Abstract 4341724: Progression of Left Atrial Volume Is Associated with Mitral Annular Calcification: Findings from MESA

Abstract

Background: The relationship between MAC burden and left atrial volume (LAV) progression over time has not been well characterized. Identifying whether MAC contributes to atrial remodeling may improve risk stratification for atrial and valvular disease. This study aimed to investigate the association between MAC burden, as quantified by cardiac computed tomography (CT), and LAV progression measured by cardiac magnetic resonance imaging (MRI) over serial examinations in a large community-based cohort. Methods: We performed a prospective analysis of data from a population-based cohort to evaluate the association between mitral annular calcium (MAC) burden and left atrial volume (LAV) progression. LAV was measured in milliliters (mL) using cardiac magnetic resonance imaging (MRI) at Exam 1 (baseline) and Exam 5 (follow-up). The primary outcome was the absolute change in LAV between exams. The primary predictor was mitral annular calcium measured at Exam 1 by non-contrast cardiac computed tomography (CT) and analyzed as a log-transformed continuous variable due to right-skewed distribution. Multivariable linear regression was used to assess the independent association between log MAC and LAV progression. The model was adjusted for cardiovascular risk factors. Interaction terms between log MAC and smoking status were tested but excluded due to lack of statistical significance. Assumption of a linear model were met. Results: A total of 126 participants with complete imaging and covariate data and mitral annular calcium (MAC) > 1 Agatston unit were included in the final analysis. Among the included sample, the mean log-transformed MAC at baseline was 4.05 ± 1.64. The mean progression in left atrial volume (LAV) between Exam 1 and Exam 5 was 35.2 ± 20.2 mL. In participants with measurable MAC burden (MAC > 1), the mean LAV progression was significantly associated with MAC severity. In the fully adjusted multivariable linear regression model, higher log MAC was independently associated with greater LAV progression (β = 2.96; 95% CI: 0.44 to 5.48; p = 0.021). The overall regression model was statistically significant (F = 2.18, p = 0.024) and R2 = 0.159. Conclusion: These findings suggest that MAC may be an early imaging biomarker of atrial structural remodeling. The relationship between valvular calcification and atrial enlargement warrants further investigation, particularly in the context of atrial fibrillation risk and atrioventricular coupling.