Differential Risk of Dementia Between Patients With Atrial Flutter and Atrial Fibrillation: A National Cohort Study

Objectives: Atrial fibrillation (AF) is linked to an increased risk of stroke and dementia. Atrial flutter (AFL) is also linked to an increased risk of stroke but different level of risk as compared to AF. Little is known about the difference in the risk of dementia between AF and AFL. This study aims to investigate whether the risk of dementia is different between AF and AFL. Methods: Patients with newly diagnosed AF and AFL during 2001-2013 were retrieved from Taiwan’s National Health Insurance Research Database. Patients with incomplete demographic data, aged <20 years, history of valvular surgery, rheumatic heart disease, hyperthyroidism, and history of dementia were excluded. The incidence of new-onset dementia was set as the primary outcome and analyzed in patients with AF and AFL after propensity score matching (PSM). Results: A total of 232,425 AF and 7,569 AFL were eligible for analysis. After 4:1 PSM, we included 30,276 AF and 7,569 AFL for analysis. Additionally, AF (n= 29,187) and AFL (n=451) patients who received oral anticoagulants were enrolled for comparison. The risk of dementia was higher in AF patients compared with AFL patients (subdistribution hazard ratio (SHR)=1.52, 95% CI 1.39 - 1.66; p <0.0001) before PSM and remained higher in AF patients (SHR=1.14, 95% CI 1.04 to 1.25; p=0.0064) after PSM. The risk of dementia was higher in AF patients without previous history of stroke after PSM but the risk did not differ between AF and AFL patients with previous history of stroke. Among patients who received oral anticoagulants, the cumulative incidences of dementia were significantly higher in AF patients than in AFL patients before and after PSM (all P <0.05). Conclusions: This study found that, among patients without history of stroke, the risk of dementia was higher in AF patients than in AFL patients, and CHA2DS2-VASc score might be useful for risk stratification of dementia between AF and AFL patients.