Effect of enalapril on exercise cardiopulmonary performance in chronic obstructive pulmonary disease : a pilot study

Background: Some studies suggest that the sympathetic nervous system and the renin-angiotensin system are activated in patients with chronic obstructive pulmonary disease (COPD), potentially resulting in negative cardiopulmonary and muscular effects. The aim of this pilot study was to evaluate the efficacy of an angiotensin converting enzyme (ACE) inhibitor on cardiopulmonary exercise performance in COPD patients. Primary outcome was the effect of treatment on the ventilatory response to exercise (VE/VCO2 slope). Secondary outcomes were exercise variables evaluated by the cardiopulmonary exercise test, and pulmonary function according to ACE genotyping. Methods: 4 weeks treatment with enalapril (10 mg od) or placebo was evaluated in 21 COPD patients (FEV1 < 60%) and without cardiovascular disease in a double-blind, cross-over study. Results: 18 patients completed the study. Enalapril did not exert a significant effect on exercise VE/VCO2 slope or on peak O2 consumption. However enalapril significantly improved peak O2 pulse and work rate compared to placebo. A mild but significant worsening of the diffusion capacity of the lung was observed. ACE genotype did not significantly affect patients' response to treatment, except for a trend toward a more evident effect of treatment in patients with II ACE genotype in terms of O2 pulse and gas diffusion. Conclusions: In this pilot study, ACE inhibition did not affect the ventilatory response to exercise in COPD patients. However, treatment resulted in improvement in work rate and O2 pulse, suggesting that ACE inhibitor therapy warrants consideration and may provide beneficial effect on the cardiovascular response to exercise in COPD.