Does electrocardiography improve methadone safety?

We commend Stringer et al.1 for their excellent summary of the literature on methadone-associated Q-T interval prolongation. However, we question their recommendation to perform routine electrocardiography before and during the course of methadone treatment as a measure to prevent torsade de pointes (TdP) tachycardia. A case needs to be made that TdP is a significant problem in clinical practice, and then a practical clinical strategy involving electrocardiography needs to be proposed to address this potentially serious event. We believe that neither of these requirements has been satisfied, and any such strategy would still need to be tested for efficacy. There is still no accepted incidence for TdP, and we were unable to find any confirmed deaths resulting directly from this complication among more than 100 cases reported in the literature. Indirect or suspected deaths still only number in single figures to the best of our knowledge. Stringer et al. cite 37 cases of TdP from 19 authors. An analysis of these reports shows that of the 16 cases in which a Q-Tc interval is provided for a time away from the TdP episode, only 4 intervals were prolonged (>460 msec). In addition, there was a clear precipitant in nearly all cases, commonly alcohol or cocaine use, hypokalemia, or prescribed medication. Thus, screening electrocardiography could have identified only a small proportion of patients who would develop TdP. Furthermore, any clinical strategy that avoided methadone or used lower dosages for those with prolonged Q-T intervals would have measurable negative consequences. These would include increased illicit drug use, more dropouts from methadone therapy, and higher mortality, largely from drug overdose.2–4 While buprenorphine is a highly effective drug, it is not suitable for high-dose methadone transfers.