Which heart structure is most commonly affected by atrial fibrillation?

Atrial fibrillation is primarily characterized by chaotic electrical activity in the atria, which leads to an irregular and often rapid heartbeat. The left atrium, in particular, is the heart structure most commonly affected by this condition.

This is largely due to the fact that atrial fibrillation often originates in the pulmonary veins, which drain into the left atrium. Structural changes, such as dilation and inflammation of the left atrium, can occur due to various factors like hypertension, heart failure, or valvular heart disease, making it more susceptible to developing atrial fibrillation.

The left atrium’s anatomy allows for the arrhythmogenic foci to establish themselves within the wall of the left atrium or its entry points from the pulmonary veins. This, combined with its role in the overall function of the heart, highlights why atrial fibrillation predominantly impacts the left atrium more than any other heart structure.

In contrast, the right ventricle, aorta, and interventricular septum are less directly involved in the mechanisms and pathophysiology underlying atrial fibrillation, thus making them less commonly affected by this arrhythmia.