A 42-year-old woman has noted progressive exercise intolerance and fatigability. Examination discloses an opening snap in the mitral area suggestive of mitral stenosis. The following is/are true:
A.	Critical mitral stenosis is defined as an orifice area reduced to 2 cm2
B.	With a fixed mitral orifice, the change from sinus rhythm to atrial fibrillation has little effect on cardiac output
C.	Mural thrombi and thromboembolism are directly related to the presence of atrial fibrillation
D.	Depressed cardiac output is usually due to depressed myocardial contractility
Answer:C
A 42-year-old woman has noted progressive exercise intolerance and fatigability. Examination discloses an opening snap in the mitral area suggestive of mitral stenosis. The following is/are true:
A.	Critical mitral stenosis is defined as an orifice area reduced to 2 cm2 B.	With a fixed mitral orifice, the change from sinus rhythm to atrial fibrillation has little effect on cardiac output C.	Mural thrombi and thromboembolism are directly related to the presence of atrial fibrillation D.	Depressed cardiac output is usually due to depressed myocardial contractility