Swedish researchers have described as outdated the standard practice of prescribing beta-blockers after a heart attack to lessen the risk of a future cardiovascular attack or death, saying there is no significant benefit to this.
In the REDUCE-AMI trial, the scientists randomly assigned participants to receive a beta-blocker after diagnosis of preserved ejection fraction following a heart attack, also called a myocardial infarction.
The findings showed no significant difference in cardiovascular outcomes between the beta-blockers group and the no-beta-blockers group, reports Medical News Today.
The trial abstract appeared in The New England Journal of Medicine.
One measurement of heart health is ejection fraction – or how well the left ventricle of the heart pushes out blood. If the measurement is low, it can indicate heart failure.
In the REDUCE-AMI trial, scientists wanted to find out if beta-blockers reduce the risk of death or another heart attack in people who had a heart attack but still had a normal ejection fraction.
The trial began in September 2017 and ended in May 2023. During that time, the researchers recruited 5 020 people from 45 healthcare centres for the study.
In addition to needing a normal heart ejection fraction, participants also had to have a coronary angiography during their hospital stay. The scientists randomly assigned which participants would take a beta-blocker (metoprolol or bisoprolol) as a long-term treatment, and had a median follow-up of 3.5 years.
They found that the beta-blockers provided no overall benefit to these participants, as any-cause death in the beta-blocker group was 3.9%, and death in the group that did not receive a beta-blocker was 4.1%.
Do beta-blockers improve survival rates?
In the beta-blocker group, 7.9% of the participants experienced what the scientists classified as a “primary outcome” of either death or a new heart attack.
This is only slightly lower than the primary outcomes in the no-beta-blockers group, which was 8.3% of the participants either dying or having a new heart attack.
The scientists do not consider this small difference to be statistically significant.
After taking a closer look at the data, they found that beta-blocker treatment showed no significant benefit in preventing any-cause death, which was 3.9% in the beta-blocker group and 4.1% in the no-beta-blocker group.
They also saw no improvement in the risk of death from cardiovascular causes or hospitalisations for atrial fibrillation (AFib) and heart failure in people who took beta-blockers.
These findings challenge the conventional belief that beta-blockers are universally beneficial after a heart attack.
Lead study investigator Tomas Jernberg, MD, PhD, a cardiology professor and HoD of Clinical Sciences at Karolinska Institutet, said: “I think the guidelines will be changed, and the prescription of beta-blockers will be reduced in patients with a heart attack (myocardial infarction) and a preserved (or normal) heart function – that is, about half of all patients with heart attack.”
However, he said the study was conducted only in patients with normal heart function after a heart attack, and not in people with a reduced ejection fraction.
Another limitation was that it was an open study versus placebo-controlled, but said this should not “affect the primary outcome, death or new myocardial infarction”.
“For patients with reduced heart function or heart failure, we know that beta-blockers improve survival and symptoms.”
Will physicians continue to prescribe beta-blockers?
Dr Cheng-Han Chen, board certified interventional cardiologist and medical director of the Structural Heart Programme at MemorialCare Saddleback Medical Centre in Laguna Hills, California, said: “This single study may not immediately change our long-standing practice regarding beta-blockers in patients with normal left ventricular function after myocardial infarction, but other similar trials are ongoing, which are examining this same question.”
He said not prescribing beta-blockers to patients with normal heart function could reduce the stress of medication management.
Study details
Beta-Blockers after Myocardial Infarction and Preserved Ejection Fraction
Troels Yndigegn, Bertil Lindahl, David Erlinge et al.
Published in The New England Journal of Medicine on 7 April 2024
Abstract
Background
Most trials that have shown a benefit of beta-blocker treatment after myocardial infarction included patients with large myocardial infarctions and were conducted in an era before modern biomarker-based diagnosis of myocardial infarction and treatment with percutaneous coronary intervention, antithrombotic agents, high-intensity statins, and renin–angiotensin–aldosterone system antagonists.
Method
In a parallel-group, open-label trial performed at 45 centres in Sweden, Estonia, and New Zealand, we randomly assigned patients with an acute myocardial infarction who had undergone coronary angiography and had a left ventricular ejection fraction of at least 50% to receive either long-term treatment with a beta-blocker (metoprolol or bisoprolol) or no beta-blocker treatment. The primary end point was a composite of death from any cause or new myocardial infarction.
Results
From September 2017 through May 2023, a total of 5020 patients were enrolled (95.4% of whom were from Sweden). The median follow-up was 3.5 years (interquartile range, 2.2 to 4.7). A primary end-point event occurred in 199 of 2508 patients (7.9%) in the beta-blocker group and in 208 of 2512 patients (8.3%) in the no–beta-blocker group (hazard ratio, 0.96; 95% confidence interval, 0.79 to 1.16; P=0.64). Beta-blocker treatment did not appear to lead to a lower cumulative incidence of the secondary end points (death from any cause, 3.9% in the beta-blocker group and 4.1% in the no–beta-blocker group; death from cardiovascular causes, 1.5% and 1.3%, respectively; myocardial infarction, 4.5% and 4.7%; hospitalization for atrial fibrillation, 1.1% and 1.4%; and hospitalization for heart failure, 0.8% and 0.9%). With regard to safety end points, hospitalisation for bradycardia, second- or third-degree atrioventricular block, hypotension, syncope, or implantation of a pacemaker occurred in 3.4% of the patients in the beta-blocker group and in 3.2% of those in the no–beta-blocker group; hospitalization for asthma or chronic obstructive pulmonary disease in 0.6% and 0.6%, respectively; and hospitalization for stroke in 1.4% and 1.8%.
Conclusions
Among patients with acute myocardial infarction who underwent early coronary angiography and had a preserved left ventricular ejection fraction (≥50%), long-term beta-blocker treatment did not lead to a lower risk of the composite primary end point of death from any cause or new myocardial infarction than no beta-blocker use.
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