Abstract Body (Do not enter title and authors here): Background: The efficacy of beta-blockers (BB) in patients with heart failure and reduced ejection fraction (EF) is well established. In fact, current guidelines widely recommend BB use after myocardial infarction (MI). However, the effects of long-term BB therapy in patients with acute myocardial infarction (AMI) and preserved EF remains uncertain.

Hypothesis: The use of BB after AMI improves long-term outcomes in patients with preserved EF.

Aims: To compare the long-term effects of BB with non-BB post AMI in patients with preserved EF.

Methods: PubMed, Embase, and Cochrane Library were systematically searched from inception to May 2024 to identify studies comparing BB with no BB use after AMI in patients with preserved EF (>50%), with a minimum follow-up of 1 year. We pooled hazard ratios (HR) with 95% confidence intervals (CI) to preserve time-to-event data in the pooled analysis. Statistical analyses were performed using R software version 4.3.1.

Results: We included two randomized controlled trials and eight cohorts comprising 25,357 patients, of whom 47% received BB and 52% were men. Mean age of patients ranged from 58 to 66.2 years. Follow-up ranged from 1 to 5.2 years. There were no significant differences between groups in all-cause mortality (HR 0.86; 95% CI 0.68-1.08; p=0.20; Figure 1A), myocardial infarction (HR 1.02; 95% CI 0.84-1.24; p=0.86; Figure 1B), or hospitalization for heart failure (HR 1.06; 95% CI 0.78-1.43; p=0.71; Figure 1C). However, when performed a leave-one-out sensitivity analysis in all-cause mortality we saw significant results favoring the use of BB after omitting each study.

Conclusion: In this meta-analysis, there were no significant differences in all-cause mortality, myocardial infarction, or hospitalization for heart failure when comparing long-term use of BB with no BB use after AMI in patients with preserved EF. Further trials are needed to clarify the role of BB in this setting.