Implantable cardioverter-defibrillators (ICD) are currently recommended for the primary prevention of sudden cardiac death (SCD) in patients with a remote (>6 weeks) myocardial infarction (MI) and a low (≤35%) left ventricular ejection fraction (LVEF).

Ventricular tachycardia (VT) and/or ventricular fibrillation (VF), which are responsible for most SCDs, result from the presence of surviving myocytes embedded within fibrotic MI-scar. The presence of these surviving myocytes, as well as their specific arrhythmic characteristics, is not captured by LVEF. Hence, the use of LVEF as a unique risk-stratifier of SCD results in a low proportion (17 to 31%) of appropriate ICD device therapy at 2 years. Consequently, most patients with a prophylactic ICD do not present VT/VF requiring ICD therapy prior to their first-ICD battery depletion. Thus, many patients are exposed to ICD complications, such as inappropriate shocks, without deriving any health benefit. Therefore, the current implantation strategy of prophylactic ICDs, based on LVEF only, needs to be improved in post-MI patients.

Inclusion Criteria:

• Age > 18 years;
• Patients with a LVEF≤35% assessed at least after a 40 to 90 days period (depending on the presence of coronary revascularization) following an index myocardial infarction;
• Left ventricular systolic impairment as defined by LVEF≤35% by any current standard technique (echocardiogram, multiple gated acquisition scan, or MRI) within 2 months;
• Able and willing to comply with all pre-, post- and follow-up testing, and requirements;
• Use of maximum tolerated doses of ACE inhibitors (or Angiotensin II Receptor Blockers if intolerant of ACE) and Beta Blockers and MRA as per ESC guidelines;
• Person affiliated to or beneficiary of a social security plan
• Person informed about study organization and having signed the informed consent

Exclusion Criteria:

• History of cardiac arrest or sustained VT or VF unless within 48 hours of an acute myocardial infarction;
• Standard contraindications for cardiac LGE-MRI;
• Hypersensitivity to gadolinium-based contrast agent;
• Currently implanted permanent pacemaker and/or ICD;
• Patient refusal of ICD/ILR implantation;
• Currently implanted permanent pacemaker and/or ICD;
• Clinical indication for or Cardiac Resynchronization Therapy (CRT);
• Severe renal insufficiency defined by a glomerular filtration rate (GFR) < 30 mL/min/1.73m²;
• Recent PTCA (within 30 days) or CABG (within 90 days);
• Baseline NYHA functional class IV;
• Contraindication for ICD implantation according to current guidelines;
• Woman of childbearing age without effective contraception;
• Person referred in articles L.1121-5, L. 1121-7 and L.1121-8 of the French Public Health Code.