Beta-blocker therapy after acute coronary syndrome in patients without heart failure or reduced ejection fraction: A target-trial emulation study

AIMS: The benefits of β-blockers in patients with acute coronary syndromes (ACS) without chronic heart failure (HF) or left ventricular ejection fraction (LVEF) < 40% remain uncertain. We evaluated the association between β-blocker therapy and clinical outcomes in a multicenter, contemporary ACS registry. METHODS: In the START-ANTIPLATELET registry (NCT02219984), patients were excluded if they had HF or LVEF <40%. Participants were stratified according to β-blocker use at discharge after ACS. A target trial emulation and inverse probability of treatment weighting (IPTW) were used. The primary endpoint was a composite of all-cause death or myocardial infarction (MI) at 1 year. RESULTS: The primary analysis included 1,315 patients with ACS without HF or LVEF <40%, of whom 949 (72.2%) were discharged on β-blockers. At 1 year, the primary endpoint occurred in 21 (2.2%) patients receiving β-blockers versus 13 (3.6%) without β-blockers, and no significant association was observed (unweighted HR 0.63, 95% CI 0.31-1.26; p = 0.192; IPTW-adjusted HR 0.66, 95% CI 0.33-1.33; p = 0.249). Exploratory subgroup analyses suggested a potentially more favourable association of β-blocker therapy in patients with ST-segment elevation MI (p-interaction=0.049), although this finding was not uniformly reproduced across sensitivity analyses. CONCLUSIONS: In a contemporary real-world cohort of ACS patients without HF or LVEF <40%, β-blocker therapy was prescribed in approximately 70% of patients and was not associated with a lower 1-year risk of death or MI.