Inclusion Criteria

• Patient is receiving a new St.Jude Medical (SJM) Implantable Cardioverter Defibrillator (ICD) or SJM Cardiac Resynchronization Therapy-Defibrillator (CRT-D) implant, which has study required programing capabilities and is appropriate for remote monitoring
• Subjects who have received the ICD / CRT-D up to 90 days prior to enrollment are also eligible. 
• Patient who has a high risk of ICD shock as shown by at least one documented Monomorphic VT (MMVT) by one or more of the following
  • Spontaneous MMVT 
  • Inducible MMVT during electrophysiology (EP) Study
  • Inducible MMVT during Non-Invasive Programmed Stimulation (NIPS) Study 
• Pleiomorphic ventricular tachycardia (VT) (multiple MMVT morphologies) is acceptable but polymorphic VT or ventricular fibrillation (VF) is not.
• 18 to 75 years of age 
• Patient has been informed of the nature of the study and has agreed to its provisions and provided written informed consent approved by the Institutional Review Board 

Exclusion Criteria

• Any history of stroke 
• S-T elevation myocardial infarction (MI) or previous cardiac surgery within 60 days prior to enrollment 
• Patient is pregnant or nursing 
• Patient has New York Heart Association (NYHA) class IV heart failure 
• Patient has incessant ventricular tachycardia (VT) necessitating immediate treatment.
  • Patients with Incessant VT have continuous sustained VTs that recur promptly despite repeated intervention for termination over several ( ≥ 3) hours
• Patient has VT/ VF thought to be from channelopathies
• Limited life expectancy (less than one year) according to Investigator 
• Patient has current class IV angina 
• Recent coronary artery bypass graft (CABG < 60 days) or percutaneous coronary intervention (PCI < 30 days) 
• Patient is currently participating in another investigational drug or device study
• Patient is unable or unwilling to cooperate with the study procedures 
• Known presence of intracardiac thrombi (i.e., positive Transesophageal Echocardiogram (TEE) for LA or LV clot)
  • TEE is required for history of left atrium (LA) or left ventricle (LV) clot and recommended for history of atrial fibrillation (AF) with CHADS > 1 
• Prosthetic mitral or aortic valve 
• Mitral or aortic valvular heart disease requiring immediate surgical intervention 
• Major contraindication to anticoagulation therapy or coagulation disorder 
• Left Ventricular Ejection Fraction < 15%
• Patient has had a previous ablation procedure for ventricular tachycardia (VT), excluding remote ( > 3 months) outflow tract tachycardia 
• Patient has glomerular filtration rate (GFR) < 30 mL/min/1.73m2 within the past 3 months 
• Patient has peripheral vascular disease that precludes LV access
• Patient has a premature ventricular contraction (PVC) or VT induced cardiomyopathy that is expected to resolve with ablation and will not require an ICD 
• Patient has reversible cause of VT
• Use of left ventricular assist device (LVAD) or Tandem Heart devices (Impella and Balloon pumps are acceptable) 
• There is a strong clinical reason to believe that, in the opinion of the investigator, the patient only has septal scar that is deep