Most common cause of embolic stroke is –
**Core Concept**
Atrial septal defects (ASDs) or patent foramen ovale (PFO) can lead to paradoxical embolism, but the most common cause of embolic stroke is actually atherosclerotic disease, specifically atherosclerosis of the carotid arteries. This condition occurs when atherosclerotic plaques, composed of lipid-laden macrophages and smooth muscle cells, rupture and embolize to the cerebral vasculature, resulting in ischemic stroke.
**Why the Correct Answer is Right**
The most common cause of embolic stroke is atherosclerotic disease, particularly involving the carotid arteries. Atherosclerosis is a chronic inflammatory process involving the accumulation of lipid-laden macrophages (foam cells) and smooth muscle cells in the arterial wall, leading to plaque formation and potential rupture. When an atherosclerotic plaque ruptures, it can embolize and occlude cerebral arteries, resulting in ischemic stroke. The carotid arteries are particularly prone to atherosclerosis, making them a common source of embolic stroke.
**Why Each Wrong Option is Incorrect**
**Option A:** While atrial septal defects (ASDs) or patent foramen ovale (PFO) can increase the risk of paradoxical embolism, they are not the most common cause of embolic stroke.
**Option B:** Cardiac sources of embolism, such as atrial fibrillation, can contribute to embolic stroke, but are not the most common cause.
**Option C:** Vasculitis or vasculopathy can rarely cause embolic stroke, but is not the most common cause.
**Clinical Pearl / High-Yield Fact**
A thorough physical examination, including auscultation of carotid bruits, can help identify patients at risk for atherosclerotic disease and subsequent embolic stroke.
**Correct Answer:** D.