Recent Data on Epicardial Ablation of Ventricular Tachycardia in Nonischemic Heart Disease

Epicardial ablation has been adopted during the last years, mainly as a supplementary technique after a failed endocardial ablation procedure, both in patients with ischemic and nonischemic ventricular tachycardias (VTs). Sosa and colleagues were the first who described the percutaneous subxiphoidal puncture to approach the epicardial space in 1996. Using the 3D electroanatomic mapping systems, the endocardial and epicardial substrate mapping have become feasible during the same procedure. Because of its complexity and its potential risks this process is performed only in high experienced centers by skilled operators with a large number of VT ablation procedures.Endocardial ablation in patients with left ventricular nonischemic cardiomyopathy (NICM) has shown worst outcome compared with ablation in ischemic cardiomyopathy. The main reason seems to be the progressive nature of the disease and the presence of epicardial and intramural slow conduction areas forming reentry circuits. The pattern of fibrosis and scar in NICM is not predictable as in ischemic cardiomyopathy where it follows the distribution of the coronary artery disease. Data from the study of Hsia et al in patients with NICM and VT episodes supported that the critical endocardial low voltage substrate was located mainly in the basal and perivalvular area. In this study, epicardial mapping was performed only in few patients revealing abnormal fragmented potentials but data from later studies highlighted the important of epicardial substrate in NICM. Cano et al3 performed both endocardial and epicardial mapping in 22 patients either because of failed endocardial ablation or because of electrocardiographic signs suggesting epicardial localization of the exit point. Electroanatomic mapping revealed extended epicardial low voltage areas in the majority of the patients (about 82%) which were located mostly in basal left ventricular lateral wall. However, Haqqani et al described 31 of 266 patients with NICM (11.6%) who had septal involvement, mainly in the basal region, without lateral low voltage areas... (excerpt