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

Abstract

<h3>BACKGROUND</h3> 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. <h3>METHODS AND RESULTS</h3> 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 (Montréal 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. <h3>CONCLUSION</h3> 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.