This will be a single arm study evaluating a new ablation technology for performing catheter ablation of ventricular tachycardia. The technology combines novel pulsed field ablation with radiofrequency ablation.

One of the limitations of conventional ventricular tachycardia (VT) ablation using radiofrequency (RF) energy is the inability to reach arrhythmogenic tissue deep in the myocardium. Pulsed field (PF) energy, which causes cell death via irreversible electroporation and is non-thermal, may improve outcomes in patients with VT since it has been shown to have better depth penetration in previously scarred tissue. Furthermore, the combination of RF and PF treatment in the same location can increase tissue lesion depth more than either energy alone. This can potentially minimize the need for epicardial ablations, or complex bipolar ablation strategies as well as associated procedural complications. RF and PF have been used extensively for atrial ablation. RF has been the mainstay for all VT ablation but PF use for VT is relatively new.

Pre-clinical work of ventricular ablation procedures in a swine model evaluated the effects of combined and co-localized PF and RF application on cardiac lesion size and their corresponding histological changes. Compared to PF alone ablation, lesion depths and widths were significantly greater in both RF-PF and PF-RF applications. Histology for both combined lesions showed central thermal necrosis surrounded by a hemorrhagic and transitional PF zone. The findings provided evidence for appropriate use of combination therapy in clinical settings.

The design of the study will be carried out as an interventional, prospective, multicenter, single-arm safety and effectiveness evaluation using the Biosense Webster PF/RF Ablation System. The study will enroll subjects with sustained symptomatic VT who are candidates for catheter ablation. Eligible subjects who sign the Informed Consent Form (ICF) and who meet all eligibility criteria will be enrolled and treated with the STSF Catheter in conjunction with the TRUPULSE™ Generator. A maximum sample size of 30 subjects is planned in the study. All study subjects will be followed-up for 6 months after the study procedure.

Inclusion Criteria:

1. Patients with two or more documented spontaneous episodes of sustained symptomatic VT within 3 months or 1 sustained episode of VT or VT storm (two or more VTs in 24 hours) which required device therapy (shock or anti-tachycardia pacing), external cardioversion, escalated antiarrhythmic therapy, and / or hospitalization

   • Documented episodes assessment will be performed by a review of ECGs, hospitalization records, and/or Implantable Cardioverter Defibrillator (ICD) interrogation
   • Patients must have an ICD implanted

2. Age ≥18 years

3. LVEF ≥ 30% as estimated by echocardiography, contrast ventriculography, radionuclide imaging or cardiac magnetic resonance imaging within the previous 30 days.

4. Willing and capable of understanding the objective, risk, and requirement of the study, and providing consent.

5. Able and willing to comply with all pre-, post- and follow-up testing and requirements.

Exclusion Criteria:

1. Definite protruding LV thrombus on pre-ablation imaging.
2. Myocardial infarction (MI) within the preceding 2 months. Patients with incessant VT (present 50% of the time with intervention for a period >12 hrs) may be enrolled if their MI is at least 3 weeks old.
3. Absence of vascular access to the heart chambers.
4. Other disease process likely to limit survival to less than 6 months.
5. Class IV heart failure.
6. Serum creatinine of ≥ 2.5 mg/dl (221 umol/L).
7. Thrombocytopenia (< 50 x 109/L) or coagulopathy.
8. Contraindication to heparin.
9. Women who are pregnant.
10. Cardiac surgery (i.e. ventriculotomy, atriotomy) within the past 2 months. Patients with incessant VT may be enrolled if their surgery is at least 3 weeks old.
11. Acute illness or active systemic infection.
12. Severe aortic stenosis or flail mitral valve.
13. Uncontrolled heart failure.
14. Significant congenital anomaly or medical problem that in the opinion of the principal Investigator would preclude enrollment in the study.
15. Enrolled in an investigational study evaluating another device or drug.
16. Unwilling to participate in the study or unavailable for follow up visits.
17. Previous VT ablation within a year.
18. Epicardial mapping or ablation is anticipated or planned before the VT ablation procedure.

All relevant data will be published at study end in final manuscript. This is a small, pilot, first-in-human study.