ASSURE Study - Arrhythmia Single Shock DFT Versus ULV: Risk Reduction Evaluation With ICD Implantations

Inclusion Criteria: * Patients who meet current indications for an ICD including cardiac resynchronization therapy (CRT) devices * Patients who sign and date a Patient Informed Consent form prior to the implant visit * Patients who remain in the clinical care of the enrolling physician in approved centers * Patients who receive only left-sided pectoral implantations with the ICD lead placed in the right ventricular apex * Patients who have a minimum R wave of at least 7 mV; or for ICD replacement, patients who have a minimum chronic R wave of at least 5 mV Exclusion Criteria: * Patients who are involved in Non-Invasive Programming Stimulation (NIPS) studies * Patients who undergo lead repositioning * Patients who are expected to receive a heart transplant during the duration of the study * Patients who 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 pregnant or plan to become pregnant during the study * Patients whose life expectancy is less than 12 months * Patients who are mentally incompetent and cannot sign a Patient Informed Consent form or comply with the study