Stroke in Patients with Atrial Fibrillation: Epidemiology, Screening, and Prognosis

Abstract

Atrial fibrillation (AF) is the most common sustained arrythmia and one of the strongest risk factors and causal mechanisms of ischemic stroke (IS). Acute IS due to AF tends to be more severe than with other etiology of IS and patients with treated AF have reported to experience worse outcomes after endovascular treatment compared with patients without AF. As cardioembolism accounts for more than a fifth of ISs and the risk of future stroke can be mitigated with effective anticoagulation, which has been shown to be effective and safe in patients with paroxysmal or sustained AF, the screening of patients with cryptogenic IS (CIS) for AF is paramount. Embolic stroke of undetermined source (ESUS) is a subtype of CIS with a high likelihood of cardioembolism. The European Stroke Organization and European Society of Cardiology guidelines recommend at least 72 h of screening when AF is suspected. The longer the screening and the earlier the time point after acute IS, the more likely the AF paroxysm is found. Several methods are available for short-term screening of AF, including in-hospital monitoring and wearable electrocardiogram recorders for home monitoring. Implantable loop monitors provide an effective long-term method to screen patients with high risk of AF after IS and artificial intelligence and convolutional neural networks may enhance the efficacy of AF screening in the future. Direct oral anticoagulants (DOACs) are preferred over vitamin K antagonists in both primary and secondary prevention of IS in AF patients. Recent data from the randomized controlled trials (RCT) also suggest that early initiation of DOAC treatment after acute IS is safe compared to later initiation. Anticoagulation treatment may still predispose for intracranial bleeding, particularly among patients with prior cerebrovascular events. Left atrial appendix closure offers an optional treatment choice for patients with prior intracranial hemorrhage and may offer an alternative to oral anticoagulation even for patients with IS, but these indications await validation in ongoing RCTs. There are still controversies related to the association of found AF paroxysms in CIS patients with prolonged screening, pertaining to the optimal duration of screening and screening strategies with prolonged monitoring techniques in patients with ESUS. In this review, we summarize the current knowledge of epidemiology, screening, and prognosis in AF patients with stroke.

Keywords: atrial fibrillation; hemorrhagic stroke; ischemic stroke; oral anticoagulation; prevention; screening.

Figure 1

Non-contrast computed tomography (A) showing a chronic embolic stroke of undetermined source (arrow) in a 66-year-old woman in the left middle cerebral artery territory. Magnetic resonance diffusion-weighted imaging (B) revealing ischemic lesions (bright spots indicated by arrows) in multiple territories in a 78-year-old man with chronic atrial fibrillation. T2*-weighted imaging (C) showing a subacute lesion (arrow) in the left middle cerebral artery territory in a patient with paroxysmal atrial fibrillation.

Figure 2

76-year-old woman with hypertension and dyslipidemia presented with a sudden onset left hemiparesis and dysarthria. Initial non-contrast computed tomography (A) showed no acute hypodensity. The patient received immediate intravenous thrombolysis after which computed tomography angiography (B) revealed a right-sided middle-cerebral artery occlusion in the M2 segment too distal to be treated with endovascular treatment. Despite thrombolysis, the next day magnetic resonance diffusion-weighted imaging (C) showed a cortical infarction (arrow) with a moderate hemorrhagic transformation in the susceptibility weighted imaging (D). Etiologic classification for the stroke was embolic stroke of undetermined source (arrow) after initial diagnostic work-up. And implantable loop monitor inserted 11 weeks later revealed a paroxysmal atrial fibrillation as the probable source of the embolism.