Lack of Benefit of an Active Pectoral Pulse Generator on Atrial Defibrillation Thresholds

Abstract

These results indicate that low atrial DFTs can be achieved using a transvenous ventricular defibrillation lead. Because no benefit was observed with the use of an active pectoral electrode for atrial defibrillation, programmable shock vectors may be useful for dual-chamber implantable cardioverter defibrillators.

Effectiveness of single‐ vs dual‐coil implantable defibrillator leads: An observational analysis from the SIMPLE study

“…The implantation of a superior vena cava defibrillation coil was not associated with an increased incidence in non‐appropriate shocks due to atrial tachyarrhythmias. The strong trend for a higher conversion rate of atrial tachyarrhythmia in patients with DC‐leads could be explained by the fact that the presence of an SVC defibrillation coil is the main determinant of atrial defibrillation efficacy …”

Optimization of Atrial Defibrillation with a Dual‐Coil, Active Pectoral Lead System

“…Organized atrial rhythms, such as atrial flutter, were excluded from study, with reinitiation or continued pacing performed to induce AF. Once AF had sustained for >1 minute, 13,14 defibrillation testing was performed. R wave synchronized defibrillation shocks were delivered with an external defibrillator (ECD model 2815, Cardiac Pacemakers Inc.), which delivers fixed 60/50 tilt biphasic shocks through a 125‐μF capacitance.…”

“…Atrial DFT was defined as the lowest‐energy shock to terminate AF. A threshold ≤3 J was defined prospectively as low energy 13,14 …”

“…For each paired comparison of atrial DFTs, electrical parameters between the two lead configurations were compared using paired t ‐tests. A sample size of at least 33 subjects was required to have 80% power to detect a DFT difference of 1.5 J, based on an atrial DFT of 4.0 ± 5.0 J with the ventricular triad and a 50% correlation between repeated measurements 13,14 . Power calculations for the second phase of the study were performed using the observed data from the first phase (atrial DFT 4.7 ± 3.7 J for ventricular triad).…”

“…The initial shocking configuration for atrial ICDs consisted of one defibrillation electrode in the coronary sinus (CS) and another electrode in the right atrium 8,9 . When combined atrial and ventricular ICDs were developed, additional shocking configurations that used an active pectoral shell and a dual‐coil defibrillation lead were tested and found to be effective 13,14 . In nonrandomized studies, adding a CS coil to this configuration has had inconsistent effects on the atrial defibrillation threshold (DFT) and adds complexity to the implant procedure 10–12 .…”