Influence of prior ACE inhibitor therapy on morbidity and mortality following acute myocardial infarction

BACKGROUND: Angiotensin-converting enzyme inhibitor (ACE-I) therapy reduces complications of acute myocardial infarction (MI) even when the therapy is started very early after an acute event. This study sought to determine whether administration of ACE-I therapy prior to acute MI is related to subsequent patient morbidity and mortality. METHODS: Chart review of 318 consecutive patients admitted between September 1995 and December 1996 with a diagnosis of acute MI. Outcome data were compared between patient groups receiving ACE-I therapy prior to infarction and those who were not. RESULTS: Sixty-four patients (20%) were receiving prior ACE-I therapy. They experienced smaller MIs, as determined by peak creatine kinase elevation (1066 +/- 134 vs. 1510 +/- 95 IU; p < 0.05), and fewer Q-wave infarctions (p < 0.05) than did patients who were not receiving prior treatment. The severity of coronary artery disease, defined by an angiographic score, was similar for the two groups. Mortality rates, including patients resuscitated from ventricular fibrillation, were similar within the first 72 hours of admission (3% vs. 2%; p = NS), but patients receiving prior ACE-I therapy showed a greater long-term in-hospital mortality rate (14% vs. 5%; p < 0.05) related to more heart failure deaths. Multivariate logistic regression analysis identified age, treatment with digoxin prior to acute MI, and left ventricular ejection fraction after infarction, but not ACE-I therapy taken prior to infarction, as significant independent predictors of mortality and combined morbidity and mortality. CONCLUSIONS: In a group of patients experiencing an acute MI, those receiving prior ACE-I therapy were more likely to sustain fewer transmural MIs and smaller infarcts.Chronic ACE-I therapy may have cardioprotective effects during acute myocardial ischemia.