Inclusion Criteria:  Adults ≥ 18 y/o referred for an outpatient echocardiogram. Clinical diagnosis of Hypertrophic Cardiomyopathy (HCM). Both amyl nitrite inhalation and squat-to-stand maneuver performed during echocardiogram.  Exclusion Criteria:  Patients < 18 at the time of echocardiogram. Studies without documented provocative maneuvers. Patients with resting obstruction (MIG > 50 mmHg). Patients unable to undergo the squat-to-stand as protocolled based because of physical limitations. Patient with contraindications to amyl nitrite administration.