Should MMT patients have special heart-health tests?

Some patients in methadone maintenance treatment (MMT) programs may have conditions or behaviors associated with increased risks of arrhythmia (irregular heart rhythm), including: abuse of cardiotoxic substances, cardiovascular disease, electrolyte imbalances, and prescribed medications that may foster cardiac disturbances. Furthermore, recent data suggest that in some individuals methadone – alone or, more commonly, in combination with other drugs and/or cardiac risk factors – can influence the development of certain arrhythmias (called long QT syndrome and/or torsade de pointes) in susceptible patients.

It is important for healthcare practitioners to be aware of medical conditions and medications that might influence the development of arrhythmia during methadone maintenance. However, these should not be used to automatically exclude patients from entering or continuing MMT. Although some factors cannot easily or quickly be corrected, others might be modified and/or closely monitored during methadone maintenance.

Current evidence, however, does not support altering routine methadone dosing practices or requiring electrocardiograms (ECGs) for all patients entering or continuing MMT. The following general steps are recommended:

• All persons entering MMT should have a medical examination that includes a general assessment of cardiac health, and this information should be periodically updated.
• Adequate methadone doses are essential for therapeutic success, and it does not appear necessary to alter methadone dosing practices – such as, arbitrarily lowering doses – solely due to concerns about possible cardiac effects. However, in patients with multiple pre-existing risk factors for arrhythmia, screening ECGs may be a sensible component of major dose increases.
• Routine ECGs, incurring added expense and inconvenience, for all patients entering or continuing MMT are not recommended. Screening ECGs should be reserved for individual patients with established cardiovascular disease or those with clinically-significant arrhythmia-risk factors.
• If an ECG is deemed necessary, results should be reviewed by a physician with experience in interpreting test results. When feasible, ECGs should be performed during peak drug concentrations.
• The use of methadone in patients already known to have significant heart disease has not been thoroughly studied and expert consultation (such as with a cardiologist or internist) might be sought in these and other cases in which there are specific concerns about cardiac complications during MMT. However, this should not necessarily deter the appropriate use of methadone in these patients.

In sum, methadone remains an effective and well-tolerated therapy for the treatment of opioid addiction when prescribed appropriately. A sound understanding of its potential association with heart rhythm disturbances in the context of other heart disease factors will allow clinicians to optimize safety during MMT.

Research in this area is ongoing and future refinements of these practices may be necessary. Meanwhile, the relatively small potential risk of adverse cardiac effects that have been reported with methadone should be weighed against the more serious risks of withholding MMT; including, a high likelihood of illicit drug use and its related morbidity, mortality, and public health ramifications.