In a randomised trial, stopping beta blockers was judged as possibly inferior to continuing them for secondary prevention.

Findings from the large, open-label, randomised REDUCE-AMI trial published earlier this year showed no benefit of beta blockers for secondary prevention in patients who had undergone revascularisation for acute myocardial infarction (MI) and had a left ventricular ejection fraction (LVEF) of 50% or greater (NEJM JW Cardiol Apr 8 2024 and N Engl J Med 2024; 390: 1372-1381). Now, results are available from another open-label, randomised trial examining beta blocker interruption versus continuation post-acute MI (ABYSS; NCT03498066).

The trial included 3698 patients with an LVEF of 40% or greater who were receiving beta blocker therapy after acute MI. None had a recent cardiovascular event or chronic heart failure. Beta blocker interruption of at least six months after MI did not improve patient-reported quality of life and did not meet criteria for non- inferiority compared with beta blocker continuation for preventing a composite primary outcome of death, nonfatal MI, nonfatal stroke or hospitalisation for cardiovascular reasons. During a median follow up of three years, the primary outcome occurred in 24% of patients interrupting beta blocker use and 21% of those continuing it.

Comment: Unequivocally, beta blockers were a game changer for reducing mortality after a heart attack in the 1980s, but their impact seems to be less significant today. Although the REDUCE-MI and ABYSS trials give us some reassurance about not using beta blockers after MI in patients with preserved LVEF, unfortunately, their open-label design leaves room for doubt. As we await more conclusive evidence that could update our guidelines, I find myself reflecting on how best to approach this medical decision with my patients. I have to consider how well they can tolerate beta blockers on top of other medications needed for long-term care of their coronary artery disease, and any chronic ischaemic symptoms. It is a balancing act, and I rely on openly review- ing specific risks and potential benefits with each patient to guide us through this uncertainty.

Vlad G. Zaha, MD, PhD, FAHA, FACC, Associate Professor of Medicine/Cardiology, Biomedical Engineering and Cancer Biology; Section Chief, Cardio-Oncology; Program Director, Cardio-Oncology Fellowship; Director, Cardio-Oncology Program, Harold C. Simmons Cancer Center, UT Southwestern Medical Center, Dallas, USA.

Silvain J et al. Beta-blocker interruption or continuation after myocardial infarction. N Engl J Med 2024 Aug 30; e-pub (https:// doi.org/10.1056/NEJMoa2404204).

The summary is taken from the following Journal Watch title: Cardiology