This study is enrolling subjects who are scheduled for a ventricular tachycardia (VT) ablation. Ventricular tachycardia is a fast heartbeat that starts with an abnormal signal in the lower chambers of the heart, which are the ventricles. An ablation is a procedure where a catheter (thin, flexible tube) with a tip that can deliver energy is used to burn the heart tissue where those abnormal signals are coming from. The catheter being used in this study is called the FlexAbilityTM Ablation Catheter and was recently approved for commercial use by the Food and Drug Administration. (FDA) Since it is newly approved, the FDA wants to continue collecting more information about the catheter and its use, so this study is called a post approval study. Participation in this study will take about 1 year. During this year, data will be collected including your medical history, cardiac medication use, ablation procedure, and any medical events that may occur. You will be seen or contacted 4 times. There is a risk of loss of confidentiality and there may be risks that are not yet known. There may be no direct benefit to you but it is hoped the information learned may contribute to knowledge in this field.

This study is enrolling subjects with an abnormal heart rhythm called ventricular tachycardia (VT - rapid heart beat coming from the bottom of the heart) that has come back despite treatment. This is a randomized study meaning subjects will be assigned to one of two groups and then undergo either a standard catheter ablation or a new treatment called cardiac radioablation for their VT. You will have a 50:50 chance of being assigned to either group. A standard catheter ablation is done by placing catheters (long hollow tubes) into a large blood vessel at the top of the leg, guiding them to the heart to first identify the signals causing the VT and then use radiofrequency (heat) energy to burn and stop these signals to stop the VT. The cardiac radioablation is an investigational treatment meaning it is not yet approved for routine clinical use by the Food and Drug Administration (FDA). Cardiac radioablation is performed in the radiation oncology department and uses radiation therapy to treat the signals causing the VT. Participation in this study will last up to 5 years and inlcude about 15 visits. Study related procedures include medical record review and data collection, electrocardiogram (tracing of heart's electrical activity), echocardiogram (ultrasound test of the heart), CT scans, blood work, questionnaires, implantable cardioverter defibrillation (ICD - device implanted in your chest that monitors and treats abnormal heart rhythms), and ablation procedure per randomization. Risks include fatigue, changes in the appearance of the lungs in the cardiac radioablation group, fatigue, pain, low or high blood pressure or excessive bruising or bleeding at the catheter insertion side in the cardiac ablation arm. There are also study procedure related risks, and risks that are not known. There is potential benefit to you and to others in learning how to better treat others in the future with this condition.