Prolonged QT Interval After Trazodone Overdose

Ms. A, a 29-year-old married woman, took an overdose of 60 units (50 mg each) of trazodone at about 9:00 p.m. and went to bed. Her normal medication regimen was fluoxetine, 40 mg every morning; trazodone, 50 mg every evening; and diazepam, 10 mg/t.i.d. as needed. She denied ingesting any other substance besides trazodone. She came to the emergency room the following morning with sedation, dizziness, and nausea. An ECG at 9:00 a.m. (12 hours after the overdose) showed sinus bradycardia (57 beats per minute), normal P-R (164 msec) and QRS (96 msec) intervals, but a prolonged corrected QT interval (607 msec) and nonspecific T-wave changes. She was treated with gastric lavage and charcoal. Cardiac monitoring over the next 30 hours showed no significant arrhythmias. An ECG given 26 hours after the overdose showed a less prolonged, corrected QT (486 msec) and the same nonspecific T-wave changes. An ECG given 3 days after the overdose showed a corrected QT of 429 msec and nonspecific T-wave changes. No pre-overdose ECG was available for comparison. Ms. A had no personal or family history of cardiac disease, syncope, or sudden death. She was taking no medication other than the psychotropic drugs. A toxicology screen was positive only for antidepressants and benzodiazepines.