Mitral regurgitation, left atrial structural and functional remodelling and the effect on pulmonary haemodynamics.

AIMS: To assess the association between mitral regurgitation (MR) and left atrial (LA) structural and functional remodelling and their effect on pulmonary haemodynamics. METHODS AND
RESULTS: Consecutive unselected patients undergoing comprehensive echocardiography were enrolled. Parameters of cardiac structure and function were obtained as well as mitral effective regurgitant orifice area (ERO) and estimation of pulmonary artery systolic pressure (PASP). Measures of LA structure [LA volume (LAV)] and function [peak atrial longitudinal strain (PALS), peak atrial contraction strain (PACS) and conduit strain (CS)] were also calculated. The study population included 102 patients (mean age 70 ± 14 years, 42% women), with a mean ejection fraction of 52 ± 13%. MR was classified as organic due to mitral valve prolapse in 14 patients (14%) and functional in 88 patients (86%). Mean ERO was 0.12 ± 0.12 cm2 and 86 patients (84%) had an ERO ≤0.2 cm2 . ERO was significantly associated with worse measures of LA structure and function. Despite the low burden of MR, the association remained significant after adjusting for clinical and echocardiographic confounders (β: 3.7, P = 0.022 for LAV; β: -3.0, P = 0.003 for PALS; β: -1.8, P = 0.027 for PACS) and was significantly related with functional MR (P for interaction <0.001). ERO was also significantly associated with PASP, and measures of LA function (PALS and PACS) significantly modified this relationship (P for interaction <0.001).
CONCLUSIONS: Even a mild degree of MR contributes to LA remodelling and this relationship plays an active role in pulmonary circulation, suggesting a potential mechanism by which these parameters contribute to the development of heart failure.