Design and rationale of the Danish trial of beta-blocker treatment after myocardial infarction without reduced ejection fraction: study protocol for a randomized controlled trial

Treatment with beta-blockers is currently recommended after myocardial infarction (MI). The evidence relies on trials conducted decades ago before implementation of revascularization and contemporary medical therapy or in trials enrolling patients with heart failure or reduced left ventricular ejection fraction (LVEF ≤ 40%). Accordingly, the impact of beta-blockers on mortality and morbidity following acute MI in patients without reduced LVEF or heart failure is unclear. The Danish trial of beta-blocker treatment after myocardial infarction without reduced ejection fraction (DANBLOCK) is a prospective, randomized, controlled, open-label, non-blinded endpoint clinical trial designed to evaluate the efficacy of beta-blocker treatment in post-MI patients in the absence of reduced LVEF or heart failure. We will randomize 3570 patients will be randomized within 14 days of index MI to beta-blocker or control for a minimum of 2 years. The primary endpoint is a composite of all-cause mortality, recurrent MI, acute decompensated heart failure, unstable angina pectoris, or stroke. The primary composite endpoint will be assessed through locally reported and adjudicated endpoints supplemented by linkage to the Danish national registers. A number of secondary endpoints will be investigated including patient reported outcomes and cardiovascular mortality. Data from similar ongoing trials in Norway and Sweden will be pooled to perform an individual patient data meta-analysis. DANBLOCK is a randomized clinical trial investigating the effect of long-term beta-blocker therapy after myocardial infarction in patients without heart failure and reduced LVEF. Results from the trial will add important scientific evidence to inform future clinical guidelines. Clinicaltrials.gov, NCT03778554. Registered on 19 December 2018. European Clinical Trials Database, 2018-002699-42, registered on 28 September 2018.