T he goal of catheter ablation strategies for the treatment of scar-related ventricular tachycardia (VT) is the interruption of critical areas of slow conduction within the VT circuits responsible for the development and maintenance of VTs. 1,2 Clinical studies have consistently shown the superiority of radiofrequency catheter ablation compared with standard medical therapy in controlling recurrent VT. 3,4 However, even after an acutely successful ablation, the long-term freedom from recurrent VT remains suboptimal, especially in patients with nonischemic substrates where the recurrence rates for longterm follow-up can be as high as 77%.5 Identification of the optimal end points for VT ablation is crucial to improve the success rate of this procedure. The response to programmed electric stimulation (PES) at the end of the procedure has been traditionally used to evaluate the acute success and predict longterm outcomes.1,2 Noninducibility by PES represents a classical end point for VT ablation and the only 1 endorsed by the current practice guidelines.1,2 Of note, a direct association between VT noninducibility at the end of the procedure and long-term arrhythmia-free survival has been suggested but not uniformly demonstrated. 4,[6][7][8][9] More recently, the increasing adoption of substrate-based ablation techniques, which target specific electrograms indexing slow conduction (ie, abnormal, split, and late electrograms) in sinus rhythm and reasonable surrogates for the VT isthmus, 10,11 has been paralleled by an increasing need for new ablation end points. Although noninducibility at PES has been used as an end point also in studies evaluating substratebased ablation approaches, other procedural end points have been described to validate the completeness of linear lesions and the elimination of abnormal potentials within the scar. This review will summarize the state of the art regarding procedural end points for catheter ablation of scar-related VT (Table 1).
Invasive PESNoninducibility at PES represents the most widely accepted end point for catheter ablation of scar-related VT. The most recent expert consensus document on VT ablation endorses noninducibility of the presumed clinical VT as the minimum end point for catheter ablation of scar-related VT; other end points beyond noninducibility are discussed but not specifically endorsed, because they have not been systematically validated.1,2 The bulk of the evidence supporting noninducibility at PES as a procedural end point derives from studies including patients with infarct-related VT (Table 2). Early experiences with catheter ablation in this clinical setting reported a significant association between noninducibility at the end of the procedure and VT-free survival.12-16 Subsequent studies including larger patient populations have provided mixed results. 4,6,7,9,12,13,15,[17][18][19][20][21][22][23][24][25][26][27] It is important to emphasize that none of these studies was specifically designed to perform a formal longitudinal evaluation of noninducibili...