This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: M.I. & Angina, Subject name: Medicine
[{'content': 'Aggravation of symptoms of angina in a patient when given nitrates is seen in : \nSelect and explain. \nA. Aortic regurgitation, B. Mitral regurgitation, C. Single left coronary artery stenosis, D. Idiopathic hypertrophic subaortic stenosis', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e Idiopathic Hypertrophic Sub Aortic Stenosis As already explained in Nov. 2000, idiopathic hypertrophic subaortic stenosis (or HOCM) is a dynamic outflow obstruction which is increased by any mechanism decreasing the preload (Nitrates decrease the preload significantly)Nitrates decrease the obstruction in AR & MRIn single left coronary artery stenosis, nitrates are helpful. By decreasing the preload decrease the cardiac work done (and hence decreased 02 requirement). A decrease in preload also improves the subendocardial perfusion (because of decrease in end-diastolic pressure, the sub-endocardial crunch is abolished).", 'role': 'assistant'}]