Diagnostic Accuracy of Transthoracic Echocardiography for Infective Endocarditis Findings Using Transesophageal Echocardiography as the Reference Standard: A Meta-Analysis

Abstract

Echocardiography is important for the diagnosis of infective endocarditis (IE), for which transesophageal echocardiography (TEE) is superior to transthoracic echocardiography (TTE). A systematic review and meta-analysis of observational studies was performed with the objective of evaluating diagnostic properties of TTE, with transesophageal findings of IE as the reference standard in patients with suspected IE. The literature search yielded 377 unique articles, of which 16 met the inclusion criteria. The 16 studies included 2,807 patients, of whom 793 (28%) had vegetations on TEE. For detecting vegetations, harmonic TTE had sensitivity of 61% (95% CI, 45%-75%) and specificity of 94% (95% CI, 85%-98%) with a negative likelihood ratio (NLR) of 0.42 (95% CI, 0.26-0.61). NLR for harmonic TTE can be improved by including only patients without prosthetic valves (NLR=0.36; 95% CI, 0.22-0.55) or by having strict criteria for conclusively negative results on TTE (NLR=0.17; 95% CI, 0.10-0.28). In the setting of patients without prosthetic valves, harmonic TTE had likelihood ratios of 0.14 (95% CI, 0.09-0.23) for a conclusively negative result, 0.66 (95% CI, 0.53-0.81) for an indeterminate result, and 14.60 (95% CI, 3.37-70.40) for a positive result. Modern harmonic TTE still has the potential to miss many vegetations detected on TEE. When limited to patients without prosthetic valves, a conclusively negative TTE under optimal view greatly decreases likelihood of IE. All other transthoracic results are not useful for ruling out IE, and subsequent TEE is almost always required.