The purpose of this study is to evaluate the performance of a new sensor-based diagnostic feature, which has been implemented in a cardiac resynchronization therapy (CRT) device. This trial will study the effectiveness of the diagnostic feature to detect heart failure events in medically stable, ICD-indicated, congestive heart failure patients.

The purpose of this study is to evaluate the performance of a new sensor-based diagnostic feature, which has been implemented in a cardiac resynchronization therapy (CRT) device. This trial will study the effectiveness of the diagnostic feature to detect heart failure events in medically stable, ICD-indicated, congestive heart failure patients. The ability of the diagnostic feature to 'detect' and 'predict' heart failure events will be studied.

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