A 70-year-old woman comes in after a syncopal episode. She s…

A 70-year-old woman comes in after a syncopal episode. She said she fainted while she was gardening. She said she’s been feeling a bit fatigued and short of breath but attributes this to not sleeping well. On examination, a systolic murmur is heard. Based on these findings, a common valvular disorder, and the most likely, is: