Heart Rate and Cardiovascular Outcomes in Post–Myocardial Infarction Patients Treated by β-Blockers: A Secondary Analysis of the ABYSS Trial

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BACKGROUND: Heart rate (HR) is a key prognostic factor after myocardial infarction (MI), but its relevance in the modern reperfusion era is uncertain. We aim to evaluate the association between HR and β-blocker interruption on cardiovascular outcomes. METHODS: A prespecified secondary analysis of the ABYSS trial (Assessment of Beta-Blocker Interruption 1 Year After an Uncomplicted Myocardial Infarction), including 3698 stable post-MI patients (left ventricular ejection fraction ≥40%) randomized to continue or interrupt β-blockers, was conducted. Patients were grouped by prerandomization HR tertiles: <60 bpm (T1), 60 to <68 (T2), and ≥68 (T3). We examined associations between HR, treatment strategy, and the primary endpoint (death, MI, stroke, or cardiovascular rehospitalization), major secondary endpoints, and on-treatment HR. RESULTS: trend=0.008). β-Blocker interruption produced a dose-dependent HR increase of ≈10-13 bpm during follow-up. The association between interruption and worse outcomes was consistent across HR tertiles (no significant interaction) and LVEF categories (40% to 49% and >50%). CONCLUSIONS: In stabilized post-MI patients with preserved ejection fraction, higher HR remains associated with adverse cardiovascular events and mortality in the reperfusion era. Interrupting β-blockers substantially increases HR and is consistently linked with worse outcomes irrespective of baseline HR, supporting continuation of β-blocker therapy.