Sodium bicarbonate treatment for QRS widening in bupropion overdoses

Bupropion cardiotoxicity widens QRS complexes by inhibiting cardiac gap junctions. Sodium bicarbonate is the standard treatment for QRS widening from sodium channel blockade, but its effect on QRS widening in bupropion cardiotoxicity is not well-studied. This is a retrospective cohort study of bupropion overdoses from 10 hospitals between January 2010 and June 2022. Patients with documented administration of sodium bicarbonate and QRS duration > 100 milliseconds on pre-bicarbonate electrocardiogram were included. Patients with no electrocardiogram within four hours of treatment or with baseline pre-overdose wide QRS and Thirteen patients were included for final analysis. The median age was 32 years, and 54% were male. Six patients developed seizures; one developed ventricular tachycardia, and four received vasopressors. The median QRS and QTc pre-bicarbonate were 116 and 495 milliseconds, respectively. The median change in QRS duration was −2.0 milliseconds, which was not statistically significant (P = 0.42). The median bicarbonate dose administered before the first post-bicarbonate electrocardiogram was 100 milliequivalents. We did not identify an association between QRS change and bicarbonate dosing (P = 0.9, R-squared = 0.001). No patient had a QRS duration Sodium bicarbonate did not significantly decrease QRS duration in this small retrospective cohort of bupropion overdoses.