A risk-benefit assessment of ACE inhibitor therapy post-myocardial infarction.

The use of ACE inhibitors in patients with myocardial infarction (MI) has been the subject of several studies conducted during recent years. These studies have demonstrated the capacity of these agents to improve both survival and morbidity of patients with MI. However, the use of ACE inhibitors in patients with MI has been shown to reduce blood pressure (BP) and so could jeopardise the ischaemic myocardium. A significant reduction in systemic BP has been demonstrated by all the studies of ACE inhibitors in patients with MI, but no relationship has been found between the occurrence of hypotension and a worse clinical outcome. An increased risk of death has been observed exclusively in association with severe and sudden hypotension, the occurrence of which can be largely prevented by the administration of the ACE inhibitor according to an increasing dose-titration scheme. Conversely, a certain degree of long term BP reduction could result in some beneficial effect in patients with MI and contribute to the lower incidence of re-infarction observed in patients with acute MI undergoing long term treatment with captopril. Since the renin-angiotensin system is strictly related to kidney function, its blockade by an ACE inhibitor could result in some degree of renal dysfunction, particularly in patients with MI and impaired ventricular function. The available results from large-scale studies suggest that abnormalities in kidney function (namely an increase in serum creatinine) are observed in 0.9 to 2.4% of patients with MI who, nevertheless, experience some benefit from treatment with ACE inhibitors. Interestingly, the administration of ACE inhibitors does not seem to further compromise severely impaired renal function, and may also represent a useful tool for the treatment of patients with renal dysfunction associated with MI. The use of ACE inhibitors in patients with MI is associated with a satisfactory clinical and laboratory safety profile. The occurrence of significant adverse effects seems to be very low and mainly attributable to a rather modest prevalence of cough (2.4 to 6.8%). Discontinuation of treatment because of biochemical and haematological abnormalities has been observed in less than 1% of treated patients. Thus, the beneficial effects of ACE inhibitor treatment seem to outweigh safety concerns, thereby reinforcing the role of ACE inhibition as a suitable therapeutic strategy in the treatment of patients with MI.