Symptomatic Second-Degree Atrioventricular Block Due to Thalidomide

Due to its anti-inflammatory, anti-angiogenic, and immunomodulatory effects, thalidomide is increasingly used in the treatment of various diseases. Previous studies have demonstrated that thalidomide may cause sinusal bradycardia. Thalidomide-associated complete atrioventricular block has been reported in only a single case, but there is no case of second-degree atrioventricular block associated with thalidomide in the literature. Here, we present the case of a 50-year-old patient who had been using thalidomide for multiple myeloma. The patient was admitted to the emergency service with syncope, and had second-degree (2:1) atrioventricular block. The patient was using thalidomide (100 mg/day) for the previous 5 months and had not had any abnormal findings in previous electrocardiographies. His heart rate on presentation was variable, from 45 to 75 bpm. He was treated with a temporary pacemaker because of hypotension and syncope. Five days after the completion of the thalidomide treatment, the patient%u2019s heart rate was 80 bpm. The following day, the pacemaker was removed and a Holter ECG did not show any abnormalities. Patients undergoing thalidomide treatment should be followed up for cardiac and electrocardiographic parameters