Treatment Effect of Beta-Blocker Therapy After Acute Myocardial Infarction With Preserved or Mildly Reduced Ejection...

Long-term use of beta-blockers has been the standard of care after acute myocardial infarction (AMI), but evidence comes largely from pre-reperfusion-era trials in patients with reduced left ventricular ejection fraction (LVEF). With modern reperfusion and optimal secondary prevention, the benefit in patients with preserved and mildly reduced LVEF remains uncertain. Most guidelines continue to recommend routine beta-blocker use in this population, yet no prior meta-analysis has been restricted to recent randomized controlled trials (RCTs). The objective of this article was to evaluate the efficacy and safety of beta-blocker versus no beta-blocker therapy after AMI in patients with preserved or mildly reduced LVEF. The Cochrane Central, PubMed, Embase, and ClinicalTrials.gov were searched for RCTs that compared beta-blocker versus no beta-blocker therapy after AMI in patients with preserved LVEF (≥50%) or mildly reduced LVEF (40-49%). The primary outcome was major adverse cardiovascular events (MACE); secondary outcomes included all‑cause mortality, cardiac death, myocardial infarction (MI), unplanned revascularization, heart failure (HF) events, malignant ventricular arrhythmia, and stroke. Trial sequential analysis (TSA) was performed to assess the conclusiveness of the evidence and whether further trials are warranted. Four RCTs comprising 19,826 patients (BB (beta blocker), n = 9892; no BB, n = 9934) were included. Beta-blockers did not significantly reduce MACE (RR 0.95, 95% CI 0.87-1.03). No difference was observed in all-cause mortality (RR 0.98, 95% CI 0.86-1.13), cardiac death (RR 1.15, 95% CI 0.88-1.51), MI (RR 0.88, 95% CI 0.75-1.04), unplanned revascularization (RR 1.01, 95% CI 0.88-1.16), HF events (RR 0.83, 95% CI 0.64-1.08), malignant ventricular arrhythmia (RR 0.84, 95% CI 0.47-1.50), or stroke (RR 1.18, 95% CI 0.85-1.64). Heterogeneity was low across outcomes. TSA demonstrated that the cumulative evidence for all-cause mortality, unplanned revascularization, and malignant ventricular arrhythmia was conclusive, while MACE and other outcomes remain inconclusive. In AMI patients with preserved or mildly reduced LVEF, beta-blockers did not reduce ischemic events, mortality, or arrhythmia. TSA suggests that additional trials are unlikely to alter conclusions for mortality and revascularization, but uncertainty persists for composite outcomes.