AAV1-CMV-Serca2a GENe Therapy Trial in Heart Failure

Inclusion Criteria: * Patients with NYHA class III / IV severe heart failure ≥ 3 months * Ischemic or non-ischemic origin * Left ventricular ejection fraction ≤35% * Patients must be receiving optimal (maximum tolerated doses) medical treatment (diuretics, renin-angiotensin-aldosterone system blockers, beta blockers, ±Ivabradine) for at least 1 month (with the exception of diuretic dose titration) and must be stable. * No decompensated congestive heart failure within the past month * With or without an ICD if the ICD was implanted over 3 months ago, with or without biventricular pacing if the RCT was implanted over 6 months ago * All women of childbearing potential must have a negative urine pregnancy test prior to administration of investigational medicinal product * Patient must have given written informed consent to participate in this study Exclusion Criteria: * \<18 or \>80 years old * AAV1 seropositivity (titer \<1:2) in the last 3 months * Atrial fibrillation in the absence of permanent ventricular pacing * Coronary revascularization or heart surgery or pacemaker implantation \< 3 months * Ischemic heart disease without at least one coronary artery with a TIMI-3 flow * Restrictive cardiomyopathy, hypertrophic obstructive cardiomyopathy, pericardial disease, cardiac amyloidosis * Heart transplant, an already implanted or needing to urgently implant external ventricular assist device * Myocardial infarction (STEMI or NSTEMI) \< 3 months * Treatment with intravenous positive inotropic agents or diuretics in the past 28 days * Pregnant or nursing patient * Female patient of childbearing age with no effective means of contraception * Severe renal failure defined by a creatinine clearance of \< 30 mL/min (last bloodwork done less than 6 months) * Liver failure, chronic liver disease or laboratory tests \> 3 x N (AST, ALT, ALP))(last bloodwork done less than 6 months) * Thrombocytopenia (\<50,000/mm3 * Patient treated with immunosuppressants, has an immunodeficiency or whose neutrophil count \< 1000 mm3 * Recent sepsis (\< 3 months) * Active neoplasia or treated \< 5 years * No medical insurance * Patient is enrolled in another randomized study * Patient does not understand the protocol procedures sponsor suspects poor compliance with the protocol