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

Abstract

Background: The 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.

Methods: 25 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.

Results: Ventilatory 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.

Conclusions: Ventilatory 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.

Keywords: Calcium channel blockers; Cardiopulmonary exercise testing; Diltiazem (PubChem CID: 2162); Diltiazem (PubChem CID: 39186); Idiopathic pulmonary arterial hypertension; Sildenafil (PubChem CID: 5212); Vasoreactivity testing.