Effect of calcium channel blockers evaluated by cardiopulmonary exercise testing in idiopathic pulmonary arterial hypertension responding to acute pulmonary vasoreactivity testing

BackgroundThe baseline exercise capacity evaluated by cardiopulmonary exercise testing (CPET) and the change after administration of calcium channel blockers (CCB) therapy in patients with vasodilator-responsive idiopathic pulmonary arterial hypertension (VR-IPAH)are unknown.Methods25 patients with newly diagnosed VR-IPAH from 1 January 2012 to 16 November 2015 were prospectively enrolled, and 28 age, sex and pulmonary vascular resistance matched newly diagnosed patients with vasodilator-nonresponsive idiopathic pulmonary arterial hypertension (VNR-IPAH) were enrolled. CPET was performed before and after 3.5 ± 0.8 months of CCB or sildenafil therapy.ResultsVentilatory efficiency at rest, anaerobic threshold (AT), and peak were significantly higher (lower in V˙E/V˙CO2@AT and higher in PETCO2@AT) in VR-IPAH group than that in VNR-IPAH group. Peak V˙O2 (13.9 ± 2.9 mL kg−1·min−1 vs 16.4 ± 4.1 mL kg−1·min−1, p = 0.001), peak O2 pulse (5.5 ± 0.8 mL min−1·beat−1 vs 6.9 ± 1.3 mL min−1·beat−1, p = 0.001), V˙E/V˙CO2@AT (34.2 ± 5.0 vs 31.6 ± 3.1, p = 0.02) and PETCO2@AT (33.1 ± 4.0 mmHg vs 35.3 ± 3.2 mmHg, p = 0.02) were significantly improved after high dose of CCB therapy, along with improvement of WHO functional class, 6-min walking distance, NT-proBNP and tricuspid regurgitation pressure gradient.ConclusionsVentilatory efficiency in patients with VR-IPAH is better than that in patients with VNR-IPAH. CCB can improve aerobic capacity and ventilatory efficiency during exercise in patients with VR-IPAH.Clinical trial registration number: ClinicalTrials.gov:NCT02061787.