This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hea Sounds, Subject name: Medicine
[{'content': 'A lady presents with grade-III dyspnea. She has severe mitral stenosis with atrial fibrillation. Along with increased ventricular rate, clots in the left atrium are seen. Which of the following should not be done? \nSelect and explain. \nA. Diltiazem to reduce the hea rate, B. Warfarin therapy, C. Open mitral commissurotomy and removal of clot, D. Cardioversion with percutaneous balloon valvotomy', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Atrial fibrillation with retained clots is due to the stasis of blood in the poorly contracting Left atrium. If cardioversion is done in this setting, the normal sinus rhythm ensues and the proper contraction of atria may result in dislodgement of clots from the atria. The PMV procedure dilates the mitral annulus, relieves the annulus and the chances of clots embolizing a bigger orifice increase. If cardioversion is indicated more urgently, then intravenous heparin should be provided and TEE performed to exclude the presence of left atrial thrombus before the procedure.', 'role': 'assistant'}]