Abstract 1577: Atrial Fibrillation Patients Predominantly Present Ischemic Stroke With Seasonal Incidence Variation Compared to Non-Atrial Fibrillation Patients: A Population-based Cohort Study in Taiwan
Background: Atrial fibrillation (AF) is an important risk factor for stroke. Patients with AF need anti-platelet or anti-thrombotic agents for primary or secondary prevention of stroke. We investigated the incidence of first stroke, the stroke subtype and seasonal variations among AF patients who underwent optimal medical care.
Methods and results: A cohort of 908,647 covered by a universal insurance program in Taiwan, with 2,347 (0.26%) AF patients, identified in 2002–2004 were followed up until 2007 and incidences of stroke were analyzed based on the AF status. Compared with the population without AF, the relative risk of stroke among AF patients was 14.1 times greater (79.4 vs. 5.65 per 1000 person-years) and the incidence of AF-related stroke was higher in cold months than in hot months. The incidence of stroke among AF patients aged > or =65 years was much higher than that among those aged 30 –39 years (101.9 vs. 32.6 per 1000 person-years). Despite a total of 1,596 (68%) AF patients had been treated with either anti-platelet (aspirin, clopidogrel) or anti-thrombotic agents (warfarin), first stroke occurred in 703 (30%) AF patients with a mean follow-up period of 4.1±0.9 years, compared to 30,235 (3.3%) in non-AF patients (P<0.001). The stroke subtype analysis revealed a higher incidence of ischemic infarction in AF patients than in non-AF ones (45.2% vs. 29.1%, P <0.001) and lower hemorrhagic stroke (5.2% vs. 12.5%, P<0.01) in AF patients. Whereas, the incidences of transient ischemic attack (15.7% vs. 19.5%) and other forms of ischemic stroke (33.9% vs. 39%) were similar between AF and non-AF patients (P=NS, respectively). Multi-variable analysis yielded an additional stroke hazard of 43% for the AF patients with co-morbidity of diabetes.
Conclusions: AF-inducing stroke remains a major healthcare challenge, despite increasingly use of anti-platelet or anti-thrombotic therapy in Chinese population in Taiwan. Most of the AF-related strokes are non-hemorrhagic type mechanistically consisting with thromboembolic origin.