In a recent study published in New England Medical JournalResearchers conducted the Randomized Evaluation of Reducing Beta-Blocker Use After Acute Myocardial Infarction (REDUCE-AMI) trial and found that long-term oral beta-blocker treatment reduced the risk of myocardial infarction-related death from any cause or accident. I decided whether it was possible. Despite acute myocardial infarction, the left ventricular ejection fraction was maintained compared to the case without β-blocker treatment.

Study: Beta-blockers and preservation of ejection fraction after myocardial infarction. Image credit: aipicte / Shutterstock

background

Beta-blockers are beneficial in the treatment of patients with heart failure or reduced ejection fraction. However, these findings came from clinical trials in the 1980s in patients with large myocardial infarctions and systolic dysfunction in the left ventricle. A meta-analysis study showed that beta-blockers do not appear to reduce mortality with modern reperfusion techniques.

Data from recent randomized clinical studies on the efficacy of long-term use of beta-blockers in patients with acute myocardial infarction with intact ejection fraction are lacking. Previous Cochrane reviews have highlighted the need for new research in this target population. Despite the lack of convincing scientific evidence regarding the effectiveness of drug therapy, current recommendations strongly recommend beta-blocker therapy after myocardial infarction.

About research

In the current open-label, prospective, parallel-group study, researchers evaluated the impact of beta-blocker therapy on reducing mortality in patients with acute myocardial infarction.

The team conducted the registry-based trial at 45 sites in New Zealand, Sweden and Estonia from September 2017 to May 2023. Researchers enrolled participants with a history of acute myocardial infarction who underwent coronary angiography and had an ejection fraction of 50% or higher from the left ventricle to receive metoprolol ≥100 mg/day or ≥5 mg/day. were randomly assigned to receive 1:1 long-term treatment with beta-blockers. administration of bisoprolol (intervention group) or no such treatment.

All participants had obstructive coronary heart disease (i.e., stenosis ≥50%, flow reserve ≤0.8, or Flow Reserve ≤0.9), as determined from pre-randomization coronary angiography. instantaneous waveless segment ratio). The primary endpoint was a composite measure of all-cause or myocardial infarction-related mortality. Secondary outcomes included cardiovascular disease-related mortality and hospitalization for atrial fibrillation or heart failure.

Safety outcomes included hospitalizations for hypotension, second- and third-degree atrioventricular block, bradycardia, syncope, or pacemaker implantation, chronic obstructive pulmonary disease (COPD), asthma, or stroke. Masu.Other endpoints included dyspnea [diagnosed using the New York Heart Association (NYHA) recommendations] Angina pectoris (diagnosed using Canadian Cardiovascular Society guidelines) 6 to 10.0 weeks or 11.0 to 13.0 months after treatment. The team used Cox proportional hazards regression to determine the hazard ratio (HR) for the analysis. They performed sensitivity analyzes adjusting for age, country, diabetes, and history of myocardial infarction. The Swedish Population Register provides data on deaths or migration, and the Swedish Web System (SWEDEHEART) registers collected data on the occurrence of myocardial infarction. The National Cause of Death Registry provided data on cardiovascular-related mortality, and the National Patient Registry provided data on atrial fibrillation, heart failure, and safety outcomes.

result

Researchers enrolled 5,020 myocardial infarction patients (95% Swedish) and followed them for a median of 3.50 years until November 16, 2023. The median age of participants was 65.0 years, 23% were female, and 35% had had a myocardial infarction, with a high incidence of myocardial infarction. ST segment. Of the participants, 46% had hypertension, 14% had diabetes, and 7.1% had a previous myocardial infarction. Of the 2,508 patients receiving beta-blockers, 1,560 (62%) received metoprolol and 948 (38%) received bisoprolol.

Coronary angiography showed 1 vessel involvement in 55% of MI patients, 2 vessel involvement in 27% of patients, and 3 vessel involvement in 17% of patients. The research team performed percutaneous coronary intervention in 96% of patients, and 3.9% underwent coronary artery bypass grafting (CABG). At discharge, 97% received aspirin, P2Y12 receptor antagonists, angiotensin-converting enzyme (ACE) inhibitors, and statins.

Researchers observed the primary endpoint in 7.9% (199 of 2,508) of beta-blocker users and 8.3% (208 of 2,512) of non-users (HR, 0.96). Beta-blockers did not reduce the cumulative incidence of secondary endpoints (all-cause mortality, 3.90% and 4.10% for beta-blocker and non-beta-blocker users, respectively). Cardiovascular disease-related mortality rates were 1.50% and 1.30%, respectively. myocardial infarction, 4.50% and 4.70%; hospitalization for atrial fibrillation, 1.10% and 1.40%; hospitalization for heart failure, 0.80% and 0.90%).

Regarding safety endpoints, researchers observed hospitalization for atrioventricular block, bradycardia, syncope, hypotension, or pacemaker implantation in 3.40% of beta-blocker recipients and 3.20% of non-recipients. Hospitalizations due to COPD or asthma were 0.60% and 0.60%, respectively, and hospitalizations due to stroke were 1.40% and 1.80% among beta-blocker users and non-users, respectively. Subgroup analyzes yielded similar results.

Overall, the study results showed that in patients with acute myocardial infarction who underwent coronary angiography, long-term use of beta-blockers did not reduce the risk of all-cause or myocardial infarction-related death, although ejection fraction from myocardial infarction ≥ 50% was maintained. Left ventricle compared with no treatment with beta-blockers.