Background: ECG criteria for identifying an epicardial origin of ventricular tachycardia (VT) have mainly been described for VTs with basal-superior and lateral origin.
Objective: The aim of this study was to determine ECG criteria for epicardial VTs with anterior origin as a guide for trans-pericardial ablation.
Results: Among 22 patients undergoing successful ablation of VTs from the anterior myocardial wall, 14 patients underwent endocardial ablation and 8 patients underwent epicardial ablation. VTs with anterior origin ablated epicardially had widened QS complexes in precordial leads with staircase-shaped notching and slowing of the descent to the nadir of S. In comparison, endocardial VTs with anterior origin usually had narrower QS complexes with a smooth and fast downstroke to the nadir of S. The duration of the negative pseudodelta wave was longer in epicardial VTs (55 ± 12 ms) compared to endocardial VTs (22 ± 12 ms). The interval "time to the nadir of S" in patients with anterior VT origin was longer in epicardial VTs (121 ± 16 ms) than in endocardial VTs (80 ± 22 ms). The QRS duration was also longer in patients with epicardial origin (212 ± 19 ms) than with endocardial VT origin (166 ± 30 ms).
Conclusions: Epicardial origin of VTs arising from the anterior myocardial wall produces a slowing, widening and staircase-shaped notching in the initial VT-QS complex. Thus, the morphology of the initial part of the QS complex in precordial leads can be used as a guide for trans-pericardial ablation of VTs with anterior origin.
Keywords: Anterior myocardial infarction; ECG; Epicardial ablation; Nonischemic cardiomyopathy; Ventricular tachycardia.