DISCUSSION
Point-by-point creation of the ablation lines using externally irrigated
ablation catheters in power control mode during PVI remain the standard
current procedure through its flexibility and ability to perform extra
PV ablation . However, there is still demand for improvement of
technologies to make procedure faster and lesions more durable.
Introduction of a new ablation system with the possibility of
temperature control mode should overcome limitations of standard
irrigated tip catheters, lead to deeper and more permanent lesions, and
reduce the incidence of the chronic reconnections. The DT Cardiac
Ablation System has several features for improved creation of the
ablation lesions. The diamond embedded tip of the catheter with very
rapid heat diffusion allows for creation of faster lesions and reduced
irrigation to 8ml/min. Reduced irrigation with a complex system of
surface thermocouples allows the use of temperature control mode with
better titration of energy during ablation with variable stability and
contact force and subsequently creates lesions more efficiently,
reliably, and safely. The composite, dual part tip of the DT catheter
enables sensing of high-resolution EGMs, which might be better for
monitoring of lesion creation and minimizing collateral injury. It is
expected, that ablation with a novel system will be faster and safer
with minimizing of pops or char formation.
The TRAC-AF study clearly shows, that despite short RF application time
in the majority of patients, durable PVI was achieved with a longterm
success rate comparable to patients ablated with standard irrigated tip
catheters . Our study confirmed the pilot results of Iwasawa et al with
a larger group of patients. We show that temperature-controlled,
saline-irrigated RF ablation with the DT Cardiac Ablation System
equipped with an array of thermocouples at the tip-tissue interface is
very efficient and safe with a high probability of achieving transmural
atrial lesions. Preclinical experimental data show that a 75% reduction
in voltage was achieved with 13.3 ± 6.0 s of RF, and complete lesion
transmurality was achieved in 92.7% of lesions .
A significantly lower total radiofrequency ablation time was seen with
the DT catheter compared to AF patients ablated with standard irrigation
catheters in other contemporary paroxysmal AF ablation studies, such as
the Fire and Ice Study (Cryoballoon or Radiofrequency Ablation for
Paroxysmal Atrial Fibrillation) and the Heartlight (CardioFocus,
Marlborough, Massachusetts) multicenter clinical trials , see Figure 3.
Total fluoroscopy time was significantly shorter in the DT group as well
(9.6 ± 6.6 min for TRACK AF patients, 16,6 ± 17,8 min. and 29.7 ± 21.0
min for Fire and Ice Study and Heartlight resp.), which is well-aligned
with the trend to decrease radiation exposure which has been
dramatically decreasing over the last decade for PVI. With older
technology we exploited our chances to decrease exposure through
operator experience, annual case volume, and technology evolution .
Contact force catheters are thought to be major contributor to the
trend, especially in more lengthy procedures for persistent AF .
Inclusion of other modalities in the ablation strategy, such as
pre-procedural computed tomography and 3D rotational angiography, has
also contributed to lower radiation exposure (11).
DT technology thus further allows to decrease exposure times for
patients and attending physicians, further decrease would be possible
only by fluorless procedures .
The 12-month rate of freedom from AF of 72.5% is similar to the success
rates of catheter ablations with standard irrigated tip catheters , , .
This data support noninferiority of the new ablation system regarding
efficacy.
From a safety view, the DT catheter seems to be as safe as standard
contact force ablation catheters. There were no audible pops, or char
formation. There was only one delayed pericardial effusion related to
the ablation procedure. Rate of complications nonrelated or possibly
related to the investigational device was 4.3% and was comparable with
complication rates during catheter ablation with standard irrigated tip
catheters
The presented study has several limitations. Our project is the first
larger study to deal with the new DT ablation system. The number of
patients is limited and the study has nonrandomized, single-arm design.
Comparison with other ablation studies is indirect and for a more
definitive confirmation of efficacy and safety, a randomized, large
study comparing this system with standard irrigated contact force
catheters is needed. Such a study which recruited patients with
paroxysmal AF has been recently completed and is to be published.