bacteria

The etiologic diagnosis of infective endocarditis is easily made in the presence of continuous bacteremia with gram-positive cocci. However, the blood culture may contain a bacterium rarely associated with endocarditis, such as Lactobacillus spp., Klebsiella spp., or nontoxigenic Corynebacterium, Salmonella, Gemella, Campylobacter, Aeromonas, Yersinia, Nocardia, Pasteurella, Listeria, or Erysipelothrix spp., that requires further investigation to establish the relationship with endocarditis, or the blood culture may be uninformative despite a supportive clinical evaluation. In the latter case, the etiologic agents are either fastidious extracellular or intracellular bacteria. Fastidious extracellular bacteria such as Abiotrophia, HACEK group bacteria, Clostridium, Brucella, Legionella, Mycobacterium, and Bartonella spp. need supplemented media, prolonged incubation time, and special culture conditions. Intracellular bacteria such as Coxiella burnetii cannot be isolated routinely. The two most prevalent etiologic agents of culture-negative endocarditis are C. burnetti and Bartonella spp. Their diagnosis is usually carried out serologically. A systemic pathologic examination of excised heart valves including periodic acid-Schiff (PAS) staining and molecular methods has allowed the identification of Whipple's bacillus endocarditis. Pathologic examination of the valve using special staining, such as Warthin-Starry, Gimenez, and PAS, and broad-spectrum PCR should be performed systematically when no etiologic diagnosis is evident through routine laboratory evaluation.

Endocarditis: clinical outcome and benefit of trans-oesophageal echocardiography

The improved prognosis for infective endocarditis (IE) seen in the last decade is due partly to more active surgical treatment and partly to improved diagnosis by echocardiography. To evaluate the clinical value of repeated trans-oesophageal echocardiography (TEE) 34 patients with 35 episodes of suspected IE were included in a prospective part of the study (group A). TEE was carried out for diagnosis, at discharge and about 5 months after hospitalization. Endocarditis was classified using Duke's criteria. In a retrospective part of the study 32 other patients with 34 episodes of IE were included (group B). Both groups were analysed regarding mortality, frequency of surgery and classification according to Duke. The diagnosis was regarded as definite in 49 and possible in 20 episodes. Vegetation-size decreased significantly (p < 0.001) during treatment. In contrast, no significant changes in valvular insufficiency were found. In episodes diagnosed as definite, the mortality was 2/49 (4.1%). The low mortality might be explained by the high frequency of surgery (22%), the inclusion of patients with right-sided IE, and 'early diagnosis'. The first TEE was important for correct diagnosis in patients with small vegetations and for those needing surgery. The clinical value of the additional investigations was low in native valve endocarditis.

Native valve infective endocarditis: what is the optimal timing for surgery?

IE remains a dreaded disease masquerading under a myriad of presentations in an evolving epidemiological environment. In our continuing endeavor against this deadly disease, echocardiography has evolved into an indispensable diagnostic tool to define structural complications and guide therapy. Timing of surgical intervention for IE remains a subject of intense debate and depends on the cardiac and systemic complications of the infection, the virulence of the organism, and the responsiveness to medical therapy. A judicious agreement among cardiologist, cardiovascular surgeon, and infectious disease specialist should define whether surgical intervention is warranted and, if so, the optimal timing. Further optimization of guidelines will help in the diagnosis and treatment of endocarditis but will never be a substitute for sound judgment and experience.

Infective endocarditis in intravenous drug users: does HIV status alter the presenting temperature and white blood cell count?

