Thalidomide-Induced Sinus Bradycardia

OBJECTIVE:To report a case of thalidomide-induced sinus bradycardia in an elderly man.CASE SUMMARY:A 72-year-old white man, with transfusion-dependent refractory anemia with ringed sideroblasts and hypertension treated with atenolol, was started on thalidomide 100 mg at bedtime. During the dose titration period (maximum dose 400 mg/d), his heart rate decreased from a baseline of 63 beats/min to as low as 44 beats/min with positive electrocardiogram findings of sinus bradycardia. After discontinuation of atenolol, the patient's heart rate increased to 68 beats/min, but symptoms of bradycardia persisted. Due to the patient's continued dizziness and lightheadedness, thalidomide was discontinued. In the 3 months following discontinuation of thalidomide, the patient's heart rate increased to an average of 74 beats/min.DISCUSSION:Clinical trials and postmarketing surveillance suggest that the incidence of thalidomide-induced bradycardia is low. The mechanism of this effect is unknown. Concurrent medications aff...