HCMR Re-Imaging Study

Inclusion Criteria: Patients in the original HCMR cohort with: 1. Obstructive HCM * Males and females between 18 and 65 years of age * BMI \< 35 kg/m2 * LVOT-G at entry as follows: Resting gradient ≥50 mmHg OR Resting gradient ≥30 mmHg and \<50 mmHg with post-Valsalva LVOT-G ≥50 mmHg • NYHA Class II or III or 2. Non-obstructive HCM * Same criteria as above except resting LVOT-G is \<30mmHg and post-Valsalva gradient \<50mm Hg * BMI \<40kg/m2 * Elevated NT-proBNP \> 300 pg/mL at the time of enrollment * LVEF ≥55% Exclusion Criteria: * Paroxysmal atrial fibrillation or flutter documented prior to entry. * Paroxysmal or permanent atrial fibrillation requiring rhythm restoring treatment (eg, direct-current cardioversion, ablation procedure, or antiarrhythmic therapy) ≤6 months prior to entry. (This exclusion does not apply if atrial fibrillation has been treated with anticoagulation and adequately rate-controlled for \>6 months.) * History of syncope or sustained ventricular tachyarrhythmia with exercise within 6 months prior to entry. * Pregnancy due to potential risk of gadolinium to the fetus * Patients with a pacemaker that are pacer-dependent as they cannot undergo MRI