Ablation options for sub-epicardially located ventricular substrates responsible for ventricular tachycardia: where is it all headed?

PURPOSE OF REVIEW: Patients with nonischemic and ischemic cardiomyopathy (NICM and ICM) exhibit re-entrant tachycardias related to scar tissue in subepicardial, in addition to typical subendocardial locations. Control of ventricular arrhythmias related to these targets has remained elusive despite advances in mapping and ablation technology.

RECENT FINDINGS: Percutaneous epicardial ablation is the standard after failed endocardial ventricular ablation, but recurrence rates are disappointing. Pulsed-field energy has been associated with coronary artery spasm and therefore may be less suitable for epicardial ablation. Commercially available energy sources, including pulsed-field, have limited depths of myocardial penetration when applied epicardially. Lateral volumetric thermal spreading of ablation injury is associated with decreasing depth of ablation and is difficult to control. A new cryoablation technology based on liquid helium and developed specifically for epicardial work may be able to overcome these limitations.

SUMMARY: Ablation strategies that can improve lesion formation in subepicardial ventricular myocardium may improve outcomes of ablation in nonsubendocardial NICM and ICM targets.