Torsade de Pointes Associated With Laxative Abuse in a Patient Receiving Methadone

“Ms. A,” a 46-year-old, white woman, had a history of cocaine and heroin dependence (discontinued 2 years ago, with negative urinary drug analysis) and cannabis dependence. She received methadone maintenance treatment, 80–200 mg/day for 4 years. The ECG recorded 3 months before the emergency department presentation was normal: Q-Tc 396 msec.

During her hospitalization to reduce methadone doses, while she received methadone 200 mg/day, the patient presented sudden death and was resuscitated after an episode of torsade de pointes. In the emergency department, the initial ECG on presentation showed ventricular tachycardia with torsade de pointes and Q-Tc 491 msec. The torsade de pointes resolved spontaneously. In the cardiac intensive care unit, she developed another episode of torsade de pointes. During hospitalization in the cardiology department, repetition of the ECG showed increased Q-Tc of 500 msec. The echocardiography found a left ventricular dysfunction (left ventricular ejection fraction: 20%−25%). Laboratory testing revealed hypokalemia (2.7 mmol/l). A treatment including ramipril and bisoprolol was started, and the patient’s condition improved. An empty box of laxatives (bisacodyl) was found in the patient's room. The patient acknowledged taking laxative to lose weight. She fulfilled DSM-IV-TR criteria for eating disorder, NOS.

The cause of torsade de pointes is generally multifactorial. Our patient presented several risk factors for torsade de pointes: 1) female gender; 2) high doses of methadone; and 3) severe hypokalemia induced by hidden laxative abuse. Also, since the patient’s maternal grandmother died from sudden death, a congenital LQTS cannot be excluded.

This case highlights the need for carefully monitoring patients treated with methadone for potentially dangerous Q-T prolongation, which can occur even after the patients have been on therapy for some time. Patients should be informed that laxative use/abuse could lead to hypokalemia and increase their risk of developing a prolonged Q-T interval.³ ECG should be repeated to look for Q-Tc prolongation, but that may not be sufficient. Clinical investigations and ionograms could help to detect surreptitious laxative abuse.