Spot diagnosis of inferior axis and concordant R-pattern predicts left ventricular inflow tract tachycardia Ablation from the great cardiac vein of an underdiagnosed entity

Background The present literature holds an enormous variation concerning origin and ablation site of idiopathic ventricular arrhythmias (VA), ranging from 2.5 to 15% for the origin within the coronary venous system (CVS). The aim of the study was to detect positive predictive ECG morphology patterns to discriminate VA stemming from the CVS. Methods 110 consecutive patients (P) with 111 premature ventricular capture beat (PVC) morphologies undergoing successful ablation for VA were retrospectively analyzed concerning their ECG patterns. Results 20/110 P (18%) displayed their VA origin in the CVS with anterior/anterolateral left ventricular inflow tract (LVIT) (epicardial/GCV) in 16 P (14%), anterior/anterolateral LVIT (endo- and epicardial/GCV) in 3 P (3%), and anterior interventricular vein (AIV) 1 P (< 1%). ECG morphology of all GCV cases demonstrated an inferior axis and concordant R-pattern in all precordial leads resulting in 100% sensitivity. One VA demonstrating this pattern was ablated outside at the LVOT resulting in 95% specificity for origin in the anterior/anterolateral LVIT. 3/20 P that were ablated in the CVS required additional endocardial ablation from the anterior/anterolateral LVIT resulting in 80% specificity for sole successful ablation in the CVS. Conclusion An inferior axis and concordant R-pattern in all precordial leads serve as diagnostic markers for an LVIT origin in the surface ECG and suggest a high primary ablation success via the GCV.