Catheter Ablation of Atrial Fibrillation: Emerging Technologies

This abstract poster session featured the topics of left atrial scar remodeling, closure of gap lesions, incidence of complete circumferential scar of the pulmonary vein antra, contact force mapping and ultrasound, antral isolation of pulmonary veins, radiofrequency ablation versus visutally guided laser balloon ablation, regional differences in left atrial wall thickness, and more. Highlights of these research posters are offered below.

This study was conducted, explained Badger, because although it is known that delayed-enhancement "MRI (DE-MRI) can characterize left atrial (LA) scar and gap lesions following AF ablation," not much is known "regarding how scar evolves over time." What Badger, et al. found is that lesion expansion that causes posterior wall scar consolidation and prior gap lesion closure are often the results of scare remodeling following AF ablation. Additionally, a correlation was seen between scar extent at 12 months after ablation and successful procedural outcomes.

Remodeling of Left Atrial Scar and Closure of Gap Lesions Following Atrial Fibrillation Ablation: Assessment with Delayed Enhancement MRI at One-year Post-procedureTroy J. Badger, Yaw A Adjei-Poku, Nathan S. Burgon, Nazem Akoum, Thomas S. Haslam, Nicholas W. Brown, Saul Kalvaitis, Eugene G. Kholmovski, Christopher J. McGann, Rob S. MacLeod, and Nassir F. Marrouche, Comprehensive Arrhythmia and Research Management Center, University of Utah School of Medicine, Salt Lake City, UT

Badger followed up the previous presentation with this one that focused on a study that looked at "the frequency of obtaining circumferential lesions using scar analysis with" DE-MRI. Preliminary data from the research show that "circumferential PV scarring persists only in a small number of patients at long-term follow up. Nevertheless, degree of LA ablation scarring seems to be a strong predictor for procedural success implicating the importance of LA substrate remodeling in achieving AF suppression."

Incidence of Complete Circumferential Scar of the Pulmonary Vein Antra Following Ablation of Atrial Fibrillation: Assessment of Contiguous Lesions With Delayed Enhancement MRITroy J. Badger, Nathan S. Burgon, Yaw A Adjei-Pok,u Nazem Akoum, Thomas S. Haslam, Nicholas W. Brown, Saul Kalvaitis, Eugene G. Kholmovski, Rob S. MacLeod, Christopher J. McGann, and Nassir F. Marrouche, Comprehensive Arrhythmia and Research Management Center, University of Utah School of Medicine, Salt Lake City, UT

Catheter Contact Force During Ablation of Atrial Flutter and Atrial Fibrillation: Results From the TOCCATA Multi-Center Clinical Study

Vivek Reddy, Mount Sinai School of Medicine, New York, NY; Petr Neuzil, Homolka Hospital, Prague, Czech Republic; Philippe Ricard, Center Hospier Princesse Grace, Monaco, Monaco; Boris Schmidt and Karl-Heinz Kuck, Asklepios Klinick St. George, Hamburg, Germany; Dipen Shah, Hopital Universitaire de Geneve, Geneva, Switzerland; Pierre Jais, Hopital Haut-Leveque, Pessac Cedex, France; Josef Kautzner, Institue for Clinical and Experimental Medicine, Prague, Czech Republic; Andrea Natale, Texas Cardiac Arrhythmia Institute, Austin, TX; Gerhard Hindricks, Herzzentrum Leipzig GmbH Abteilung fur Rhythmologie, Leipzig, Germany; Claudia Herrera, Herz-Zentrum Bad Krozingen, Bad Krozingen, Germany; Yury Vanekov and Hendrik Lambert, Endosense SA, Geneva, SwitzerlandDuring ablation, explained Reddy, "catheter contact force (CF) with the target tissue is inferred by indirect fluoroscopic, electrical and mapping cues." So, in this "multicenter clinical study (TOCCATA), a novel irrigated radiofrequency ablation (RFA) catheter with an integrated force sensor was employed to ablate" atrial flutter and atrial fibrillation, with CF evaluated "during catheter ablation as a function of both the ablation site and inter-operator variability." Reddy and colleagues saw, during catheter ablation of atrial flutter and atrial fibrillation, a "wide range of inter- and intra-operator CFs" that were "characteristic areas of low CF during AF ablation." They also found that observed CF was greatly increased with the use of long sheaths.

