Frequency and effect of optimal anticoagulation before onset of ischaemic stroke in patients with known atrial fibrillation

Abstract

Background: The aims of the study were (i) to examine which antithrombotic therapy patients with known atrial fibrillation use at the point of time when they suffer an ischaemic stroke, (ii) to evaluate the effects of optimal antithrombotic treatment on outcome and severity of the stroke.

Methods: Patients with known atrial fibrillation before onset of acute ischaemic stroke, and age >60 years were included. Antithrombotic therapy on admission was classified into four groups: no antithrombotic therapy, aspirin, sub-optimal anticoagulation (warfarin and international normalized ratio, INR<2.0) and optimal anticoagulation (warfarin and INR>or=2.0).

Primary outcome: modified Rankin Scale (mRS) 5 or 6 at day 7 poststroke.

Secondary outcomes: (i) death or discharge to a nursing home, (ii) death, (iii) stroke severity on admission assessed by Scandinavian Stroke Scale.

Results: A total of 394 patients were included. On admission 109 (28%) patients used no antithrombotic therapy, 169 (43%) aspirin, 52 (13%) warfarin and had an INR<2.0, and 64 (16%) used warfarin and had an INR>or=2.0. The proportion of patients with an mRS 5 or 6 and the corresponding odds ratios were: in the warfarin group with INR<2.0, 16 (31%), OR 3.1 (CI: 1.2-8.0), (P=0.019), in the group with no antithrombotic therapy 29 (27%), 2.5 (1.1-5.9), (P=0.034), and in the aspirin group 41(24%), 2.2 (1.0-5.1) (P=0.054), compared with the warfarin group with INR>or=2.0, where eight (13%) patients had a poor outcome. A significantly higher proportion of patients died or were discharged to a nursing home in the warfarin group with an INR<2.0 (P=0.014), in the aspirin group (P=0.018) and in the no-treatment group (P=0.035), compared with the warfarin group with an INR>or=2.0. No significant differences were found regarding death alone and stroke severity on admission.

Discussion: Few patients with known atrial fibrillation who suffer an ischaemic stroke receive optimal antithrombotic therapy prior to the onset of stroke. Optimal anticoagulation does not only reduce the risk of ischaemic stroke, but also appears to reduce death and severe dependency as well as the need for nursing home care, if an ischaemic stroke occurs.