Inclusion Criteria: 

• Structural heart disease (ischemic or non-ischemic) with one of the following: 
  • Confirmed diagnosis via echocardiography and/or cardiac MRI; or 
  • Left ventricular ejection fraction (EF) <40% (documented within the last 6 months via TTE; or 
  • Arrhythmogenic RV cardiomyopathy/dysplasia (per 2010 ARVC/D Task Force Criteria).
• At least one documented episode of sustained MMVT by either EGM or ECG in the 6 months prior to enrollment.
• Implanted with a market released ICD or CRT-D for at least 30 days prior to index ablation procedure.
• Refractory (i.e., not effective, not tolerated or not desired) to at least one anti-arrhythmic medication (either amiodarone or sotalol) for treatment of MMVT.
• At least 18 years of age.
• Informed of the nature of the study, agreed to its provisions and has provided written informed consent as approved by the Institutional Review Board/Ethics Committee (IRB/EC) of the respective clinical study site.
• Able and willing to comply with all study requirements.

Exclusion Criteria:

• Implanted with a subcutaneous ICD.
• Implanted with a ventricular assist device (VAD) (e.g., TandemHeart) .
• Currently receiving support, or anticipated to receive support prior to the index ablation procedure, via extracorporeal membrane oxygenation (ECMO).
• Presence of intracardiac thrombus verified via computer tomography (CT), magnetic resonance imaging (MRI), transesophageal echocardiogram (TEE), or transthoracic echocardiogram (TTE) within 48 hours prior to the index ablation procedure or intra-procedure intracardiac echocardiography (ICE).
  • For subjects with a history of AF, this verification must be done via TEE or ICE.
• ST elevation myocardial infarction (MI) within 60 days prior to index ablation procedure.
• Previous cardiac surgery (e.g., ventriculotomy, atriotomy, coronary artery bypass graft), within 60 days prior to index ablation procedure.
• Percutaneous coronary intervention (PCI) within 30 days prior to index ablation procedure.
• Idiopathic VT.
• Incessant VT (continuous sustained VT that promptly recurs despite repeated intervention for termination over ≥ 3 hours) necessitating immediate treatment or requiring hemodynamic support prior to the ablation procedure.
• VT/VF thought to be from channelopathies.
• Reversible cause of VT.
• Severe aortic stenosis or flail mitral valve.
• Mechanical mitral and aortic valve.
• History of stroke with modified Rankin scale > 3.
• Unstable angina.
• Chronic NYHA Class IV heart failure.
• Ejection fraction < 15%.
• Thrombocytopenia (defined as platelet count < 80,000) or coagulopathy.
• Contraindication to systemic anticoagulation (i.e., heparin, warfarin, or a direct thrombin inhibitor).
• Women who are pregnant or nursing.
• Active uncontrolled infection.
• Other anatomic or co morbid conditions or other medical, social, or psychological conditions that, in the investigator’s opinion, could limit the patient’s ability to participate in the study or to comply with follow up requirements, or impact the scientific soundness of the study results.
• Enrolled in an investigational study evaluating another device or drug that would confound the results of this study.
• Have a life expectancy of less than 12 months due to any condition.