Does prior antithrombotic therapy influence recurrence and bleeding risk in stroke patients with atrial fibrillation or atrial flutter

Background: Whilst antithrombotic therapy is recommended in people with atrial fibrillation (AF), little is known about the survival benefits of antithrombotic treatment in those with both high ischemic and bleeding risk scores. We aim to describe the distribution of these risk scores in those with a prior diagnosis of AF who have suffered stroke and to determine the net clinical benefit of antithrombotic treatment. Methods: We used regional stroke register data in the UK. Patients with a prior diagnosis of AF and ischemic or hemorrhagic stroke patients were selected and their CHA2DS2-VASc and HEMORR2HAGES scores retrospectively calculated. Logistic regression and Cox-proportional hazards models were constructed to determine the association between antithrombotic therapy prior to stroke and in hospital and long term mortality. Results: 1928 stroke patients (mean age 81.3 years (SD 8.5), 56.8 % women) with prior AF were included. Of these, 1761 (91.3%) suffered ischemic stroke. The most common phenotype (64%) was those with both high CHA2DS2-VASc (≥2) and high HEMORR2HAGES score (≥4). In our fully adjusted model, patients on antithrombotic treatment with both high ischemic and bleeding risk had a significant reduction in odds of 31% for in hospital mortality (OR 0.69;95%CI 0.48,1.00: p=0.049)) and 17% relative risk reduction for long term mortality (HR 0.83;95%CI 0.71,0.97: p=0.02)). Conclusions: Our study suggests that antithrombotic treatment has a prognostic benefit following incident stroke in those with both high ischemic risk and high bleeding risk. This should be considered when choosing treatment options in this group of patients.