<prompt> Atrial fibrillation may occur in all of the following conditions, except?Mitral stenosisHypothyroidismDilated cardiomyopathyMitral regurgitation  <response>: 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. 