Long Term Efficacy and Side Effects of Antral Isolation of Pulmonary Veins with Cryoballoon Technique in a Large Patient Cohort with Atrial Fibrillation

Juergen Vogt, Johannes Heintze, Georg Noelker, and Klaus J. Gutleben, Dieter Horstkotte Heart and Center North Rhine-Westphalia, Ruhr University Bochum, Bad Oeynhausen, GermanyBecause circumferential "substrate modification of the antrum of pulmonary veins (PV) with radiofrequency energy includes the risk of PV stenoses and esophago-left atrial fistula," explained Vogt, this study was conducted to look at the "success and side effects in antral isolation of PV with the cryoballoon technique." The researchers working with Vogt determined that antral "cyoisolation of the PV with balloon technique is highly efficient." Additionally, they found that minimization of persistent phrenic nerve palsy can be achieved with the pacing technique, frozen lung tissue can result from freezing too far inside the PV, and isolation of "mismatching veins with two balloon sizes may be associated with a lower recurrence rate of AF.

Does Visually-guided Placement of Contiguous Ablation Lesions Result in Reliable and Persistent Pulmonary Vein Isolation?

Vivek Reddy, Srinivas Dukkipati, and Andre d'Avila, Mount Sinai School of Medicine, New York, NY; Petr Neuzil, Homolka Hospital, Prague, Czech Republic; Shephal K. Doshi, St. Johns Hospital, Santa Monica, CA; Humer Ahmed and Kathryn Henault, University of Miami, Miami, FLReddy returned for this presentation of a study that tested a "novel compliant balloon ablation catheter (BAC) able to deliver visually-guided short arcs of laser energy" in order to "determine if visual guidance could predict reliable and persistent PVI." As it turns out, using the above device for this procedure is "feasible, reliable, and persistent."

Use of an Endoscopic Laser Balloon for Epicardial Mapping and Ablation in a Swine Model

Edward P. Gerstenfeld and John Michele, University of Pennsylvania Hospital, Philadelphia, PA

Because epicardial (epi) "mapping and ablation has numerous challenges, including poor catheter epi contact and the potential to damage epi vasculature and the phrenic nerve," and the "Cardiofocus endoscopic laser balloon ablation system (ELBAS) allows direct visualization of cardiac structures and ablation using light energy," Gerstenfeld and Michele "hypothesized that these features would be suited to epi mapping and ablation." What they found is that the unique attributes of the endoscopic laser balloon-"visualization of epi fat and vasculature, direct contact with the LV epi, displacement of the phrenic nerve, and large volume ablation lesion"-appear to be well suited to epi mapping and ablation.

Regional Differences in Left Atrial Wall Thickness in Patients with Atrial Fibrillation

Roy Beinart, Kevin Heist, Sheldon Singh, Rajesh Kabra, Dan Blendea, David Donaldson, Jacob Koruth, Conor Barrett, Jeremy Ruskin, and Moussa Mansour, Massachusetts General Hospital, Boston, MA

This study, explained Beinart, was conducted to "evaluate regional LA wall thickness in patients with AF," as LA wall thickness is "relevant both for procedural efficacy (the creation of transmural lesions in thick regions) and safety (prevention of perforation in thin regions) due to the required creation of transmural lesion in the LA for successful catheter ablation of AF. Study findings show both inter- and intra-patient LA muscular wall thickness variability in patients with persistent AF. What are consistent are thicker roof and isthmus, compared to posterior wall and floor, in most patients.

Short Term Results of the Convergent Endo-Epicardial Ablation Procedure for the Treatment of Long Standing Persistent Atrial Fibrillation

Shane Bailey and Andrew Hume, Texas Cardiac Arrhythmia Institute at St. David's Medical Center, Austin, TX; Luigi Di Biase, Rodney Horton, and Andrea Natale, University of Texas, Austin, Department of BME and Texas Cardiac Arrhythmia Institute at St. David's Medical Center; Andy Kiser and Mark Landers, FirstHealth Arrhythmia Center, Pinehurst, NC; Borut Gersak, Department of Cardiovascular Surgery, University Medical Center Ljubljana, Ljubljana, Slovenia; Majaz Sinkovec and Andrej Pernat, Department of Cardiology, University Medical Center Ljubljana, Ljubljana, SloveniaThe aim of this study, said Di Biase, was to "devise a closed chest procedure which combines endo and epi ablation," as an "endoscopic trans-diaphragmatic approach with conventional percutaneous endo ablation enables a closed chest procedure that increases the completeness of the lesion pattern." Di Base and his colleagues found short-term success in patients with long-standing persistent atrial fibrillation using the "convergent experience combining surgical and electrophysiological expertise;" however, to understand the long-term efficacy of the approach, additional data is needed.