Study Finds Beta Blockers May not Help After Heart Attack

What are beta-blockers?

Beta-blockers, which include drugs like metoprolol and bisoprolol, work by blocking the effects of adrenaline and stress hormones on the heart, causing it to slow down. During a heart attack, slowing down the heart reduces its need for oxygen, which can help to limit damage when there is restricted blood flow.

Which patients did not benefit from beta-blockers?

The patients that did not see a benefit were those that had the normal amount of blood pumping via the left ventricle. This is also called preserved left ventricular ejection fraction.

Ejection fraction refers to the percentage of blood pumped out by the heart every time it beats.

Preserved ejection fraction, or normal ejection fraction, means that the heart’s pumping is within an acceptable range.

Reduced ejection fraction, on the other hand, means that the heart muscle is pumping out blood at a reduced rate that is below an acceptable range. The study defined preserved ejection fraction as 50% or greater.

“In light of these findings, [our study] challenges the routine prescription of beta-blockers for myocardial infarction patients with preserved ejection fraction and provides an opportunity to tailor treatments to individual patient profiles,” Troels Yndigegn, M.D. an interventional cardiologist at Lund University in Sweden, and lead author of the study, told Healthline.

Keith C. Ferdinand, MD, Chair of Preventative Cardiology at Tulane University School of Medicine who wasn’t affiliated with the research, called it, “an excellent study.”

“It gives us greater confidence that especially if the left ventricular function has been preserved, beta blockers can be discontinued,” he said.

Beta-blocker’s benefit was not statistically significant

Yndigegn and his team conducted an open-label trial, meaning patients and doctors were aware of the drugs being prescribed, across 45 centers in Sweden, Estonia, and New Zealand.

The study took place between 2017 and 2023, including more than 5,000 patients, some 95% of whom were from Sweden.

The goal of the study was to determine if giving beta blockers to individuals presenting with a heart attack and preserved ejection fraction improved health outcomes following the event.

During an average 3.5 year follow-up period, patients in the beta-blocker group showed only a 4% lower combined risk of death or another heart attack, an outcome that the researchers said wasn’t significant.

Nor did beta blockers lead to benefits for other outcomes, including hospitalization for atrial fibrillation, heart failure, or stroke.

“The conventional theory that beta blockers should be applied to everyone with acute myocardial infarction may not be true in the modern setting when patients have preserved left ventricular function and are treated intensively with appropriate evidence-based therapies,” Abinash Achrekar, MD, MPH, Executive Vice Chair of Medicine in the division of cardiology at the University of New Mexico who wasn’t affiliated with the research, told Healthline.

How heart attack treatment has improved

Experts say that improvements to heart attack treatment have made serious advances in the past decades, which is why beta-blockers may no longer be as effective as in the past.

Achrekar calls beta blockers a “torch bearer,” in cardiovascular medicine, but that much has changed since they were first indicated for heart attack treatment.

The trials and scientific evidence in support of beta-blockers come primarily from the 1980s, a time in which heart attack treatments were quite limited, and patients tended to have worse outcomes.

“You look at the older studies, patients show up later with bigger myocardial infarctions, more reduced ejection fraction, maybe the beta blockers are indeed life-saving for these patients. Today, if you get to the hospital quicker, get an angioplasty, and your left ventricular function is preserved, the beta-blockers may have less benefit,” said Ferdinand.

Modern therapies that are quickly able to restore blood flow to the heart during an acute myocardial infarction, are now standard. They include treatments such as:

• Antithrombotics – anti-clotting medication that can restore blood flow through veins and arteries.
• Angioplasty – a procedure in which a catheter tube is guided through a vein to the site of a blockage and, using an inflatable balloon, restores blood flow by squishing the plaque against the walls of the artery.

Why experts aren’t going to give up on beta-blocker treatment

While the study size was quite large, its homogeneity — 95% of patients were from Sweden and only 22% were women — makes it hard to apply broadly.

“With the overwhelming majority in Sweden, there’s always some hesitancy applying these data to the heterogeneous, racially, ethnically diverse population seen in the United States,” said Ferdinand.

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

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

“We still continue to give beta blockers in this patient population until we know otherwise. But if we do know otherwise, by collecting more of this science, we may start to use less beta blockers in this patient population,” he said.

The bottom line

Beta-blockers have been used in the treatment of heart attacks and other cardiovascular disease for decades.

Novel research now indicates that in patients with healthy heart functioning (preserved ejection fraction), beta blockers offer little to no benefit.

Major advancements in heart attack treatment, such as stenting and anti-clotting medications, are likely part of why beta blockers are no longer as effective.