The aim of the study is to assess the negative predictive value of the T amplitude variance as a method for risk stratification for patients with an increased risk for SCD.

Inclusion Criteria:

Patient has been prescribed the implantation of an SORIN GROUP OvatioTM DR 6550 / VR 6250 system according to relevant currently-approved guidelines

• CHF since > 3 months and
• LVEF < 35% and
• NYHA class II or III

OR

• Prior Myocardial infarction since more than 4 weeks and
• LVEF < 30%

Exclusion Criteria:

• Documented spontaneous sustained ventricular tachycardia
• Prior implant of any device for ventricular cardiac pacing
• Existing indication for permanent ventricular pacing
• Myocardial infarction within 4 weeks prior to enrollment
• Arrhythmogenic RV-Dysplasia
• Brugada syndrome
• Long QT syndrome
• Performed within 3 months prior to enrollment or scheduled (within 3 months) cardiac revascularization (interventional or surgical)
• Any indication for CRT accordingly to the relevant currently-approved ACC/AHA1 or ESC35 guidelines for the implantation of a CRT system.
• Excisting or planned administration of amiodarone - initiation of amiodarone therapy during the run of the study will lead to immediate exclusion of the patient
• Permanent chronic atrial fibrillation / flutter
• Patient is unable to attend the scheduled follow-up visits at the participating centre
• Patient is already included in another ongoing clinical study
• Patient is unable to understand the objectives of the study
• Patient refuses to cooperate
• Patient is unable or refuses to provide informed consent
• Patient is minor (less than 18-year old)
• Patient has life expectancy of less than 1 year
• Patient is pregnant.