Most data on the clinical epidemiology of atrial fibrillation (AF) are reported from Western populations, and data for Asians are limited. We aimed to investigate the 10-year trends of the prevalence and incidence of non-valvular AF and provide prevalence projections till 2060 in Korea. We also investigated the annual risks of adverse outcomes among patients with AF. Using the Korean National Health Insurance Service database involving the entire Korean population, a total of 679,416 adults with newly diagnosed AF were identified from 2006 to 2015. The incidence and prevalence of AF and risk of adverse outcomes following AF onset were assessed. The prevalence of AF progressively increased by 2.10-fold from 0.73% in 2006 to 1.53% in 2015. The trend of its incidence was flat with a 10-year overall incidence of 1.77 per 1,000 person-years. The prevalence of AF is expected to reach 5.81% (2,290,591 patients with AF) in 2060. For a decade, the risk of all-cause mortality following AF declined by 30% (adjusted hazard ratio [HR]: 0.70, 95% confidence interval [CI]: 0.68-0.72), heart failure by 52% (adjusted HR: 0.48, 95% CI: 0.44-0.51), and ischemic stroke by 9% (adjusted HR: 0.91, 95% CI: 0.88-0.93). The burden of AF among Asian patients is increasing. Although the overall risks of cardiovascular events and death following AF onset have decreased over a decade, the event rates are still high. Optimized management of any associated comorbidities should be part of the holistic management approach for patients with AF.

Aims: Accumulating evidence shows that atrial fibrillation (AF) is associated with an increased risk of dementia. Catheter ablation for AF prolongs the duration of sinus rhythm, thereby improving the quality of life. We investigated the association of catheter ablation for AF with the occurrence of dementia. Methods and results: Using the Korean National Health Insurance Service database, among 194 928 adults with AF treated with ablation or medical therapy (antiarrhythmic or rate control drugs) between 1 January 2005 and 31 December 2015, we studied 9119 patients undergoing ablation and 17 978 patients managed with medical therapy. The time-at-risk was counted from the first medical therapy, and ablation was analysed as a time-varying exposure. Propensity score-matching was used to correct for differences between the groups. During a median follow-up of 52 months, compared with patients with medical therapy, ablated patients showed lower incidence and risk of overall dementia (8.1 and 5.6 per 1000 person-years, respectively; hazard ratio 0.73, 95% confidence interval 0.58–0.93). The associations between ablation and dementia risk were consistently observed after additionally censoring for incident stroke (hazard ratio 0.76, 95% confidence interval 0.61–0.95) and more pronounced in cases of ablation success whereas no significant differences observed in cases of ablation failure. Ablation was associated with lower risks of dementia subtypes including Alzheimer’s disease and vascular dementia. Conclusion: In this nationwide cohort of AF patients treated with catheter ablation or medical therapy, ablation was associated with decreased dementia risk. This relationship was evident after censoring for stroke and adjusting for clinical confounders.

Background Stroke risk in atrial fibrillation (AF) is often assessed at initial presentation, and risk stratification performed as a ‘one off’. In validation studies of risk prediction, baseline values are often used to ‘predict’ events that occur many years later. Many clinical variables have ‘dynamic’ changes over time, as the patient is followed up. These dynamic changes in risk factors may increase the CHA₂DS₂-VASc score, stroke risk category and absolute ischaemic stroke rate. Objective This article evaluates the ‘dynamic’ changes of CHA₂DS₂-VASc variables and its effect on prediction of stroke risk. Patients and Methods From the Korea National Health Insurance Service database, a total of 167,262 oral anticoagulant-naive non-valvular AF patients aged ≥ 18 years old were enrolled between January 1, 2002, and December 31, 2005. These patients were followed up until December 31, 2015. Results At baseline, the proportions of subjects categorized as ‘low’, ‘intermediate’ or ‘high risk’ by CHA₂DS₂-VASc score were 15.4, 10.6 and 74.0%, respectively. Mean CHA₂DS₂-VASc score increased annually by 0.14, particularly due to age and hypertension. During follow-up of 10 years, 46.6% of ‘low-risk’ patients and 72.0% of ‘intermediate risk’ patients were re-classified to higher stroke risk categories. Among the original ‘low-risk’ patients, annual ischaemic stroke rates were significantly higher in the re-classified ‘intermediate’ (1.17 per 100 person-years, p < 0.001) or re-classified ‘high-risk’ groups (1.44 per 100 person-years, p = 0.048) than consistently ‘low-risk’ group (0.29 per 100 person-years). The most recent CHA₂DS₂-VASc score and the score change with the longest follow-up had the best prediction for ischaemic stroke. Conclusion In AF patients, stroke risk as assessed by the CHA₂DS₂-VASc score is dynamic and changes over time. Rates of ischaemic stroke increased when patients accumulated risk factors, and were re-classified into higher CHA₂DS₂-VASc score categories. Stroke risk assessment is needed at every patient contact, as accumulation of risk factors with increasing CHA₂DS₂-VASc score translates to greater stroke risks over time. Minjae Yoon and Pil-Sung Yang contributed equally to the article. Gregory Y. H. Lip and Boyoung Joung are senior co-authors of the article. M. Yoon and P.S. Yang drafted the manuscript, had full access to all of the data and takes responsibility for the integrity of the data and the accuracy of the data analysis. E. Jang, H.T. Yu, T.H. Kim, J.S. Uhm, J.Y. Kim, H.N. Pak and M.H. Lee contributed to data collection. B. Joung and G.Y.H.L. contributed to data interpretation, critical revision and final approval of the manuscript.

