Study of Hypertrophic Cardiomyopathy Under Stress Conditions. Concordance Between Two Complementary Tests: Stress MRI and Exercice Stress Echocardiography

Hypertrophic cardiomyopathy (HCM) is a primitive myocardic disease and the first of genetic cardiac diseases. The definition of HCM is an increase of the myocardial thickness of the left ventricle (LV) wall without any other causes of hypertrophy. It's characterized by an important heterogeneity of prognosis and clinical expression going from a asymptomatic state until the devastating sudden death occurring in a young person.The diagnosis of HCM is definite by a myocardial thickness greater or equal to 15mm (or 13mm if there is a familial history).This hypertrophy is often accompanied by other abnormalities detected by echocardiography: dynamic left ventricular outflow obstruction at rest or stress, mitral regurgitation …Now, the current challenge is to determine the prognosis factors of the disease that could help to identify the patients with high risk of sudden death. Some prognosis factors are knowed and used in the calculation of a new risk score. This risk score allows to estimate the risk of sudden death at 5 years and propose depending on the result, the implantation of a defibrillator for primary prevention.The physiopathological mechanism of HCM is very complex and still misunderstood. Myocardial fibrosis could be a major mechanism of the disease evolution. Indeed, fibrosis is responsible of scar areas where ventricular tachycardia may develop. Moreover, if the fibrosis is very extensive, it can be the responsible of a systolic or diastolic dysfunction of the left ventricle leading to heart failure.Myocardial ischemia caused by a microvascular dysfunction is now recognized as an important mechanism of the disease evolution. Acute ischemic events could be a trigger of malignant arrhythmia whereas chronic ischemia leads to fibrosis.Left ventricle function is long time preserved in HCM. Segmentary hypokinesia corresponding to extensive fibrosis appears at a very advanced stage of the disease. Exercice stress echocardiography permits to detect myocardial ische