Combined Study of ATrial Strain and Voltage by High Density Mapping in Young Patients With Atrial Fibrillation.

Atrial The treatment of atrial fibrillation (AF) includes 2 axes: the prevention of the cardio-embolic risk and rhythm control. The possibilities for this control are antiarrhythmic drugs and, above all, catheter ablation, an interventional cardiology technique which consists in treating the areas responsible for the initiation and perpetuation of AF by applying radiofrequency energy or cryotherapy to the myocardial tissue.

Limited research has been done on the combination of different parameters to manage AF, especially during the initial stage of the disease. A translational and multimodal approach could make it possible to better characterize this pathology and thus, help to adjust the therapeutic management for the patients.

The combined analysis of regional electrophysiological, morphological, and functional parameters of the left atrium could make it possible to better detect early atrial cardiomyopathy and predict recurrences of atrial fibrillation.

The electrophysiological substrate for patients with persistent atrial fibrillation is heterogeneous with areas of atrial myocardium of low voltage amplitudes and areas of rapid fragmented signals in arrhythmia. The targets of ablation treatment in these cases are currently poorly defined. Several promising strategies have emerged, such as the isolation of fibrotic areas, low voltage.

An integration analysis of regional electrophysiological, morphological, and functional parameters of the left atrium, therefore, open up a new area of research that has not been studied to date and could help to better guide the therapeutic management of patients with AF.

The study aims to assess the association between regional and global myocardial strain abnormalities on magnetic resonance imaging (MRI) and the amplitude of the atrial intracardiac electrical potential, in young subjects with symptomatic AF.

Eligibility Criteria:
Inclusion Criteria:

1. Patient aged 18 to 60 years
2. Established diagnosis of paroxysmal or persistent symptomatic atrial fibrillation (AF) for at least 3 months with indication of catheter ablation
3. AF episode documented by ECG in the last 12 months
4. Structurally healthy heart, with an LVEF\> 50%, an interventricular septum \<12 mm and an OG volume \<40mL / m ² by TTE
5. Having given their informed consent in writing
6. Affiliated with or entitled to a French social security scheme

Exclusion Criteria:

1. Mitral valve disease with grade 2 to 4 insufficiency
2. Heart failure (NYHA stage II to IV in sinus rhythm and LVEF \< 50%), hypertrophic heart disease or congenital heart disease
3. Contraindication to oral anticoagulation
4. Intracardiac thrombus
5. History of ablation of the left atrium
6. History of heart surgery
7. Contraindication to performing MRI or using the DOTAREM™ contrast medium (pacemaker, defibrillator, prosthesis, old generation heart valves, old generation ferromagnetic vascular surgical clips, treatment type endocranial aneurysms, neurosimulator, cochlear implants, automated injection device such as insulin pump, and more generally any non-removable electronic medical device or equipment, kidney disease with GFR \< 30 mL/min, hypersensitivity to gadoteric acid or to excipients)
8. History of myocardial infarction or coronary angioplasty within the last three months
9. Chronic obstructive pulmonary disease
10. Under guardianship or curatorship
11. Women who are pregnant, breastfeeding or of childbearing age in the absence of effective contraception
12. Participation in another interventional research involving a health product