Atrial defibrillation with a transvenous lead - A randomized comparison ofactive can shocking pathways

OBJECTIVES The purpose of this study was to compare transvenous atrial defi brillation thresholds with lead configurations consisting of an active left pectoral electrode and either single or dual transvenous coils. BACKGROUND Low atrial defibrillation thresholds are achieved using complex lead systems including coils in the coronary sinus. However, the efficacy o f more simple ventricular defibrillation leads with active pectoral pulse g enerators to defibrillate atrial fibrillation (AF) is unknown. METHODS This study was a prospective, randomized assessment of shock config uration on aerial defibrillation thresholds in 32 patients. The lead system was a dual coil Endotak DSP lead with a left pectoral pulse generator emul ator. Shocks were delivered either between the right ventricular coil and a n active can in common with the proximal atrial coil (triad) or between the atrial coil and active can (transatrial). RESULTS Delivered energy at defibrillation threshold was 7.1 +/- 6.0 J in t he transatrial configuration and 4.0 +/- 4.2 J in the triad configuration ( p < 0.005). Moreover, a low threshold (less than or equal to 3 J) was obser ved in 69% of subjects in the triad configuration but only 47% in the trans atrial configuration. Peak voltage and shock impedance were also lowered si gnificantly in the triad configuration. Left atrial size was the only clini cal predictor of the defibrillation threshold (r = 0.57, p < 0.002). CONCLUSIONS These results indicate that low atrial defibrillation threshold s can be achieved using a single-pass transvenous ventricular defibrillatio n lead with a conventional ventricular defibrillation pathway. These data s upport the development-of the combined atrial and ventricular defibrillator system. (C) 1999 by the American College of Cardiology.