Diagnostic accuracy of M-mode echocardiography in active infective endocarditis and prognostic implications of ultrasound-detectable vegetations.

Sensitivity, specificity, diagnostic accuracy, and prognostic implications of the M-mode echocardiographic pattern of vegetations were examined prospectively in consecutive patients referred with potential active infective endocarditis (IE). A pattern of definite echo vegetations was present in 37% of 51 patients diagnosed clinically to have active IE. Specificity in 138 patients without IE was 96%. Diagnostic accuracy of a positive test was 76% and that of a negative test was 80%. Five of six false positive studies involved patients with prior IE or valvular thrombosis. If possible echo vegetations were included, sensitivity increased to 47% and specificity decreased to 89%. Echographic vegetations were significantly correlated with congestive heart failure and need for valve replacement and/or death. Seven of eight patients with definite aortic valve vegetations died or required surgery, compared with 1 of 11 patients with mitral or tricuspid vegetations alone. Prognostic importance of echocardiographically documented vegetations appears to depend upon their site within the heart.