Torsade de pointes associated with very-high-dose methadone.

BACKGROUND Methadone is an effective treatment for opioid dependency and chronic pain. A methadone derivative, levacetylmethadol, was withdrawn from the European market after being associated with torsade de pointes. To date, no association between methadone and this arrhythmia has been described. OBJECTIVE To evaluate a series of methadone-treated patients experiencing torsade de pointes. DESIGN Retrospective case series. SETTING Methadone maintenance treatment programs in the United States and a pain management center in Canada. PATIENTS 17 methadone-treated patients who developed torsade de pointes. MEASUREMENTS Chart review for concomitant arrhythmia risk factors and quantification of corrected QT interval (QTc). RESULTS The mean daily methadone dose was 397 +/- 283 mg, and the mean QTc interval was 615 +/- 77 msec. Fourteen patients had a predisposing risk factor for arrhythmia. A cardiac defibrillator or pacemaker was placed in 14 patients; all 17 patients survived. CONCLUSIONS This series raises concern that very-high-dose methadone may be associated with torsade de pointes. Given the likely expansion of methadone treatment into primary care, further investigation of these findings is warranted.