Long-Term Treatment with Angiotensin-Converting Enzyme Inhibitors, Beta-Blockers or a Combination of Angiotensin-Converting Enzyme Inhibitors and Beta-Blockers in Low-Risk Patients after Acute Myocardial Infarction: The ABC Study

Background: Therapy with angiotensin-converting enzyme (ACE) inhibitors and beta-blockers improves the prognosis of patients with impaired ventricular function, and of patients with symptoms of heart failure after acute myocardial infarction. Long-term treatment strategies for low-risk patients after acute myocardial infarction have not as yet been elucidated by clinical studies. Objective: The objective of this study is to deliver evidence of a possible additional, long-term effect from the combination of ACE inhibitors and beta-blockers, as compared with monotherapy with ACE inhibitors or beta-blockers, for patients after acute myocardial infarction but with only slightly restricted left ventricular function, and without symptoms of heart failure. Methods: In 160 patients who have suffered myocardial infarction, but do not have appreciable impairment of left ventricular ejection fraction, i.e. ejection fraction ≥40%, or symptoms of heart failure, we shall administer either monotherapy with ramipril or metoprolol, or combination therapy in the form of ramipril and metoprolol. The primary end point will be the left ventricular ejection fraction after 18 months. Secondary end points will be mortality, arrhythmia, cardiac stress tolerance, development of heart failure and the need for revascularization.