Assessment of QT dispersion in electrocardiogram of patients with acute poisoning of methadone

QT dispersion means the difference between the minimum and maximum QT interval in a standard twelve standard electrocardiogram, which indicates ventricular repolarization and electrical instability of the heart. In this study, we try to find a link between methadone poisoning and the change in QT dispersion, so that we can accurately assess the patient's condition and medical needs in the future.

In a descriptive, randomized/ cross-sectional study in the poisoning ward of Imam Reza Hospital in Mashhad from October 2013 to April 2015, all patients who referred to the emergency department because of their methadone toxicity or symptoms, had an ECG with 12 leads taken from them, at the time of the arrival. QT dispersion was calculated manually in comparison to other parameters. Also their blood sample were taken to the lab in order to measure different electrolytes (Mg, K, Ca). To ensure the accuracy of study, patient’s urine samples were taken and tested for methadone. There was no intervention in this study. The control group was also not considered QT scattering and dispersion was compared with normal reference in this study.

In this study, 100 patients were studied, 65 of them males (65%) and 35 females (35%). Mean age of subjects entering the study was 33.87±14.5. The average dose of methadone in these cases was 35.5±35.7 mg. However, their usual dose was 1.11±4.85 mg prior to overdoses, and the average duration of use mentioned in patients who had a history of usage was 5.1 months, but 90% of the subjects did not mention any history. The average measured potassium was 3.99±0.5 meq/l, calcium was 8.94±0.5 meq/l, and magnesium was 1.98±0.26 mg/dl. Average measured oxygen saturation at the time of admission was 94.43±5.6%. Mean QT dispersion was 0.041±0.018 millisecond.

In our study, no significant correlation was found between QT dispersion and methadone poisoning.