Purpose: Angiotensin converting-enzyme (ACE) inhibitors decrease mortality after myocardial infarction among patients with depressed left ventricular function. Beta blockers may also improve survival in these patients. We compared the relative effects of these agents on the survival of elderly patients with a left ventricular ejection fraction less than 40% after myocardial infarction.
Subjects and methods: The Cooperative Cardiovascular Project collected data on patients aged 65 years and older who were admitted with myocardial infarction from April 1994 to July 1995, including 20,902 with a measured left ventricular ejection fraction less than 40% before discharge. Using proportional hazard regression models that adjusted for patient characteristics and in-hospital treatments, we compared survival among patients discharged on ACE inhibitors, beta blockers, both medications, or neither medication.
Results: Among patients surviving hospitalization with reduced left ventricular function, 9,108 (44%) were discharged on ACE inhibitors, 2,613 (13%) on beta blockers, 3,309 (16%) on both medications, and 5,872 (28%) on neither medication. Patients treated with ACE inhibitors were more likely to have a prior diagnosis of heart failure and less likely to have undergone revascularization, whereas those treated with beta blockers were more often treated with thrombolytic therapy and aspirin. Patients treated with ACE inhibitors [hazard ratio (HR = 0.80), 0.80; 95% confidence interval (CI), 0.73 to 0.87] or beta blockers (HR = 0.76, 0.76; 95% CI, 0.64 to 0.90) had lower adjusted 1-year mortality than those who were not treated with either medication. The combination of both medications was associated with additional benefit (HR = 0.68, 0.68; 95% CI, 0.59 to 0.80). The relative benefit of each medication was greatest among patients with an ejection fraction less than 30%, a serum creatinine level 2.0 mg/dL or greater, or both. To prevent a death within a year, the number of patients who needed to be treated with both medications varied from 5 to 15, depending on ejection fraction and renal function.
Conclusion: ACE inhibitors and beta blockers were associated with similar improvements in survival among elderly patients with reduced left ventricular ejection fraction after myocardial infarction. Our results suggest that patients who can tolerate both medications gain additional benefit from the combination.