Investigating the Association Between Atrial Fibrillation and Out-of-Hospital Cardiac Arrest: A Danish Nationwide Matched Cohort Study

BACKGROUND: Atrial fibrillation (AF) is an impending global epidemic, and out-of-hospital cardiac arrest (OHCA) is associated with high mortality. Although emerging evidence links AF with OHCA, research has been challenged by shared risk factors, especially ischemic heart disease and heart failure.

OBJECTIVES: This study aimed to investigate the association between AF and OHCA in light of risk factors for ischemic heart disease and heart failure.

METHODS: This was a Danish, nationwide matched cohort study using the Danish Cardiac Arrest Registry (June 1, 2001, to December 31, 2022) in individuals aged 18 to 85 years. Exposure was an AF diagnosis, and outcomes were OHCA and all-cause mortality. A 1:4 matching of AF patients with non-AF patients upon sex, birth year, ischemic heart disease, heart failure, diabetes, cancer, hypertrophic cardiomyopathy, dilated cardiomyopathy, and statin usage was performed. Multivariable Cox regression models were used and results presented as cumulative incidences from time of AF diagnosis/matching and HRs of OHCA and all-cause mortality.

RESULTS: The study included 6.47 million individuals, of whom 368,639 had AF. A total of 309,010 patients with AF (only newly diagnosed in the time period) were matched to 1,236,040 non-AF patients. Adjusted HRs of OHCA and all-cause mortality were higher in AF patients vs non-AF patients (1.66 [95% CI: 1.62-1.70] and 1.79 [95% CI: 1.78-1.81], respectively).

CONCLUSIONS: Findings suggest that AF remains a risk factor for OHCA, even after adjustments for ischemic heart disease and heart failure. Future studies should explore subsets of patients with AF at highest risk of OHCA to tailor preventive efforts toward this patient group.