Background: Frail patients with atrial fibrillation (AF) are less likely to receive anticoagulation than nonfrail patients with AF despite frailty being associated with poorer clinical outcomes including stroke. Using a population-based cohort, we sought to assess the effectiveness and safety of oral anticoagulants (OACs) in frail patients with AF. Methods: This retrospective cohort study analyzed 83 635 patients aged at least 65 years with AF and frailty (≥5 Hospital Frailty Risk Score) between January 1, 2013 and December 31, 2016 from the Korean National Health Insurance Service database. To account for the differences between patients receiving OAC or not and across different OAC regimens, propensity score–weighting was used. Net adverse clinical event, defined as the first event of ischemic stroke, major bleeding, or cardiovascular death, was compared. In addition, each individual outcome was examined separately. Results: In the study population (57.1% women; mean age, 78.5±7.2 years), a total of 14 968 net adverse clinical event, 3718 ischemic stroke, 5536 major bleeding, and 6188 cardiovascular death occurred. In comparison with no OAC use, OAC use was associated with lower risks of net adverse clinical event (hazard ratio, 0.78 [95% CI, 0.75–0.82]), ischemic stroke (hazard ratio, 0.91 [95% CI, 0.86–0.97]), and cardiovascular death (hazard ratio, 0.52 [95% CI, 0.49–0.55]), but no difference was observed for major bleeding (hazard ratio, 1.02 [95% CI, 0.95–1.10]). Compared with warfarin, all four individual direct OAC were associated with decreased risks of net adverse clinical event, ischemic stroke, major bleeding, and cardiovascular death. The associations for OAC use (compared to no OAC use) or direct OAC use (compared to warfarin) with favorable outcomes were more prominent in individuals with a higher CHA ₂ DS ₂ -VASc score of at least 3. Conclusions: Among frail patients with AF, OAC treatment was associated with a positive net clinical outcome. Direct OACs provided lower incidences of stroke, bleeding, and mortality, compared with warfarin.

Background and Purpose—: Edoxaban is a direct oral factor Xa inhibitor with proven efficacy and safety among patients with atrial fibrillation. Concerns have been raised about an excess of stroke among patients with creatinine clearance (CrCl) >95 mg/mL treated with edoxaban. We assessed the real-world effectiveness and safety of edoxaban in atrial fibrillation patients in relation to CrCl. Methods—: In the Korean National Health Insurance Service data during the period from January to December 2016, we identified 9537 edoxaban-treated patients. Effectiveness and safety outcomes were compared between high-dose edoxaban regimen (HDER, 60 mg daily, n=2840) and a propensity score–matched warfarin group (n=2840) and between low-dose edoxaban regimen (LDER, 30 mg daily, n=3016) and matched warfarin group (n=3016). Results—: The median follow-up period was 5.0 months (interquartile range, 2–7 months). The mean age was 68 years, and 63% were men in HDER group, and the mean age was 73 years, and 52% were men in LDER group. Compared with warfarin, both HDER and LDER significantly decreased the risk for ischemic stroke or systemic embolism (S/SE; HDER: adjusted hazard ratio [aHR], 0.44; 95% CI, 0.31–0.64; LDER: aHR, 0.57; 95% CI, 0.42–0.78), major bleeding (HDER: aHR, 0.40; 95% CI, 0.26–0.61; LDER: aHR, 0.61; 95% CI, 0.43–0.85), and mortality (HDER: aHR, 0.34; 95% CI, 0.22–0.53; LDER: aHR, 0.55; 95% CI, 0.41–0.73). In patients with CrCl >95 mL/min, the incidence of S/SE was higher with LDER than warfarin and comparable between HDER and warfarin group. There was lower effectiveness for the prevention of S/SE with LDER compared with warfarin at higher CrCl levels ( P for interaction=0.023). Conclusions—: In real-world practice, both doses of edoxaban were associated with reduced risks for S/SE, major bleeding, and mortality compared with warfarin. LDER had lower effectiveness for the prevention of S/SE compared with warfarin at higher levels of CrCl (>95 mL/min).