Ischemic stroke in patients with atrial fibrillation receiving oral anticoagulation

Atrial fibrillation is the most common cause of embolic stroke associated to heart disease. Oral anticoagulation with vitamin K antagonists substantially reduces this risk.

We assessed a group of patients with prior diagnosis of atrial fibrillation who sustained an ischemic stroke while receiving an adequate regime of oral anticoagulation.

We evaluated consecutive patients with ischemic stroke and prior diagnosis of atrial fibrillation. We determined demographics, clinical characteristics, TOAST stroke subtypes, CHADS2 scores, and prior or concomitant use of oral anticoagulants.

We studied 112 patients. Thirty nine of them (35%) had received an adequate dose of a vitamin K antagonist during the 24-hour period preceding the stroke. There were no differences in demographics, vascular risk factors, CHADS2 scores, nor medications use between patients who were or were not receiving anticoagulation. Other potential etiologies for stroke occurrence were found in 8 (21%) anticoagulated patients, and in 3 (4%) non-anticoagulated subjects (p<0.01). Anticoagulated patients had a mean international normalized ratio (INR) of 2.3 ± 1.3 (median 2.05), and INR was within therapeutic ranges (i.e., ≥ 2) in 54% of these subjects.

A substantial proportion of patients with atrial fibrillation who have an ischemic stroke are already receiving oral anticoagulation. Sub-optimal levels of anticoagulation and additional etiologies explain, only in part, this failure. Further research is needed to help find adequate therapeutic strategies in atrial fibrillation patients who sustain an ischemic stroke while receiving oral anticoagulation.