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: Medicine
Atrial fibrillation may occur in all of the following conditions, except? 
Select and explain. 
A. Mitral stenosis, B. Hypothyroidism, C. Dilated cardiomyopathy, D. Mitral regurgitation
B: Hypothyroidism
Answer: B: Hypothyroidism 
Explanation: Causes of Atrial fibrillation: Rheumatic heart disease (MS and MR), Nonrheumatic mitral valve disease, Hypertensive cardio-vascular disease, dilated cardiomyopathy, atrial septal defect, Coronary heart disease, Thyrotoxicosis, Acute alcohol excess and alcohol withdrawal.