Evaluation of Cardiac Compass With OptiVol in the Early Detection of Decompensation Events for Heart Failure

Inclusion Criteria The following criteria apply to all subjects: * Subject has a CRT-D or dual chamber ICD with Cardiac Compass and OptiVol Fluid Status Monitoring implanted in the pectoral region at least 30 days prior to enrollment. CRT-D/ICD must be supported by the Medtronic CareLink Network. * Subject has a market-released, transvenous, high voltage RV lead * Subject has a market-released RA lead * If subject has an LV lead, it must be compatible, not Y-adapted and not currently under investigation * Subject's heart failure regimen (i.e. beta blocker and ACE inhibitor (or substitute) unless documented evidence of intolerance is available) adheres to current ACC/AHA guidelines for management of chronic heart failure in adult patients * Subject has a history of at least one heart failure related hospitalization, Emergency Department (ED) visit, or urgent visit necessitating IV diuretic, IV inotropic, IV vasodilator, or other parenteral therapy within 12 months prior to baseline evaluation * Subject is at least 18 years of age * Subject is willing and able to comply with the Clinical Investigation Plan (e.g. willing and able to remain available for follow-up visits, use SentryCheck, etc.) * Subject is willing and able to transmit data using the Medtronic CareLink Network * Subject (or subject's legally authorized representative) is willing and able to sign and date the study Informed Consent and HIPAA Authorization (U.S.) Exclusion Criteria The following criteria apply to all subjects: * Subject is post heart transplant or actively listed on the transplant list and reasonable probability (as defined by investigator) of undergoing transplantation in the next year * Subject received a coronary artery bypass graft or valve surgery in the last 90 days * Subject had a myocardial infarction (MI) in the last 90 days. * Subject is indicated for valve replacement/repair * Subject's life expectancy due to non-cardiac reasons is less than six months * Subject has serum creatinine \> 2.5 mg/dL measured within 30 days prior to enrollment. * Subject is on chronic renal dialysis * Subject is on continuous or intermittent (\> 2 stable infusions per week) infusion therapy for HF * Subject has complex and uncorrected congenital heart disease * Subject is enrolled in a Disease Management Program where an outside vendor, company or service is employed to determine, monitor, and/ or alert a clinician or subject to weight changes or other HF signs or symptoms via interactive or passive systems * Subject is implanted with a cardiac hemodynamic monitor or left ventricular assist device(LVAD) * Subject is enrolled in a concurrent study, with the exception of a study approved by the Medtronic PRECEDE-HF Clinical Trial Leader prior to enrollment