Atrial myopathy is considered to be the underlying cause of a large proportion of embolic strokes of undetermined source. However, the definition of this atrial condition is not well delineated while its identification could lead to prescription on anticoagulation in order to avoid stroke recurences. This study aims to identify new markers of atrial myopathy and choosed a multi parametric approach with electrical, echographical, biological and 4D flow CMR derived markers.

Inclusion Criteria:

Groupe1:Ischemic embolic stroke of undetermined source (ESUS) according to TOAST criteria (N =10)

• Age ≥ 18 years old
• Non-gap ischemic stroke diagnosed on MRI or CT scan of the brain (gap stroke defined as a cerebral infarction ≤ 1.5 cm / ≤2.0 cm on diffusion sequences).
• No major cardio-embolic source (episode of atrial fibrillation or flutter > 6min, intracardiac thrombus, LVEF <30 percent recent myocardial infarction (<4 weeks), mitral stenosis, valvular vegetation or infectious endocarditis).
• Absence of atherosclerosis causing stenosis ≥ 50 percent of the lumen of the intra or extra cranial arteries that vascularise the infarcted cerebral area.
• No other specific cause identified (arteritis, arterial dissection, migraine/vaso-spasm, toxic cause).
• Affiliation to a social security scheme
• Patient who signed the consent

Group 2: Non-paroxysmal AF (N=10)

• Age ≥ 18 years old
• Subject with documented non-paroxysmal AF
• Affiliation to a social security scheme
• Patient who signed the consent

Group 3: Healthy volunteers (N=10)

Pre-inclusion criteria :

• Age ≥ 45 years old
• Patient with no documented cardiac or neuro-vascular history
• Affiliation to a social security scheme
• Patient who signed the consent
• Registration on the VRB file (Volontaires Recherches Biomédicales, https://vrb.sante.gouv.fr) or response to the published announcement

Criteria for inclusion :

• ECG in sinus rhythm
• Holter ECG: no AF
• Normal Trans thoracic echocardiography
• Patient with no neuro-vascular history

Group 4: Stroke-ESUS or non-paroxysmal AF with cardiac MRI (N=10)

• Age ≥ 18 years old
• Subject with a documented stroke-ESUS or documented non-paroxysmal FA
• Subject with cardiac MRI
• Affiliation to a social security scheme
• Subject having given its non-opposition

Exclusion Criteria:

Groupe1: Ischemic embolic stroke of undetermined source (ESUS) according to TOAST criteria (N =10)

• Risk of pregnancy or pregnancy (proven on interrogation data or pregnancy test).
• Contraindication to MRI ferromagnetic material (in particular pacemaker, implantable defibrillator, cardiac valve prosthesis, cochlear implant, neuro-stimulator, implanted automated injection material, intraocular metallic foreign body, neurosurgical and vascular clips, claustrophobia)
• Less than 8 weeks after implantation of a stent
• Subject participating in another intervention research including a period of exclusion still in progress at the pre-inclusion stage.

Group 2: Non-paroxysmal AF (N=10)

• Risk of pregnancy or pregnancy (proven on interview data or pregnancy test).
• Contraindication to MRI ferromagnetic material (in particular pacemaker, implantable defibrillators, cardiac valve prosthesis, cochlear implant, neurostimulators, implanted automated injection equipment, intraocular metallic foreign body, neurosurgical and vascular clips, claustrophobia).
• Less than 8 weeks after implantation of a stent
• Subject participating in another intervention research including a period of exclusion still in progress at the pre-inclusion stage.

Group 4: Stroke-ESUS or non paroxysmal AF with cardiac MRI (N=10)

• History of neuro-vascular or cardiac pathology
• Risk of pregnancy or pregnancy (proven on interrogation data or pregnancy test).
• Contraindication to MRI (ferromagnetic material (in particular pacemaker, implantable defibrillator, cardiac valve prosthesis, cochlear implant, neuro-stimulator, implanted automated injection material, intraocular metallic foreign body, neurosurgical and vascular clips, claustrophobia)
• Subject participating in another intervention research including a period of exclusion still in progress at the pre-inclusion stage.