Evaluation of β-Blocker-Induced Bradyarrhythmia Using an Analysis of the Japanese Adverse Drug Event Report Database

β-Adrenergic receptor blockers (β-blockers) are used to treat hypertension, ischemic heart disease, chronic heart failure, and tachyarrhythmia. The main side effects of treatment include bradycardia, atrioventricular block, and hypotension. Bradycardia may result in pacemaker implantation as well as the discontinuation of β-blockers. Bradycardia is difficult to confirm at a single institution because it diagnosed only by symptoms when electrocardiogram (ECG) are not routinely performed. Previous studies reported an increase in bradycardia in heart failure patients treated with β-blockers; however, limited information is currently available for non-heart failure patients. Bradycardia induced by β-blockers has not yet been comprehensively examined. Therefore, the present study investigated data on the incidence and duration of bradyarrhythmia caused by β-blockers using the Japanese Adverse Drug Event Report database (JADER). Cases of adverse effects associated with this medication were extracted from JADER and Fisher's exact test was performed to assess whether each β-blocker caused bradyarrhythmia. In addition, only data from patients who reported bradyarrhythmia after β-blocker treatment were extracted, and the Weibull distribution was used to analyze the time-to-onset of bradyarrhythmia. Thirteen β-blockers caused bradyarrhythmia and signals were observed for 12 drugs, except nadolol. Bradyarrhythmia induced by oral β-blockers was more likely to be of the early failure type, and developed within 2 months of treatment initiation with most β-blockers. A comprehensive analysis of bradyarrhythmia with β-blockers suggests that careful monitoring is needed, particularly early in the initiation of treatment.