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.