Atrial fibrillation is a significant risk factor for stroke. As this diagram shows, an episode of Afib can lead to series of events that could cause a blood clot to travel to the brain and cause a stroke. The risk of stroke is one major reason it’s important to talk with your medical team about treatments for atrial fibrillation and stroke prevention. Media provided courtesy of Boston Scientific. © 2015 Boston Scientific Corporation or its affiliates. All rights reserved.

The heart is made up of four chambers. The upper chambers are known as the right and left atria, while the lower chambers are known as the right and left ventricles. The two upper chambers are separated by a wall of tissue known as the interatrial septum. The wall that separates the two lower chambers is called the interventricular septum.

At the top of the heart, on the left side of the left atrium, is a small sac known as the left atrial appendage (or LAA). As the heart pumps, blood travels through the atria and the ventricles. The LAA is hollow, so it fills with blood when the left atrium receives blood and it empties when blood travels out of the left atrium.

In most people the left atrial appendage is of little or no concern. But for people with atrial fibrillation, where the heart is beating erratically, the LAA can become a source of problems.

The LAA and Stroke

People who have atrial fibrillation (also known as Afib or AF) are at increased risk for stroke in part because of the LAA. During Afib, the heart’s natural pacemaker (the sinoatrial node) sends irregular signals, causing the heartbeat to be erratic and the heart to pump inefficiently. In Afib, the contractions of the atria are ineffective, the blood is drawn through mostly by the stronger ventricle, which continues pumping. The atrium’s inefficient pumping allows blood to pool in the left atrial appendage instead of being pushed out of the heart and into the blood vessels that supply oxygen to the rest of the body. If blood remains in the LAA too long, it begins to form clots. If one or more of the clots eventually is pumped out of the LAA and travels to the brain, an ischemic stroke can result.

The risk for stroke is one reason that it is important to work with your medical team to manage Afib. This may mean making lifestyle changes and taking medications, or having a procedure that prevents the atrial fibrillation episodes (ablation or cardioversion), keeps the heart beating in normal sinus rhythm or stops blood from accumulating in the LAA (left atrial appendage closure, or LAAC).

• To learn about the options for treatment, visit the SecondsCount Atrial Fibrillation Center.
• For information about ablation and cardioversion, click here.
• For information about left atrial appendage closure (LAAC) procedures, click here.