title: Differences in ventricular tachyarrythmias and antitachycardia pacing effectiveness according to the ICD indication (primary versus secondary prevention): an analysis based on the stored electrograms.
abstract: OBJECTIVE
  To determine whether monomorphic ventricular tachycardias (VTs) have different characteristics and/or responses to antitachycardia pacing (ATP) with respect to the indication-primary prevention (PP) versus secondary prevention (SP)-among ICD patients with left ventricular dysfunction.
  
  
  METHODS
  We prospectively studied 551 VT (cycle length [CL] 329 ± 35 ms; PP 34%) occurring in 67 ICD patients with left ventricular dysfunction (LVEF 35 ± 8%). ICD programming was standardized, including ATP for slow (CL 400-321 ms) and fast VT (CL 250-320 ms). We analyzed the following aspects: CL, percentage of variability of the 12 RR intervals prior to ATP (P-RR)-which was calculated by dividing the mean difference between each R-R interval with the next one by the CL × 100-and type of termination: immediate (VT ceased immediately upon ATP completion) or delayed (VT persisted after ATP).
  
  
  RESULTS
  ATP was successful in 86% of VTs. VTs occurring in SP patients had a lower P-RR, median (IQR) 2.7% (1.2-3.7) versus 1.9% (0.9-3.2); p = 0.002; they terminated immediately after ATP less frequently (27% versus 12%; p < 0.001), and although they were more frequently slow (51% versus 67%; p = 0.01), ATP was less effective in them, 92 versus 80% (p = 0.02).
  
  
  CONCLUSIONS
  VTs occurring in SP patients are slower, more stable, and they terminate less frequently at ATP. Therefore, compared with PP, SP patients seem to have fewer self-terminating VTs.
authors: Cardiology Department, Biomedical Research Institute of Salamanca (IBSAL), University Hospital, Paseo de San Vicente, 58-182, 37007, Salamanca, Spain. jimenezcandil@secardiologia.es.
authors: Javier
authors: J
authors: Jiménez-Candil
authors: Cardiology Department, Biomedical Research Institute of Salamanca (IBSAL), University Hospital, Paseo de San Vicente, 58-182, 37007, Salamanca, Spain.
authors: Jesús
authors: J
authors: Hernández
authors: Cardiology Department, Biomedical Research Institute of Salamanca (IBSAL), University Hospital, Paseo de San Vicente, 58-182, 37007, Salamanca, Spain.
authors: Ana
authors: A
authors: Martín
authors: Cardiology Department, Biomedical Research Institute of Salamanca (IBSAL), University Hospital, Paseo de San Vicente, 58-182, 37007, Salamanca, Spain.
authors: José
authors: J
authors: Moríñigo
authors: Cardiology Department, Biomedical Research Institute of Salamanca (IBSAL), University Hospital, Paseo de San Vicente, 58-182, 37007, Salamanca, Spain.
authors: Pedro
authors: P
authors: Perdiguero
authors: Cardiology Department, Biomedical Research Institute of Salamanca (IBSAL), University Hospital, Paseo de San Vicente, 58-182, 37007, Salamanca, Spain.
authors: Loreto
authors: L
authors: Bravo
authors: Cardiology Department, Biomedical Research Institute of Salamanca (IBSAL), University Hospital, Paseo de San Vicente, 58-182, 37007, Salamanca, Spain.
authors: Sonia
authors: S
authors: Ruiz
authors: Cardiology Department, Biomedical Research Institute of Salamanca (IBSAL), University Hospital, Paseo de San Vicente, 58-182, 37007, Salamanca, Spain.
authors: Pedro L
authors: PL
authors: Sánchez
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods / Q000706:statistics & numerical data; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D022062:Electrophysiologic Techniques, Cardiac / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D011322:Primary Prevention / Q000706:statistics & numerical data*; D012008:Recurrence; D012307:Risk Factors; D055502:Secondary Prevention / Q000706:statistics & numerical data*; D013030:Spain / Q000453:epidemiology; D017180:Tachycardia, Ventricular / Q000453:epidemiology* / Q000517:prevention & control*; D013813:Therapy, Computer-Assisted / Q000379:methods / Q000706:statistics & numerical data; D016896:Treatment Outcome
keywords: Antitachycardia pacing; Implantable cardiac defibrillator; Shock; Ventricular tachycardia