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Figure 1 Morphology of hypertrophic cardiomyopathy (HCM). Anatomical phenotype of HCM seen in this cohort is depicted. A total of 155 of the patients (53%) had HCM characterized by asymmetric septal hypertrophy and left ventricular outflow tract obstruction (LVOTO). Apical = no gradient and hypertrophy predominantly in the distal one-third of the left ventricle (LV); HCM with LVOTO = resting gradient >50 mm Hg; Mid-cavitary obstruction = dynamic obstruction at the level of papillary muscle head or deeper within the LV cavity; Labile = resting gradient <50 mm Hg but provokable to >50 mm Hg with either Valsalva maneuver or amyl nitrite; Non-obstructive = no obstruction present at rest or with provocation.