Prognostic value of exercise right ventricular-pulmonary arterial coupling in primary mitral regurgitation

Abstract Background Exercise-induced pulmonary hypertension (mPAP/CO slope >3mmHg/L/min) was recently associated with worse outcome in >moderate PMR. However, the prognostic value of right ventricle to pulmonary artery coupling (RVPAc) is unknown. Purpose Assess the prognostic value of RVPAc; determine the additional value of exercise over rest RVPAc and compare these findings to the mPAP/CO slope. Methods Cohort study including consecutive pts submitted to CPET-echo with >moderate PMR, no/discordant symptoms, preserved LV function and without >moderate concomitant valvular disease or atrial fibrillation (AF). Thorough assessment of RV systolic function and RVPAc (TAPSE/sPAP ratio) was obtained by echocardiography using a dedicated RV window. mPAP and CO were obtained by Doppler echocardiography. Primary outcome was the composite of all-cause mortality, cardiovascular hospitalization (CVH), new-onset AF and valvular intervention; secondary outcome was the composite of CVH and new-onset AF. Results A total of 128 consecutive pts (64±11 years, 61% men) underwent CPET-echo. Event-free survival rate was 55% and 46% at 1 and 2 years. Pts that reached the primary combined endpoint were significantly older, had larger left atrium indexed volumes (LAVi), higher proportion of grade 4 MR, lower absolute and normalized peak VO2, and a significantly higher mPAP/CO slope (2,1±0,8 vs.3,7±2,6). They had a significantly lower rest and exercise TAPSE/sPAP, RV global and free wall longitudinal strain, rest and exercise TAPSE and exercise RV free wall S’. Rest and low exercise TAPSE/sPAP scored the highest accuracy in predicting the primary combined endpoint among variables statistically significant in the univariate analysis and therefore were used in the multivariate model. Sequentially adding rest and low exercise TAPSE/sPAP significantly improved the baseline predictive model (age, LAVi and MR grade). Low exercise TAPSE/sPAP and LAVi remained as significant independent variables in the multivariate model. They also correlated with new-onset AF and CVH; with rest and low exercise TAPSE/sPAP constituting significant steps (Fig 2). Replacing low exercise TAPSE/sPAP for mPAP/CO slope in the proposed model only slightly improved its accuracy in predicting the primary and secondary composite outcomes. Adding predicted peak VO2 (≥80% vs