Evaluation of a Diagnostic Feature in a Cardiac Resynchronization Therapy (CRT) Device

Inclusion Criteria: * Subject eligible for implantation of a CRT-D device according to current available guidelines for cardiac resynchronization therapy * Subject has severe heart failure (NYHA Class III or IV) * Subject has experienced at least one heart failure event within six months prior to enrollment * Subject continues to have heart failure symptoms despite receiving optimal medical therapy * Schedule for implant of a PARADYM CRT-D (Model 8770) * Subject has signed and dated an informed consent form Exclusion Criteria: * Any contraindication for standard cardiac pacing * Any contraindication for ICD therapy * Abdominal implantation site * Hypertrophic or obstructive cardiomyopathy * Acute myocarditis * Unstable coronary symptoms (unstable angina or myocardial infarction) within the last month * Recent (within the last month) or planned cardiac revascularization or coronary angioplasty * Correctable valvular disease that is the primary cause of heart failure * Mechanical tricuspid valve * Receiving continuous intra-venous infusion of positive inotropic therapy or intermittent therapy (intravenous infusion) more than twice per week * Heart transplant recipient * Renal insufficiency requiring dialysis * Already included in another clinical study * Life expectancy less than 12 months * Inability to understand the purpose of the study or refusal to cooperate * Inability or refusal to provide informed consent or HIPAA * Unavailability for scheduled follow-up at the implanting center * Known sensitivity to 1mg dexamethasone sodium phosphate (DSP) * Under guardianship * Age of less than 18 years * Pregnancy