Left Atrial Stiffness Index as a Predictor of Effort Intolerance and Hemodynamics Evaluated by Invasive Exercise Stress Testing in Degenerative Mitral Regurgitation.

In patients with degenerative mitral regurgitation (DMR), peak oxygen consumption is the significant prognostic factor, and exercise intolerance has been considered a trigger for surgical intervention. The significant mitral regurgitation (MR) induces left atrial (LA) remodeling, but the significance of LA stiffness calculated by the ratio of E/e' to LA reservoir strain in degenerative MR has not been elucidated. A total of 30 patients with asymptomatic or minimally symptomatic grade ≥III + DMR underwent the cardiopulmonary exercising test simultaneously with invasive hemodynamic assessment. LA stiffness index significantly correlated with exercise hemodynamic deterioration, including pulmonary arterial wedge pressure (r = 0.71, p <0.01), systolic pulmonary arterial pressure at peak exercise (r = 0.73, p <0.01), and pulmonary circulatory reserve (mean pulmonary arterial pressure/cardiac output slope, r = 0.45, p = 0.012). Multiple linear regression analysis revealed that the higher LA stiffness index was significantly associated with decreased percent predicted peak oxygen consumption (per 0.1 increase, β -4.0, 95% confidence interval -6.9 to -1.3, p <0.01) independently of MR deterioration during exercise. In conclusion, increased LA stiffness was associated with exercise intolerance through hemodynamic deterioration during exercise in patients with asymptomatic or minimally symptomatic severe DMR.