Wireless Stimulation Endocardially for Cardiac Resynchronization Therapy

Inclusion Criteria: Patients with standard indication for CRT based upon the most recent guidelines AND meeting criteria for one of these three categories: 1. Patients with previously implanted pacemakers or ICD's and meeting standard indications for CRT - referred to as "upgrades" 2. Patients in whom attempted coronary sinus lead implantation for CRT has failed - referred to as "untreated" 3. Patients with previously implanted CRT device, not responding to CRT (no change or worsening of symptom or NYHA functional class after 6 months of treatment confirmed by investigator) - referred to as "non-responders" Exclusion Criteria: 1. Inability to comply with the study follow-up or other study requirements 2. Contraindication to heparin 3. Contraindication to both chronic anticoagulants and antiplatelet agents 4. Contraindication to iodinated contrast agents 5. Intracardiac thrombus by transesophageal echocardiography 6. Age less than 18 years 7. Attempted IPG implant within 3 days 8. Life expectancy of \< 12 months 9. Chronic hemodialysis 10. Myocardial infarction within one month 11. Major cardiac surgery within one month 12. Female of childbearing potential, pregnant, or breastfeeding 13. Noncardiac implanted electrical stimulation therapy devices