Overview

• REBOOT randomized 8,505 post–myocardial infarction patients with ejection fraction above 40% across 109 hospitals in Spain and Italy and found no reduction in death, reinfarction or heart‑failure hospitalization over roughly four years with beta blockers versus none.
• A prespecified analysis reported higher rates of death, recurrent heart attack or heart‑failure hospitalization in women prescribed beta blockers, including a 2.7 percentage‑point higher mortality over follow‑up.
• The excess risk in women appeared concentrated in those with normal ejection fraction (≥50%) and at higher beta‑blocker doses, while men showed no significant difference in outcomes.
• Results were presented at the European Society of Cardiology congress in Madrid and published in the New England Journal of Medicine, with the sex‑specific substudy in the European Heart Journal.
• Investigators announced a joint meta‑analysis of randomized trials to refine ejection‑fraction– and sex‑specific guidance, noting some data suggest benefit when ejection fraction is 40–49%, and clinicians advise patients not to stop medications without medical guidance.