Comparing the Efficacy and Safety of a Novel Monophasic Waveform Delivered by the Passive Implantable Atrial Defibrillator With Biphasic Waveforms in Cardioversion of Atrial Fibrillation

Abstract

Background-The passive implantable atrial defibrillator (PIAD) (with no battery or discharging capacitor and powered transcutaneously by radio-frequency energy) delivering a novel monophasic low-tilt waveform is more efficacious than the standard monophasic waveform at atrial defibrillation. Standard biphasic (STB) waveforms, however, are more efficacious and safer than monophasic waveforms. This study compared the efficacy and safety of the PIAD waveform with biphasic waveforms. Methods and Results-Sustained atrial fibrillation (AF) was induced by rapid atrial pacing. Cardioversion was attempted via 2 atrial defibrillation leads. The efficacy of the PIAD was compared with 3 biphasic waveforms (standard, single rounded, and double rounded) at varying voltage settings in 10 pigs. After a synchronized shock, hemodynamic changes between the PIAD, standard biphasic, and monophasic waveforms were compared at 1.5 and 3.0 J in 12 pigs. Myocardial injury (biochemical and histological) after ten 5-J PIAD shocks was compared with a no-shock group in 14 pigs. The PIAD 100-V setting was significantly more efficacious than the STB (100/Ϫ50 V: 100% [1.88Ϯ0.02 J] versus 90% [0.89Ϯ0.0 J]; Pϭ0.025). No arrhythmic, hemodynamic, or myocardial injury was observed with the PIAD waveform. Conclusions-Defibrillation with the PIAD is more efficacious than with the STB waveform and appears safe. This device could provide a more effective option for cardioversion.

A Pilot Study of a Low‐Tilt Biphasic Waveform for Transvenous Cardioversion of Atrial Fibrillation: Improved Efficacy Compared with Conventional Capacitor‐Based Waveforms in Patients

“…waveform lowers the peak voltage for successful cardioversion, support previous laboratory studies. [3][4][5] It has been shown in several studies that peak voltage is directly related to shock tolerability rather than the total delivered energy for internal cardioversion. 9,10 Although there is always a level of discomfort associated with all shocks it can be postulated that lowering the mean voltage and increasing the overall success at low voltages is beneficial in improving tolerability to the extent that this may reduce the sedation requirements for internal cardioversion.…”

“…Various waveform parameters have been studied in order to increase success. We have previously shown that low-tilt monophasic 3,4 and biphasic 5 waveforms are more successful than conventional higher tilt capacitorbased waveforms for the cardioversion of AF in the laboratory. The aim of this pilot study was to investigate if the low-tilt biphasic waveform was more successful and could be delivered safely in patients with persistent and induced AF.…”

“…We therefore compared a low-tilt biphasic waveform with a conventional waveform for the internal cardioversion of persistent and inducible AF in patients (all other waveform parameters were identical and set according to previously published work). [3][4][5]…”

Plateau Waveform Shape Allows a Much Higher Patient Shock Energy Tolerance in AF Patients

“…Experimental and clinical data tend to support the ventricular DFT predictions of this modeling approach 31–33 . Experimental data have also shown that a flat‐topped monophasic waveform had no energy DFT penalty for atrial cardioversion 34 . In fact, “low tilt” waveforms have been shown to have lower DFTs for atrial cardioversion, with a mean DFT of only 2.1 joule 17 .…”

Low‐Tilt Monophasic and Biphasic Waveforms Compared with Standard Biphasic Waveforms in the Transvenous Defibrillation of Ventricular Fibrillation

“…Low‐tilt (LT) waveforms can potentially optimize defibrillation success with the added benefit of delivering lower energy shocks. Previous studies have supported the use of these waveforms in both atrial and ventricular defibrillation . Recent work by our group, initially in a porcine model of ventricular fibrillation (VF) and later in a clinical study, comparing a LT biphasic waveform and a commercially available higher tilted waveform in the transthoracic defibrillation of VF suggested that LT waveforms can achieve similar success rates to standard waveforms but at significantly lower energy levels .…”