Abstract
BACKGROUND: Transthoracic echocardiographic (TTE) parameters of left atrial (LA) size and function are independent risk factors for cardioembolic events. Nevertheless, they are not included in current decision trees evaluating the necessity of transesophageal echocardiography (TOE) before rhythm control. OBJECTIVE: To evaluate whether TTE-assessed LA cardiomyopathy predicts LA thromboembolic substrate (LATS), defined as spontaneous echo contrast (SEC) ≥2+, sludge, or thrombus in the LA appendage (LAA). METHODS: This retrospective study included 645 patients undergoing same-session TTE and TOE; 384 in sinus rhythm (SR) and 261 with atrial fibrillation/flutter (AF/AFL). A low-risk subgroup (n = 323) was defined per guideline criteria and were categorized as SR with prior AF (n = 105), AF/AFL (n = 157), or controls without AF (n = 61). TTE images regarding LA size and function were analyzed and correlated with TOE findings of LATS. RESULTS: LA thromboembolic substrate was present in 59/323 (18.3%) low-risk patients, including 54/157 (34.4%) of those with AF/AFL. Among low-risk AF/AFL patients, 8.9% had LAA sludge or thrombus. Multivariable analysis showed only LA strain (LAS) independently predicted LATS; each 1% increase in LAS was associated with an 18% reduction in the odds of LATS (odds ratio 0.819, P < .001). Model discrimination improved markedly once LAS was added to a clinical-only model (area under the curve 0.86 vs 0.91, P < .001). CONCLUSION: LAS was the most accurate TTE parameter for identifying LATS, indicating that reliance solely on clinical risk scores may miss high-risk patients. Assessment of LA cardiomyopathy by TTE could guide individualized decisions regarding TOE before elective rhythm-control procedures.