New atrio-ventricular indices derived from conventional cine MRI correlate with functional capacity in patients with asymptomatic primary mitral regurgitation

Abstract

Mitral regurgitation (MR) is associated with morphological and functional alterations of left atrium (LA) and ventricle (LV), possibly inducing LA-LV misalignment. We aimed to: (1) characterize angulation between LA and mitral annulus from conventional cine MRI data and feature-tracking (FT) contours, (2) assess their associations with functional capacity in MR patients, as assessed by oxygen consumption (peak-VO₂) and minute ventilation to carbon dioxide production (VE/VCO₂) slope, in comparison with MRI LA/LV strain indices. Thirty-two asymptomatic primary MR patients (56 [40; 66] years, 12 women) underwent cardiac MRI resulting in LA/LV conventional FT-derived strain indices. Then, end-diastolic angles were derived from FT LA contours: (1) α, centered on the LA centre of mass and defined by mitral valve extremities, (2) γ, centered on the mitral ring anterior/lateral side, and defined by LA centre and the other extremity of the mitral ring. Cardiopulmonary exercise testing with simultaneous echocardiography were also performed; peak-VO₂ and VE/VCO₂ slope were measured. While peak-VO₂ and VE/VCO₂ slope were not correlated to LA/LV strains, they were significantly associated with angles (α: r = 0.50, p = 0.003 and r = - 0.52, p = 0.003; γ: r = - 0.53, p = 0.002 and r = 0.52, p = 0.003; respectively), independently of age and gender (R² ≥ 0.29, p ≤ 0.03). In primary MR, the new LA/mitral annulus angles, computed directly from standard-of-care MRI, are better correlated to exercise tolerance than conventional LA/LV strain.

Fig. 1

LA-mitral annulus angles extracted from FT-derived contours on cine SSFP long-axis images. 2- (left) and 4- (right) chamber view cine SSFP image at diastolic phase for a patient with high exercise capacity (a) and low exercise capacity (b). (c) Angle curves with end-diastolic values (black filled stars) of patient with high (solid line) and low (dashed line) exercise capacity.

Fig. 2

Linear regressions of peak VO₂ and VE/VCO₂ slope with end-diastolic angle indices. (a) End-diastolic LA α angle. (b) End-diastolic LA γ angle.