The intent of this study was to determine if HIV seropositivity alters the maximum temperature (T(max)) and WBC count of febrile intravenous (i.v.) drug users with infective endocarditis (IE). A review of 497 charts of patients with endocarditis provided 228 eligible patient visits (46%), with 158 cases (69.3%) of IE among 126 patients (74 HIV+ and 52 HIV-). Mean T(max) for all patients with IE was 39.1 degrees C (102.4 degrees F). Mean T(max) was similar between the HIV+ (39.1 degrees C, 102.4 degrees F) and HIV- (39.2 degrees C, 102.5 degrees F) groups. There were no differences in mean T(max) among HIV+ patients with CD4 counts > 200 (39.0 degrees C, 102.3 degrees F), those with CD4 < or =200 (39.2 degrees C, 102.5 degrees F), and the HIV- group (39.2 degrees C, 102.5 degrees F). Nearly 8% of i.v. drug users with confirmed IE presented to the ED with a T(max) below 37.8 degrees C (100.0 degrees F). Mean WBC count was significantly lower in HIV+ (11.1 k/mm(3)) than in HIV- patients (15.4 k/mm(3)) and significantly lower in the group with CD4 < or =200 (8.0 k/mm(3)) than in the HIV- group. In conclusion, HIV infection was not associated with lower T(max), but it was associated with decreased WBC count in the general HIV+ group and in the group with CD4 < or =200.

Clinical information determines the impact of transesophageal echocardiography on the diagnosis of infective endocarditis by the duke criteria

BACKGROUND

Although transesophageal echocardiography (TEE) is more sensitive than transthoracic echocardiography (TTE) in detecting echocardiographic evidence of infective endocarditis (IE), the impact of TEE on the clinical diagnosis of IE has not been clearly delineated.

METHODS AND RESULTS

We studied 112 patients with 114 suspected episodes of IE over a 6-year period who underwent both TTE and TEE during their diagnostic evaluation. Using the results of these studies along with clinical and microbiologic data, we attempted to determine the incremental value of TEE to the Duke Endocarditis Diagnostic Criteria. Patients were initially classified into a diagnostic category of the Duke criteria with TTE data, and then the diagnostic classification was reconsidered with TEE data. A diagnostic category reassignment occurred in 25 of 114 episodes of IE evaluated when TEE results were incorporated into the evaluation with the Duke criteria (22 patients were reclassified from possible IE to definite IE whereas 3 patients were reclassified from rejected to possible IE). Diagnostic reclassification occurred in 9 (11%) of the 80 episodes of suspected IE with native cardiac valves and 13 (34%) of 34 episodes with prosthetic cardiac valves. Most patients reclassified from possible IE to definite IE with TEE data (19 of 22) had an intermediate clinical likelihood of IE, whereas 92% of patients had negative TTE results. Pathologic examination of valvular tissue in 22 of the 114 episodes of suspected IE revealed that the positive predictive value of the Duke criteria with TEE data for diagnosis of IE was 85% in patients with native valves and 89% in patients with prosthetic valves.

CONCLUSIONS

When clinical evidence of IE is present, TEE improves the sensitivity of the Duke criteria to diagnose definite IE. TEE data appears to be especially useful for the diagnostic evaluation of patients with suspected IE who have prosthetic valves.

Proposed modifications to the Duke criteria for the diagnosis of infective endocarditis

Although the sensitivity and specificity of the Duke criteria for the diagnosis of infective endocarditis (IE) have been validated by investigators from Europe and the United States, several shortcomings of this schema remain. The Duke IE database contains records collected prospectively on >800 cases of definite and possible IE since 1984. Databases on echocardiograms and on patients with Staphylococcus aureus bacteremia at Duke University Medical Center are also maintained. Analyses of these databases, our experience with the Duke criteria in clinical practice, and analysis of the work of others have led us to propose the following modifications of the Duke schema. The category "possible IE" should be defined as having at least 1 major criterion and 1 minor criterion or 3 minor criteria. The minor criterion "echocardiogram consistent with IE but not meeting major criterion" should be eliminated, given the widespread use of transesophageal echocardiography (TEE). Bacteremia due to S. aureus should be considered a major criterion, regardless of whether the infection is nosocomially acquired or whether a removable source of infection is present. Positive Q-fever serology should be changed to a major criterion.

