Cohort Study - SBRT for VT Radioablation

Condition(s) studied

Investigational drug(s) / intervention(s)

Stereotactic Body Radiotherapy (SBRT) ablation of VT: Additional imaging for SBRT planning and implementation: * Planning CT (pCT) - CT simulator that utilizes a respiratory positioning monitoring (RPM) optical tracking system and SBRT immobilization setup to provide necessary data to allow for monitoring of the patient's deep inspiration breath-hold (DIGH) maneuver during treatment delivery. * SBRT treatment - 30 min procedure on a TrueBeam 1 linear accelerator using SBRT fixation. Patient alignment and DIBH maneuver from the pCT will be replicated using the on-board cone-beam CT (CBCT) guidance and RPM systems.

Study summary

Ventricular tachycardia (VT) contributes to over 350,000 sudden deaths each year in the US. Malignant VTs involve an electrical "short circuit" in the heart, formed by narrow channels of surviving tissue inside myocardial scar. Current treatment for VT consists of either implantable defibrillators (ICDs), suppressive drug therapy, catheter ablation or a combination of all 3.

Implantable Defibrillators (ICDs) reduce sudden death and can terminate some ventricular tachycardia (VT) without shocks, but they don't prevent VT. The occurrence of ≥1 ICD shock is associated with reductions in mental well-being and physical functioning, and increases in anxiety and sometimes depression. Further, ICD shocks have been consistently associated with adverse outcomes, including heart failure and death. Furthermore, the most important predictor of ICD shocks is a history of prior ICD shocks.

Therapies to suppress VT include antiarrhythmic drug therapy and catheter ablation, neither however is universally effective. When VT recurs despite antiarrhythmic drug therapy and catheter ablation, novel yet invasive, approaches may be required. Such invasive procedures carry consequent risks of cardiac and extra-cardiac injury.

Stereotactic body radiotherapy (SBRT) is a non-invasive technique that delivers high doses of radiation precisely to specified regions in the body, while minimizing exposure to adjacent tissue. This technique is currently, and commonly used in the treatment of cancer. Conventional application of SBRT has made use of its ability to spare non-target tissue, including for treatment of tumors near the heart. More recently, clinicians have changed the paradigm, by focusing radioablative energy on ventricular scar responsible for ventricular tachycardia. Pre-clinical studies have supported the concept and were followed by first-in-human VT therapeutic experience in 2017. Subsequent studies have had encouraging results for patients who failed or were unable to tolerate conventional treatment.

Eligibility

Primary outcome measure(s)

• Comparative analysis of ventricular arrhythmia events — During the first 6 months post blanking period vs. 6 months prior to treatment.
  Number of patients with a reduction in the absolute number of ventricular arrhythmia events following ablation and blanking period, in comparison with those prior to treatment.
• Comparative analysis of targeting methods assessed by volume of sparred healthy tissue — From time of enrollment to 7.5 ,months post treatment.
  Effectiveness of different myocardial substrate targeting methods on sparing non-target tissue. Delivered treatment approach as compared to a proposed calculated treatment plan using a single phase of the 4DcCT. Measured differences between 2 target-method volumes will equate to the volume of sparred tissue.

Trial sites (1)

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