Assessment of exercise tolerance using cardiopulmonary exercise test in patients with chronic obstructive pulmonary disease and secondary pulmonary arterial hypertension treated with Sildenafil versus those receiving only standard-of-care

Abstract

Pulmonary arterial hypertension (PAH) is a common complication of chronic obstructive pulmonary disease (COPD), which can lead to shorter survival and poor clinical outcomes. Patients suffering from PAH display a cardiopulmonary exercise testing (CPET) profile with several atypical factors, such as decreased work rate, limited ability to do aerobic activities, and ventilatory insufficiency. To assess and compare exercise tolerance by CPET in COPD patients with secondary PAH receiving cGMP-specific phosphodiesterase type-5 (PDE-5) inhibitor (sildenafil) versus those who are receiving standard-of-care only. This is a prospective, cross-sectional research in which a total of 30 COPD patients with mild to severe obstruction and secondary PAH were recruited; all patients were treated with standard-of-care treatment for COPD; moreover, half of the recruited patients were also on sildenafil 60 mg/day for at least 3 months at the time of recruitment (sildenafil users) as specific therapy for PAH while the other half were not (non-users). All patients underwent CPET to assess their exercise capacity. No significant statistical differences were observed between sildenafil users and non-users in all CPET parameters except in respiratory exchange ratio (RER) during both exercise and recovery with sildenafil users showing a lower RER in both phases compared to non-users (p = 0.02, 0.01, respectively). Also, resting diastolic blood pressure (DBP) was significantly lower in sildenafil users (p = 0.02). In addition, sildenafil users did not exhibit significant differences compared to non-users in terms of Modified Medical Research Council (mMRC) score, COPD assessment test (CAT) score, or spirometric parameters. Our findings suggest that there were no significant differences in overall exercise capacity, nor in symptoms or spirometric parameters between COPD patients with secondary PAH receiving sildenafil and those who were not.