title: Effect of coronary sinus electrode on the optimal atrial defibrillation pathway for an atrioventricular defibrillator.
abstract: BACKGROUND
  Previous studies have demonstrated significant failure in converting atrial fibrillation (AF) using a conventional ventricular pathway. The aim of this study was to assess the benefit of incorporating a coronary sinus (CS) lead into the atrial defibrillation pathway in atrial defibrillation threshold (ADFT) reduction in patients with persistent AF.
  
  
  RESULTS
  This study was a prospective, randomized assessment of shock configuration on ADFT in 18 patients undergoing elective internal cardioversion for persistent AF (mean AF duration: 8 +/- 9 months). The lead system included a dual-coil defibrillation lead (Endotak DSP, Guidant) with a distal right ventricular (RV) electrode and a proximal superior vena cava (SVC) electrode, a CS lead (Perimeter, Guidant), and a left pectoral cutaneous electrode (Can). In each patient, dual step-up ADFTs were determined for each of three vectors: (1) RV --> SVC+Can; (2) CS --> SVC+Can; and (3) RV --> CS+SVC+Can (group 1, n = 8) or RV+CS --> SVC+Can (group 2, n = 10), using R wave-synchronized biphasic shocks. Successful defibrillation was achieved in all patients without any ventricular proarrhythmia. ADFT of CS --> SVC+Can (11.8 +/- 5.6 J) was significantly lower than ADFT of RV --> SVC+Can (16.5 +/- 7.8 J, P = 0.021). ADFT of CS --> SVC+Can was similar to RV --> CS+SVC+Can (group 1: 12.0 +/- 6.5 J vs 17.4 +/- 4.8 J, P = 0.16), but it was significantly higher than RV+CS --> SVC+Can (group 2: 9.0 +/- 3.9 J vs 11.6 +/- 5.0 J, P = 0.049).
  
  
  CONCLUSIONS
  Patients with persistent AF of substantial duration can be reliably cardioverted using a conventional implantable cardioverter defibrillator (ICD) lead set; however, the incorporation of a CS lead to the conventional ICD lead configuration significantly lowered ADFT. The optimal shock vector that incorporates a CS lead for atrial defibrillation requires future studies.
authors.affiliation: Division of Cardiology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong, China. hftse@hkucc.hku.hk
authors.forename: Hung-Fat
authors.initials: HF
authors.lastname: Tse
authors.forename: Carl
authors.initials: C
authors.lastname: Timmermans
authors.forename: Luz-Maria
authors.initials: LM
authors.lastname: Rodriguez
authors.forename: Chu-Pak
authors.initials: CP
authors.lastname: Lau
authors.forename: Hein J J
authors.initials: HJ
authors.lastname: Wellens
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000628:therapy*; D001283:Atrioventricular Node / Q000503:physiopathology / Q000601:surgery*; D004554:Electric Countershock; D017097:Electric Impedance; D004562:Electrocardiography; D004567:Electrodes, Implanted; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006325:Heart Atria / Q000503:physiopathology / Q000601:surgery; D006352:Heart Ventricles / Q000503:physiopathology / Q000601:surgery; D006723:Hong Kong; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D013318:Stroke Volume / Q000502:physiology; D016896:Treatment Outcome