How does atrial fibrillation influence the risk of stroke?

Atrial fibrillation significantly increases the risk of stroke primarily due to the potential for blood clots to form in the atria. In this condition, the heart's electrical signals are disrupted, leading to an irregular and often rapid heartbeat. This disorganization of electrical activity prevents the atria from contracting effectively, creating areas of stagnant blood flow in the heart. When blood flow is stagnant, it predisposes to the formation of thrombi, or blood clots. If these clots dislodge, they can travel to the brain and cause an ischemic stroke, which results from the blockage of blood supply to brain tissue.

The other options misinterpret the relationship between atrial fibrillation and stroke risk. Blood flow does not improve with atrial fibrillation; rather, the chaotic rhythm and the resultant blood flow stasis increase the chance of clot formation. Stating there is no impact on stroke risk overlooks the established connection between atrial fibrillation and increased stroke incidence in the medical literature. Lastly, while atrial fibrillation may increase heart rate, this elevation does not lead to a reduced stroke risk; in fact, it is the irregular pumping action that heightens the risk of clot development and subsequent stroke.