Impact of left ventricular ejection fraction on the effect of beta-blocker therapy on one-year mortality in acute coronary syndrome patients.

While the beneficial effect of beta-blocker (BB) therapy for acute coronary syndrome (ACS) patients with left ventricular ejection fraction (LVEF) <40% is established, its role in those with LVEF >40% is controversial. We assessed the relationship between BB therapy at discharge and one-year mortality according to LVEF in a large contemporary ACS cohort. Patients enrolled in the Acute Myocardial Infarction in Switzerland (AMIS plus) registry between 2005 and 2024 with information on BB at discharge, LVEF, and one-year mortality were studied. The association between BB therapy and one-year mortality and the interaction with LVEF (>40% versus ≤40%) were analyzed. Among 7820 patients (65% with ST segment elevation myocardial infarction), 1570 (20.1%) had LVEF ≤40%. At discharge, 6211/7820 (79.4%) patients were on BB (LVEF >40%: 78.1%, LVEF ≤40%: 84.5%). One-year mortality was higher in patients with LVEF ≤40% versus >40% (7.1% versus 2.3%; p<0.001). Overall, BB therapy was associated with reduced mortality [unadjusted odds ratio 0.67 (95% confidence interval 0.51-0.89), p=0.005]. Among patients with LVEF ≤40%, mortality was lower in patients with BB compared to those without (5.9% versus 14%; p<0.001). In contrast, in patients with LVEF >40%, mortality did not differ between patients with and without BB (2.1% versus 2.6%; p=0.3). A statistically significant interaction between BB therapy and LVEF stratum was identified (pinteraction=0.02). Data from our large, nationwide registry suggest an overall benefit of BB therapy at discharge on one-year mortality in ACS with most of the survival advantage observed in patients with LVEF <40%.