Risk of sick sinus syndrome in patients diagnosed with atrial fibrillation: A population-based cohort

Background: Sinoatrial node dysfunction and atrial fibrillation (AF) frequently coexist and interact with each other, often to initiate and perpetuate each other. Objective: To determine the effect of AF on the incidence and risk of sick sinus syndrome (SSS). Methods: The association of incident AF with the development of incident SSS was assessed from 2004 to 2014 in 302 229 SSS- and pacemaker-free subjects aged ≥60 years in the Korea National Health Insurance Service-Senior cohort. Results: During an observation period of 1 854 800 person-years, incident AF was observed in a total of 12 797 subjects (0.69%/year). The incidence of SSS was 3.4 and 0.2 per 1000 person-years in the propensity score-matched incident AF and no-AF groups, respectively. After adjustment, the significantly increased risk of SSS was observed in the incident AF group, with a hazard ratio (HR) of 13.4 (95% confidence interval [CI]: 8.4–21.4). This finding was consistently observed after censoring for heart failure (HR: 16.0; 95% CI: 9.2–28.0) or heart failure/myocardial infarction (HR: 16.6; 95% CI: 9.3–29.7). Incident AF also was associated with an increased risk of pacemaker implantation related with both SSS (HR: 21.8; 95% CI: 8.7–18.4) and atrioventricular (AV) block (HR: 9.5; 95% CI: 4.9–18.4). These results were consistent regardless of sex and comorbidities. Conclusion: Incident AF was associated with more than 10 times increased risk of SSS in an elderly population regardless of comorbidities. The risk of pacemaker implantations related with both sinus node dysfunction and AV block was increased in the elderly population with incident AF.