AKT-0260

A 32-year-old man presents for an insurance medical. He has no significant medical history. During the examination, his BMI is 23 kg/m2, blood pressure is 110/70 mmHg, and auscultation of the heart reveals a mid-systolic click and a late systolic murmur (which are more pronounced when he stands up).
What is the most likely diagnosis based on these findings?