Epicardial Outflow Tract Ventricular Tachycardia: Distal Great Cardiac Vein and Coronary Cusp Origin

Abstract

The origin of outflow tract ventricular arrhythmia (OT-VA) can be predicted by ECG analysis. Recently, we devised a method to identify an epicardial OT-VA using the peak deflection index (PDI) in an inferior ECG lead. We will present our method of epicardial OT-VA identification and introduce how we determine the ablation site. Methods: An epicardial origin (10[14%] of the 70 patients) indicates that the successful ablation site of the OT-VA was in the distal great cardiac vein (GCV) (n=3) or on the coronary cusps (n=7). PDI is determined in the inferior lead presenting the tallest R wave by dividing the time from QRS onset to peak QRS deflection by total QRS duration. Results: A PDI of >0.6 predicted epicardial cases with a 90% sensitivity and a 95% specificity. In the 7 patients with coronary cusp ventricular arrhythmia (CC-VA), a discrete pre-potential (DPP) was recorded in 4 patients (57%). The DPP recorded at the successful ablation site on the coronary cusp preceded QRS onset by 63±16 ms (range, 50–84 ms). In those patients, excellent pace mapping was not always necessary. Conclusions: A PDI of >0.6 can be predictive of cases of epicardial OT-VA ablation in which the OT-VA origin is the distal GCV or the coronary cusps. In CC-VA, a DPP with activation time of ≥50 ms may be an indicator of successful ablation.