Whether beta-blocker therapy at discharge improves outcomes for patients with ST-segment elevation myocardial infarction (STEMI) treated with contemporary percutaneous coronary intervention (PCI) and drug-eluting stents (DES) remains uncertain, particularly in the absence of reduced left ventricular ejection fraction. Risk-guided prescribing using the Global Registry of Acute Coronary Events (GRACE) score may identify patients most likely to benefit.

We performed a retrospective analysis of two nationwide Korean AMI registries (KAMIR-NIH, 2011-2015; KAMIR-V, 2016-2020). Adults with STEMI who underwent successful PCI with DES and were discharged alive were included; patients with failed PCI, bare-metal stents, balloon-only interventions, in-hospital death, NSTEMI, or missing key data were excluded. The primary outcome was all-cause death at 1 and 3 years; secondary outcomes included major adverse cardiac events (MACE: all-cause death, myocardial infarction, any repeat revascularization) and component endpoints. Associations were evaluated in crude cohorts and after propensity-score matching (PSM); heterogeneity of treatment effect (HTE) across baseline risk used inverse-probability-of-treatment-weighted (IPTW) models with GRACE modeled continuously. GRACE discrimination for 6-month mortality was assessed by ROC analysis, with prespecified risk strata at <85 and ≥180.

Among 13,397 eligible STEMI survivors, 12,861 (83.8%) received a beta-blocker at discharge. In crude analyses, beta-blocker prescription was associated with lower 1-year all-cause death (1.8% vs. 4.4%; HR, 0.40; 95% CI, 0.30-0.52) and MACE (5.4% vs. 8.5%; HR, 0.62; 95% CI, 0.51-0.74). After PSM (n=1,802 per group), 1-year all-cause death remained lower (2.7% vs. 4.2%; HR, 0.63; 95% CI, 0.44-0.91) and MACE was reduced (6.0% vs. 8.3%; HR, 0.71; 95% CI, 0.55-0.92). At 3 years, point estimates favored beta-blockers but were attenuated (death HR, 0.84; 95% CI, 0.64-1.10; MACE HR, 0.85; 95% CI, 0.70-1.03). GRACE showed good 6-month discrimination; HTE analyses demonstrated minimal absolute benefit below GRACE 85, increasing benefit from ~90 to a peak at ~150-170, and attenuation at higher scores. In the prespecified strata, benefits were consistent in GRACE 85-180, whereas effects were trivial in GRACE <85.

In revascularized STEMI survivors, beta-blocker prescription at discharge was associated with lower 1-year mortality and MACE, with attenuation by 3 years. Benefit varied markedly by GRACE risk: negligible in low-risk patients (GRACE <85) and greatest in intermediate-risk ranges. These findings support a risk-guided approach to post-MI beta-blockade that complements ejection-fraction-based decisions.