title: Elucidation of hidden slow conduction by double ventricular extrastimuli: a method for further arrhythmic substrate identification in ventricular tachycardia ablation procedures.
abstract: Identification of local abnormal electrograms (EGMs) during ventricular tachycardia substrate ablation (VTSA) is challenging when they are hidden within the far-field signal. This study analyses whether the response to a double ventricular extrastimulus during substrate mapping could identify slow conducting areas that are hidden during sinus rhythm.
  
  
  
  Consecutive patients (n = 37) undergoing VTSA were prospectively included. Bipolar EGMs with >3 deflections and duration <133 ms were considered as potential hidden slow conduction EGMs (HSC-EGM) if located within/surrounding the scar area. Whenever a potential HSC-EGM was identified, a double ventricular extrastimulus was delivered. If the local potential delayed, it was annotated as HSC-EGM. The incidence of HSC-EGM in core, border-zone, and normal-voltage regions was determined. Ablation was delivered at conducting channel entrances and HSC-EGMs. VT inducibility after VTSA obtained was compared with data from a historic control group. 2417 EGMs were analyzed. 575 (23.7%) qualified as potential HSC-EGM, and 198 of them were tagged as HSC-EGMs. Scars in patients with HSC-EGMs (n = 21, 56.7%) were smaller (35.424.7 vs 67.639.1 cm2; P = 0.006) and more heterogeneous (core/scar area ratio 0.250.2 vs 0.450.19; P = 0.02). 28.8% of HSC-EGMs were located in normal-voltage tissue; 81.3% were targeted for ablation. Patients undergoing VTSA incorporating HSC analysis needed less radiofrequency time (17.411 vs 2310.7 minutes; P = 0.016) and had a lower rate of VT inducibility after VTSA than the historic controls (24.3% vs 50%; P = 0.018).
  
  
  
  Ventricular tachycardia substrate ablation incorporating HSC analysis allowed further arrhythmic substrate identification (especially in normal-voltage areas) and reduced RF time and VT inducibility after VTSA.
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Acosta
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Andreu
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: Penela
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Mario
authors.initials: M
authors.lastname: Cabrera
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Carlosena
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Viatcheslav
authors.initials: V
authors.lastname: Korshunov
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Francesca
authors.initials: F
authors.lastname: Vassanelli
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Roger
authors.initials: R
authors.lastname: Borras
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Mikel
authors.initials: M
authors.lastname: Martínez
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Fernández-Armenta
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Markus
authors.initials: M
authors.lastname: Linhart
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Tolosana
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Lluis
authors.initials: L
authors.lastname: Mont
authors.affiliation: Arrhythmia Section, Cardiology Department, Thorax Institute, Hospital Clínic and IDIBAPS (Institut d'Investigació Agustí Pi i Sunyer), C/Villarroel 170, 08036 Barcelona, Catalonia, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Berruezo
mesh_terms: D000200:Action Potentials; D000368:Aged; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D011237:Predictive Value of Tests; D011446:Prospective Studies; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome
keywords: Hidden slow conduction; Substrate ablation; Ventricular tachycardia