Anticoagulation Usage and Thrombolytic Therapy in Subjects with Atrial Fibrillation Associated Ischaemic Stroke

Abstract Atrial Fibrillation (AF) has been Identified as the single largest cause of ischaemic stroke in the Irish population. Previous research showed that widespread adoption of Direct Oral Anticoagulant (DOAC) prophylaxis had not been associated with a reduction in AF associated stroke prevalence. The Irish National Audit of Stroke (INAS) undertook a more detailed study to determine the characteristics of anticoagulation practice in AF associated stroke particularly adherence to prescribing guidelines and effect on thrombolysis rate. Methods Data from INAS were analysed for the period 2017-2022 inclusive as part of a cross-sectional, cohort study. An enhanced dataset with additional questions about adherence with prescription and International Normalized Ratio (INR) control was collected for 2022 was also considered separately. Results Complete AF Data were available on 22485 of 26829 incidents admitted over this period. Of these, 19260 (85.6%) were ischaemic strokes, mean age was 71.8 and 57.1% were male. In 5321 of these cases, the AF was identified and in 2835 (53.3%) recognized before the stroke and 2281 (80.4%) had been prescribed anticoagulation. The population with previously unknown AF were significantly younger on average than those on anticoagulation (76.8 years vs. 79.1 years (p<0.0001, t-test)), Group C; 78.8 years (p<0.0001), they were also much more likely to have received thrombolysis (17.3 % vs. 4.0% (Chi Sq, p<0.0001)). There were 4999 stroke in 2022, 4272 (85.4%) were ischemic and 1270 (29.7%) of these were AF associated. Of the 660 total strokes, 597 (90.5%) anticoagulated at presentation were receiving DOACs, of which 557 were ischaemic. Forty-eight (9.5%) had their anticoagulation paused and 40 admitted to poor compliance (7.9%). Conclusion Nearly half of people with AF detected after stroke was previously unknown. Those with known AF were mainly appropriately treated with DOACs and constitute breakthrough strokes. Subjects receiving DOACs were much less likely to receive thrombolytic therapy even than those taking Warfarin.