Angiotensin-II receptor antagonists (ARBs) are as effective as ACE inhibitors in patients with established, or at high risk of, CVD, a large study has found.

The ONTARGET study enrolled 25,620 patients with coronary heart disease, diabetes, peripheral artery disease or cerebrovascular disease. Patients with heart failure were excluded. After a run-in period to exclude patients with poor compliance and those who experienced side-effects, participants were randomised to ramipril 10mg per day (initially 5mg per day), telmisartan 80mg per day, or a combination of both drugs.

The median duration of follow-up was 56 months. The primary endpoint was a composite of cardiovascular death, MI, stroke, or hospitalisation for heart failure.

Throughout the study period, mean blood pressure reduction was marginally greater in the telmisartan and combination groups than the ramipril group (mean reductions 0.9/0.6mmHg and 2.4/1.4mmHg greater than the ramipril group respectively).

There was no significant difference in the primary endpoint between the groups (telmisartan vs ramipril RR=1.01, 95% CI 0.94-1.09; combination vs ramipril RR=0.99, 95% CI 0.92-1.07). There was also no significant difference observed in all-cause mortality or in any of the individual endpoints. The telmisartan group had a lower incidence of cough and angiooedema but a higher incidence of hypotensive symptoms compared with the ramipril group. The combination group had a higher incidence of hypotensive symptoms, syncope, renal dysfunction and hyperkalaemia compared with the ramipril group.

ONTARGET is a large and important study but has not thrown up any surprises. It has shown that telmisartan is an equally effective alternative to ramipril in high-risk patients; however, there appears to be no added advantage in using ACE inhibitor/ARB combination therapy.

In practical terms, this study provides reassurance that substituting an ARB for an ACE inhibitor in patients intolerant to ACE inhibitors is an effective strategy.