Clinical Factors Associated With Ventricular Dysrhythmia in Emergency Department Patients With Severe QTc Prolongation After Drug Overdose

Background: Management of severe prolongation of the corrected QT interval (QTc) following acute drug overdose presents a challenge to clinicians, as resulting ventricular dysrhythmias are rare but life-threatening. This study aimed to identify which patients with severe QTc prolongation on presentation to the emergency department (ED) after overdose will develop ventricular dysrhythmias, death, cardiac arrest, the need for rhythm control, or extracorporeal membrane oxygenation utilization. Methods: Secondary analysis of Toxicology Investigators Consortium Core Registry data from 2013 to 2023. We included patients ≥ 13 years old with acute or acute-on-chronic overdose, toxicology consultation in the inpatient or ED setting, and initial ED electrocardiogram QTc ≥ 500 ms. We excluded patients with no or unknown toxicologic exposure, symptoms unlikely or unknown whether related to exposure, or missing data. The primary outcome was ventricular dysrhythmia. Secondary outcomes included death, cardiac arrest, rhythm control, and extracorporeal membrane oxygenation. Independent variables included patient and overdose characteristics, initial QTc and bicarbonate values, clinical findings, and drug exposures. Multivariable logistic regression was performed with ventricular dysrhythmia as the dependent variable to identify potential predictors. Diagnostic test characteristics were calculated for risk factors identified in the regression model. Results: Of 2764 patients screened, 1265 were included. Forty-eight (3.79%) patients developed ventricular dysrhythmias. Bradycardia (aOR 3.12, 95% CI 1.35–6.90), acidosis (aOR 3.02, 95% CI 1.42–6.23), and shock (aOR 4.54, 95% CI 2.07–9.75) were independently associated with ventricular dysrhythmia on regression analysis and were each associated with every secondary outcome. The absence of any of these findings had a negative predictive value of 98.2% (97.2%–98.9%) for developing ventricular dysrhythmia. Conclusions: In this large international data registry, we identified predictors of ventricular dysrhythmia in patients presenting to the ED after overdose in the setting of severe QTc prolongation.