Renin-angiotensin-aldosterone system blockers and cardiovascular outcomes: a meta-analysis of randomized clinical trials

OBJECTIVE
Hypertension is the most prevalent modifiable risk factor for cardiovascular (CV) and cerebrovascular morbidity and mortality. This study aimed to assess the effects of renin-angiotensin-aldosterone system (RAAS) blockade on CV outcomes.

METHODS
This study was designed according to the Preferred Reporting Items for Systemic reviews and Meta-Analyses statement. Databases were searched for articles published as of December 2014. Two sets of studies were selected. One set included randomized clinical trials comparing RAAS blocker (angiotensin II receptor blocker [ARB] or angiotensin-converting enzyme inhibitor [ACEI]) with placebo or active treatment. Second set included head-to-head randomized clinical trials comparing an ARB with an ACEI. Studies in both sets had reported any CV outcome parameter or death, i.e., all-cause mortality, CV mortality, emergence of CV events, myocardial infarction, cerebrovascular event, stroke, heart failure, and hospitalization for heart failure.

RESULTS
Fifty-four pairwise comparisons of 51 trials with 277,609 patients were included. Statistically significant differences in favor of RAAS blockers vs non-RAAS blockers (risk ratio [RR] ranging from 0.805 to 0.967) were observed in terms of most CV outcomes, including all-cause mortality, CV mortality, CV events, myocardial infarction, heart failure and stroke. ARBs and ACEIs were found to be completely comparable (RR ranging from 0.923 to 1.090, all non-significant).

CONCLUSION
RAAS blockers are superior to medications other than RAAS blockers with respect to impact on CV outcomes in patients with hypertension. ARBs and ACEIs are comparable in terms of these outcomes.