Repolarization abnormalities and outcomes following return of spontaneous circulation after cardiac arrest
Authors: Banna S , Schenck C , Kim N , Gilmore E J , Greer D M , Beekman R , Miller P E 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: Private hospital(s). Main funding source(s): Boston Medical Center

Background
Prolongation of ventricular repolarization, as measured by the corrected QT interval (QTc), is common in patients resuscitated from cardiac arrest and is exacerbated by targeted temperature management. In this population, QTc prolongation appears to be transient and may not be associated with risk for malignant arrhythmia. The T-peak to T-end interval (TpTe), which represents transmural dispersion of repolarization in the left ventricle, is an emerging marker of risk for sudden cardiac death.

Purpose
We sought to evaluate the association of prolonged QTc and TpTe with in-hospital mortality and favorable neurologic outcome at discharge in comatose survivors of cardiac arrest.

Methods
We conducted a retrospective analysis of patients enrolled in the Multimodal Outcome CHAracterization in cardiac arrest patients (MOCHA) study at a single academic center. Participants were comatose survivors of cardiac arrest aged 18-89 years who had an electrocardiogram (ECG) obtained after return of spontaneous circulation between 2011-2020. Prolonged QTc was defined as QTc &gt;450 ms in males and QTc &gt;460 ms in females as measured by automated algorithm. Prolonged TpTe was defined as TpTe &gt;90 ms as measured by two trained assessors. The primary outcomes were in-hospital mortality and favorable neurologic outcome at hospital discharge (Cerebral Performance Category 1-2). Multivariable logistic regression, adjusted for age, medical comorbidities (diabetes, chronic kidney disease, heart failure, malignancy) and arrest characteristics (location, initial rhythm, witnessed status, bystander CPR) was used to test the association between QTc prolongation and TpTe prolongation and outcomes.

Results
471 (89.0%) patients met inclusion criteria and were included in this analysis; 58 (11.0%) were excluded due to missing post-ROSC ECG. The median age was 62 years (Interquartile range (IQR): 51-73 years), and 284 (60.4%) were male. 297 (63.2%) presented with out-of-hospital cardiac arrest and 138 (29.4%) presented with a shockable rhythm. The median QTc was 479 ms (IQR: 445-517 ms) and the median TpTe was 82.5 ms (IQR: 66-102 ms). Patients with and without prolonged QTc had similar incidence of mortality (71.2% vs 65.5%, P=0.22) and favorable neurologic outcome (22.4% vs 26.9%, P=0.29). Mortality was higher among patients with prolonged TpTe (75.4% vs 65.8%, P=0.03), which persisted after multivariable adjustment (OR 1.91; 95% CI: 1.20-3.04, P&lt;0.01). Patients with prolonged TpTe had lower incidence of favorable neurologic outcome (18.3% vs 27.1%, P=0.03), which persisted after multivariable adjustment (OR 0.47; 95% CI: 0.28-0.79, P&lt;0.01).

Conclusion
TpTe prolongation, but not QTc prolongation, was independently associated with higher mortality and worse neurologic outcome in comatose survivors of cardiac arrest. Further research is needed to clarify the clinical significance of repolarization abnormalities in patients presenting with cardiac arrest.