Pislaru, S V

Abstract Background Lipomatous atrial septal hypertrophy (LASH) is generally viewed as a benign anatomical finding. Although extracardiac fat depots have been linked to adverse cardiometabolic outcomes, the prognostic implications of LASH have not been well defined. Purpose To evaluate whether LASH thickness is independently associated with long-term all-cause mortality. Methods We reviewed adult patients who underwent diagnostic transesophageal echocardiography at our Clinic sites from 2010–2017. LASH was identified by a dumbbell-shaped interatrial septum with maximal thickening ≥5 mm in the bicaval midesophageal view. All-cause mortality through January 1, 2024, served as the primary endpoint. Septal thickness was evaluated using restricted cubic splines and Cox proportional hazards models adjusted for age, sex, body mass index, Charlson Comorbidity Index, and left ventricular ejection fraction. Results Among 1,397 patients (mean age 69±12 years; 60% male), median LASH thickness was 14.2±4.4 mm. LASH severity was classified as mild (<15 mm; n=763), moderate (15-20 mm; n=522), or severe (>20 mm; n=112). During 7.5±4.0 years of follow-up, 586 deaths (42%) occurred. Mortality was higher with increasing septal thickness (37%, 46%, and 56%; p < 0.001). Each 1-mm increase in LASH-thickness was associated with higher adjusted mortality (adjusted-hazard-ratio 1.03; 95%-confidence-interval 1.01-1.05). Spline modeling suggested a risk increase beginning near 16 mm; thickness >16 mm carried a 26% higher mortality risk (adjusted-hazard-ratio 1.26; 95%-confidence-interval 1.06-1.50). Conclusions LASH was associated with long-term mortality independent of BMI and other clinical factors. Septal fat accumulation may provide a useful, noninvasive marker that complements broader cardiac risk assessment.Risk for all-cause mortality across LASHFor image description, please refer to the figure legend and surrounding text.