The purpose of the study is to compare the effectiveness of the Cool Flex Irrigated Catheter Ablation System to routine drug therapy without ablation to treat VT or prevent VT from developing in patients at risk. The study will also evaluate the safety of the catheter device. Information on the patients overall heart condition, number of hospital visits, and quality of life will also be collected to see if there are improvements. The target population for this study are patients who require an ICD device and who have documented or inducible monomorphic VT. Key eligibility for this study are patients who require an ICD implant or currently have an implant. These patients would also need to have documented episodes of MMVT or have inducible MMVT. If they do not they will be placed into the registry section of this study. Main interventions of this study are dependent upon randomization of this patient. So, if patient has MMVT and ICD implanted they will either be randomized to VT ablation with the Coolflex catheter system OR randomized to study drug (standard AAD medication) If they do not have MMVT then they will be placed in a registry.

You may be eligible for this study if you meet the following criteria:

• Conditions: Tachycardia, ventricular, ventricular, tachycardia
• Age: 1 years - 99 years
• Gender: All