Association between Preexisting Electrocardiographic Abnormalities and Shockable Initial Rhythm in Out-of-Hospital Cardiac Arrest.

Authors

Berat Ulusoy, Mathias Hindborg, Filip Gnesin, Mikkel Porsborg Andersen, Christoffer Polcwiartek, Claus Graff, Kristian Kragholm, Marc Meller Brøchner, Rasmus Bo Hasselbalch, Harman Yonis, Helle Collatz Christensen, Stig Nikolaj Fasmer Blomberg, Fredrik Folke, Christian Torp-Pedersen

Published in

Resuscitation. Pages 111227. Jul 27, 2026. Epub Jul 27, 2026.

Abstract

The initial rhythm in out-of-hospital cardiac arrest (OHCA) strongly predicts survival. However, the association between electrocardiographic (ECG) abnormalities preceding OHCA and the initial rhythm remains unclear.
Individuals experiencing a first OHCA between 2016 and 2021 were identified from the Danish Cardiac Arrest Registry and linked to the most recent hospital-recorded ECG obtained 30-365 days prior to arrest, when available. The outcome was a shockable initial rhythm. Adjusted odds ratios (ORs) were estimated using logistic regression, with normal ECGs as reference. Analyses were stratified by witness status.
Among 22,516 individuals experiencing a first OHCA, 11,167 (49.6%) were bystander-witnessed. Of these, 4,321 (38.7%) had a preceding ECG. Among bystander-witnessed arrests, shockable rhythms occurred in 21.8% of individuals with normal ECGs, compared with 29.9% (OR 1.44, 95% CI 1.10-1.90) in those with ≥1 abnormality and 37.0% (OR 1.65, 95% CI 1.28-2.16) in those without a prior ECG. Among specific abnormalities, higher odds of a shockable rhythm were observed for pathological Q-waves (31.5%, OR 1.40, 95% CI 1.16-1.69), left ventricular hypertrophy (27.0%, OR 1.47, 95% CI 1.14-1.89), atrial fibrillation (33.9%, OR 1.70, 95% CI 1.38-2.10), intraventricular conduction delay (42.8%, OR 1.85, 95% CI 1.38-2.46) and left bundle branch block (39.7%, OR 2.03, 95% CI 1.49-2.77). Among unwitnessed arrests, the prevalence of a shockable initial rhythm was lower and associations were less consistent.
Among bystander-witnessed arrests, pathological Q-waves, left ventricular hypertrophy, atrial fibrillation, intraventricular conduction delay and left bundle branch block on the most recent hospital-recorded ECG within 30-365 days before OHCA were associated with higher odds of a shockable initial rhythm compared with individuals with normal ECGs.

PMID:
42508599
Bibliographic data and abstract were imported from PubMed on 28 Jul 2026.

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