Accuracy of a novel ECGi system in localising the critical isthmus exit site in scar-dependant re-entrant ventricular tachycardia

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Vision in ventricular onset (VIVO) is a novel, non-invasive, mapping system designed to locate the site of earliest activation in ventricular arrhythmia. VIVO utilises a mathematical algorithm, cross-sectional imaging data (CT or MRI), 3D images of the electrodes on the patient torso, and a 12-lead electrocardiogram (ECG) to identify the site of earliest ventricular activation.(1) The system has been shown to accurately predict earliest activation of focal premature ventricular contractions (PVCs), but its accuracy in scar dependant re-entrant ventricular tachycardia (VT) has not been investigated.(1-3) Objective To assess the accuracy of VIVO in localising the VT exit site for patients with ischaemic cardiomyopathy (ICM) and scar related re-entrant VT. Methods 5 patients with ICM (age 56 ± 19 yrs, male n = 5) were investigated (table 1). All patients had an implantable cardioverter-defibrillator with standard indications for VT ablation. Invasive electro-anatomical mapping was performed with the Advisor HD Grid multipolar catheter and maps were generated using omnipolar electrograms (EGMs). The VT exit site was identified using activation ± pace-maps and the location defined by the primary operator using the American Heart Association (AHA) 17 segment model of the left ventricle.(4) Using the intra-procedural VT ECG recordings, VIVO maps were constructed post-procedure. The VIVO predicted VT exit site was identified using the AHA 17-segment model by a second operator, blinded to the results of the procedure. A "complete match" was defined as exact segment concordance between the two operators, "partial match" as adjacent segments, and "no match" if neither requirements satisfied. Results Mean left ventricular ejection fraction was 30.5 ± 9.0%. Mean procedure time was 233 ± 31 minutes, with a mean ablation time of 24 ± 18 minutes. A total of 11 re-entrant VTs were mapped. The VT exit site was identified in all cases (10 activation-map; 1 pace-map). A complete match was seen in 91% of VTs and partial match in 9% (table 2). None of the cases demonstrated a "no match" between the invasive and VIVO maps. There were no procedural complications. Conclusion The VIVO mapping system can accurately predict the VT exit site in scar dependant re-entrant VT. Further studies to assess the feasibility of VIVO-guided ablation in scar dependant VT are ongoing.