Discussion
The present study demonstrated the promising outcomes and safety of
combining AF catheter ablation and LAAC under ICE guidance for patients
with symptomatic drug-refractory AF and high stroke risk. The study data
showed an excellent efficacy profile in avoiding ischemic stroke despite
two device-related thrombi and confirmed the impressive lowering rate of
major bleeding events during 12 months of follow-up. Specifically, this
report proposed an original multi-planner ICE protocol (FLAVOR approach)
providing four views equivalent to TEE planes under Carto-Sound feature
guidance for assessment of LAA occluder implantation during the
procedure with minimal fluoroscopic exposure. In addition, this study
revealed most of the iatrogenic ASDs developed by a single transseptal
access for left atrial ICE to guide LAAC could closed spontaneously
during 12 months follow-up.
The application of ICE during AF ablation has increased over the years
and is associated with lower procedural complications and in-hospital
mortality.14 Very few studies to date have evaluated
the feasibility and outcome of zero-fluoroscopy catheter ablation of AF
with combined use of a three-dimensional electro-anatomic mapping system
and ICE.15,16 Our study applied the currently
available technologies: ICE, CARTOSOUND electroanatomical mapping system
and contact force sensing catheter, along with high power ablation
strategy17 and AI guidance18. This
study demonstrated that AI-guided high-power
fluoroless ablation for AF under ICE
guidance is fully effective and safe.
The feasibility of ICE to guide LAAC was recently established, and ICE
is now considered an alternative to TEE to decrease esophageal injury,
logistical burden, and risk associated with general
anesthesia.19,20 In most studies, the ICE probe is
placed at one or two positions in the left
atrium.9,10,21 In some of these studies, the probe was
placed only at the entrance of the LSPV.9,21 Hemam et
al.22 imaged the LAA from four different locations to
evaluate the LAA and device, including the central LA body, deeper into
the LSPV and LIPV, and transmitral. However, without using the LA
geometry map described in the present study, this approach is limited by
the varied anatomical relationships among the LAA, pulmonary veins, and
mitral valves and the technical challenges in manipulation with ICE
catheter. Additionally, the technique might increase the risk of
complications such as LA rupture or pulmonary vein laceration. However,
no contemporary studies have provided a fully comprehensive,
reproducible method to guarantee efficient and safe LAAC with ICE
guidance. Our present work introduced the novel step-by-step FLAVOR
approach, which presents comparable ICE images with the four standard
views of TEE. The three-dimensional LA geometry map improved the
reproducibility and safety of ICE probe manipulation without fluoroscopy
and facilitated thorough assessment of the LAA and device. The LAA
ostium is highly eccentric, and Westcott et al.23revealed that 52% of implant leaks occurred along the posterior segment
of the LAA ostium using a clock-face representation (6:00 to 9:00 axis
corresponding to the 135° TEE view). An explanation might be that the
long axis of the LAA ostium usually centers along the 135° axis of the
TEE view. Accordingly, in our study cohort, the LAA ostium was
numerically the largest in the 0° to 45° ICE view and the smallest in
the 135° ICE view. Most of the leaks after device release were detected
at45° and 90° ICE views, none at 135° ICE view. In consistence,
peri-device leaks were most frequently detected in the TEE 135° view
(79.3%) and 90° view (65.2%) at the 2-month follow-up. This suggests
that ICE protocols with fewer views, especially only one view from the
entrance of the LSPV, may have significant limitations in comprehensive
and accurate evaluation of the position and peri-device leakage of LAA
occluders. Furthermore, ICE-guided catheter ablation and LAAC with the
FLAVOR approach resulted in low X-ray exposure with a mean assessment
time of only 2.1 minutes. The FLAVOR approach was facilitated by the ICE
probe which was soft, blunt and flexible, that would allow for safe
manipulation in LA under Carto-Sound integrated into a 3D mapping
system.
Because AF ablation is considered only symptomatic treatment, clinical
practice guidelines recommend undefined long-term oral anticoagulation
in patients with high risk of thromboembolic events following catheter
ablation therapy.4 Recent studies have proved the
efficacy and safety of combined catheter ablation and LAAC for treatment
of AF.6,7 Nevertheless, the combined procedures
require general anesthesia and TEE guidance. A recent study showed that
the use of TEE for guiding structural heart disease interventions,
including LAAC, was associated with a significant degree of esophageal
or gastric injury.24 Esophageal injury during catheter
ablation for AF was not uncommon. Whether the two aggravate esophageal
damage remains a great concern. The use of ICE in combined procedures
prevents this problem. Although the cost of an ICE catheter limits its
extensive application, it would be appealing for patients undergoing
combined AF ablation and LAAC because the catheter would be needed for
transseptal punctures, LA geometry mapping, and guiding ablation.
A single transseptal access for LAAC under left atrial ICE guidance is
commonly used in ICE-guided LAAC. Iatrogenic ASDs secondary to
catheterization have become an issue of great concern. The PROTECT-AF
trial showed an encouraging spontaneous closure rate of iatrogenic ASDs
with a 14-Fr outer diameter Watchman transseptal sheath. A total of 87%
of iatrogenic ASDs were detected immediately after catheterization, with
7% remaining at 1 year.25 Korsholm et
al.20 compared ICE-guided LAAC under local anesthesia
with TEE-guided LAAC under general anesthesia using an Amplatzer Cardiac
Plug or Amulet device. Follow-up TEE at a mean of 55 days after the
procedure showed no significant difference in the incidence (35% vs.
26%) or size of iatrogenic ASDs between the two groups. The incidence
of iatrogenic ASD in the long term after left atrial ICE guided LAAC
using a single transseptal access remains unknown. Intriguingly, our
study demonstrated a 57.9% incidence of iatrogenic ASD at 2 months and
a 4.2% incidence at 1 year. It therefore seems safe to perform left
atrial ICE guided LAAC with the LAmbre device using a single transseptal
access.
This is a pilot, single center prospective observational study with
small-scale. We did not compare this strategy with combined treatment
under TEE guidance. We only used the LAmbre device and SoundStar ICE
catheter; hence, the study results cannot be fully extrapolated to other
LAA occluders and ICE catheters. Finally, the ICE catheter was
maneuvered by experienced electrophysiologists. Further large-scale,
multicenter prospective clinical trials are required to confirm the
efficacy and safety of this strategy.