title: New diagnostic criteria for identifying left-sided ventricular ectopy using non-contact mapping and virtual unipolar electrogram analysis.
abstract: OBJECTIVE
  To assess the efficacy of non-contact mapping for outflow tract premature ventricular contraction (PVC) and ventricular tachycardia (VT) ablation in patients without structural heart disease and a precordial transition at V3 or later and to determine the diagnostic accuracy of new virtual unipolar electrogram criteria for distinguishing left from right-sided foci using a multi-electrode array positioned within the right ventricular outflow tract.
  
  
  RESULTS
  Virtual unipolar electrograms at early activation (EA) and break out (BO) sites in 100 patients (36 left-sided foci) who underwent acutely successful outflow tract ablation were analysed and voltage and timing-based criteria measured. The best performing parameters were then re-assessed in 41 patients (14 left-sided) prospectively. Of the candidate criteria for determining a left from right-sided focus, the voltage at 20 ms after EA (EA-V20) and the time from BO to QRS onset (BO-QRS) were the best discriminators with area under the curve (AUC) values based on receiver operator characteristics (ROCs) of 0.947 (0.905-0.989), P < 0.001, and 0.951 (0.907-0.995), P < 0.001, respectively. These two parameters were subsequently assessed prospectively in a further 41 patients (14 left-sided) using the pre-specified cut-off values of -2 mV for EA-V20 and 10 ms for BO-QRS which demonstrated excellent diagnostic accuracy and sufficient inter-beat and inter-observer reproducibility.
  
  
  CONCLUSIONS
  This large single-centre experience demonstrates that a strategy for outflow tract PVC/VT ablation using non-contact mapping allows for excellent success rates. Furthermore, detailed analysis of virtual unipolar electrograms allows accurate and reproducible determination of left from right-sided foci that may be used to guide mapping and ablation.
authors.affiliation: Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Via Olgettina 60, Milan, Italy trevisi.nicola@hsr.it.
authors.forename: Nicola
authors.initials: N
authors.lastname: Trevisi
authors.affiliation: Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Via Olgettina 60, Milan, Italy.
authors.forename: John
authors.initials: J
authors.lastname: Silberbauer
authors.affiliation: Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Via Olgettina 60, Milan, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Radinovic
authors.affiliation: St Jude Medical Italia S.p.A., Agrate Brianza, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Bavila
authors.affiliation: Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Via Olgettina 60, Milan, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Sala
authors.affiliation: Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Via Olgettina 60, Milan, Italy.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Vergara
authors.affiliation: Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Via Olgettina 60, Milan, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Della Bella
mesh_terms: D000328:Adult; D018780:Body Surface Potential Mapping / Q000379:methods*; D003937:Diagnosis, Differential; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000150:complications / Q000175:diagnosis*; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000209:etiology; D018879:Ventricular Premature Complexes / Q000150:complications / Q000175:diagnosis*
keywords: Catheter ablation; Non-contact mapping; Premature ventricular beats; Ventricular tachycardia