High prevalence of atrial fibrillation among patients with ischemic stroke

Abstract

Background and purpose: Atrial fibrillation (AF) is a common cause of devastating but potentially preventable stroke. Estimates of the prevalence of AF among patients with stroke vary considerably because of difficulties in detection of intermittent, silent AF. Better recognition of AF in this patient group may help to identify and offer protection to individuals at risk. Our aim was to determine the nationwide prevalence of AF among patients with ischemic stroke, as well as their use of oral anticoagulation.

Methods: Cross-sectional study of unselected patients in cross-linked nationwide Swedish health registers. All 94 083 patients with a diagnosis of ischemic stroke in the nationwide stroke register Riks-Stroke between 2005 and 2010 were studied. Information about previously diagnosed AF, and comorbidity, was obtained from the nationwide Patient Register and cross-referenced with the national Drug Register containing data on all dispensed pharmacological prescriptions in Sweden.

Results: Combination of data from Riks-Stroke and from the Patient Register showed that 31 428 (33.4%) patients with ischemic stroke had previously known, or newly diagnosed, AF. Of those, only 16.2% had received warfarin in a pharmacy within 6 months before stroke onset. After hospital discharge, only 35.0% of the survivors received warfarin within the first 3 months after discharge. The likelihood for underlying AF was strongly correlated to the CHA2DS2-VASC score, which is a point based scheme for assessment of stroke risk in AF but which also predicts likelihood of AF. In this scheme points are given for age, previous stroke or transient ischemic attack, hypertension, heart failure, diabetes, vascular disease and female sex.

Conclusions: Access to nationwide register data shows that AF is more common among patients with ischemic stroke than those previously reported. Few patients with stroke and AF had anticoagulant treatment before the event, and few got it after the event. CHA2DS2-VASc could be a useful monitoring tool to intensify efforts to diagnose AF among patients with cryptogenic stroke.

Keywords: atrial fibrillation; stroke.