Atrial fibrillation and the risk of sudden cardiac death: Incidence, impact and implications

Background: Atrial fibrillation(AF) may be linked to increased sudden cardiac death (SCD) risk, but patients with AF are often neglected in studies on ECG risk factors for SCD. We aimed to clarify the long-term SCD incidence in AF among patients undergoing coronary angiography. Methods: SCD incidence was retrospectively assessed between 2007 and 2018 in patients with suspected or known coronary artery disease referred for elective angiography and in patients with acute coronary syndrome (ACS). Follow-up extended until 31 December 2022. SCD (defined per American Heart Association/American College of Cardiology/Heart Rhythm Society/European Society of Cardiology guidelines) and SCD-equivalent events occurring during follow-up were identified through in-depth review of medical records, including accounts of circumstances leading to deaths. History of AF was identified through review of medical records, while AF at baseline and during follow-up was detected using the GE HealthCare Marquette 12SL algorithm. Results: 9622 ACS and 11 799 elective patients were included, with 955 SCD events during follow-up. The 10-year SCD incidence among patients with AF was 7.7% in ACS and 6.4% in elective patients, compared with 4.5% and 6.4% in those without AF. In competing risk models adjusted for baseline risk factors including left ventricular ejection fraction, AF was associated with SCD (ACS: subdistribution hazard 1.33 (95% CI 1.05 to 1.67); elective: 1.37 (95% CI 1.10 to 1.71)), but this was no longer evident in the elective cohort after adjusting for incident heart failure hospitalisations, which AF preceded in 57.5% by an average of 1.4 years. Overall, 33% of SCD cases occurred in patients with known AF (paroxysmal, persistent or permanent), and 21% of SCD victims had AF on their last ECG. Conclusions: A significant proportion of SCDs occur in patients with AF, but the risk appears mediated by heart failure hospitalisations rather than AF itself.