Abstract 18699: Negative Predictive Value of Transthoracic Echocardiography for Infective Endocarditis in the Modern Era

Abstract

BACKGROUND: Transesophageal echocardiography (TEE) is often recommended to exclude infective endocarditis (IE) in patients presenting with bacteremia despite a negative transthoracic echocardiogram (TTE). Previous studies showing inadequate sensitivity of TTE for native valve endocarditis are dated, and do not reflect modern advances in ultrasound image optimization technology. We hypothesized that with current generation echocardiography technology, a TTE absent mobile echo targets and without significant valvular abnormalities would have sufficient negative predictive value to exclude IE. METHODS: The Duke Echocardiographic Database was queried from 1/1/2007 [[Unable to Display Character: –]] 2/28/2014 for TTEs performed within 7 days prior to a TEE ordered for bacteremia/endocarditis. The dominant imaging platform used for both TTE and TEE during this era was the Philips IE33, with frequent use of fundamental frequencies to enhance spatial resolution beyond that of harmonic imaging alone. TTE studies identified as having poor sound transmission were excluded. A normal TTE was defined by the demonstration of normal cardiac anatomy, at most trivial valvular regurgitation, and absence of valvular stenosis, mobile/oscillating echo targets on valves, and hardware including catheters. The demonstration of an oscillating target on TEE along with clinical criteria based on chart review defined IE. RESULTS: A total of 974 unique patients had a TTE followed by a TEE within a week. IE was suggested in 209 of these patients by TEE. Among 107 patients meeting the a priori normal criteria on TTE, 3 patients had an abnormal TEE consistent with IE. These results correspond to a negative predictive value (NPV) of 97.2% (95% C.I. 91.4% - 99.3%) for a normal TTE to exclude IE. CONCLUSIONS: In this retrospective analysis from an academic medical center echocardiography laboratory, we demonstrated that an adequate quality TTE alone in a patient with a structurally normal heart without indwelling hardware has a high NPV for IE. Current TTE image optimization approaches may obviate the need to pursue TEE in patients after a recent preceding normal TTE.