Atrial fibrillation (AF) is the irregular, chaotic beating of the upper chambers of the heart. Electrical impulses discharge so rapidly that the atrial muscle quivers or fibrillates.
The most serious consequence of AF is ischemic stroke. It is estimated that AF patients have five times the stroke risk of patients without AF.1 Most AF patients, regardless of the severity of their symptoms or frequency of episodes, require treatment to reduce the risk of stroke.
In patients with AF, blood tends to pool and form clots in an area of the heart called the left atrial appendage (LAA), a thin, sack-like appendix located in the upper left chamber of the heart. A blood clot that breaks loose from this area may migrate through the blood vessels and eventually plug a smaller vessel in the brain or heart resulting in a stroke or heart attack. In non-valvular AF, over 90% of stroke-causing clots that come from the heart are formed in the LAA.6
LAA forms during the third week of gestation and serves as the left atrium in the fetus