Introduction Skeletal muscle impairment is a well recognised complication of COPD, predicting mortality in severe disease.1 Evidence from animal models, genetic studies and observational cohorts suggest a role for the renin-angiotensin system in control of muscle phenotype.2 We hypothesised that angiotensin-converting enzyme (ACE) inhibition would have a beneficial effect on quadriceps function in patients with COPD.
Methods A single-centre, double-blind randomised controlled parallel-group trial investigating the effect of fosinopril versus placebo on quadriceps muscle dysfunction in COPD patients with quadriceps weakness. Muscle weakness was defined as a quadriceps maximum voluntary contraction (QMVC) less than 120% of the body mass index.1
Measurements The primary outcome was change in non-volitional quadriceps endurance at 3 months, measured using repetitive magnetic stimulation. QMVC, mid-thigh CT cross-sectional area (MTCSA), incremental shuttle walk distance (ISWD) and serum inflammatory markers were secondary outcomes.
Results 80 patients were enrolled (mean(SD), 65(8) years, FEV1 43(21)% predicted, 53% male). 67 patients (31 fosinopril and 36 placebo) completed the trial, with the treatment group demonstrating a significant reduction in systolic blood pressure (Δ-10.5mmHg, 95%CI –19.9 to –1.1, p=0.03) and serum ACE activity (Δ-20.4units/L, 95%CI –31.0 to –9.8, p<0.001) compared to placebo. At 3 months, no significant difference was observed in quadriceps muscle endurance half-time (fosinopril Δ5.1s, 95%CI –4.3 to 14.5, p=0.27 vs. placebo Δ4.6s, 95%CI –5.8 to 15.1, p=0.37; between group Δ0.5s, 95%CI –13.3 to 14.3, p=0.94). QMVC improved significantly in both groups (fosinopril Δ1.1kg, 95%CI 0.03 to 2.2, p=0.045 vs. placebo Δ3.6kg, 95%CI 2.1 to 5.0, p<0.0001) with a greater increase in the placebo arm (between group Δ2.5kg, 95%CI 0.7 to 4.3, p<0.01). There was no significant change in MTCSA (p=0.09), ISWD (p=0.51) or serum inflammatory markers (C-reactive protein, p=0.17) between the groups. Stratification based on ACE genotype did not influence study outcomes.
Conclusion This randomised controlled trial found that ACE-inhibition did not improve quadriceps function in a COPD population with quadriceps weakness. Study funded by the Medical Research Council. Trial registration: NCT01014338.
Swallow EB, et al. Thorax 2007; 62:115–20.
Shrikrishna D, et al. Clin Sci 2012; 123:487–98.
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.