The role of QRS complex prolongation in predicting severe toxicity in single-xenobiotic overdose

Abstract

Objective

The QRS complex duration is commonly used to prognosticate severity, predict outcomes, and indicate treatment in overdose. However, literature to support this practice is mixed in tricyclic antidepressant overdoses and absent in non-tricyclic antidepressant overdoses. Our objective was to assess the validity of QRS complex duration as a prognostic marker in overdose.

Methods

This was a secondary analysis of cases reported to the Toxicology Investigators Consortium between January 1, 2010, and December 31, 2022. Cases were assessed to determine the six xenobiotics most associated with QRS complex prolongation. All cases involving these six xenobiotics, regardless of QRS complex duration, constituted the study cohort. Inclusion criteria were cases of patients older than 12 years old with single-xenobiotic exposures. Clinical outcomes evaluated were seizure, ventricular dysrhythmia, metabolic acidosis, and death.

Results

Of 94,939 total cases, diphenhydramine, amitriptyline, bupropion, quetiapine, nortriptyline, and cocaine were most associated with QRS complex prolongation. Inclusion criteria were met by 4,655 cases of exposure to these xenobiotics. QRS complex prolongation was associated with increased odds ratio of seizure in all included xenobiotics, of ventricular dysrhythmia in all included xenobiotics except nortriptyline, and of metabolic acidosis or death in all included xenobiotics except nortriptyline and quetiapine. A normal QRS complex duration had a negative predictive value of greater than or equal to 93.0 percent of developing metabolic acidosis and 98.0 percent of developing a ventricular dysrhythmia or death from the xenobiotics studied.

Discussion

This study demonstrates that patients with QRS complex prolongation from all six xenobiotics studied had an increased prevalence and odds of developing severe outcomes. Furthermore, patients who did not develop QRS complex prolongation were unlikely to develop a ventricular dysrhythmia, metabolic acidosis, or death. These findings were noted in six xenobiotics that mechanistically can cause QRS complex prolongation through sodium channel or gap junction inhibition.

Conclusion

Identification of patients at risk for severe outcomes after overdose can be aided by measuring the QRS complex duration. If prospectively validated, these outcomes have implications on risk stratification, disposition level of care, and appropriateness of treatments.

Keywords:

• Sodium channel blocking
• overdose
• seizure
• ventricular dysrhythmia
• QRS complex

Authors’ contributions

MS, SK, KM, CH, and JB conceived the study. MS, SK, and KM performed the data request and data analysis. MS drafted the manuscript. MS, SK, KM, CH, and JB contributed substantially to the revisions and rewriting of the manuscript. MS takes responsibility for the paper as a whole.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

Data for this manuscript was obtained by request from the American College of Medical Toxicology’s Toxicology Investigators Consortium: https://www.acmt.net/toxic/

Additional information

Funding

There are no funding sources to declare for this manuscript.