Effects of methadone on QT-interval dispersion.
OBJECTIVE
To evaluate the effects of methadone on QT-interval dispersion.


METHODS
Single-center, prospective, cohort study.


METHODS
Methadone maintenance treatment facility.


METHODS
One hundred eighteen patients who were newly admitted to the facility. Intervention. Twelve-lead electrocardiograms (ECGs) were performed in patients at both baseline and 6 months after the start of methadone therapy.


RESULTS
The ECGs were manually interpreted, and investigators were blinded to time interval and methadone dose. At least eight discernible ECG leads were required for study inclusion. Mean differences between baseline and follow-up rate-corrected QT (QTc) interval and QT dispersion were compared. Multivariate associations between clinical characteristics and magnitude of change in QT dispersion were assessed using linear regression. Mean +/- SD baseline QT dispersion was 32.9 +/- 12 msec, which increased to 42.4 +/- 15 msec (+9.5 +/- 18.6 msec, p<0.0001) after 6 months of therapy. The QTc increased by a similar magnitude (+14.1 msec, p<0.0001). No QT dispersion value exceeded 100 msec. The only variable associated with a greater increase in QT dispersion was antidepressant therapy (20 vs 8.5 msec, p=0.04).


CONCLUSIONS
Methadone modestly increased both QTc interval and QT dispersion. Increased QT dispersion reflects heterogeneous cardiac repolarization and occurs with nonantiarrhythmic agents, such as synthetic opioids. However, the magnitude of this effect appears to be substantially less with methadone than with antiarrhythmic drugs.
Krantz
Mori J
MJ
Department of Medicine, Denver Health Medical Center, Denver, Colorado 80204, USA. Mkrantz@dhha.org
Lowery
Christopher M
CM
Martell
Bridget A
BA
Gourevitch
Marc N
MN
Arnsten
Julia H
JH
D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D015331:Cohort Studies; D004562:Electrocardiography / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008691:Methadone / Q000494:pharmacology*; D008875:Middle Aged; D011446:Prospective Studies
D000889:Anti-Arrhythmia Agents; D008691:Methadone