Can a specific ECG metric identify idiopathic epicardial left ventricular tachycardia originating remote from the sinus of Valsalva to guide successful ablation?
A delayed precordial maximum deflection index ≥0.55 is highly sensitive and specific for identifying idiopathic epicardial VT remote from the ASOV, facilitating targeted ablation.
BACKGROUND: Despite the success of catheter ablation for treatment of idiopathic ventricular tachycardia (VT), occasional patients have been reported in whom VT could not be ablated from the right or left ventricular endocardium or from the aortic sinus of Valsalva (ASOV). METHODS AND RESULTS: In 12 of 138 patients (9%) with idiopathic VT referred for ablation, an epicardial left ventricular site of origin was identified >10 mm from the ASOV. Coronary venous mapping demonstrated epicardial preceding endocardial activation by >10 ms (41+/-7 versus 15+/-11 ms before QRS onset; P or =0.55 identified epicardial VT remote from the ASOV with a sensitivity of 100% and a specificity of 98.7% relative to all other sites of origin (P<0.001). CONCLUSIONS: Although clinically underrecognized, idiopathic VT may originate from the perivascular sites on the left ventricular epicardium. The mechanism is consistent with triggered activity. It is amenable to ablation by transvenous or transpericardial approaches, although technical challenges remain. Recognition of a prolonged precordial maximum deflection index and early use of transvenous epicardial mapping are critical to avoid protracted and unsuccessful ablation elsewhere in the ventricles.
Daniels et al. (Tue,) studied this question.