Study the consequences on heart muscle of the stenosis aortic valve before and after the replacement procedure, the repercussion on heart. Study the impact on the heart of "sick" valve can affect on "well-being" and prognosis in the year following the surgery.

Inclusion Criteria:

• major patient freely accepting to participate in the study
• non-opposition signed
• aortic surface <1cm² or <0.6cm² / m² of indication surgical restraint
• oriented to short interventional management surgical term
• LVEF Left ventricular ejection fraction> 50%
• In the subgroup "MRI-fibrosis", absence of indication for performing MRI

Exclusion Criteria:

• patient under guardianship, curatorship or safeguard of justice
• minor patient
• pregnant woman
• patient with significant polyvalvulopathy for which it is from the start programmed more than aortic valve replacement
• patient with severe coronary artery disease requiring revascularization
• allergy to the contrast product

Patients with tight aortic stenosis with an indication of surgical treatment.