title: Morphology of far-field electrograms and antitachycardia pacing effectiveness among fast ventricular tachycardias occurring in ICD patients: a multicenter study.
abstract: BACKGROUND
  Fast ventricular tachycardias (FVT) are less likely to be terminated by antitachycardia pacing (ATP). No information is available regarding the ability of far-field electrogram (Ff-EG) morphology (Ff-EGm) in predicting the result of the subsequent ATP. Our objective is to determine the relationship between Ff-EGm and ATP efficacy.
  
  
  RESULTS
  In this multicenter study we analyzed 289 FVT (cycle length [CL]: 250-320 milliseconds) occurring consecutively in 52 ICD patients with Medtronic devices (LVEF: 37 ± 6; pacing site: right ventricular apex). FVT programming was standardized, including a single ATP burst as initial therapy. The configuration of Ff-EG was HVA versus HVB. FVTs were classified in QFVT or non-QFVT according to the presence or absence of a negative initial deflection in the Ff-EG. The mean CL was 291 ± 24 milliseconds. We observed 4 Ff-EGm: QS (n = 14, 5%), QR (n = 158, 55%), R (n = 93, 32%), and RS (n = 24, 8%). The ATP effectiveness was 80% (86% in QS, 85% in QR, 74% in R, 62% in RS). The frequency of successful ATP was higher in QFVT: 86 versus 71% (P = 0.002). By logistic regression analysis, a QFVT pattern (OR = 2.3; P = 0.015) remained as an independent predictor of effective ATP. ATP was safer in QFVTs, the frequencies of shock (14% vs 29%; P = 0.002), acceleration (5.1 vs 12.3%; P = 0.02), and syncope (4.6 vs 12.3%; P = 0.01) being lower.
  
  
  CONCLUSIONS
  Since ATP is less effective in non-QFVTs, they are less well tolerated. Therefore, the substrate of non-QFVTs may need a specific treatment.
authors.affiliation: Cardiology Department, IBSAL-Hospital Universitario, Salamanca, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Jiménez-Candil
authors.forename: Ignasi
authors.initials: I
authors.lastname: Anguera
authors.forename: Claudio
authors.initials: C
authors.lastname: Ledesma
authors.forename: Javier
authors.initials: J
authors.lastname: Fernández-Portales
authors.forename: José Luis
authors.initials: JL
authors.lastname: Moríñigo
authors.forename: Paolo
authors.initials: P
authors.lastname: Dallaglio
authors.forename: Ana
authors.initials: A
authors.lastname: Martín
authors.forename: Teresa
authors.initials: T
authors.lastname: Cano
authors.forename: Jesús
authors.initials: J
authors.lastname: Hernández
authors.forename: Xavier
authors.initials: X
authors.lastname: Sabaté
authors.forename: Cándido
authors.initials: C
authors.lastname: Martín-Luengo
mesh_terms: D002304:Cardiac Pacing, Artificial / Q000379:methods*; D022062:Electrophysiologic Techniques, Cardiac; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D011237:Predictive Value of Tests; D013030:Spain; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome
keywords: antitachycardia pacing; heart failure; implantable cardiac defibrillator; sudden death; ventricular tachycardia