Hemoglobin levels and platelet counts have been associated with adverse clinical outcomes in patients with cardiovascular conditions. We aimed to assess the impact of oral anticoagulant use for patients with atrial fibrillation and concomitant anemia or thrombocytopenia.

We used medical data from a multicenter health care system in Taiwan including 37,074 patients with atrial fibrillation. Patients were categorized into 3 groups based on hemoglobin and platelet levels: Group 1 (hemoglobin >10g/dL and platelet>100 K/µL; n = 29,147), Group 2 (hemoglobin<10 g/dL or platelet<100 K/µL; n = 7078), and Group 3 (hemoglobin <10 g/dL and platelet <100 K/µL; n = 849). Patients in each category were further stratified as 3 groups according to their stroke prevention strategies: no oral anticoagulant use (non-OAC), warfarin, or nonvitamin K antagonist oral anticoagulants (NOACs).

A higher hemoglobin or platelet level was associated with a higher risk of ischemic stroke/systemic embolism but lower risks of intracranial hemorrhage and major bleeding. The composite risks of ischemic stroke/systemic embolism, intracranial hemorrhage and major bleeding were higher in Group 3 or Group 2, compared with Group 1 (6.79% a year vs 6.41% year vs 4.13% year). Compared to non-OACs, warfarin was not associated with a lower composite risk in the 3 groups. NOACs were associated with a lower composite risk in Group 1 (adjusted hazard ratio:0.68, [95% confidence interval:0.60-0.76]) and Group 2 (adjusted hazard ratio:0.73, [95% confidence interval:0.53-0.99]) but was nonsignificant in Group 3.

Patients with atrial fibrillation with anemia or thrombocytopenia were a high-risk population. Compared with no OAC use, NOACs were associated with better clinical outcomes for patients with atrial fibrillation and advanced anemia (hemoglobin <10g/dL) or thrombocytopenia (platelet <100 K/µL) but not for those with both conditions.