Purpose: Circadian rhythms in sudden cardiac death have been reported globally over the last 3 decades, but recent data from Oregon have questioned these findings.1 Our aim was to explore the daily circadian pattern of shockable arrhythmias in an out-of-hospital cardiac arrest (OHCA) patient cohort from Arizona (2009-2019).
Methods: Patients from the Save Hearts in Arizona Registry & Education (SHARE) database were analyzed assessing the association between initial arrest rhythm and occurrence time. The data were analyzed for both shockable (ventricular fibrillation-VF, ventricular tachycardia-VT) and non-shockable rhythms [asystole, pulseless electrical activity (PEA), and others]. Cases were divided into four 6-hour time epochs based on EMS dispatch time [morning (6.00-11.59h), afternoon (12.00-17.59h), evening (18.00-23.59h), and night (0.00-5.59h)] and stratified by shockable versus non-shockable rhythms. We used logistic regression to examine the circadian pattern. Covariates included age (≥18 years), weight, and sex.
Results: Out of 2857 OHCA events, 596 (20.9%) initial rhythms were VT/VF. Non-shockable rhythms included: asystole (1589; 55.6%), PEA (567; 19.9%), and other (105; 3.7%). Logistic regression revealed that the odds ratio (OR) for shockable rhythm compared to the morning (reference time) was significant for afternoons (1.4, 95% CI 1.07-1.83; p=0.014) and night (0.71, CI 0.50-0.99; p=0.044), but not significant for evenings (1.2, CI 0.91-1.59; p=0.196); see Table below. In the model, age (OR=1.00) and weight (OR=0.99) were not significant, but male sex was (OR=1.78, CI 1.41-2.25; p<0.01).
Conclusions: Our results show a significant circadian pattern for shockable rhythms among OHCA patients in Arizona with the afternoon timeframe having the highest incidence.
Table
Epoch Odds Ratio 95% CI p Value Morning Reference Afternoon 1.4 1.07-1.83 0.014 Evening 1.2 0.91-1.59 0.196 Night 0.71 0.50-0.99 0.044 Reference:
1. Ramireddy A and Chugh SS. Trends Cardiovasc Med; 31(3):172-176. 2021.

Circadian Pattern of Shockable Rhythms in Out-of-Hospital Cardiac Arrest in Arizona

Implementation of the Guidelines - How do we put the new ERC Guidelines into practice?

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