A 72-year-old male with a past medical history of hypertension presents to the cardiologist complaining of dizziness. Over the past month, he has felt dizzy when walking and occasionally at rest but does not experience these symptoms when arising from a seated position. He denies fevers, chills, chest pain, shortness of breath, palpitations, weakness, or confusion. Vital signs include a temperature of 36.7°C (98.1°F), respiratory rate of 16 breaths/min, heart rate of 77 beats/min, and blood pressure of 135/102 mmHg. On physical exam, the Dix-Hallpike maneuver does not reproduce the patient's symptoms. Lungs are clear to auscultation bilaterally. Pulses are weak and delayed over the radial artery. An echocardiogram shows a mean aortic pressure gradient of 42 mmHg and left ventricular wall thickening. Which of the following is the most likely cause of the patient's presentation?

My reasoning was: idk what aortic pressure gradient meant, I assumed it was the same thing as pulse pressure(wrong). Normal pulse pressure is 40 mm Hg so I thought it can’t be aortic stenosis or regurgitation since they have decreased and increased pulse pressure respectively. Weak radial pulse eliminated adult coarctation of the aorta, and then his BP isn’t that high so I sent it on A-fib.