Response of QT interval in methadone maintenance treated patients to the rapid changes in heart rate provoked by brisk standing: Comparison to healthy controls and patients with long QT syndrome

Background: Patients on methadone maintenance therapy are somehow similar to patients with congenital long QT syndrome (LQTS) because they have malfunction of potassium channels caused by a drug that cannot be easily discontinued. We tested patients on methadone therapy with the "stand-up" test, which has been shown to unravel pathologic QT-prolongation in congenital long-QT patients. Methods: "Stand-up" test results of methadone-users, healthy volunteers and congenital LQTS patients were compared. Methadone serum levels and doses were collected. The prognostic value of the test was evaluated after 4 years of follow-up. Results: The QT-response of methadone-users to the "stand-up" test resembled that of healthy volunteers more than the response of LQTS-patients. Differences in the QTc of methadone treated patients and controls, which were statistically significant at baseline, became no longer significant after standing. Within 52 months of follow-up, one patient had suffered unexplained death and one had documented ventricular tachycardia. Conclusions: The QT-response of methadone-users to the "stand-up" test is similar to that of healthy volunteers, not to that of LQTS-patients. (C) 2013 Elsevier Inc. All rights reserved.