Efficacy and Safety of Epicardial VT Ablation Using Contact Force Irrigated Tip Catheter - Pilot Study

Pilot Study Design The investigators will select 20 ischemic or non-ischemic cardiomyopathy patients with scar related Ventricular tachycardia with indication of VT ablation. After informed consent, these patients will be randomized to endocardial only (Control Group) or combined endocardial and epicardial ablation (Treatment Group).

Inclusion Criteria Patients with ischemic and non-ischemic cardiomyopathy and recurrent sustained monomorphic VT requiring cardioversion or antiarrhythmic drug administration with ≥4 episodes in the previous 6 months despite an ICD or antiarrhythmic drug therapy. Patients without ICD were eligible after 2 episodes of sustained VT.

Exclusion Criteria Creatinine level >2.5mg/dL; LV ejection fraction <10%; NYHA Class IV; mobile thrombus on LV; absence of vascular access to the LV; life-expectancy of less than 12 months; previous open-chest cardiac surgical procedure; unstable angina; myocardial infarction in the last 2 months; severe aortic stenosis; severe mitral regurgitation secondary to leaflet or chordae rupture; pregnancy and age of less than 18 years old.

Ablation Technique In the patients randomized for combined epicardial and endocardial ablation, subxyphoid puncture will be performed according to previously described technique. Following successful epicardial access on the combined epi and endocardial ablation and following the venous puncture on the endocardial only group, a puncture of femoral artery will be performed. If the patient has peripheral artery disease, the catheter will be positioned on the left ventricle through transeptal puncture.

Electroanatomic voltage map will be constructed of the endocardial and epicardial surface. After map construction, programmed ventricular stimulation of the apex of the RV with S4 extrastimuli will be performed aiming for VT inducibility. If the induced VT is well tolerated, activation mapping of the VT will be constructed in addition to entrainment mapping. If the VT is not hemodynamically tolerated, it will be reverted either by Burst or electrical cardioversion, than substrate modification in the scar combined with pace-mapping and local abnormal electrograms (late potentials) ablation will be performed. In the patients in the endocardial only group, only the endocardial surface of the right or left ventricle will be ablated.

In the combined epicardial and endocardial group, the choice of the surface to be ablated will be guided by the tachycardia mapping (mesodiastolic and pre-systolic potentials), extension of the scar, pace-mapping in both surfaces. ECG criteria suggesting epicardial surface will also be considered to define the epi or endo surface to be ablated.

Following ablation, a repeated programmed ventricular stimulation with S4 will be performed to evaluated reinducibility of the VT. Additional RF applications can be performed according to clinical criteria, and the procedure will be considered terminate when no VT is inducible or by clinical criteria. In the endo only group that endocardial scar could not be observed or following extensive endocardial ablation the clinical VT still remain inducible, and the ECG criteria suggests epicardial VT will underwent epicardial mapping and ablation and this will be considered as a Cross-over.

Outcomes

Primary Outcome:

Safety: The investigators will evaluate the rate of complications related to irrigated tip catheter use on epicardial surface. It is expected that the combined epicardial and endocardial ablation group do not present an increase in the rate of catheter-related complications.

Efficacy: The investigators will evaluate if the procedure was succeeded. The investigators consider success as follows: (1) Complete Success: prevention of induction of any VT following ablation; (2) Partial Success: prevention of induction of the clinical VT, remaining the induction of at least one non-clinical faster VT; (3) Failure: Remaining the induction of the clinical or initially induced VT.

Secondary Outcome:

Safety: The investigators will evaluate the rate of complications related to the epicardial access. It is expected a rate of hemopericardium of no more than 20%, with less than 5% rate of major complications as procedure related death, cardiac surgery due to cardiac perforation or blood cell transfusion.