Sodium bicarbonate treatment for QRS widening in bupropion overdoses

Abstract

Introduction

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.

Methods

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 < 10 milliseconds widening from baseline were excluded. The primary outcome was a change in QRS duration between the pre-bicarbonate electrocardiogram and the first electrocardiogram after initial bicarbonate administration. Secondary outcomes included prevalence of post-bicarbonate QRS < 100 milliseconds, change in electrocardiogram intervals after total bicarbonate administration, and change in metabolic parameters and hemodynamics. Wilcoxon signed-rank testing was performed on the primary outcome. Linear regression modeling was performed to test for an association between change in QRS and bicarbonate dosing.

Results

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 < 100 milliseconds after the initial bicarbonate dose. There was minimal change in QTc, electrolytes, heart rate, or blood pressure; alkalemia post-bicarbonate was achieved in eight patients.

Conclusion

Sodium bicarbonate did not significantly decrease QRS duration in this small retrospective cohort of bupropion overdoses.

Keywords:

• Bupropion
• cardiotoxicity
• QRS
• sodium bicarbonate
• gap junctions

Acknowledgments

The content is solely the responsibility of the authors and does not necessarily represent the official views of Harvard Catalyst, Harvard University and affiliated academic healthcare centers, or the National Institutes of Health.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was conducted with support from Harvard Catalyst, specifically statistical support from Rie Maurer, M.A. Harvard Catalyst consulting is provided by The Harvard Clinical and Translational Science Center (National Center for Advancing Translational Sciences, National Institutes of Health Award UL1 TR002541) and financial contributions from Harvard University and affiliated academic healthcare centers.