Ventricular arrhythmias in patients treated with methadone for opioid dependence

Over the last decade, there has been a significant rise in reported cases of methadone induced QT prolongation (QTP) and Torsades de Pointes (TdP) in patients treated for opioid dependence. Optimal management of these patients is challenging. We report a case series of 12 consecutive patients admitted to our institution with methadone-induced QTP and ventricular arrhythmias. All patients survived the presenting arrhythmia. Successful transition to buprenorphine was accomplished in three patients. QT interval normalized and none of these patients had recurrent arrhythmias. Methadone dose was reduced in five patients with improvement of QT interval and resolution of arrhythmia. Four patients, including two with ICDs, refused or did not tolerate a reduction in their methadone dose. Ventricular arrhythmias in patients on methadone are an uncommon but important problem. Buprenorphine, a partial A mu-opiate-receptor agonist and a kappa-opiate-receptor antagonist does not cause QTP or TdP. Buprenorphine is a useful and effective alternative to methadone in a select group of patients, including those with documented ventricular arrhythmias on methadone. Pacemakers or defibrillators should be reserved for patients who have failed buprenorphine or a reduced methadone dose.