Prospective, randomized comparison of two biphasic waveforms for the efficacy and safety of transthoracic biphasic cardioversion of atrial fibrillation
Section snippets
Methods
The study was approved by the Mayo Foundation Institutional Review Board. All procedures used in this study were in accordance with Mayo Clinic Cardioversion Unit practice guidelines. All patients gave written informed consent. This investigator-initiated study was funded completely by the Mayo Foundation, without any commercial support or commercial data analysis.
Patient characteristics
Of the 188 patients initially enrolled, 47 were excluded from the final analysis because of one of the following conditions: presence of atrial flutter in the immediate precardioversion ECG upon blinded review (n = 25), presence of an intracardiac mass on precardioversion transesophageal echocardiogram (n = 7), or failure to adhere to study protocol (n = 15). Of the 15 protocol deviations, six resulted from immediate recurrence of atrial fibrillation (within 1 minute) following shock delivery;
Efficacy and safety of biphasic direct-current cardioversion
Both the BTE and the BR waveforms proved to be highly effective and safe for treatment of patients referred for direct-current cardioversion of AF, with cumulative success rates of 97% and 93%, respectively. This finding is in accordance with results of previous studies4, 19, 20 and significantly exceeds results obtained with monophasic direct-current cardioversion.3, 4, 19 Ricard et al19 reported a 93% success rate in converting AF in 30 patients treated with a BTE waveform. Mittal et al4
Conclusion
Both BTE and BR waveforms are highly effective and safe for direct-current cardioversion of AF in humans. The optimal first-shock energy for transthoracic biphasic direct-current cardioversion of AF should be 150 J. Impedance is not a determinant of direct-current cardioversion success with biphasic waveforms.
Acknowledgments
The authors thank Robert Walker of Medtronic Physio-Control and Don Boucher of Zoll Medical Corporation for assistance with waveform specifications.
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