Stroke and death in elderly patients with atrial fibrillation in Japan compared to the United Kingdom

Data on stroke, mortality and associated comorbidities in elderly atrial fibrillation (AF) patients in Japan may differ from Western countries. There has never been a systematic comparison between stroke risk profiles and outcomes amongst community-based elderly patients with AF in Japan and the United Kingdom (UK). Objective and Methods: We compared clinical characteristics, stroke risk and outcomes amongst elderly AF patients from the Fushimi AF Registry (Japan; N=1791) and the Darlington AF registry (UK; N=1338). Results: The Fushimi cohort had a mean age 81.8 years and CHA2DS2- VASc score 4.3(1.4), whereas the Darlington cohort had a mean age 83.6(5.7) years and CHA2DS2-VASc score 4.4(1.4). Over a 12 month follow-up period, observed stroke and mortality rates in Fushimi were 3.4%(n=61) and 11.5%(n=206), whilst corresponding event rates in the Darlington cohort were 4.4%(n=59) and 14.1%(n=188), respectively. Appropriate use of oral anticoagulation (OAC, essentially vitamin K antagonist) was <60% in both registries. On multivariable analysis, ethnicity (Japan vs.UK) was neither associated with the risk of stroke (Odds Ratio[OR] 0.92, 95%CI 0.63-1.36; p=0.69) nor death(OR 0.92, 95%CI 0.80-1.27; p=0.92). In a subgroup analysis of elderly patients not receiving OAC(n=1489), a prior history of stroke was associated with the risk of stroke(OR 2.42; 95%CI 1.39–4.12; p=0.002), but not ethnicity(OR 0.86; 95%CI 0.50-1.47; p=0.58). Conclusions: Elderly(age≥75) AF patients in both Japan and the UK are at similarly high risk of stroke and death, with OAC still under-utilised in both populations. Ethnicity was not independently associated with the risk of stroke, regardless of OAC use or non-use.