BACKGROUND: Myocardial infarction (MI) remains one of the main causes of mortality worldwide. Beta-blockers (BBs) are an essential component in the pharmacological treatment for MI. The long-term role of BB in patients with preserved left ventricular ejection fraction (LVEF) is not yet well established. Thus, we performed a systematic review and meta-analysis to synthesize the impact of long-term use of BB on reducing mortality in patients with preserved LVEF after MI. METHODS: This study adhered to the guidelines outlined by the Cochrane Collaboration and the PRISMA statement. The predefined research protocol was registered in PROSPERO under the ID CRD42024554630. A systematic search was conducted in Embase, the Cochrane Central Register of Controlled Trials, and PubMed for studies published in English up to September 1, 2024, using the succeeding medical subject terms: 'myocardial infarction', 'preserved ejection fraction', and 'beta-blockers'. Data were extracted for: (I) death from any cause
(II) death from cardiovascular causes
(III) MI
(IV) stroke
and (V) hospitalization for heart failure (HF). The risk of bias of each article was analyzed using the tool risk of bias in non-randomized studies of interventions (ROBINS-I) and risk-of-bias tool for randomized trials (RoB2). These outcomes were compared using pooled hazard ratios (HRs) to maintain the integrity of time-to-event data from individual studies. RESULTS: A total of 85,607 patients from 11 studies were included in this meta-analysis, of whom 65,790 (76.8%) were using BBs after MI with preserved ejection fraction. The use of BBs demonstrated a significant reduction in all-cause mortality in the global analysis of the included studies [HR =0.81
95% confidence interval (CI): 0.67-0.98
P=0.03]. However, when performing sensitivity analyses to assess the impact of methodological biases and the robustness of the results, this reduction was no longer significant (HR =0.79
95% CI: 0.62-1.02
P=0.07). Regarding reinfarction, there was no difference between BB users and non-users (HR =1.00
95% CI: 0.92-1.09
P>
0.99). Similarly, hospitalization for HF showed no significant variation between groups (HR =1.05
95% CI: 0.89-1.24
P=0.55). Stroke incidence was also comparable between the groups, though with substantial heterogeneity (I CONCLUSIONS: Long-term BB use in patients with preserved LVEF after MI did not decrease all-cause mortality, cardiovascular mortality, or major adverse cardiac events (MACEs). There was also no identified reduction in hospitalizations for HF, MI, or stroke in the average follow-up of 3 years.