What arrhythmia is notably associated with increased risk of stroke?

Atrial fibrillation is notably associated with an increased risk of stroke due to its ability to lead to the formation of blood clots in the atria of the heart. During atrial fibrillation, the atria do not contract effectively, which can cause turbulent blood flow. This turbulence can promote the development of thrombi, particularly in the left atrial appendage, where blood tends to pool. If a clot breaks free, it can travel to the brain and cause an ischemic stroke.

In contrast, the other arrhythmias listed do not carry the same level of stroke risk. Bradycardia, characterized by a slow heart rate, and heart block, which involves delays in the conduction system, typically do not lead to thrombus formation in the same way. Ventricular fibrillation, while life-threatening, can lead to sudden cardiac arrest rather than directly resulting in ischemic stroke. Understanding the distinct mechanisms of these arrhythmias highlights why atrial fibrillation poses a significant concern for stroke risk.