One-year Prognostic Impact of Microcirculation Assessed by NH IMR Angio in Patients Hospitalized for Acute Myocarditis

Inclusion Criteria: * Male or female patients over the age of 18. * Patients hospitalized between June 2015 and July 2025. * Patients who presented with chest pain and at least 1 diagnostic criterion; or, in the absence of chest pain, at least 2 of the following diagnostic criteria: * Electrocardiographic abnormalities (ST-segment elevation or depression, T-wave inversions, conduction disturbances such as type 3 atrioventricular block), * Elevated troponin levels, * Abnormal kinematics on echocardiography. * Associated with MRI findings of ≥2 tissue abnormalities (edema, hyperemia, myocardial fibrosis). * Coronary angiography performed during the initial hospitalization * Patient enrolled in or eligible for a social security program. * Patient who has expressed consent to participate. Exclusion Criteria: * Absence of coronary artery disease confirmed by coronary angiography * Myocarditis secondary to immunotherapy * Presence of documented coronary artery disease (coronary angiography or cardiac CT) * Presence of cardiomyopathy (hypertrophic cardiomyopathy, dilated cardiomyopathy) * Infiltrative heart disease (sarcoidosis or cardiac amyloidosis) * Severe valvular heart disease * Takotsubo syndrome * Constrictive or chronic pericarditis * Loeffler's endocarditis * Left ventricular noncompaction * Cardiac tumor * Pulmonary embolism * Coronary spasm * Patients covered by Articles L1121-5 through L1121-8 of the Public Health Code (pregnant women, women in labor, and breastfeeding women; persons deprived of their liberty by judicial or administrative decision; adults under guardianship)