Individual value of each of the Duke criteria for the diagnosis of infective endocarditis

OBJECTIVES: To assess the value of each of the Duke criteria for the diagnosis of infective endocarditis (IE). METHODS: Detailed review was done of charts of all cases discharged with the diagnosis of IE, and classification as 'definite', 'possible' and 'rejected' cases was made according to the Duke criteria. The diagnostic impact of each criterion was assessed by reclassifying each 'definite' case after subtraction of each individual criterion and by reclassifying each 'possible' and 'rejected' case after addition of each individual criterion. RESULTS: From 1983 to 1993, 179 cases were identified in the databases of two hospitals. When the Duke criteria were applied, 124 (6967%) were classed as 'definite', 43 (2466%) as 'possible' and 12 (763%) as 'rejected' cases. Of the 67 pathologically proven cases, 52 (78610%) were 'definite' cases when the criteria were applied before pathology. If the major microbiological criterion is subtracted, 53% (69%) of the 'definite' cases become 'possible' or 'rejected'. When the echocardiographic criterion is subtracted, 34% (68%) of the 'definite' cases become possible or rejected. Among minor criteria, fever and predisposition, contributing to the classification of respectively 31% (68%) and 27% (68%) of the 'definite' cases, were the most powerful. On the other hand, the minor microbiological criterion and immunologic phenomena were responsible for the classification of only 2% (62%) and 6% (64%) respectively, of the 'definite' cases. CONCLUSIONS: Depending on the criterion examined, 47-98% of the 'definite' cases of IE would remain 'definite' if this particular criterion were absent. The major microbiological criterion had the highest relative importance. In this retrospective study, in which only 32 (18%) patients had a transesophageal echocardiogram, the echocardiogram contributed to 15% (66%) of the 'definite' cases according to the major criterion and to 19% (66%) according to the minor criterion. This study illustrates that the degree of certainty of the diagnosis of IE often depends on the presence/absence of only one criterion.

Echocardiography for the Diagnosis of Staphylococcus aureus Infective Endocarditis

Staphylococcus aureus bacteremia (SAB) is a serious and growing problem. A longstanding controversy in infectious diseases has centered around the duration of therapy for patients with SAB. Fortunately, the refinement of echocardiography and the creation of new diagnostic criteria have aided in the diagnosis of infective endocarditis in patients with SAB. These advancements have resulted in the development of an algorithm that combines clinical, microbiologic, and echocardiographic findings to stratify patients with SAB into different treatment regimens.

Value and limitations of the Duke criteria for the diagnosis of infective endocarditis

OBJECTIVES

The purpose of this study was to assess the value and limitations of Duke criteria for the diagnosis of infective endocarditis (IE).

BACKGROUND

Duke criteria have been shown to be more sensitive in diagnosing IE than the von Reyn criteria, but the diagnosis of IE remains difficult in some patients.

METHODS

Both classifications were applied in 93 consecutive patients with pathologically proven IE. Blood cultures, and transthoracic and transesophageal echocardiography were performed in all patients.

RESULTS

Sensitivities for the diagnosis of IE were 56% and 76% for von Reyn and Duke criteria, respectively. Fifty-two patients were correctly classified as "probable IE" by von Reyn and "definite IE" by Duke criteria (group 1). However, discrepancies were observed in 41 patients. Eleven patients (group 2) were misclassified as "rejected" by von Reyn, but were "definite IE" by Duke criteria; this difference could be explained by negative blood cultures and positive echocardiogram in all patients. In eight patients (group 3), the diagnosis of IE was "possible" by von Reyn but "definite" by Duke criteria. This difference was essentially explained by the failure of the von Reyn classification to consider echocardiographic abnormalities as major criteria. Twenty-two patients (group 4) were misclassified as possible IE using Duke criteria, being false negative of this classification. Echocardiographic major criteria were present in 19 patients, but blood cultures were negative in 21 patients. The cause of negative blood cultures was prior antibiotic therapy in 11 patients and Q-fever endocarditis diagnosed by positive serology in three cases.

CONCLUSIONS

Twenty-four percent of patients with proved IE remain misclassified as "possible IE" despite the use of Duke criteria, especially in cases of culture-negative and Q-fever IE. Increasing the diagnostic value of echographic criteria in patients with prior antibiotic therapy and typical echocardiographic findings and considering the serologic diagnosis of Q fever as a major criterion would further improve the clinical diagnosis of IE.