Left atrioventricular coupling index in transthyretin amyloid cardiomyopathy: Association with mortality

Background: Left atrioventricular coupling index (LACI) has emerged as a powerful marker of cardiac remodeling across a variety of cardiac diseases, however its prognostic value in the setting of transthyretin amyloid cardiomyopathy (ATTR-CM) remains largely unexplored. Methods: Patients with ATTR-CM who underwent prospective evaluation comprising full echocardiographic assessment between 2021 and 2025 were included. LACI was measured as the ratio between the left atrial (LA) and the left ventricular (LV) end-diastolic volumes. The population was stratified based on LACI terciles. The study endpoint was all-cause mortality. Results: A total of 202 patients (median age 80 years, 80% male) were included, with a predominance of wild-type subtype (70%). LACI terciles cutoffs were: ≤59.5% (first tercile), from 59.5% to 88.1% (second tercile) and > ≥88.1% (third tercile). Higher LACI terciles were associated with a greater prevalence of wild-type disease and atrial fibrillation (AF) and more advanced NAC stage. Higher LACI terciles were associated with significantly smaller LV volumes and larger LA volumes, as well as worse parameters of LV systolic and diastolic function. Three-year survival rates progressively declined across increasing LACI terciles (97%, 68% and 55%, p < 0.001). LACI demonstrated higher discriminatory power for predicting 3-year mortality (AUC 0.789, 95% CI 0.717-0.861), in comparison to LA dimensional parameters. After adjusting for age, NAC stage, AF and LV longitudinal strain, LACI terciles remained significantly associated with all-cause mortality (adjusted HR 1.942, 95% CI 1.078-3.499; p = 0.027). Conclusions: In patients with ATTR-CM, increasing LACI is associated with markers of disease severity and worse long-term survival.