Signal-Averaged Electrocardiography as a Noninvasive Tool for Evaluating the Outcomes After Radiofrequency Catheter Ablation of Ventricular Tachycardia in Patients With Ischemic Heart Disease

Since the late 1980s, the signal-averaged electrocardiography (SAECG) has been used for assessment of the risk for sudden cardiac death in patients after myocardial infarction. It is believed that the late potentials (LPs) in the terminal portion of the averaged QRS complex represent the slow and inhomogeneous intraventricular conduction as a consequence of the myocardial scarring. The tissue derangements in the areas of healing myocardial infarction may serve as a prerequisite for the occurrence of re-entry ventricular tachycardia (VT). Ablation techniques aiming at the elimination of the endocardial LPs and scar homogenization have been proven effective in treating VT. Although the VT noninducibility after catheter ablation (CA) is commonly used as a procedural end point, some important limitations question the role of programmed ventricular stimulation (PVS) as a proof of long-term success after ablation. We suggested that the LPs in SAECG correlate with the endocardial scar area and LPs in electro-anatomic maps of patients with ischemic cardiomyopathy. Further, we hypothesized that substrate-guided ablation and abolition of the endocardial LPs can result in normalization of the SAECG. This way, SAECG may be used as an additional noninvasive end point and predictor of success after VT ablation.