Applicability of Echocardiographic Strict Negative Criteria for Suspected Infective Endocarditis

Echocardiography is the cornerstone imaging technique in the diagnosis of infective endocarditis (IE) but is often misused in clinical practice. Recently, strict negative criteria have been proposed to avoid unnecessary follow-up echocardiograms. We aimed to evaluate the use of echocardiography in real-world clinical daily practice and the usefulness of these criteria in the diagnosis of IE. We retrospectively retrieved every echocardiogram performed in our center for suspected IE between 2014 and 2018, including 905 transthoracic echocardiograms (TTEs). Of these, 451 (49.8%) fulfilled the strict negative criteria (group 1). In this group, IE was seldom diagnosed (n = 4, 0.9%). In 338 patients (37.4%) no signs of IE were evident, but they did not fulfill the strict negative criteria (group 2). A follow-up echocardiogram and definitive diagnosis of IE were more frequent (n = 48, 14.2% and n = 20, 5.9%). Finally, in 116 patients (12.8%) the initial TTE showed typical or suggestive signs of IE, in whom the diagnosis was confirmed in 48 patients (41.4%). A definitive diagnosis of IE was established in a minority of the study population (n = 72, 8%). Only 1 readmission for underdiagnosis of IE was noted on group 2. We conclude that in a real-life setting only a minority of patients in whom IE was suspected had a definitive diagnosis. An initial TTE for suspected IE fulfilling the strict negative criteria predicts both a low probability of requesting a follow-up study and of a definitive diagnosis of IE.