Effect of angiotensin-converting enzyme inhibition on C-reactive protein levels: the ramipril C-reactive pRotein randomized evaluation (4R) trial results.

Background: Plasma levels of the inflammatory biomarker C-reactive protein (CRP) predict cardiovascular risk and may represent a target for treating and/or monitoring risk-reduction strategies. The effect of angiotensin-converting enzyme inhibitors on CRP levels has not been adequately studied.

Methods: A total of 264 men and women, with CRP levels of 2 mg/L or greater and no history of cardiovascular disease, were enrolled in a 12-week randomized, double-blind, placebo-controlled study. Participants were randomly assigned to receive 10 mg/day of ramipril (n=132) or placebo (n=132) for 12 weeks. The main outcome measure was the change in CRP levels from baseline to 12 weeks in the ramipril- versus placebo treated patients.

Results: The mean (+/- SD) age was 53+/-9 years (60% men). Baseline demographics were similar between the volunteers allocated to receive either placebo or ramipril. The geometric mean CRP at baseline was 3.84 mg/L (95% CI 3.62 mg/L to 4.06 mg/L). The percentage change in geometric mean CRP values over 12 weeks was --13.2% (95% CI --22.3% to --3.2% ) in the placebo group compared with --21.1% (95% CI --29.9% to --11.2%) in the ramipril group (P nonsignificant), indicating no significant reduction in the primary end point of the trial.

Conclusions: A 12-week ramipril treatment protocol for healthy middle-aged volunteers did not lower CRP levels compared with placebo. However, because of the inherent variability of CRP levels, a much larger study is required to exclude a small treatment effect.