Title of Trial
Biphasic versus Monophasic Shock Waveform for Conversion of Atrial Fibrillation:
The Results of an International Randomized, Double-Blind Multicenter Trial (BiCard)

Date and Citation of Primary Publication(s) or References
Page RL. Kerber RE. Russell JK. Trouton T. Waktare J. Gallik D. Olgin JE. Ricard P. Dalzell GW. Reddy R. Lazzara R. Lee K. Carlson M. Halperin B. Bardy GH. BiCard Investigators. Biphasic versus monophasic shock waveform for conversion of atrial fibrillation: the results of an international randomized, double-blind multicenter trial. Journal of the American College of Cardiology. 39(12):1956-63, 2002 Jun 19

Purpose of the Trial
The purpose of this study was to compare monophasic and biphasic waveform shocks for cardioversion of atrial fibrillation

Study Category
Atrial Fibrillation. Prospective, multicenter, randomized double-blind trial.

Patient Population
Patients undergoing elective cardioversion of atrial fibrillation

Inclusion Criteria
To be eligible for enrollment in the study patients had to be scheduled for elective cardioversion of hemodynamically stable atrial fibrillation. Prior to cardioversion, documented evidence of either anticoagulation with an INR>2.0 for at least 3 weeks prior to cardioversion or intravenous heparin and a transesophageal echocardiogram negative for left atrial thrombus was required. For cardioversion of atrial fibrillation of less than 48 hours duration neither of these criteria had to be met.

Exclusion Criteria
Patients were excluded from the trial any of the following were present: epicardial defibrillation electrodes, pacemaker dependence, concurrent enrollment in an anti-arrhythmic trial, vasopressor dependence, or inability to place the defibrillation electrodes in the specified position.

Study Design
Patients were randomized to either biphasic or monophasic cardioversion. Devices and defibrillation electrodes were identical to allow for blinding of the operator and patient. Defibrillation electrodes were placed in the AP configuration. Up to 5 shocks were delivered during the protocol. The first four shocks were delivered by the device which the patient was randomized to, at 100J, 150J, 200J, and 200J for biphasic devices or 360J for monophasic devices. If still in atrial fibrillation, crossover to a maximum output shock on the other device was used. The protocol was terminated by either conversion to sinus rhythm, defined by two consecutive p waves within 30 seconds of a shock, or delivery of 5 shocks.

Endpoint
The endpoint of the study was successful cardioversion of atrial fibrillation. The occurrence of skin burns measured on a pre-specified scale was also recorded.

Baseline Characteristics

	Monophasic (n=107)	Biphasic (n=96)	P value
Mean Age (years)	65	65	0.86
Male (%)	68	72	0.65
MeanWeight (kg)	88	87	0.70
EF >55% (%)	59	62	NS
EF <25%(%)	3	4	NS
LA diameter (mm)	4.8	4.8	0.69
Class I/III antiarrhythmic medication (%)	50	46	0.57
AF episode <48hrs (%)	13	13	NS
AF episode 48hrs to 6 months (%)	59	66	NS
AF episode 6-12 months (%)	17	14	NS
AF episode >12 months (%)	10	6	NS

Time to Follow-up: 
There was no follow up beyond the cardioversion other than a follow-up 24 to 48 hours after either by phone interview or direct inspection for assessment of skin burns.

Results

Cumulative Shock Success

	Monophasic (n=107)	Biphasic (n=96)	P value
1 shock (100J)	22%	60%	<0.0001
2 shocks (100J, 150J)	44%	77%	<0.0001
3 shocks (100J, 150J, 200J)	53%	90%	<0.0001
4 shocks (100J, 150J, 200J)	85%	91%	0.29

More shocks and higher total energies were required to successfully convert atrial fibrillation in the monophasic group (2.48 shocks and 548J monophasic vs. 1.7 shocks and 217J biphasic, p<0.0001 for both factors). There was significantly less skin injury with biphasic shocks compared to monophasic shocks.

Sponsor
Hearstream, Philips Medical System, Seattle, Washington

Trial Status: Completed