Impact of prolapsing leaflet location on exercise pulmonary hypertension in mitral regurgitation

We aimed to evaluate whether prolapsing leaflet-specific exercise pulmonary hypertension (PHT) exists and to identify the related mechanisms.

Resting and bicycle exercise transthoracic echocardiography was performed in 35 consecutive patients (aged 56 ± 11, 69% men) with asymptomatic, moderate-to-severe, and degenerative mitral regurgitation (MR). The patients were classified into two groups according to the prolapsing leaflet: an anterior mitral leaflet (AML) group (n = 17) and a posterior mitral leaflet (PML) group (n = 18). At rest, the MR severity and systolic pulmonary artery pressure (SPAP) were similar between the two groups. During exercise, changes in the regurgitant volume (ΔRV) were markedly increased in the PML group compared with the AML group (23.9 ± 13.6 vs. 13.9 ± 10.5 mL, P= 0.022). Moreover, exercise-induced changes in SPAP (ΔSPAP) were more significant in the PML group (35.8 ± 10.7 vs. 26.7 ± 8.7 mmHg, P= 0.009). Further analysis of the resting left atrial (LA) characteristics revealed decreased LA reservoir function and a more ellipsoid left atrium in the PML group. Multiple linear regression analysis revealed that ΔRV was an independent determinant of ΔSPAP (β= 0.34, P= 0.013) after adjustment for other confounding factors.

PML prolapse is associated with a greater increase in exercise-induced SPAP, and the prominent increase in MR severity in PML prolapse is thought to be the main mechanism responsible for this increase. The current study suggests the need for more frequent follow-up of patients with PML prolapse.