Methadone and the heart: what the clinician needs to know.

Evidence has emerged in recent years on methadone's cardiac arrhythogenic potential - i.e. QT prolongation and Torsades de Pointes (TdP). Given the potentially fatal consequences of these adverse effects, clinicians need to be alert to avoid this going unrecognised and untreated. In this paper, we briefly discuss normal cardiac conduction and electrocardiogram (ECG) waveforms, and look at theories of methadone - induced QT prolongation and TdP. We then present a summary of the existing evidence base for methadone - associated TdP and offer guidance for the clinician on the need for cardiac screening of patients on methadone treatment.