Stroke associated with atrial fibrillation

Fernando Testai MD PhD (Dr. Testai of the University of Illinois College of Medicine at Chicago received research grants from Dart NeuroScience, the NIH, and the American Heart Association and consulting fees from Medico-legal Consulting.)
Gabriela Trifan MD (

Dr. Trifan of The University of Illinois College of Medicine has no relevant financial relationship to disclose.

)
Steven R Levine MD, editor. (Dr. Levine of the SUNY Health Science Center at Brooklyn has received honorariums from Genentech for service on a scientific advisory committee and a research grant from Genentech as a principal investigator.)
Originally released June 20, 1996; last updated January 3, 2018; expires January 3, 2021

This article includes discussion of stroke associated with atrial fibrillation and cardioembolic stroke. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Stroke is the leading cause of disability in United States. Cardioembolism is a particularly disabling stroke subtype that accounts for 20% to 30% of all stroke cases. Observational studies demonstrated that almost half of the cardioembolic strokes are related to atrial fibrillation. In this article, the authors discuss the association of atrial fibrillation with stroke, the role of anticoagulation in stroke prevention, the available risk stratification tools, and the pathogenic mechanisms of thrombus formation associated with this cardiac arrhythmia.

Key points

 

• Atrial fibrillation confers a 3- to 5-fold increase in stroke risk and accounts for 15% to 30% of all ischemic strokes.

 

• Prolonged cardiac monitoring is superior to short-term monitoring for the detection of occult atrial fibrillation.

 

• CHA2DS2-Vasc score of 2 and above in the presence of atrial fibrillation is an indication for anticoagulation.

 

• Direct thrombin or factor Xa inhibitors are not inferior to warfarin in the prevention of stroke or systemic embolism in atrial fibrillation patients and have lower incidence of major hemorrhagic complications.

 

• The addition of aspirin to anticoagulation may be indicated in patients who have concomitant coronary artery disease.

Historical note and terminology

As early as 1628, Harvey had observed undulation in the right atrium of a dying animal heart (McMichael 1982); in 1874, Vulpian reported uncoordinated twitching of the atrium, "fremissement fibrillaire" after application of an electrical current (Vulpian 1874). Nothnagel published 3 arterial pulse curves showing irregular heart rates in the mid-1800s and called the arrhythmia "delirium cordis" (Nothnagel 1876), which was defined by the complete irregularity of heartbeats continuously changing in "height and tension." However, the association between these atrial fibrillary contractions and the irregular pulse was not formally made until 1907 (Cushny 1907).

In 1940, Karl Paul Link synthesized dicumarol, a substance found in spoiled sweet clover known to cause a hemorrhagic disease in cattle; in 1947, its use was advocated for the prevention of cardiac embolism in patients with rheumatic atrial fibrillation (Wright 1947). However, the risk of stroke in patients with chronic nonvalvular atrial fibrillation was generally believed to be too small to require medication. It was not until 1978 that the results of the Framingham Study clearly demonstrated an increase in stroke incidence in patients with chronic nonrheumatic atrial fibrillation (Wolf et al 1978). Vitamin K antagonists, including warfarin, have been the treatment of choice for the prevention of stroke or systemic embolism in patients with atrial fibrillation for many decades. More recently, however, large randomized placebo-control studies demonstrated the efficacy and safety of different non-vitamin K antagonists or novel oral anticoagulants in the treatment of nonvalvular atrial fibrillation.

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