Assessment of Beta-Blocker Induced Bradycardia in Post-Myocardial Infarction Patients: A Dose–Response Analysis

Abstract

Objective: To assess the frequency, severity, and dose–response relationship of beta-blocker–induced bradycardia in post-MI patients and identify associated clinical predictors.

Study Design: Cross-sectional study.
Place and Duration of Study: This study was conducted at the Poonch Medical College, Rawalakot, from June 2024 to June 2025.

Methods: This study included 185 post-MI patients receiving beta-blocker therapy. Patients were grouped by beta- blocker type (metoprolol, bisoprolol, carvedilol) and dosage (low, moderate, high). Heart rate and clinical parameters were monitored during follow-up. Bradycardia was defined as a resting heart rate <60 bpm, with severity categorized as mild (50–59 bpm), moderate (40–49 bpm), or severe (<40 bpm).

Results: The mean age of patients was 59.7 ± 9.8 years, with 136 males (73.5%) and 49 females (26.5%). Hypertension (65.9%) and diabetes mellitus (49.2%) were the most frequent comorbidities. Metoprolol was prescribed in 56.2% of patients, bisoprolol in 28.1%, and carvedilol in 15.7%. Bradycardia occurred in 58 patients (31.4%), including mild in 34 (18.4%), moderate in 19 (10.3%), and severe in 5 (2.7%). The incidence of bradycardia increased significantly with higher doses—12.1% in low-, 36.7% in moderate-, and 62.5% in high-dose groups (p < 0.001). Bisoprolol showed the highest rate of bradycardia (40.4%), followed by metoprolol (29.8%) and carvedilol (24.1%). Independent predictors of bradycardia were high-dose therapy (OR 4.62, 95% CI 2.38–8.95, p <
0.001) and age >65 years (OR 2.13, 95% CI 1.09–4.15, p = 0.03).

Conclusion: Beta-blocker–induced bradycardia is a common, dose-dependent adverse effect in post-MI patients, particularly among elderly individuals and those receiving higher doses.