<prompt> Atrial fibrillation occurs in all exceptMitral stenosisHypothyroidismDilated cardiomyopathyMitral regurgitation  <response>: Atrial fibrillation can occur in hypehyroidism, not hypothyroidism. Other causes are: CAD Valvular hea diseases Hypeension Sinoatrial disease Alcohol Cardiomyopathy Congenital hea disease Chest infection Pulmonary embolism Pericardial disease Idiopathic Reference Harrison 20th edition pg 1433 