Searching for Atrial Fibrillation Poststroke

Abstract

Cardiac thromboembolism attributed to atrial fibrillation (AF) is responsible for up to one-third of ischemic strokes. Stroke may be the first manifestation of previously undetected AF. Given the efficacy of oral anticoagulants in preventing AF-related ischemic strokes, strategies of searching for AF after a stroke using ECG monitoring followed by oral anticoagulation (OAC) treatment have been proposed to prevent recurrent cardioembolic strokes. This white paper by experts from the AF-SCREEN International Collaboration summarizes existing evidence and knowledge gaps on searching for AF after a stroke by using ECG monitoring. New AF can be detected by routine plus intensive ECG monitoring in approximately one-quarter of patients with ischemic stroke. It may be causal, a bystander, or neurogenically induced by the stroke. AF after a stroke is a risk factor for thromboembolism and a strong marker for atrial myopathy. After acute ischemic stroke, patients should undergo 72 hours of electrocardiographic monitoring to detect AF. The diagnosis requires an ECG of sufficient quality for confirmation by a health professional with ECG rhythm expertise. AF detection rate is a function of monitoring duration and quality of analysis, AF episode definition, interval from stroke to monitoring commencement, and patient characteristics including old age, certain ECG alterations, and stroke type. Markers of atrial myopathy (eg, imaging, atrial ectopy, natriuretic peptides) may increase AF yield from monitoring and could be used to guide patient selection for more intensive/prolonged poststroke ECG monitoring. Atrial myopathy without detected AF is not currently sufficient to initiate OAC. The concept of embolic stroke of unknown source is not proven to identify patients who have had a stroke benefitting from empiric OAC treatment. However, some embolic stroke of unknown source subgroups (eg, advanced age, atrial enlargement) might benefit more from non–vitamin K-dependent OAC therapy than aspirin. Fulfilling embolic stroke of unknown source criteria is an indication neither for empiric non–vitamin K-dependent OAC treatment nor for withholding prolonged ECG monitoring for AF. Clinically diagnosed AF after a stroke or a transient ischemic attack is associated with significantly increased risk of recurrent stroke or systemic embolism, in particular, with additional stroke risk factors, and requires OAC rather than antiplatelet therapy. The minimum subclinical AF duration required on ECG monitoring poststroke/transient ischemic attack to recommend OAC therapy is debated.

Cardiac Imaging After Ischemic Stroke or Transient Ischemic Attack

“…ESUS is defined as an imaging-confirmed non-lacunar stroke without extra-or intracranial atherosclerosis causing ≥ 50% stenosis in an artery supplying the area of recent brain ischemia, apparent major-risk cardioembolic source determined by echocardiography (using TTE or TEE), no episode of AF ≥ 6 min within 24 h of ECG monitoring, and no other specific cause of stroke [73]. Results from long-term ECG monitoring led to the assumption, that a significant proportion of cryptogenic stroke as well as ESUS might have been caused by subclinical AF as well [4,11]. As a clear biological gradient between AF burden and stroke risk has to be questioned, the concept of atrial cardiomyopathy as an alternative source of cardioembolism was proposed [74][75][76].…”

“…In recent years, reports on the use of cardiac magnetic resonance imaging (MRI) and computed tomography (CT) after stroke have been increasingly published, particularly in patients with unknown stroke etiology [7][8][9][10]. Cardiac work-up after stroke might lead to changes in secondary stroke prevention, guide screening for atrial fibrillation, and serve as a screening tool for (coronary) heart disease given the strong overlap of cerebrovascular and cardiovascular risk factors [11,12]. While screening for AF after stroke has become common practice, cardiac imaging after ischemic stroke is less well established [4,11,13].…”

“…Cardiac work-up after stroke might lead to changes in secondary stroke prevention, guide screening for atrial fibrillation, and serve as a screening tool for (coronary) heart disease given the strong overlap of cerebrovascular and cardiovascular risk factors [11,12]. While screening for AF after stroke has become common practice, cardiac imaging after ischemic stroke is less well established [4,11,13].…”

Efficacy and safety of thrombolysis for acute ischemic stroke with atrial fibrillation: a meta-analysis

“…Two reviewers (YZ Hu and CM Ji) independently conducted the study selection. Studies were considered potentially to be eligible for this systematic review if they met the following criteria: (1) comparing the efficacy and safety of thrombolysis in AF and non-AF patients. (2) comparing the efficacy and safety of AF patients treated IVT or not.…”

“…Atrial fibrillation (AF) is a major risk factor for cardioembolic stroke, which is responsible for up to onethird of ischemic stroke (IS) [1]. AF is associated with a 4-5 fold increased risk of IS [2], and AF-related strokes are more frequently fatal or disabling compared to those without a history of AF [3].…”