PEGASUS CRT Study: Atrial Support Study in Cardiac Resynchronization Therapy (PEGASUS CRT)

Inclusion Criteria: Patients who meet current indications for the CONTAK RENEWAL® family of cardiac resynchronization therapy defibrillator (CRT-D) devices or future Food and Drug Administration (FDA) approved Guidant CRT-D devices Patients who sign and date a Patient Informed Consent at, or prior to, the implant visit Patients who are in sinus rhythm at the time of implant Patients who remain in the clinical care of the enrolling physician in approved centers Patients who are on optimal pharmacologic therapy or who have developed a recent implantable cardioverter defibrillator (ICD) indication that necessitates ICD therapy concurrent with the optimization of pharmacologic therapy Exclusion Criteria: Patients whose medical condition is expected to preclude the use of the protocol-required pacing mode (dual chamber pacing [DDD or DDDR]) and respective lower rate limits Patients with permanent atrial fibrillation or atrial flutter Patients who are in complete heart block Patients who have previously had a pacemaker, ICD, or CRT device Patients whose life expectancy is less than 12 months due to other medical conditions Patients who are expected to receive a heart transplant during the duration of the study Patients who have other cardiac surgeries or procedures planned but not yet performed Patients who currently have or who are likely to receive a tricuspid valve prosthesis Patients who are currently enrolled in another investigational study or registry that would directly impact the treatment or outcome of the current study. Patients who are younger than 18 years of age Patients who are mentally incompetent and cannot sign a Patient Informed Consent form or comply with the study Patients who are or become pregnant