Beta-blockers, such as metoprolol and bisoprolol, block the effects of adrenaline and stress hormones on the heart, slowing it down. During a heart attack, the slowing of the heart reduces the need for oxygen, minimizing damage even when blood flow is restricted.

Patients who did not respond were those whose left ventricle was pumping a normal amount of blood. This is also called preserved left ventricular ejection fraction.

Ejection fraction refers to the percentage of blood pumped out each time the heart beats.

A preserved ejection fraction, or normal ejection fraction, means that the heart’s pumping action is within acceptable limits.

On the other hand, a decreased ejection fraction means that the heart muscle is pumping blood less quickly than it can tolerate. In this study, we defined preserved ejection fraction as 50% or higher.

“Given these findings, [our study] “We challenge the routine prescription of beta-blockers for patients with myocardial infarction with preserved ejection fraction and provide an opportunity to tailor treatment to the individual patient profile,” said the Department of Cardiology at Lund University in Sweden. said Dr. Troels Indigan, an interventionist and lead author of the study. health line.

Keith C. Ferdinand, MD, chair of preventive cardiology at Tulane University School of Medicine, who was not involved in the study, called the study “a great study.”

“We now have more confidence that beta-blockers can be discontinued, especially if left ventricular function is preserved,” he said.

Indigen and his team conducted an open-label trial at 45 sites in Sweden, Estonia, and New Zealand. That is, patients and doctors were aware of the drugs being prescribed.

The study was conducted between 2017 and 2023 on more than 5,000 patients, approximately 95% of whom were from Sweden.

The purpose of the study was to determine whether giving beta-blockers to people who had a heart attack and had preserved ejection fraction would improve health outcomes after a heart attack.

During an average follow-up of 3.5 years, patients in the beta-blocker group had only a 4% lower overall risk of death or another heart attack, and researchers said the results were not significant.

Beta-blockers also had no benefit in other outcomes, including atrial fibrillation, heart failure, and stroke hospitalizations.

“The conventional theory is that beta-blockers should be applied to all patients with acute myocardial infarction if the patient maintains left ventricular function and is treated intensively with appropriate evidence-based therapy. That may not be true in the modern environment,” Avinash Ashrekar, MD, MPH, medical vice chair of the Division of Cardiology at the University of New Mexico, who was not involved in the study, told Healthline.

Experts say that beta-blockers may not be as effective as they once were, as heart attack treatments have improved significantly over the past few decades.

Dr. Ashrekar calls beta-blockers the “torchbearers” of cardiovascular medicine, but much has changed since they were first indicated to treat heart attacks.

The trials and scientific evidence supporting beta-blockers primarily date back to the 1980s, when heart attack treatments were very limited and patient outcomes tended to be worse.

“If you look at older studies, patients have larger myocardial infarctions later on and have lower ejection fractions, and maybe beta-blockers may actually be lifesaving for these patients. Currently, “The earlier you arrive at the hospital, undergo angioplasty, and maintain left ventricular function, the less effective the beta-blockers may be,” Ferdinand said.

Modern treatments that can quickly restore blood flow to the heart during acute myocardial infarction are now standard. Treatments include:

• Antithrombotics – Anticoagulants that can restore blood flow in veins and arteries.
• Angioplasty – A procedure that restores blood flow by guiding a catheter tube through a vein to the blockage and using an inflatable balloon to collapse plaque on the artery wall.

Although the study was very large, its homogeneity (95% of patients were from Sweden and only 22% were women) makes it difficult to apply broadly.

“There is always a reluctance to apply these data to the disparate, racially and ethnically diverse population found in the United States, because Sweden is the overwhelming majority,” Ferdinand said.

Experts agreed that the findings were robust, but more research was needed.

“This is certainly important data to build on,” Achrekar said.

“We will continue to give beta-blockers to this patient population until we find that this is not the case. But if we find that this is not the case, then as we gather more of this science, we will “We may be able to reduce the use of beta-blockers in patients,” he said.

Beta blockers have been used for decades to treat heart attacks and other cardiovascular diseases.

New research shows that in patients with healthy heart function (maintained ejection fraction), beta-blockers have little or no effect.

Major advances in heart attack treatment, such as stenting and anticoagulants, may be part of the reason why beta blockers are no longer as effective.