CORRESPONDENCE: LETTER TO THE EDITOR
Safety and Efficacy of Remote Magnetic Ablation for Atrial Fibrillation
Carlo Pappone, MD* and
Vincenzo Santinelli, MD
* Department of Cardiology, Electrophysiology, and Cardiac Pacing Unit, San Raffaele University Hospital, Via Olgettina 60, 20132 Milan, Italy (Email: carlo.pappone{at}hsr.it).
We read the recent study by Di Biase et al. (1) published in the Journal. Our pivotal experience demonstrated that remote ablation is effective and safe without tip charring (2). These results were subsequently confirmed in hundreds of patients undergoing atrial fibrillation ablation. What is surprising in this study (1) is that after their initial "presumably ineffective" 48 procedures, the investigators continued to use it, further exposing their patients to the risk of charring and embolic events and that the ethics committee further approved the study despite potentially dangerous complications.
Considering Natale's extensive experience, he certainly understands that unlike the perpendicular orientation of manual catheters, the stable parallel wall contact obtained with soft magnetic catheters results in rapid and effective lesions, within a few seconds from the onset of radio frequency (RF) application, thus preventing charring. However, if abatement of the atrial potentials is not rapidly achieved because the magnetic tip is not completely aligned with the endocardial wall, continuous and prolonged application of high RF energy, as performed by the investigators (1), could result in charring and ineffective lesions. No data were reported on important parameters including tip orientation, temperature, RF energy, and impedance values before and at the time of charring formation. We presume that parameters and potential changes were collected throughout, but surprisingly were not reported precluding any possible interpretation and discussion to explain why charring formation and ineffective lesions were so frequent in their experience. We know that even a single RF application of long duration by a soft magnetic catheter requires an accurate and continuous monitoring of all parameters to evaluate potential changes to prevent catheter tip charring. Remote ablation is a novel and simple system, but at the beginning, it may be complex because it is totally different from the conventional system. Optimization of RF application by this system is crucial and may be challenging at the beginning, requiring a learning curve. However, once familiarized with this system, "effective" remote ablation can be easily performed. Currently, in our laboratory, "joystick" ablation is performed by many electrophysiologists after widely different learning curves. In our pilot study, we specified that remote ablation was performed by a single expert operator after his learning curve. How many of the 20 reported investigators (1) actually performed the initial 48 procedures and how many the final ones? It is surprising that remote ablation was demonstrated to be safe and effective in eliminating even left-sided accessory pathways and not atrial potentials. On the other hand, it is well known that prolonged RF applications can result in charring even with manual catheters. It seems that the purpose of that study was to limit the enthusiasm of preliminary encouraging results of joystick ablation. However, this will not delay robotic development because irrigated-tip magnetic catheters are already available, making remote procedures less challenging.
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References
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1. Di Biase L, Fahmy TS, Patel D, et al. Remote magnetic navigation. Human experience in pulmonary vein ablation. J Am Coll Cardiol 2007;50:868-874.[Abstract/Free Full Text]2. Pappone C, Vicedomini G, Manguso F, et al. Robotic magnetic navigation for atrial fibrillation ablation J Am Coll Cardiol 2006;47:1390-1400.[Abstract/Free Full Text]
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