Physio-Control LIFEPAK 20e - Manual (Page 169)

Append
ix B
Clinical Summaries
LIFEPAK 20e Defibrillator/Monitor Operating Instructions B-3
©2006-2013 Physio-Control, Inc.
EXTERNAL CARDIOVERSION OF ATRIAL FIBRILLATION
Overview
The performance of the Physio-Control biphasic truncated exponential (BTE) waveform was
compared to the conventional monophasic damped sine (MDS) waveform in an international,
multi-center, prospective, randomized clinical study of adult patients undergoing elective
cardioversion of atrial fibrillation (AF). A total of 80 patients were enrolled in the study and were
treated with one or more study shocks. The primary dataset consisted of 72 enrolled patients
confirmed to have been in AF. Data from seven patients with atrial flutter were analyzed
separately. One patient who did not satisfy all protocol criteria was excluded from analysis.
Subjects were randomized to receive biphasic or monophasic shocks from LIFEPAK 12
defibrillator/monitors. Progressive shocks of 70, 100, 200 and 360 J of the assigned waveform,
and a 360 J crossover shock of the other waveform, were delivered if AF persisted. Shocks were
delivered using EDGE System QUIK-COMBO
® Pacing/Defibrillation/ECG electrodes applied in
the standard anterior-lateral position. Successful cardioversion was defined as the confirmed
removal of AF after delivery of a shock, as determined by ECG over-read by two cardiologists
with no knowledge of the shock waveform. Patients rated skin pain on a scale from 0 to 8 after
the procedure.
This study showed that these biphasic shocks provide higher efficacy for cardioversion of atrial
fibrillation, requiring fewer shocks, 65% less current and 65% less energy to cardiovert atrial
fibrillation. Patients undergoing elective cardioversion with the biphasic protocol, as compared to
those receiving the monophasic protocol, reported significantly less post-procedure pain.
Objectives
The primary objective of the study was to compare the cumulative efficacy of biphasic and
monophasic shocks of 200 J or less for cardioversion of atrial fibrillation. A triangular sequential
design was used to test for a statistically significant difference between groups of patients treated
with these two waveforms.
Secondary objectives included 1) providing an estimation of the dose response relationship for
the two waveforms which would allow clinicians to make well-informed selections of energy
doses for cardioversion with biphasic shocks and 2) comparing the pain experienced by patients
following treatment with monophasic and biphasic shocks.
Results
Seventy-two of the patients enrolled were in atrial fibrillation and 7 were in atrial flutter. On
average, patients had been in atrial fibrillation for 88 days, were 66 years old, weighed 81 kg and
had 72 ohms of transthoracic impedance. Sixty-three percent were male and 46% had been
previously cardioverted. There were no significant differences between the groups of patients
treated with monophasic and biphasic shocks, either in these baseline characteristics or in left
atrial dimension, cardiac medications or diagnosis.
The cumulative success rates for cardioversion of atrial fibrillation are presented in Table B-1 and
Figure B-1 . These data provide a reasonable estimate of the expected probability of cardio-
version success for a single shock at any given energy level within the range studied. Energy
and peak current delivered for all shocks at each energy setting are presented in
Table B-2 .