HCM patient clinical characteristics. (A) LV end-diastolic wall thickness was ∼30 mm, with a pattern of asymmetric septal hypertrophy. No LV noncompaction cardiomyopathy was observed. (B) Three-chamber view on cardiac magnetic resonance imaging. Note significant left atrium enlargement of ∼50 mm. (C) Pseudonormal mitral filling pattern on Doppler interrogation with a short mitral deceleration time. Lateral E′ velocity (not shown in this image) was also significantly reduced. (D) Electrocardiogram strip showing LV hypertrophy and repolarization abnormalities in multiple leads. This electrocardiogram shows normal sinus rhythm, but the patient is at high risk of developing atrial fibrillation in the future. aVF, augmented vector foot; aVL, augmented vector left; aVR, augmented vector right; MV, mitral valve; PG, peak gradient; PW, pulsed wave; Vel, velocity.