This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Most common cause of systemic thromboembolism is? 
Select and explain. 
A. Paradoxical emboli, B. Intracardiac murals, C. Aortic aneurysms, D. Unknown origin
B: Intracardiac murals
Answer: B: Intracardiac murals 
Explanation: Most systemic emboli (80%) arise from intracardiac mural thrombi; two-thirds of these are associated with left ventricular infarcts and another 25% with dilated left atria (e.g.secondary to mitral valve disease). The remainder originate from aortic aneurysms, thrombi overlying ulcerated atherosclerotic plaques, fragmented valvular vegetations, or the venous system (paradoxical emboli); 10% to 15% of systemic emboli are of unknown origin.