Unique cardioprotective potential of angiotensin converting enzyme inhibitors: a hypothesis still to be tested on humans.

'Primary cardioprotection' has, arguably, already been shown with thiazide diuretics and probably with beta-blockers. The proven safety and efficacy of these established drugs override any theoretical or experimental considerations in favour of ACE inhibitors. It is unfortunate that, as yet, the number of hypotheses generated in support of ACE inhibitors has not been matched by large scale clinical trials employing these drugs. The first report of the clinical use of an ACE inhibitor was in 1984; it is high time comparative studies with conventional, and proven, agents were undertaken. With regard to 'secondary cardioprotection', there is overwhelming evidence in favour of the use of beta-blockers in patients with myocardial ischaemia. Indeed, we would argue that ACE inhibitors should be used with caution in such patients to avoid impairment of coronary infusion. In the patient with acute myocardial infarction, intravenous nitrates are cheap, easy to use, safe and seem to be effective (in preventing early remodelling and reducing mortality). In the subacute phase, beta-blockers improve prognosis and, according to the currently available evidence in humans, nitrates are as effective as captopril in altering late remodelling; as in the acute situation, nitrates are cheaper, simpler to use and have a track record of long-term safety. ACE inhibitors improve symptoms, exercise capacity and prognosis in chronic heart failure. In this condition, they have been a major therapeutic advance and, on the available evidence, are to be initially preferred to other vasodilators though they should be given in addition to diuretics.(ABSTRACT TRUNCATED AT 250 WORDS)