OC 74.2 - Evaluation of Stroke Risk Scores in Patients with Atrial Fibrillation and Active Cancer

Background: Patients with cancer have an increased risk of developing atrial fibrillation (AF). AF quadruples the risk of stroke, causing significant morbidity and mortality. Risk scores predict ischemic stroke to guide decision making regarding primary prophylaxis with anticoagulant therapy; however, these scores were developed and validated in cohorts largely excluding patients with active cancer.

Aims: We aimed to assess performance of two stroke risk scores, CHADS2 and R2CHADS2, in a cohort of patients with active cancer and AF receiving aspirin or anticoagulant therapy.

Methods: Using a nationwide cohort of US Veterans, we identified patients with active cancer and AF starting on aspirin or anticoagulant therapy (Time 0) between 2012-2018. Incident ischemic stroke, within 1 and 3 years, was identified using ICD-9/10 codes limited to the first two inpatient positions. The association between risk score and stroke was analyzed using competing risk analysis through the methods of Fine and Gray. Model discrimination was evaluated with Harrell's c-statistic.

Results: We identified a cohort of 7479 patients with active cancer and AF of whom 1763 were prescribed aspirin monotherapy and 5716 anticoagulant therapy. Baseline differences between these groups are listed in Table 1. Ischemic stroked occurred in 1.1% of patients on aspirin therapy and 0.7% of patients on anticoagulant therapy at 1 year. Major bleeding occurred in 5% (n=87) and 6% (n=345) of patients on aspirin and anticoagulation at 1 year, respectively. The association of each risk score, per 1-point increase, and ischemic stroke is shown in Table 2.

Conclusion(s): CHADS2 and R2CHADS2 modestly discriminated the risk of ischemic stroke in patients with active cancer. The rate of incident ischemic stroke and major bleeding was similar between patients on aspirin or anticoagulation at 1 year. Research into stroke risk factors specific to patients with cancer and AF is warranted to improve selection of prophylactic therapy.