Overuse of transthoracic echocardiography in the diagnosis of native valve endocarditis

Background: Infective endocarditis (IE) is a diagnostic challenge due to its variable presentation and nonspecific clinical findings. The use of transthoracic echocardiography (TTE) has greatly improved the ability to diagnose IE early, and therefore reduce high mortality and morbidity rates. However, reliance on TTE to exclude IE may lead to overuse of this technology in patients with a low pretest probability of IE. Methods: Prospective observational study of all patients referred for TTE to diagnose IE. Clinical factors were used to determine likelihood of IE based on the Von Reyn criteria, and the resulting diagnostic probabilities were correlated with abnormal TTE findings as well as duration of antibiotic therapy. Results: One hundred eleven TTEs performed on 98 patients were included in the analysis. Over 70% of TTEs were obtained in patients in whom the diagnosis of IE was rejected by Von Reyn criteria. Therapeutic management (prolonged antibiotic administration) was associated significantly with Von Reyn categorization, and not significantly affected by TTE results. Conclusions: Most TTEs are obtained in patients with a low pretest probability of IE and do not contribute to therapeutic decision making. We propose a diagnostic algorithm to direct the use of TTE to patients with intermediate or high pretest probability of IE.