OMNI Study--Assessing Therapies in Medtronic Pacemaker, Defibrillator, and Cardiac Resynchronization Therapy Devices.

The purpose of the OMNI study is to characterize therapy and diagnostic utilization in study participants implanted with study devices and to describe Implantable Cardioverter Defibrillator(ICD)therapy utilization for life threatening arrhythmias in primary and secondary prevention study participants. This study will assess therapies in Medtronic pacemaker, defibrillator, and cardiac resynchronization therapy devices.

The first therapy is for reducing unnecessary pacing in pacemaker patients. The second therapy provides pacing therapy in an attempt to stop fast or life threatening ventricular arrhythmias in lieu of delivering a defibrillation shock. The third therapy is a diagnostic measurement of a patient's fluid status and provides the physician information on the patient's heart failure status.

The study will also assess the time to a patient's first defibrillation shock and will verify that the shock was for a fast or life threatening ventricular rhythm.