The primary purpose of this study is to demonstrate that changes in plasma levels of circulating neurohormones (mainly BNP and NT-proBNP), measured at rest and post-exercise correlate with exercise functional limitation (assessed by exercise peak VO2) and exercise ultrasonic parameters (as left ventricular filling, obstruction, and mitral regurgitation)

The secondary purposes are to study the kinetics of secretions of natriuretic peptides, and their relationships with extent of MRI myocardial fibrosis with the degree of exercise functional limitation.

Inclusion Criteria:

• - Age 18 to 75 years
• Primary (sarcomeric) hypertrophic cardiomyopathy, obstructive or non obstructive, with studies of exercise peak oxygen consumption and cardiac MRI with gadolinium late-enhancement
• Informed consent
• Patient with a social insurance Patient at rest
• - Age 18 to 75 years
• Primary (sarcomeric) hypertrophic cardiomyopathy, obstructive or non obstructive
• Informed consent
• Patient with a social insurance

Exclusion Criteria:

• - Insufficient echogenicity
• Permanent atrial fibrillation
• Complete BBB on the ECG
• LVEF < 35 %
• Previous septal ablation (surgical or percutaneous)
• Simultaneous participation to another biomedical research

If exercise needed:

• contraindication to exercise : hemodynamic instability, uncontrolled high blood pressure (>220/120 mmHg), severe aortic stenosis
• Inability to exercise (muscular, pulmonary, elderly patient)