Optimal duration of medical therapy for patients with acute myocardial infarction

Abstract

Optimal medical therapy, including Beta-blockers (BB), inhibitors of the renin-angiotensin system (RAS), and statins, is recommended for patients with acute myocardial infarction (AMI) in the absence of contraindications. However, the optimal duration of these medications has not been clearly established in clinical studies. This observational study aimed to investigate the period during which these medications are associated with improved clinical outcomes. Among patients enrolled in the Korea Acute Myocardial Infarction Registry-National Institute of Health (KAMIR-NIH), in-hospital survivors were selected. In a Cox-proportional hazard analysis of 12,200 patients, BB (hazard ratio [HR] = 0.73; 95% confidence interval [CI] = 0.57-0.95; P = .019), RAS inhibitors (HR 0.70; 95% CI = 0.55-0.89; P = .004), and statins at discharge (HR = 0.65; 95% CI = 0.48-0.87; P = .004) were all associated with lower 1-year cardiac mortality. At 1-year, 10,613 patients without all-cause death, myocardial infarction, revascularization, or re-hospitalization due to heart failure were selected for further analysis. RAS inhibitors (HR = 0.53; 95% CI = 0.37-0.76; P = .001) and statins (HR = 0.30; 95% CI = 0.14-0.61; P = .001) prescribed at 1-year were associated with lower 2-year cardiac mortality, whereas BB were not (HR = 0.79; 95% CI = 0.51-1.23; P = .23). However, none of these medications prescribed at 2-years were associated with reduced 3-year cardiac mortality among the 9232 patients who remained event-free until then. RAS inhibitors and statins were associated with reduced cardiac mortality for up to 2-years, and BB for up to 1-year after the initial attack. The effectiveness of these medications beyond these periods remains questionable.

Figure 1.

Selection of patients for analysis. BB, beta-blockers; Echo, echocardiography; KAMIR-NIH, Korean Acute Myocardial Infarction Registry-National Institute of Health; MACE, major adverse cardiac events; RASI, inhibitors of the renin-angiotensin system.

Figure 2.

Unadjusted Kaplan–Meier curves, adjusted hazard ratio (HR) and 95% confidence interval (CI) for 3-yr cardiac death. (A) Beta-blockers (BB). (B) Renin-angiotensin system inhibitors (RASI). (C) Statins.

Figure 3.

Adjusted hazard ratio and 95% confidence interval (CI) for 3-yr cardiac death according to initial left ventricular ejection fraction (EF). (A) Beta-blockers (BB). (B) Renin-angiotensin system inhibitors (RASI). (C) Statins.

Figure 4.

1- and 2-yr landmark analysis for cardiac death: unadjusted Kaplan–Meier curves, adjusted hazard ratio (HR) and 95% confidence interval (CI) for cardiac death. (A) Beta-blockers (BB). (B) Renin-angiotensin system inhibitors (RASI). (C) Statins.