PANCE Practice Test 6

A 24-year-old man comes to the clinic because he nearly fainted twice while playing basketball in the past month. His father died suddenly at age 41. Pulse is 66/min and blood pressure is 122/74 mm Hg. A grade 3/6 harsh systolic murmur is heard at the left lower sternal border without radiation to the carotids. The murmur becomes louder when he stands from a squatting position and during the strain phase of the Valsalva maneuver, and softer with sustained handgrip. ECG shows left ventricular hypertrophy with deep, narrow Q waves in leads I, aVL, V5 and V6. Which of the following is the most likely diagnosis?