What is one significant complication of untreated atrial fibrillation?

Atrial fibrillation is characterized by an irregular and often rapid heart rate that can lead to the formation of blood clots in the atria of the heart. One of the most significant complications of untreated atrial fibrillation is the risk of stroke due to embolism. In this condition, the disorganized electrical activity in the atria can cause blood to pool and form clots. If these clots dislodge, they can travel to the brain, resulting in an ischemic stroke, which occurs when blood supply to a part of the brain is interrupted.

The potential for stroke is a major concern because it can lead to severe long-term disabilities or even death. The importance of managing atrial fibrillation often revolves around anticoagulation therapy, which helps prevent the formation of these clots and, consequently, the risk of embolic stroke.

Other options mentioned do not represent significant complications related to untreated atrial fibrillation. For instance, decreased cholesterol levels and improved exercise tolerance are outcomes not typically associated with atrial fibrillation; in fact, the opposite can be true, where patients may experience reduced exercise capacity. Increased heart muscle mass can occur due to various reasons but is not a direct complication of atrial fibrillation itself. Thus,