title: The correlation between prolonged corrected QT interval with the frequency of respiratory arrest, endotracheal intubation, and mortality in acute methadone overdose.
abstract: Corrected QT interval (QTc) prolongation is long considered as a predisposing factor for the occurrence of torsade de pointes (TdP) and sudden cardiac arrest in methadone maintenance treatment. We aimed to elucidate the correlation between QTc prolongation and in-hospital death, respiratory arrest, and endotracheal intubation in acute methadone-intoxicated patients presenting to the emergency department and to assess the value of QTc in predicting these outcomes. A prospective cross-sectional study with a convenience sample of patients with acute methadone overdose was done. Participants were 152 patients aged 15-65 with negative urinary dipstick test for cyclic antidepressants, no history of other QTc-prolonging conditions and co-ingestions, no severe comorbidities affecting the outcomes, and positive urinary dipstick results for methadone. QTc intervals were measured and calculated in triage-time electrocardiogram (ECG). Death was correlated with QTc (P = 0.014) and length of ICU admission (P < 0.001). In multivariable analysis, death was independently associated only with length of ICU admission [odds ratio (OR) 95 % confidence intervals (95 % CI) 1.36 (1.14-1.61)]. Intubation and respiratory arrest were independently associated with QTc interval [OR (95 % CI) 1.03 (1.02-1.04) and 1.02 (1.01-1.03), respectively]. The receiver operating characteristics curves drawn to show the ability of QTc to predict death, intubation, and respiratory arrest showed thresholds of 470, 447.5, and 450 ms with sensitivity (95 % CI) and specificity (95 % CI) of 87.5 (47.3-99.7), 86.8 (74.7-94.5), and 77.3 (62.2-88.5), respectively. Our study showed that QTc is a potential predictor for adverse outcomes related to acute methadone intoxication. The correlations shown in this study between triage-time QTc and in-hospital respiratory arrest or intubation in methadone overdose may be of clinical value, whether these outcomes are hypothesized to be a reflection of background TdP or intoxication severity.
authors.affiliation: Department of Emergency Medicine, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Davood
authors.initials: D
authors.lastname: Farsi
authors.forename: Amirhossein
authors.initials: A
authors.lastname: Mirafzal
authors.forename: Hossein
authors.initials: H
authors.lastname: Hassanian-Moghaddam
authors.forename: Zahra
authors.initials: Z
authors.lastname: Azizi
authors.forename: Nyoosha
authors.initials: N
authors.lastname: Jamshidnejad
authors.forename: Shahriar
authors.initials: S
authors.lastname: Zehtabchi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D062787:Drug Overdose / Q000150:complications* / Q000401:mortality* / Q000652:urine; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D008133:Long QT Syndrome / Q000209:etiology* / Q000401:mortality*; D008297:Male; D008691:Methadone / Q000506:poisoning* / Q000652:urine; D008875:Middle Aged; D012119:Respiration / Q000187:drug effects*; D016171:Torsades de Pointes / Q000209:etiology; D055815:Young Adult
chemical_list: D008691:Methadone