Mechanisms relating to thrombus formation in atrial fibrillation are poorly understood and may differ in patients established on anticoagulation.

Traditional teaching tells us thrombus formation in atrial fibrillation (AF) is caused by venous stasis due to a fibrillating left atrium. Indeed, this is often the line we tell our patients, perhaps miming a fibrillating heart with our hands. We try to quantify the risk of stroke using various tools, most often the CHA₂DS₂VASc but in doing so we may neglect to consider and manage other relevant stroke risk factors inside and outside of the heart.

Yaghi and colleagues present an analysis from the initiation of anticoagulation study.1 In this subanalysis, patients with AF who are established on anticoagulation have a higher risk …