PREDICTORS OF STROKE IN PATIENTS ON ORAL ANTICOAGULANT: AN OBSERVATIONAL STUDY

BACKGROUND Anticoagulation therapy is effective in preventing atrial fibrillation (AF)-related strokes. The incidence of stroke despite oral anticoagulation nevertheless occurs in 1.5-4%, yet little is known about the underlying mechanisms. We sought to describe the characteristics of patients presenting with acute stroke while on oral anticoagulant therapy. METHODS AND RESULTS Data regarding consecutive acute stroke patients while on oral anticoagulants (OAC) were retrospectively collected between December 1st 2017 and March 31st 2021 from a single-center Canadian prospective cohort (Montreal Neurovascular and STrokE Repository, MONSTER). Baseline characteristics including details surrounding anticoagulant use, imaging data, and reperfusion therapy data were collected. A total of 188 patients with acute ischemic stroke despite therapeutic anticoagulation were included (median age 78.2(10.1); 53.7% women). All patients were on oral anticoagulation for the prevention of AF-related strokes. Forty-three patients (22.9%) had a coronary artery disease, 32 (17%) patients had a valvulopathy and 26 (13.8%) patients had heart failure. Median [Q1-Q3] CHADS-VASC was 3[3–4]. Median baseline NIHSS was 15[7-22]. Twenty-one patients (11.2%) received IV-thrombolysis and 105(55.9%) patients were treated with endovascular therapy. At discharge the median ΔNIHSS (difference between baseline NIHSS and discharge NIHSS) was -3[-8 – 0], therapeutic anticoagulation was modified in 38(20.2%) patients at discharge. Regarding stroke mechanism, thirty-three patients (17.6%) had stopped OAC prior to their strokes (due to either low compliance or periprocedural interruption), 32(17.0%) had an inappropriate dosage. In sixty-eight (36.2%) patients, stroke mechanism was cryptogenic following a standard etiology workup. CONCLUSION In patients presenting with ischemic stroke despite therapeutic anticoagulation, lack of treatment compliance, treatment interruption, and inappropriate dose are frequent causes for stroke. However, there exists a significant proportion of patients in whom the underlying stroke mechanism is unknown despite standard workup. These findings highlight the need to improve stroke prevention strategies in AF patients.