Echocardiography in infective endocarditis. Lack of specificity in patients with valvular pathology.

59 patients with suspected infective endocarditis on a natural valve were studied by M-Mode echocardiography to determine the specificity of the ultrasonic technique in detecting valvular vegetations. All echocardiograms were read independently by two observers who were unaware of the final diagnosis. Among 40 patients who later proved not to have infective endocarditis, two (5%) were diagnosed by echocardiography as having either possible or probably vegetation by at least one observer. Both patients with a false positive diagnosis of vegetation had pre-existing valvular pathology, the presence of which greatly complicated the interpretation of the echocardiogram. Inter-observer disagreement occurred in 5 of the 59 studies (8.5%). The results of this study suggest that caution should be exerted in the echocardiographic diagnosis of vegetation in patients with pre-existing valvular pathology.