Prognosis and Natural History of Drug-Related Bradycardia

BACKGROUND AND OBJECTIVES The prognosis and natural history of bradycardia related to drugs such as beta-blockers and non-dihydropyridine calcium channel blockers are not well known. SUBJECTS AND METHODS We retrospectively analyzed 38 consecutive patients (age 69+/-11, 21 women) with drug-related bradycardia (DRB) between March 2005 and September 2007. A drug-associated etiology for the bradycardia was established based on the medical history and patient response to drug discontinuation. The mean follow-up duration was 18+/-8 months. RESULTS The initial electrocardiogram (ECG) showed sinus bradycardia (heart rate </=40/min) in 13 patients, sinus bradycardia with junctional escape beats in 18 patients, and third-degree atrioventricular (AV) block in seven patients. Drug discontinuation was followed by resolution of bradycardia in 60% of patients (n=23). Among them, five (17.8%) patients resumed taking the culprit medication after discharge and none developed bradycardia again. Bradycardia persisted in 10 (26.3%) patients despite drug withdrawal, and a permanent pacemaker was implanted in seven of them. Third-degree AV block, QRS width, and bradycardia requiring temporary transvenous pacing were significantly associated with the bradycardia caused by drugs. CONCLUSION Beta-blockers were the most common drugs associated with DRB. However, in one quarter of the cases the DRB was not associated with drugs; in these patients permanent pacemaker implantation should be considered.