Abstract 10129: Long-Term Prescription of Beta-Blockers After Myocardial Infarction with Preserved Left Ventricular Function is Associated with Reduction in Recurrent ACS but Not Repeat Revascularization or All-Cause Mortality

Abstract

Background: Beta-blockers (BB) are cornerstones of medical therapy for acute coronary syndromes (ACS). However, benefits of long-term treatment with preserved left ventricular ejection fraction (LVEF) are not well established. We examined whether long-term BB prescription is associated with risks of recurrent ischemic events or all-cause mortality in patients with LVEF>50% after ACS. Methods: We conducted a retrospective observational study in Alberta, Canada by linking data from provincial databases (APPROACH, echo, discharge and pharmacy). We included patients with NSTEMI or STEMI between 2008-2017, in-hospital LVEF≥50%, who survived ≥180 days after index discharge and had a new prescription for a BB post ACS. We used adjusted Cox proportional hazards models to determine the association between duration of BB therapy (dichotomized at 180 days) and the primary composite outcome of recurrent ACS, repeat revascularization or all-cause mortality ≥180 days after index ACS. Secondary outcomes were the components of the composite. Results: Of 4,768 included patients (mean age 62.0y, 28.1% female), 1155 (24.2%) discontinued BB before 180 days. During a median follow up time of 56.6 months, 964 patients (20.2%) had a primary outcome event. In the overall population, early BB discontinuation was not associated with an increased risk of the primary outcome (adjusted HR 1.13, 95% CI:0.99-1.29 p=0.07) but was associated with the secondary outcome of recurrent ACS (HR 1.43; 95% CI: 1.164-1.756, p<0.001). In the subgroup with STEMI (n=2,428) early BB discontinuation was associated with increased risk of the primary outcome (HR 1.27; 95% CI: 1.054-1.524, p=0.01), again driven by recurrent ACS. Early BB discontinuation was not associated with secondary outcomes of receipt of repeat revascularization or all-cause mortality. Conclusion: In patients discharged after ACS with preserved LVEF, continuation of BB beyond 180 days was not associated with a reduced risk of the composite primary outcome overall, though subgroup analysis suggested a benefit in the subgroup with STEMI, and in the secondary outcome of recurrent ACS. Large-scale randomized trials are required to clarify the appropriate duration of BB therapy after ACS in patients with preserved LVEF.