Impaired 3D left atrial pump function is associated with accelerated progression of mitral regurgitation in mitral valve prolapse

Abstract Background Patients with mitral regurgitation (MR) that develop atrial fibrillation and thus lose the left atrial (LA) pump function often present with clinical deterioration and increased morbidity after mitral valve repair. Despite the clinical importance of LA pump function, the factors contributing to its decline during MR progression and the relationship between the three-dimensional (3D) LA pump function and the threshold for mitral valve intervention in mitral valve prolapse (MVP) has been unclear. Objective To explore the covariates and the prognostic relevance of impaired 3D LA contractile strain (LASct), a validated marker for reduced LA pump function, in patients with MVP and at least moderate MR. Methods In the prospective 3D Echocardiography and Cardiovascular Prognosis in Mitral Regurgitation (3D-PRIME) study, patients with moderate or greater MR underwent comprehensive 2D/3D echocardiographic evaluation, including 3D peak LASct (Figure 1). The analysis included only patients presenting with sinus rhythm at baseline. Impaired 3D LASct was defined as ≥-4.4% in women and ≥-3.8% in men. The primary outcome was MR progression towards mitral valve intervention. Results Among the included 99 patients (mean age 65±14 years, 35% women), 25% had impaired 3D LASct. Low LASct was associated with increased LA stiffness and a higher prevalence of coronary artery disease (both p0.05). Moreover, impaired 3D LASct was independently associated with larger 3D mitral posterior leaflet and annulus area (OR 1.7, 95% CI 1.2-2.6, p=0.006) after adjustment for MR severity, total mitral annulus area, maximal 2D LA volume index, left ventricular global longitudinal strain, and comorbidities. Cox regression analysis identified 3D LASct as an independent predictor of accelerated progression towards MR intervention (HR 6.3, 95% CI 1.1–37.6, p=0.04), independent of MR regurgitant fraction, biplane left ventricular end-systolic volume, maximal 2D LA volume index, and systolic pulmonary artery pressure. The model incorporating LASct demonstrated superior predictive performance compared to a guideline-based model including left ventricular end-systolic volume, maximal 2D LA volume index, and systolic pulmonary artery pressure (AIC=56.0 vs 58.2, ΔAIC=2.2). Adding LASct improved the model fit (likelihood ratio test: x²=4.20, df=1, p=0.04). In Kaplan-Meier analysis, the 1-year event-free survival rate was 69% for the overall cohort but significantly lower in patients with impaired pump function: 48% vs. patients with preserved 3D LASct: 73% (p=0.026, Figure 2). Conclusion Impaired 3D LA pump function is associated with increased remodeling of the posterior mitral valve apparatus and predicts earlier need for mitral valve intervention in MVP. These findings provide insights into the complex valvular-atrial interactions during MR progression and suggest that routine assessment of LA function may help identify patients at risk for rapid disease progression.