Introduction: Left atrial (LA) structure and function are associated with future cardiovascular (CV) events and risk factors. Studying the longitudinal change of LA structure and function with age may provide important insights into the natural history of LA remodeling.
Hypothesis: The aim of this study is to evaluate associations between age and gender with longitudinal changes in LA remodeling in a large multi-ethnic cohort free of clinical CV disease at baseline.
Methods: Cardiac magnetic resonance (CMR) was used to identify longitudinal changes in LA structure and function in 2882 MESA participants who underwent baseline (year 2000-2002) and 10-year follow-up CMR imaging. Multimodality tissue tracking (MTT, Toshiba) software was used to calculate LA structure (LA maximum, minimum and pre-atrial contraction volumes indexed to body surface area - LA Vmax, Vmin and VpreA) and function (LA total, passive and active emptying fraction, LATEF, LAPEF, and LAAEF). Data were analyzed with multivariable mixed-effects regression models in which the outcome was CMR LA measurements, and the covariates included follow-up time and CV risk factors (hypertension, diabetes, smoking, race/ethnicity, body mass index, and lipid levels).
Results: Participants were aged 45-84 years at baseline, and 53% were women. At baseline, men had lower LATEF than women (58.4 vs 63.4%, p<0.05), while they had similar LA Vmax (30.3 vs 29.9 ml/m2, p=NS) and larger Vmin (13.1 vs 11.5 ml/m2, p=NS). Median time between baseline and follow-up CMR imaging was 9.4 years. Over this period, LA Vmax and Vmin increased in both men (by 4.8 and 5.2 ml/m2 respectively, p<0.05) and women (by 4.9 and 4.6 ml/m2 respectively, p<0.05); while LATEF decreased in both (-7.3 % in women, and -6.1% in men, p<0.05).
Conclusions: In a population free of CV disease, at baseline women had higher LA function than men, as well as lower LA volumes. Aging was associated with increased LA volume and decreased LA function in both men and women.