title: Clinical predictors of atrial defibrillation thresholds with a dual-coil, active pectoral lead system.
abstract: OBJECTIVE
  The purpose of this study was to identify clinical predictors of atrial defibrillation thresholds (DFTs) with standard implantable cardioverter-defibrillator (ICD) leads.
  
  
  BACKGROUND
  Atrial defibrillation can be achieved with active pectoral, dual-coil transvenous ICD lead systems. If clinical predictors of atrial defibrillation efficacy with these lead systems were identified, they could be used to predict which patients may require more complex lead systems for atrial defibrillation, such as a coronary sinus electrode.
  
  
  METHODS
  This was a prospective study of 135 consecutive patients undergoing initial ICD implant for standard indications. The lead system evaluated was a transvenous defibrillation lead with coils in the superior vena cava (SVC) and right ventricular apex (RV), and a left pectoral pulse generator emulator (CAN). The shocking pathway was RV-->SVC+CAN. Atrial DFT was measured using a step-up protocol. Clinical and echocardiographic parameters were evaluated as predictors of atrial DFT and multiple linear regression was performed.
  
  
  RESULTS
  Mean atrial DFT was 4.6 +/- 3.8 J. Atrial DFT was < or =3 J in 70 patients (52%) and < or = 10 J in 97% of patients. The highest atrial DFT was 20 J (one patient). Left atrial size (r = 0.21, P = .01) and left ventricular end-diastolic diameter (r = 0.19, P = .02) were independent predictors of atrial DFT. However, these two predictors accounted for only 6% of the variability in atrial DFT.
  
  
  CONCLUSIONS
  Clinical parameters are of limited use in predicting atrial DFT with a dual-coil, active pectoral ICD lead system. Because the RV--> SVC + CAN shocking pathway provides reliable atrial and ventricular defibrillation, this configuration should be preferred for combined atrial and ventricular ICDs.
authors.affiliation: Division of Cardiology, University of Maryland School of Medicine, Baltimore, 21201, USA. erashba@medicine.umaryland.edu
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Rashba
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Shorofsky
authors.forename: Traci
authors.initials: T
authors.lastname: Brown
authors.forename: Robert W
authors.initials: RW
authors.lastname: Peters
authors.forename: Michael R
authors.initials: MR
authors.lastname: Gold
mesh_terms: D001281:Atrial Fibrillation / Q000628:therapy*; D017147:Defibrillators, Implantable; D004554:Electric Countershock; D004567:Electrodes, Implanted; D022062:Electrophysiologic Techniques, Cardiac; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies