Individual patient assessment of methadone-induced QT prolongation with digital holter recording.

A 27-year-old male who had been on methadone therapy for 6 months was investigated with a 12-lead digital holter because of a prolonged QT on a standard 12-lead electrocardiogram (ECG). The patient had 24-hour holter recording on and off methadone therapy and multiple digitized 12-lead ECG data were captured for on-screen measurement of the QT interval. For each 24-hour period QT-HR pairs were plotted on the QT nomogram showing QT prolongation on methadone but not when it was ceased. This provides a highly accurate method for evaluating drug-induced QT prolongation.