Cardiovascular Outcomes in High-Risk Patients without Heart Failure Treated with ARBs
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- Al Khalaf, M.M., Thalib, L. & Doi, S.A.R. Am J Cardiovasc Drugs (2009) 9: 29. doi:10.1007/BF03256593
Background and objective
Angiotensin II type 1 receptor antagonists (ARBs) are widely used as a substitute for angiotensin-converting enzyme inhibitors (ACEIs) to treat patients without heart failure, but their effect on cardiovascular morbidity and mortality has not been clearly determined. A systematic review and metaanalysis was undertaken to determine the impact of ARBs on cardiovascular outcomes in high-risk patients without heart failure.
A computerized literature search was carried out using PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, and EMBASE, from January 1990 to April 2008. The following search terms were used: ‘hypertension’, ‘clinical trial’, ‘sartan’, ‘ARB’, ‘angiotensin receptor antagonist’, ‘losartan’, ‘candesartan’, ‘valsartan’, ‘irbesartan’, ‘eprosartan’, ‘telmisartan’, ‘olmesartan’, ‘coronary disease’, ‘coronary heart disease’, ‘myocardial infarction’, ‘cardiovascular disease’, ‘cerebrovascular disease’, and ‘stroke’. Criteria for inclusion of clinical trials in our meta-analysis were the use of a randomized control group not receiving an ARB and the availability of outcome data for any one of four endpoints: myocardial infarction (MI), stroke, cardiovascular death, and all-cause death (these were not always pre-specified endpoints in all trials). Out of 45 potentially relevant studies, 37 trials met the inclusion criteria. We tabulated all occurrences of these four adverse outcomes.
Homogenous subgroups were combined by means of a fixed-effects model, while heterogenous subgroups were not combined. In the subgroup without heart failure, ARBs, when compared with the control group, had an odds ratio of 1.09 (95% CI 1.00, 1.18; p = 0.05) for MI. Other endpoints, namely, cardiovascular death and all-cause death, did not reach statistical significance. There was a clear trend for fewer strokes in the ARB group, but these studies were clearly heterogenous, and therefore a pooled risk estimate was not computed.
After pooling more than 89 000 patients, there is no evidence to suggest that ARBs confer cardiovascular protection akin to ACEIs, and the results that emerged are not in favor of ARB therapy in terms of its use as a substitute for ACEIs in non-heart failure patients. ARBs may have a small benefit in terms of stroke risk, but the studies are heterogenous, making it very difficult to quantify this effect. Given that ACEIs protect against both stroke and MI, caution is advised in the use of ARBs as a substitute for ACEIs in patients without a heart failure indication, who are tolerant of an ACEI.