Impaired right ventricular lusitropy is associated with ventilatory inefficiency in PAH

Cardiopulmonary exercise testing (CPET) is an important tool to assess functional capacity and prognosis in pulmonary arterial hypertension (PAH). However, the association of CPET parameters with the adaptation of right ventricular (RV) function to afterload remains incompletely understood. Thirty-seven patients with PAH (idiopathic in 31 cases) underwent single-beat pressure-volume loop measurements of RV end-systolic elastance (Ees), arterial elastance (Ea) and diastolic elastance (Eed). They also underwent magnetic resonance imaging of pulmonary arterial stiffness. The results were correlated to CPET variables. Predictive relevance of RV function parameters for clinically relevant ventilatory inefficiency, defined as minute ventilation/carbon dioxide production (VE/VCO2) slope >48, was evaluated using logistic regression analysis. Median [interquartile range] of VE/VCO2 slope was 42 [32–52], of VE/VCO2 nadir was 40 [31–44], and mean±sd of peak end-tidal CO2 tension (PETCO2) was 23±8 mmHg. Ea, Eed and parameters reflecting pulmonary arterial stiffness (capacitance and distensibility) were correlated to VE/VCO2 slope, VE/VCO2 nadir, PETCO2 and peak oxygen pulse. RV Ees and RV-arterial coupling as assessed by the Ees/Ea ratio showed no correlations with CPET parameters. Ea (univariate odds ratio: 7.28; 95% confidence interval: 1.20–44.04) and Eed (univariate odds ratio: 2.21; 95% confidence interval: 0.93–5.26) were significantly associated with ventilatory inefficiency (p Our data suggest that impaired RV lusitropy and increased afterload are associated with ventilatory inefficiency in PAH.