Most common cause of cardioembolic stroke is
**Core Concept**
The question is testing the understanding of cardioembolic stroke, which is a type of ischemic stroke caused by the embolization of a blood clot from the heart. This condition is often related to cardiac abnormalities that lead to the formation of thrombi.
**Why the Correct Answer is Right**
The most common cause of cardioembolic stroke is atrial fibrillation (AF), a type of supraventricular tachycardia characterized by an irregular and often rapid heart rhythm. In AF, the left atrium becomes dilated and stasis of blood occurs, leading to the formation of thrombi on the atrial walls. These thrombi can then break loose and embolize to the brain, causing a cardioembolic stroke. The presence of atrial fibrillation significantly increases the risk of stroke, and anticoagulation therapy is often prescribed to prevent this complication.
**Why Each Wrong Option is Incorrect**
* **Option A:** While hypertension is a risk factor for stroke, it is not a direct cause of cardioembolic stroke.
* **Option B:** Atrial septal defects can lead to paradoxical embolism, but they are not the most common cause of cardioembolic stroke.
* **Option D:** Mitral valve prolapse can increase the risk of stroke, but it is not the most common cause of cardioembolic stroke compared to atrial fibrillation.
**Clinical Pearl / High-Yield Fact**
Atrial fibrillation is a significant risk factor for cardioembolic stroke, and anticoagulation therapy is often prescribed to prevent this complication. It is essential to diagnose and manage AF promptly to reduce the risk of stroke.
**Correct Answer: A. Atrial fibrillation**