Beta blockers may not be as beneficial after heart attack for some: Study

A new study is challenging the idea that beta blockers help everyone who has experienced a heart attack. Researchers at the Spanish National Center for Cardiovascular Research (CNIC) found beta blockers did not offer a clinical benefit for patients whose heart did not deteriorate after the attack. 

In an international clinical trial done in collaboration with the Mario Negri Institute for Pharmacological Research in Milan called REBOOT, 8,505 patients with a left ventricular ejection fraction above 40% after a heart attack across 109 hospitals in Spain and Italy were analyzed. Patients were randomly chosen regarding whether or not they were given beta blockers after leaving the hospital. 

There were no significant differences between those who got the beta blockers and those who did not when it came to death, recurrent heart attack or hospitalization rates. 

While cardiac contractile function can be reduced after a heart attack, a press release from the CNIC stated that the “vast majority” of patients, 70%, preserve their cardiac function and 20% have moderately reduced function. The REBOOT trial enrolled patients from these groups. 

“While the trial results showed no benefit of beta blockers for the study population overall, the treatment did appear to benefit the patient subgroup with moderately reduced contractile function,” the press release said. “However, this subgroup constituted a relatively small proportion of the study population, and the small sample size prevented the team from drawing firm conclusions on this subgroup.”

To learn more about the subgroup, researchers also went through a joint meta-analysis with other smaller trials,the results of which were published in The Lancet scientific journal. This research did confirm that beta blockers significantly reduced negative outcomes for that subgroup. 

“Taken together, these two studies provide compelling evidence that post-infarction patients with fully preserved contractile function (ejection fraction above 50%) do not benefit from beta blockers, whereas those with moderate or greater dysfunction (ejection fraction below 50%) do,” CNIC scientist Dr. Xavier Rosselló, a cardiologist at University Hospital Son Espases in Mallorca and one of the REBOOT study leaders, said in a statement.

Speaking to ABC News, Dr. Gregg Fonarow, a professor of cardiovascular medicine at the University of California, Los Angeles, said “beta blockers were developed at a time before routine reperfusion therapy for acute heart attacks and the evolution of more potent medications, and care has really evolved.”

Fonarow said if people can continue taking beta blockers safely, they should keep doing so, but more studies are needed to understand which patients can benefit most from them.