Overview

• REBOOT, a randomized trial of 8,505 patients at 109 hospitals in Spain and Italy, found no difference in death, recurrent myocardial infarction, or heart‑failure hospitalization over nearly four years when beta blockers were routinely prescribed after uncomplicated MI with ejection fraction above 40%.
• A prespecified REBOOT analysis reported higher risk for women on beta blockers, including a 2.7% absolute increase in mortality, concentrated in those with fully preserved ejection fraction of 50% or higher, while men showed no excess risk.
• Investigators noted that women in the trial were older, had more comorbidities, more non‑obstructive infarctions, and were less often prescribed some guideline secondary‑prevention therapies, contextualizing the sex‑specific outcomes.
• A separate Scandinavian trial, BETAMI–DANBLOCK, reported fewer non‑fatal repeat heart attacks with beta blockers but no mortality benefit, highlighting divergent results across contemporary studies.
• A pooled analysis published in The Lancet indicated benefit for patients with mildly reduced ejection fraction (about 40–49%), reinforcing calls to reassess guidelines and tailor post‑MI beta‑blocker use by cardiac function and sex.