Discussion
The present study revealed no statistical difference between CF ablation
technology and traditional RF methods. There was wide variability in the
total procedure time, successful lesion time, time spent mapping and
ablating the pathway, and number of lesions delivered, resulting in
similar averages in both cohorts. Although a trend toward higher acute
success was observed in the CF group, we also saw more long-term
recurrence compared to control, though neither outcome achieved
statistical significance. To our knowledge, this is the first pediatric
study directly comparing ablation outcomes for CF and standard RF
catheters for AVRT.
There has been significant research on use of CF in the adult
population, however there have been fewer pediatric studies, and even
less standard of practice recommendations for use of CF. Extensive
research of CF in adult atrial fibrillation shows several benefits,
however through our study we saw the outcomes do not differ from using
traditional RF ablation. It is difficult to tell whether these results
are due to the unique pediatric population with APs, or if it reflects
our early experience with this new technology and further research could
elucidate statistically significant benefits from CF in pediatrics.
Contact force technology has largely been studied in adult patients with
atrial arrhythmias and is overall shown to decrease procedure times and
improve outcomes.2 However, even within the adult
population, variation exists depending on specific study parameters and
arrhythmia characteristics, as seen by Jarman et al with improved
outcomes in ablation of paroxysmal atrial fibrillation, but not in
non-paroxysmal atrial fibrillation.4 While some groups
found that CF did not change total procedure length, fluoroscopy
exposure, or one-year follow-up outcomes5,6, other
studies dispute this showing CF reduced procedure times and number of
touch-up ablation lesions.7 Some variation in the
adult literature can be attributed to the lack of unified protocol
amongst the studies. Although studies such as the TOCCATA and EFFICAS I
trials attempted to consolidate and hone recommendations, different
facilities are still free to use their own criteria for adequate contact
force.8,9 Similarly, to date there are no pediatric
specific recommendations for CF and force-time measurements for
successful ablation.
Radiofrequency ablation has been used for decades in the pediatric
population and newer CF technology is successfully being implemented as
well, but more research on the amount of force and outcomes is required
to better define the role of this technology in pediatric patients. The
early research on CF in pediatrics has been mainly on safety and force
recommendations. The FEDERATION study looked at the original adult
protocol formed in the TOCCATA trial of 2012, and investigated the
recommendations specifically in a pediatric population, concluding CF
can safely be used in a pediatric population and significantly less
force is needed for successful ablation.3 Although the
study indicated patients with AVNRT and AVRT may not require transmural
lesions, a concrete protocol for use of CF in pediatrics still does not
exist and there remains minimal evidence on the benefit of CF in
ablation of pediatric APs.
Currently, recommendations for transmural lesions in adult atrial
fibrillation ablation include a CF of 20 g and force-time integral (FTI)
> 400 gs.8 Pediatric studies have shown
that less force may be necessary in ablation of APs in children,
suggesting CF of 6 g and FTI of 153 gs may be
sufficient.3 Children’s Wisconsin used these
recommendations and operator experience to identify a protocol
suggesting ideal ablations with > 3 g of force for 60
seconds or a maximum of 400 gs, but further research is needed in order
to create solid CF criteria for ideal ablation outcomes. Though not
statistically significant, we observed a trend towards more long-term
recurrence in the CF cohort than in the control. This recurrence rate
could be attributed to the Children’s Wisconsin protocol, and different
criteria may improve outcomes in the future.
Only four patients (2.0% of CF and 3.9% of control patients) in our
study experienced complications including mild aortic insufficiency on
follow up echocardiogram, ischemia and VF secondary to ventricular
pacing, cardiac perforation during transseptal puncture, and a groin
hematoma. The aortic insufficiency was observed while using the
Tacticath CF catheter for ablation of a left-sided pathway using a
retrograde approach. Aortic insufficiency is a known complication of
this approach,10 and it is unclear whether the stiffer
nature of the Tacticath catheter would increase this risk. However, the
remainder of the complications observed are related to the procedure
itself, unrelated to the ablation catheter used, and all patients made a
full recovery. Mansaur et al and several other studies have shown low
complication rates using CF ablation, and the technology has been proven
effective and safe both in adult and pediatric
populations.2,11
The CF catheters used in our study cost approximately $1900 more than
our typical non-irrigated, non-CF catheters, reflecting an almost
three-fold cost difference per catheter. Given the comparable outcomes
presented in our study, it is challenging to justify this additional
cost in the absence of any identifiable benefit. However, should further
experience and refinement of protocols using this catheter ultimately
result in improved procedural outcomes and lower recurrence rates, then
the overall cost-effectiveness of the catheter may improve when compared
to the cost of repeat ablation procedures. Alternatively, further
studies may identify particular pathway locations where catheter contact
may be associated with higher recurrence rates, such as right free wall
pathways, where outcomes are improved with using CF
technology.12