WHAT HAVE THE ACE-INHIBITOR TRIALS IN POSTMYOCARDIAL PATIENTS WITH LEFT-VENTRICULAR DYSFUNCTION TAUGHT US

A series of elegant experimental studies and careful clinical observat ion over a decade or more have led to the concept of 'infarct expansio n' and 'remodelling' of the heart, culminating in a number of major mo rtality studies indicating the effectiveness of angiotensin-converting enzyme (ACE) inhibitors in patients after myocardial infarction (MI). But has this concept been too narrow in predicting which patients mig ht benefit from treatment with ACE inhibitors? Measurable infarct-expa nsion with progressive dilatation probably occurs in less than 20% of patients, whereas increase in volume and hypertrophy of the heart as r esponses to compromised function are likely wherever significant myoca rdial damage has occurred. Irrespective of infarct expansion, cumulati ve extensive damage can lead to an inevitable downward spiral with gro ss ventricular dilatation and death in heart failure. But in the major ity of patients after MI a 'new equilibrium' is established in which i nitial dilatation and subsequently hypertrophy restore adequate functi on. Is it possible to distinguish patients in whom the cost and inconv enience of long-term therapy with an ACE inhibitor justify the likely benefit from treatment after an MI? The SAVE, AIRE and recent TRACE st udies allow a rational approach for the clinician, indicating the effe ctiveness of these drugs in patients with evidence of impaired ventric ular function. However, the prospect that ACE inhibitors prescribed lo ng term might also prevent myocardial reinfarction could justify wider use. Post-MI patients are an easily identifiable high-risk group for a cost-effective programme of secondary prevention. Reinfarction in an already damaged ventricle carries a particularly poor prognosis and i ts prevention by ACE inhibitors could make a major contribution to the undoubted benefit from these agents. The recently completed TRACE stu dy with its long-term follow-up may help resolve this issue, which is also being investigated in a number of long-term prospective studies i n populations at high risk of cardiovascular disease.