Aboozar Fakhr-Mousavi - Cardiovascular Diseases Research Center, Department of Cardiology, Heshmat Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
Amir Salari - Orthopedic Research Center, Department of Orthopedics, Poursina Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
Azin Vakilpour - Cardiovascular Diseases Research Center, Department of Cardiology, Heshmat Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
Seyed Mehdi Mousavi - Cardiovascular Diseases Research Center, Department of Cardiology, Heshmat Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
Seyed Mahdi Zia Ziabari - Guilan Road Trauma Research Center (GRTRC), Guilan University of Medical Sciences, Rasht, Iran.
Tolou Hasandokht - School of Medicine, Guilan University of Medical Sciences, Rasht, Guilan, Iran.
Fatemeh Salehi-Nik - Cardiovascular Diseases Research Center, Department of Cardiology, Heshmat Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.

Background and objective: Despite the benefits of methadone and its widespread use in opioid treatment programs, this drug has various adverse side effects even at therapeutic doses. This study aimed to determine the frequency of long QT intervals in patients treated with methadone with doses lower than ۱۰۰ mg.Materials and methods: In this cross-sectional study, all the patients between ۳۰-۶۵ years of age admitted for methadone maintenance treatment were enrolled. A matched group of patients with no history of using methadone was included. Screening electrocardiography was performed for all participants at the beginning. Demographic data, drug history, QT interval, and Maximum QTc time were evaluated. The mean QT interval was compared with the defined normal value using the one sample t-test. Also, the mean QT interval based on the methadone dose consumption and other variables was analyzed using t-test or ANOVA statistical tests. P-value less than ۰.۰۵ was considered significant. The statistical analysis was performed using SPSS version ۱۸.Results and conclusion: Out of ۱۹۶ subjects, ۹۷ patients were in the methadone group. ۸۳.۵% of methadone users and ۶۸.۷% of the control group were males. The mean age was ۴۳.۸, and ۴۴.۵ in the methadone and control group, respectively. ۸۳.۵% of methadone users and ۶۸.۷% of the control group were males. In the methadone group, ۱۷.۵% had abnormal QTc-Max, while only ۲% of the control group had abnormal QTc-Max (P=۰.۰۰۰۱). Of the people who consumed less than ۴۰ mg of methadone daily, ۳.۷%, and those who consumed more than ۴۰ mg, ۳۴.۹% experienced abnormal QTc-Max (P=۰.۰۰۰۱). This survey revealed that methadone use in even doses lower than ۱۰۰ mg could also increase the risk of QT prolongation. Therefore, the treatment team needs to be aware that arrhythmias might occur within a wide range of methadone treatment doses.

Dysrhythmia, Methadone, opioid, QT-interval, Toxicity