Hypertrophic cardiomyopathy (HCM) is the most frequent genetic cardiac disease characterized by an asymmetric hypertrophic. In two third of patients, an obstruction to blood ejection is observed within the left ventricle which is named left ventricular outflow tract obstruction (LVOTO). This phenomenon can occur at rest or during exercise and is associated with symptoms such as dyspnea, dizziness or chest pain that can significantly limit day life adaptation. To now, medical or interventional treatments such as betablocacker, calcium blockers or septal alcoholisation or surgery present with a limited efficiency. Recent studies from investigators group revealed new concepts about the role of venous return to the LVOTO. Therefore the investigators hypothesis that BX1514M generating a venous vascular constriction, could improve symptoms of HCM patients by reducing LVOTO.

Inclusion Criteria:

• Patients with a typical or atypical hypertrophic cardiomyopathy (HCM) confirmed by imaging modalities (echo and MRI) and/or genetic tests or a relative history of HCM
• Left ventricular obstruction during exercise on treadmill (above 50 mmHg)
• Positive response to leg lifting test (obstruction reduction above 20 mmHg) at rest or in early recovery phase
• Daily symptoms as shortness of breath during exercise (NYHA2-3), non coronary chest pain, dizziness
• Correct ultrasound windows quality
• Sinus rhythm
• Optimal medical treatment
• For women, pregnancy test or contraception
• Written consent form obtained

Exclusion Criteria:

• Previous treatment by BX1514M
• Extra-cardiac pathology with life expectancy below than 1 year
• No capability of consent form written
• Pregnancy women
• Secondary hypertension hypertrophy, secondary valvular disease hypertrophy
• Permanent atrial fibrillation
• Severe ventricular arrhythmia without Implantable Cardioverter Defibrillator (ICD)
• Severe coronary disease
• Severe non stabilized hypertension
• Severe cardiopathy (ejection fraction below 40% or demonstrated elevated end diastolic pressure or pulmonary pressure above 60 mmHg)
• Bradycardia
• Narrow angle glaucoma
• Vascular prethrombotic diseases
• Vascular spams
• Thyrotoxicosis
• Pheochromocytoma
• Severe renal failure (<30ml/mn)
• Patients at risk of urinary retention secondary to prostatic severe disease
• Raynaud's disease
• Non selective Monoamine Oxidase Inhibitors (MAOIs), iproniazid, nialamide or ephedrine, methylphenidate, phenylephrine, pseudoephedrine or digitalic
• Procedures modifying the peripheral venous return
• Participation to other research protocol