Transthoracic signs of left atrial cardiomyopathy predict presence of left atrial thromboembolic substrate

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 necessity of transesophageal echocardiography (TOE) before rhythm control. Objective To evaluate whether TTE-assessed LA cardiomyopathy predicts left atrial thromboembolic substrate (LATS), defined as spontaneous echo contrast (SEC) ≥2+, sludge, or thrombus in the left atrial 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 Left atrial 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 left atrial appendage sludge or thrombus. Multivariable analysis showed only left atrial strain (LAS) independently predicted LATS; each 1% increase in LAS was associated with an 18% reduction in the odds of LATS (OR 0.819, p < 0.001). Model discrimination improved markedly once LAS was added to a clinical-only model (AUC 0.86 vs. 0.91, p