Left Atrial to Left Ventricular Volume Ratio in Patients With Severe Functional Mitral Regurgitation

Severe functional mitral regurgitation (fMR) is a heterogenous disease that exhibits different underlying pathophysiological mechanisms and represents independent entities. The aim of this study was to characterize remodeling patterns defined by the left atrial (LA) to left ventricular (LV) volume ratio in patients with severe fMR and heart failure, and to examine its prognostic implications.

A total of 13 052 patients with fMR were included. Based on the LA/LV volume ratio, patients with severe fMR were divided into 2 distinct groups: predominant LV remodeling (PLVR [ratio ≤0.56, n=581]) and predominant LA remodeling (PLAR [ratio >0.56, n=582]).

Patients with PLAR were more often female, with the peak age a decade later. PLAR was associated with lower leaflet tethering indices, as indicated by the leaflet tenting area (PLVR versus PLAR: 227 mm² versus 181 mm², P<0.001) and angles (PLVR versus PLAR: posterior leaflet: 42° versus 36°, P<0.001; anterior leaflet: 28° versus 23°, P<0.001). PLAR was the predominant subtype in heart failure with preserved (76%) and heart failure with mildly reduced ejection fraction (61%), but a significant proportion could be observed in heart failure with reduced ejection fraction (32%). The median follow-up time for severe fMR was 66 months (interquartile range, 60-85). After 4 years, 42.1% with PLAR and 34.1% with PLVR had died. At 8 years, 57.3% of patients with PLAR, and 49.6% of patients with PLVR had died. Compared with PLVR, PLAR showed excess mortality, with a hazard ratio of 1.37 ([95% CI, 1.13-1.65]; P=0.001) in the univariate analysis. This effect remained after multivariable adjustment.

The LA/LV volume ratio indicates the prevailing remodeling pattern in severe fMR. It is associated with morphological features of valve apparatus distortion resulting from differential remodeling. A strong correlation is observed between the LA/LV volume ratio and mortality.