METHADONE AND CARDIAC ARRHYTHMIAS – THERE’S CAUSE FOR FEARING FEAR ITSELF!

What do we really know about the cardiac “risks” of methadone maintenance? There have been many reports of prolonged QT intervals on electrocardiograms – but what does this mean? Consider a very recent report in the French Revue de Medicine Interne (vol 28, 2007, pages 709-710), which describes a single case – a 51 year-old man who had been on methadone maintenance for nine years and on hospitalized for alcohol-induced cirrhosis and complications, but apparently without cardiac symptoms of any kind. He was found to have a prolonged QT interval on admission, which appears t have necessitated no treatment, and did not prompt change in the methadone regimen.

One of the references cited in the paper also deserves mention – a 2003 report in the form of a letter published by Annals of Internal Medicine (vol. 139, no. 2, pages 154-155). That publication described a study of 132 patients for two months following induction on methadone maintenance. They demonstrated prolonged QT intervals, but there was no mention of any signs or symptoms of cardiac illness, and none of the patients apparently had the treatment plan modified as a result of the EKG changes. The authors concluded by noting that “A critical question . . . is whether the QTc prolongation is clinically significant … [and] whether changes in QTc interval in patients receiving methadone are in fact associated with adverse cardiac outcomes.” Yes indeed – those are the questions! And while they are being considered and answers sought, we must keep in mind the caution of the authors of the 2003 paper: “Any potential risk associated with [methadone’s] use must be weighed against its substantial demonstrated benefits.”