Effect of angiotensin-converting-enzyme inhibition compared with conventional therapy on cardiovascular morbidity and mortality in hypertension: the Captopril Prevention Project (CAPPP) randomised trial

Background Angiotensin-converting-enzyme (ACE) inhibitors have been used fo r more than a decade to treat high blood pressure, despite the lack of data from randomised intervention trials to show that such treatment affects ca rdiovascular morbidity and mortality. The Captopril Prevention Project (CAP PP) is a randomised intervention trial to compare the effects of ACE inhibi tion and conventional therapy on cardiovascular morbidity mortality in pati ents with hypertension. Methods CAPPP was a prospective, randomised, open trial with blinded endpoi nt evaluation. 10 985 patients were enrolled at 536 health centres in Swede n and Finland. Patients aged 25-66 years with a measured diastolic blood pr essure of 100 mm Hg or more on two occasions were randomly assigned captopr il or conventional antihypertensive treatment (diuretics, beta-blockers). A nalysis was by intention-to-treat. The primary endpoint was a composite of fatal and non-fatal myocardial infarction, stroke, and other cardiovascular deaths. Findings Of 5492 patients assigned captopril and 5493 assigned conventional therapy, 14 and 13, respectively, were lost to follow-up. Primary endpoint events occurred in 363 patients in the captopril group (11.1 per 1000 pati ent-years) and 335 in the conventional-treatment group (10.2 per 1000 patie nt-years; relative risk 1.05 [95% CI 0.90-1.22], p = 0.52). Cardiovascular mortality was lower with captopril than with conventional treatment (76 vs 95 events; relative risk 0.77 [0.57-1.04], p = 0.092), the rate of fatal an d non-fatal myocardial infarction was similar (162 vs 161), but fatal and n on-fatal stroke was more common with captopril (189 vs 148; 1.25 [1.01-1.55 ]. p = 0.044). Interpretation Captopril and conventional treatment did not differ in effic acy in preventing cardiovascular morbidity and mortality. The difference in stroke risk is probably due to the lower levels of blood pressure obtained initially in previously treated patients randomised to conventional therap y.