People who experience a heart attack that is not classed as severe may not benefit from taking long-term beta blockers, a heartbeat-stabilizing drug commonly prescribed as a long-term treatment for people who experience myocardial infarction.
The results of the REBOOT trial, presented at the European Society of Cardiology Conference this week in Madrid and published in NEJM, showed that long-term beta blockers were not helpful for preventing future cardiovascular events in people who have a milder heart attack (classed as having a left ventricular ejection fraction above 40% after treatment).
The same researchers, based at Spain’s National Center of Cardiovascular Research (CNIC) in Madrid, also showed in a sub study published in the European Heart Journal that long term use of these drugs could be harmful in women who experience heart attack but not men.
“Beta-blockers have long been a foundational treatment after acute myocardial infarction; their use was initially supported by the results of early randomized trials, which showed a 23% lower risk of death among patients who received beta-blockers than among those in control groups at two years,” write senior investigator Borja Ibáñez, MD, PhD, CNIC’s scientific director, and colleagues.
“However, these trials were conducted in an era that predates what is now modern standard care—routine reperfusion, invasive management, complete revascularization, and potent adjunctive therapies such as dual antiplatelet therapy and statins.”
The REBOOT trial included 8,438 patients—aged 61 years on average and 19% female—who experienced acute myocardial infarction (with or without ST-segment elevation) who had a left ventricular ejection fraction above 40%. Half these individuals were randomly assigned to follow up treatment with a beta blocker and half with no beta blocker.
After a median of 3.7 years of follow up, 316 patients in the beta blocker group and 307 in the no beta blocker group died from any cause, or had a reinfarction, or hospitalization for heart failure. This difference between groups was not statistically significant, suggesting that beta blockers were not beneficial to these patients.
In the sub study, which looked specifically at outcomes by sex, women had a 45% increased risk for adverse cardiovascular events or death from any cause if they were prescribed beta blockers versus no beta blockers after their initial heart attack. Men in the study had no significant increase or decrease in risk linked to taking beta blockers.
The increased risk in women seemed to be mostly linked to increased mortality and higher doses of beta blockers.
“REBOOT will change clinical practice worldwide,” said Ibáñez, who presented the results at the conference, in a press statement. “Currently, more than 80 percent of patients with uncomplicated myocardial infarction are discharged on beta blockers. The REBOOT findings represent one of the most significant advances in heart attack treatment in decades.”
Notably, another smaller study also presented at the same conference and published in NEJM did show a small improvement in outcomes in patients who experienced heart attack and a left ventricular ejection fraction of at least 40% who were prescribed beta blockers. Although the analysis was carried out on all patients, the most benefit was gained by patients with a left ventricular ejection fraction of 40-50%.