AFACART Clinical Trial: Preliminary Results of the CardioInsight—ECVUE System in Multiple Centers
By Steve s. Ryan, PhD, July 2015
Pr. Sebastian Knecht from CHU Brugmann, Brussels, (now AZ Sint Jan, Brugge), Belgium gave a presentation entitled “AFACART Trial—Design and Preliminary Results.” (AFACART stands for “Non-Invasive Mapping of Atrial Fibrillation,” a new name for ECGI).
In preparation for their ablation the patient dons the ECGI vest-like device. The data generated creates an image of the heart and pinpoints sites (“drivers”) producing A-Fib signals. This 3-D computer model of the patient’s heart is used during the ablation procedure.
AFACART Clinical Trial Design and Participants
The AFACART trial is a European multicenter, feasibility, non-randomized study using “Panoramic Electrographic Non-Invasive Mapping”, specifically the CardioInsight—ECVUE System, for ablation of persistent A-Fib.
AFACART stands for “Non-Invasive Mapping of Atrial Fibrillation,” a new name for ECGI
Ablation patients are to be followed for 12 months. The effectiveness of Panoramic Electrographic Non-Invasive Mapping is to be compared to conventional mapping and ablation procedures.
Eight European centers in France, Belgium and Germany are participating in this clinical trial. None of these centers had any practical experience with this system before this study.
Ablation Steps One to Three
In an important change to standard ablation procedures, the first step in the ECGI/ECVUE ablation process is ablation of A-Fib drivers (rotors and foci). (This is in comparison to the step-wise approach that begins with ablation of the pulmonary vein openings.)
If A-Fib doesn’t terminate to sinus rhythm or stable atrial tachycardia isn’t achieved (> 5 min), then a standard PVI is performed.
This is followed by linear lesions. And finally by Electrocardioversion.
AFACART Trial Preliminary Results
• Step One (driver ablation only): 64% of the persistent A-Fib patients had their A-Fib terminated.
• Step Two (driver and PVI ablation): 66% termination
• Step Three (driver, PVI, and LA linear lesions) 73% termination
For our technical readers, Dr. Knecht defined ‘drivers’ as “local reentrant circuits (> 1.5 rotations) or focal breakthroughs (>2) that appear at the same spatial location per window.”
In 94% of patients, driver ablation had a significant impact on the A-Fib termination process. A-Fib cycle length was prolonged in all persistent patients except for 6%. Even patients who were not terminated (27%) had their A-Fib cycle length prolonged by driver ablation.
After 12 months, 72% of patients were A-Fib free and no longer taking antiarrhythmic meds (AADs). 31% had Atrial Tachycardia recurrence, but many had a second ablation.
Overall 83% were A-Fib free, 17% had Atrial Tachycardias and only 9% were still in A-Fib.
Ablation procedure time averaged only 44.7 minutes. As the number of driver regions increased, the ablation success rate decreased. 66% of drivers were in the Left Atrium, 34% in the right. 70% of termination sites were in the left atrium, 30% in the right.
Driver Sites and CFAEs
• In these persistent A-Fib patients, 50% of both atria had CFAEs.
• Most (but not all) driver sites contained CFAEs.
• Successful driver ablation only ablated 19% of both atria (this is a major improvement and resulted in much less ablation damage to the heart compared to trying to ablate all CFAE areas).
Dr. Knecht stated that “use of the ECVUE system seems to result in a more specific selection of CFAEs leading to a more targeted ablation strategy.”
Dr. Knecht’s Conclusions
Ablation of A-Fib drivers is associated with a high rate of A-Fib termination.
• Drivers are distributed in both atria (2/3 LA and 1/3 RA).
• Results are reproducible among centers without prior practical experience with the system.
• Preliminary chronic results are very promising.
Driver Ablation More Important Than PVI in Persistent A-Fib: ECGI is changing the way ablations are done and our understanding of A-Fib. In persistent A-Fib, the mapping and ablation of drivers is more important and is done before a PVI ablation. While driver ablation had a 64% success rate, doing a standard PVI after driver ablation only improved results by 2%.
ECGI/ECVUE Major Improvement in Ablation Success Rate: An 83% success rate after 12 months following ablations for tachycardias, is a major improvement and source of hope for persistent A-Fib patients. These results were even better when one considers that only 9% were still in A-Fib.
ECGI/ECVUE Results in Much Fewer Ablation Burns: Previous protocols for ablating persistent A-Fib usually involved mapping and ablating CFAEs. But CFAEs in persistent A-Fib patients can cover 50% of the atria surfaces which often necessitated a lot of burns and debulking.
Too many ablation burns could result in the development of fibrosis (dead heart tissue where the ablation catheter produced burns and scarring) and a stiffening of the atria with loss of pumping ability. ECGI/ECVUE only requires ablating 19% of the CFAE areas resulting in much less lasting damage to heart tissue.
Driver Ablation Prolongs A-Fib Cycle Length: Driver ablation had a major effect on the A-Fib termination process. A-Fib cycle length was prolonged in all but 6% of the persistent A-Fib patients. This is perhaps a first step in improving outcomes for persistent A-Fib patients.
Reproducibility: The most important finding of Dr. Knecht’s report is that ECGI/ECVUE works in other centers without doctors (operators) having to undergo extensive training.
These preliminary results from this multi-center clinical trial are quite impressive for the treatment of patients with persistent A-Fib. Hopefully it won’t be long before the ECGI/ECVUE system is available in more countries. (ECGI was invented at Washington Un. in St. Louis, MO and is available there on a limited basis.)
To learn more about ECGI, see Non-Invasive Electrocardiographic Imaging (ECGI): Presentation Summary and Comments from the 2013 AF Symposium. You may want to read this report in conjunction with Dr. Haissaguerre’s 2015 AF Symposium presentation The Changing Ablation World: Going Beyond PVI With ECGI Mapping and Ablation Techniques.
Last updated: Friday, January 1, 2016