Impact of atrial fibrillation on cardiac arrest: a nationwide cohort study

Atrial fibrillation (AF) is the most common heart rhythm disorder and cardiac arrest (CA) is one of the leading causes of death. Growing evidence indicates an association between AF and CA.[1-2] However, research into the correlation between AF and CA has so far been challenged by shared risk factors between AF and ischemic heart disease and heart failure - two prevalent conditions commonly associated with CA in elderly.[3]

The aim was to investigate whether AF is associated with a higher risk of CA, independent of risk factors such as ischemic heart disease and heart failure.

This study was performed as a Danish register-based nationwide cohort study. The Danish National Population Register was employed to identify all individuals aged 18-85 years and present in Denmark from 1st June 2001 to 31st December 2021. The Danish Cardiac Arrest Registry was used to identify all out-of-hospital CAs (OHCA) receiving resuscitation efforts during this time period. Follow-up began at the latest of 1st June 2001 (study start), immigration date, or 18th birthday and ended at the first of OHCA, death, emigration date, 85th birthday, or 31st December 2021 (study end). Exposure was defined as presence of an AF diagnosis at start of follow-up, defined using ICD-codes and the Danish National Patient Register (DNPR). Comorbidities and medications were defined using respectively the DNPR and ICD-codes and Danish National Prescription Register and ATC-codes, and considered present if so at start of follow-up. Primary outcomes were OHCA and all-cause mortality (ACM). Analyses were performed using multivariable cox regression models using age as a time scale and results are presented as hazard ratios with death as a competing risk.

The study included 6.2 million individuals, of which 51,964 (0.8%) had AF by start of follow-up. The average age was 38 years in non-AF patients (50% male) versus 69 years in AF patients (59% male). Compared with non-AF patients, AF patients had a significantly higher hazard of OHCA (HR 1.89, CI: 1.82-1.97) and ACM (1.66, 1.64-1.68). After adjusting for sex, heart failure, ischemic heart disease, myocardial infarction, chronic obstructive pulmonary disorder, peripheral arterial disease, stroke, hypertension, diabetes, cancer, statin usage, and betablocker usage, the hazard for OHCA (1.06, 1.01-1.10) and ACM (1.13, 1.12-1.14) remained significantly higher in AF patients.

This study suggests that AF is a risk factor for OHCA, even after adjusting for ischemic heart disease and heart failure. Future studies should explore which subsets of AF patients are at highest risk and examine potential genetic, molecular, or structural mechanisms underlying this link. This could lead to more targeted OHCA prevention and determine whether AF in combination with other risk factors warrants inclusion in sudden cardiac death risk assessment for implantable cardioverter defibrillator implantation.Table 1

– Baseline characteristics