Abstract 244: A Prospective Randomized Study of the Efficacy of Rectilinear and Truncated Exponential Biphasic Waveforms in the Elective Cardioversion of Atrial Fibrillation

Abstract

INTRODUCTION: Several different biphasic waveforms are now available for clinical use. Few studies have compared differences in the efficacy of these waveforms. We compared biphasic rectilinear (BR) and biphasic truncated exponential (BTE) waveforms in their efficacy to cardiovert patients undergoing elective cardioversion for atrial fibrillation. METHODS: In a prospective randomised study, sequential adult patients undergoing elective cardioversion for atrial fibrillation were recruited. Patients were randomised to receive synchronised defibrillation using either a BR or BTE waveform, both using a 50J, 100J, 150J, 200J, 200J selected energy escalating protocol. Successful cardioversion was defined as a return to sinus rhythm immediately after a given shock. Failure to cardiovert after a second 200J shock was classed as failed defibrillation. The power of this study was 80% with 5% significance level to detect a difference of 20% or greater between groups. Survival analysis was used to assess the total energy delivered (and number of shocks) to achieve successful cardioversion between groups. RESULTS: A total of 202 patients were recruited over a four-year period, of which data was complete for 199 (100 BR waveform; 99 BTE waveform). There was no major difference in demographic data (Median age; BR 65.5 yrs, BTE 68.0 yrs: Median weight; BR 90.2 kg, BTE 88.9 kg; Median duration of AF; BR 7.0 months, BTE 6.0 months: Amiodarone; BT 23.8%, BTE 18.2%). Cardioversion rates and associated energy delivered are shown below. Median number of shocks to achieve cardioversion was 2 for the BR waveform and 3 for the BTE waveform (Log rank test, P=0.059). CONCLUSIONS: BR and BTE waveforms show similar efficacy in the elective cardioversion of atrial fibrillation.