Benefit of beta blockers in patients with MI and preserved LVEF comes under question

medwireNews: Long-term beta-blocker treatment does not reduce the risk for any-cause death or new myocardial infarction (MI) compared with no betablocker use in patients with an acute MI, preserved left ventricular ejection fraction (LVEF), and obstructive coronary artery disease, suggests the REDUCE-AMI trial. However, treatment crossover between the beta-blocker and no beta-blocker groups in the open-label, parallel-group trial may have contributed to the null finding, note the researchers in The New England Journal of Medicine. For the study, conducted at 38 centers in Sweden, six in New Zealand, and one in Estonia, Troels Yndigegn (Lund University, Sweden) and colleagues enrolled 5020 patients at 1 to 7 days (median 2 days) after an MI, who had a LVEF of 50% or more and obstructive coronary artery disease, as documented by coronary angiography. The investigators randomly assigned the participants to receive either daily oral selective beta-1 receptor blockers (n=2508) or no beta blockers (n=2512) for the remainder of their hospital stay and after discharge until the occurrence of a contraindication. Metoprolol, at a median target dose of 100 mg/day, was the first choice of beta blocker; bisoprolol, at a median target dose of 5 mg/day, was the alternative, and these choices were reflective of their extensive use in the countries involved, explain the researchers. Patients assigned to the no beta-blocker group were discouraged from using beta blockers if there was no other indication for their use. Patients assigned to the no beta-blocker group who were already on beta-blocker treatment when enrolled were tapered off their beta blockers over 2 to 4 weeks. The participants had a median age of 65.0 years, 77.5% were men, and 35.2% had an ST-segment elevation MI. On admission to hospital, 11.6% of the patients were receiving beta blockers. Obstructive coronary artery disease was revealed in one vessel for 55.4% of patients, in two vessels for 27.0% of patients, and in three vessels for 16.6%. Percutaneous coronary intervention was performed in 95.5% of the patients. “[B]eta-blocker treatment did not result in a lower cumulative incidence of the composite primary end point of death from any cause or new myocardial infarction,” say the researchers. After a median follow-up of 3.5 years, the primary end point occurred in 7.9% of patients in the beta-blocker group, at an annual rate of 2.4%, and in 8.3% of patients in the no beta-blocker group, at an annual rate of 2.5%, a nonsignificant difference. Likewise, the team notes that beta-blocker treatment “did not appear to lead to a lower cumulative incidence of the secondary end points of death from any cause, death from cardiovascular causes, myocardial infarction, hospitalization for atrial fibrillation, and hospitalization for heart failure.” The occurrence of the safety endpoints was also similar between the beta-blocker and no beta-blocker groups, namely hospitalization for bradycardia, second- or third-degree atrioventricular block, hypotension, syncope, or implantation of a pacemaker (3.4 vs 3.2%, respectively), hospitalization for asthma or chronic obstructive pulmonary disease (0.6 vs 0.6%), and hospitalization for stroke (1.4 vs 1.8%). After 1 year of follow-up, around 18% of patients assigned to receive beta blockers had stopped taking them, and around 14% of those assigned to the no beta-blocker group had started taking them. A finding that Philippe Gabriel Steg, from Universite Paris-Cite in France, says in a related editorial “indicates that the crossover issue is not negligible.” Current guidelines widely recommend beta-blocker use after MI, despite “the lack of clear evidence of benefit in the contemporary setting,” say Yndigegn et al. However, they also note that in their trial, patients were generally “at low risk for new cardiac events,” and that the annual event rates were lower than they had expected before starting the trial, which was powered to detect a 25% lower risk for death or MI with beta blockers versus no beta blockers. Steg cautions that the trial cohort consisted of patients with near-normal LVEF who had undergone revascularization and received excellent care. He emphasizes that the results should therefore “not be applied to higher-risk patients, such as those with [an LVEF] below 50% or those who have not undergone revascularization.” Steg concludes: “Given the difficulty of unambiguously showing an absence of benefit with beta-blocker therapy and the limitations of a single, somewhat underpowered, open-label trial, it may be too early to cut beta-blockers from the ‘secondary prevention team’ definitively.” The trial was also presented at the American College of Cardiology Scientific Sessions 2024 in Atlanta, Georgia, USA. medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2024 Springer Healthcare Ltd, part of the Springer Nature Group N Engl J Med 2024; 390: 1372–1381 N Engl J Med 2024; 390: 1434–1436 ACC 2024; Atlanta, Georgia, USA: 6–8 April

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Benefit of beta blockers in patients with MI and preserved LVEF comes under question

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