Effect of Coronary Sinus Electrode on the Optimal Atrial Defibrillation Pathway for an Atrioventricular Defibrillator

Atrial Defibrillation Pathway. Introduction: 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.

Methods and 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 ± 6.5J vs17.4 ± 4.8 J, P = 0.16), but it was significantly higher than RV+CS → SVC+Can (group2: 9.0 ± 3.9J vs11.6 ± 5.0 J, P = 0.049).

Conclusion: 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.