Continuous QTc Monitoring for Patients Intoxicated with QTc Prolonging Medication in the Emergency Department: A Proof of Principle Study

Marit Bot; Raymond J van Wijk; Hermie J Hermens; David N van der Kooi; Thomas Luttmer; Eva M Boetje; Jan C Ter Maaten; Hjalmar R Bouma; Ewoud Ter Avest

doi:10.1016/j.jemermed.2024.11.007

Continuous QTc Monitoring for Patients Intoxicated with QTc Prolonging Medication in the Emergency Department: A Proof of Principle Study

J Emerg Med. 2025 May:72:46-55. doi: 10.1016/j.jemermed.2024.11.007. Epub 2024 Nov 13.

Authors

Marit Bot¹, Raymond J van Wijk², Hermie J Hermens³, David N van der Kooi², Thomas Luttmer², Eva M Boetje², Jan C Ter Maaten², Hjalmar R Bouma⁴, Ewoud Ter Avest⁵

Affiliations

¹ Department of Acute Care, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Department of Biomedical Signals and Systems, University of Twente, Enschede, The Netherlands.
² Department of Acute Care, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
³ Department of Biomedical Signals and Systems, University of Twente, Enschede, The Netherlands.
⁴ Department of Acute Care, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
⁵ Department of Acute Care, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; London's Air Ambulance and Bart's Health National Health Service Trust, Royal London Hospital, London, United Kingdom.

PMID: 40158897
DOI: 10.1016/j.jemermed.2024.11.007

Abstract

Background: It can be challenging to determine when patients presenting with an overdose of QT interval prolonging drugs can be discharged safely, especially when the moment of intoxication or the substance ingested is unknown.

Objective: In a proof of principle study, we aimed to determine whether continuous corrected QT interval (QTc) analysis can be used to establish optimal observation duration of patients intoxicated with QTc prolonging medication.

Methods: For patients presenting with an intoxication with QT interval prolonging drugs in the emergency department, electrocardiography signals sampled at 500 Hz were preprocessed and the mean heart rate QTc per 5 min was calculated and plotted against time. A third order polynomial was fitted to visualize when the QTc would be highest (i.e., electrophysiological time to maximum concentration [T_max]). This point in time was compared with the estimated T_max based on pharmacokinetic properties of the ingested substance.

Results: In a retrospective biobank-based study, a total of 22 emergency department visits (of 15 patients) were analyzed. An electrophysiological T_max could be calculated for 17 of 22 visits. The remaining 5 patients presented either long after the electrophysiological T_max (n = 4) or were admitted to the ward before reaching the T_max (n = 1). The mean (SD) difference between the estimated T_max based on drug properties and the calculated electrophysiological T_max was 18 (133) min (range -158 to 296 min). Despite the wide range, there was a significant correlation between recorded electrophysiological T_max and estimated T_max (r = 0.67, p = 0.012).

Conclusions: Continuous electrophysiological monitoring can be used as an adjunct to determine the toxicokinetic T_max for patients presenting with an intoxication, especially when the time of ingestion or the substance ingested is unknown.

Keywords: QTc; continuous ECG monitoring; intoxication; tricyclic antidepressants.

MeSH terms

Adult
Drug Overdose*
Electrocardiography* / methods
Emergency Service, Hospital / organization & administration
Emergency Service, Hospital / statistics & numerical data
Female
Heart Rate / drug effects
Humans
Long QT Syndrome* / chemically induced
Male
Middle Aged
Monitoring, Physiologic / methods
Proof of Concept Study
Retrospective Studies