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 ß-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 ß-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: Median age in the study population was 63.5 years (55.9-71.1), and there were 621 women (17.1%). Baseline HR was not associated with the primary endpoint (22.4% versus 21.8% versus 21.6%; P=0.867). Higher HR was associated with increased risk of death, MI, or stroke (5.5% versus 6.4% versus 9.2%; P<0.001; T3 versus T1 adjusted hazard ratio, 1.55; 95% CI, 1.14-2.12) and death, MI, stroke, or heart failure (6.5% versus 7.1% versus 10.4%; P=0.007; T3 versus T1 adjusted hazard ratio, 1.47; 95% CI, 1.11-1.97). All-cause mortality rose across tertiles (2.9% versus 3.4% versus 5.9%; P=0.004; P trend=0.008). ß-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 ß-blockers substantially increases HR and is consistently linked with worse outcomes irrespective of baseline HR, supporting continuation of ß-blocker therapy.
| Discipline Area | Score |
|---|---|
| Family Medicine (FM)/General Practice (GP) |  |
| General Internal Medicine-Primary Care(US) | |
| Internal Medicine | |
| Cardiology | |
Stopping a B-blocker in post-MI patients, considering withdrawal after 1+ year, should be carefully discussed as a shared decision with the patient, particularly if they are stable and tolerating well. Any discontinuation should be gradual and monitored. Discontinuation increases pulse rate, which is an independent risk factor for cardiovascular events. It is also an opportunity to address ongoing optimization of secondary prevention, e.g., smoking, lipids, diabetes, and CKD.
Using beta-blockers post-MI is controversial. This study suggests continuing them.
