Beta-blocker interruption effects on blood pressure and heart rate after myocardial infarction: the AβYSS trial

Abstract Background and Aims This study aims to report the effects of β-blocker interruption on blood pressure (BP) and heart rate (HR) in the AβYSS trial where patients were randomized to interruption or continuation of β-blocker treatment after a myocardial infarction (MI). Methods Changes in HR and BP from baseline to post-randomization are reported using linear mixed repeated model, in the 3698 patients of the AβYSS trial with a median follow-up of 3.0 years. Additionally, changes in HR and BP and the impact on the primary endpoint (death, MI, stroke, hospitalization for cardiovascular reason) in the pre-specified subgroups of patients with or without history of hypertension were assessed using linear mixed repeated and adjusted Cox proportional hazards model, respectively. Results β-blocker interruption was associated with significant increase {least square mean difference [95% confidence interval (CI)]} in systolic BP [+3.7 (2.6, 4.8) mmHg, P < .001], diastolic BP [+3.3 (2.6, 4.0) mmHg, P < .001], and resting HR [+10 [9, 11) b.p.m., P < .001] at 6 months that persisted over the duration of follow-up despite an increase in antihypertensive drugs in the β-blocker interruption group. The effects were observed in both hypertensive (43% of the population) and non-hypertensive patients. Hypertensive patients were at higher risk of events (25.8% vs. 19.2%) as compared with patients without hypertension (adjusted hazard ratio 1.18, 95% CI 1.01–1.36, P = .03). Patients with hypertension had a particularly marked increase in the primary endpoint (risk difference 5.02%, 0.72%–9.32%, P = .014) when randomized to β-blocker interruption. Conclusions Interruption of β-blocker treatment after an uncomplicated MI led to a sustained increase in BP and HR, with potentially deleterious effects on outcomes, especially in patients with history of hypertension.