Novel streamlined technique for left atrial appendage closure using a radiofrequency wire‐based large access system

Transseptal puncture (TSP) to allow for large delivery sheath left atrial (LA) access remains a challenging aspect of LA appendage closure (LAAC) in patients with prior history of TSP, thick or lipomatous septum, atrial septal aneurysms, or other complex cardiac anatomies. This study investigates the use of the VersaCross large access (VLA) system (Baylis Medical/Boston Scientific) to improve procedural efficiency of LAAC compared to the standard needle workflow.


| INTRODUCTION
Patients with nonvalvular atrial fibrillation (AF) are associated with an increased risk of cardioembolic events such as stroke. 1,2 Oral anticoagulants are prescribed to reduce the risk of cardioembolic events; however, increasing the risk of extracranial bleeding and intracranial hemorrhage. 1,2 Percutaneous left atrial appendage closure (LAAC) has become a widespread alternative treatment option in reducing thromboembolic events in patients with AF, sealing the left atrial appendage (LAA), and thereby restricting the main source of cardiac thrombi from entering the circulation. [3][4][5] As more patients become eligible for LAAC, including those with previous cardiac procedures or challenging anatomies, left atrial (LA) access using transseptal puncture (TSP) becomes an increasingly challenging and variable step. Advances in TSP technology, such as the use of purpose-built radiofrequency (RF) needles, have been shown to improve TSP success and safety compared to conventional mechanical needles by requiring minimal tenting and force on the atrial septum to reduce the risk of accidental slippage, perforation, or puncturing at undesirable locations. 6,7 The VersaCross RF wire transseptal system (Baylis Medical/Boston Scientific) uses similar principles to the RF needle to achieve TSP, with the added benefit of serving as starter guidewire and stiff exchange rail for the LAAC delivery sheath to reduce device exchanges and the associated risks of injury and air embolism. [8][9][10] In addition to LA access, precise TSP is important for successful implant deployment and LAAC; position on the septum must be optimized to provide coaxial trajectory of the LAAC delivery sheath with the LAA ostium to ensure proper device placement, and reduce the risk of procedural complications, leaks, or device embolization. 11 After TSP, further difficulties may be encountered arise while introducing large diameter delivery sheaths used for LAAC, requiring more force to overcome the resistance at the septum, and presenting additional risks of tissue injury. The use of a 12.5 Fr large access integrated sheath-dilator transseptal system has been shown to dilate the septum and reduce the force required to advance LAAC implant delivery sheaths 12 ; it is unclear, however, whether the use of a large transseptal system has a significant impact on puncture site specificity, procedural efficiency and acute LAAC procedural success.
The aim of this study is to report the first clinical experience using the seamless dilator sheath device, VersaCross Large Access (VLA) transseptal system, and LAAC procedural efficiency to the previous standard of practice at our center using the RF needle.  F I G U R E 2 Three fewer device exchanges using the VersaCross Large Access system than the standard needle workflow, and ability to directly access the LAA to confirm LAA size and optimize WATCHMAN FLX Device position with VLA. LAA, left atrial appendage; VLA, VersaCross Large Access. maintain an activated clotting time ≥ 250 s. Vascular access was obtained using an 8 Fr (Merit Medical Systems) or 7 Fr (Terumo) short introducer sheath inserted in the right femoral vein. Position on the fossa was selected to be infero-anterior for most patient anatomies to ensure coaxiality with the LAA ostium. In patients undergoing LAAC procedure using the VLA system, the 0.035" VersaCross RF wire (Baylis Medical/ Boston Scientific) ( Figure 1) was used to canulate the superior vena cava, tent the septum, perform TSP, and access the LAA ( Figure 2). The blunt, atraumatic, 24 mm pigtail RF wire was used to estimate LAA size and served as an exchange rail to introduce the WATCHMAN delivery sheath directly into the LAA. Contrast was injected through the delivery sheath into the LAA to obtain LAA angiogram and confirm anatomy and device size ( Figure 2). In the needle workflow, a 0.032" guidewire was used to introduce a SL1 transseptal sheath and dilator (Swartz Braided Transseptal Guiding Introducer, Abbott). The guidewire was exchanged for the NRG RF needle to drop down to the fossa ovalis and perform TSP; the needle was then exchanged for a ProTrack pigtail wire (Baylis Medical/Boston Scientific) to exchange the transseptal sheath for the WATCHMAN delivery sheath. A 6 Fr catheter was placed through the delivery sheath to inject contrast for LAA angiography. In both workflows, WATCHMAN FLX device deployment and release were conducted per standard protocol using the PASS criteria.

| Statistical analysis
Variables between the VLA group and the standard needle-based group were compared using descriptive statistics. Continuous variables were reported as the mean ± standard deviation, and categorical variables were reported as percentages. Procedure efficiency and patient population metrics were compared between VLA workflow and standard workflows using two-tailed Student t-tests for continuous variables or Fisher exact tests for categorical variables. A p < 0.05 was considered statistically significant.

| Procedural success and efficiency
TSP was successful in all cases without any transseptal related complications ( Table 2). Time to TSP was faster, but not significant, using the VLA system from both femoral access (12.4 ± 4.0 min vs. 13.7 ± 4.2 min; p = 0.31) and wire insertion into the femoral vein (2.6 ± 1.1 min vs. 3.0 ± 1.8 min; p = 0.38, Figure 3A). Time to VLA sheath across the septum was on average 12.5 ± 4.1 min without any additional challenges crossing the septum ( Table 2). Secondary septal dilation was required in one patient in the VLA group due to large right atrium and difficulty reaching anterior septum.
Acute WATCHMAN FLX LAAC procedure success was in 100% of patients in both groups, with no intraprocedural complications. Median implant size was 31 mm in both groups. Time to WATCHMAN sheath LA access from femoral access was 12% faster, but not significant in the VLA group. Time to WATCHMAN sheath LA access from TSP was on average 27% faster in the VLA group compared to the needle group (1.5 ± 0.8 min vs. 2.1 ± 0.9 min; p = 0.03, Figure 3B). Time to angiography from WATCHMAN sheath LA across was 26% faster with the VLA workflow compared to the needle workflow (1.6 ± 0.6 min vs. 2.2 ± 0.6 min; p = 0.002, Figure 3C). Time to WATCHMAN release from femoral access was 15% faster in the VLA group compared to the needle group (22.9 ± 4.9 min vs. 27.0 ± 5.9 min; p = 0.01, Figure 3D). Time from TSP to  Figure 3E). Overall procedure time was 15% faster using the VLA workflow compared to our previous needle workflow (30.4 ± 5.1 min vs. 36.0 ± 6.6 min; p = 0.003, Figure 3F). Total implant device recaptures were higher in 20% more cases in the needle workflow compared to the VLA workflow (52% vs. 32%, respectively; p = 0.16, Table 2) with greater number of recaptures using the needle workflow.
Fluoroscopy time was 25% lower with the VLA workflow compared to the needle workflow (4.0 ± 2.2 min vs. 5.5 ± 2.3 min; p = 0.003, Figure 4A). Fluoroscopy dose was 60% lower in the VLA group compared to the needle group (97.0 ± 91.7 mGy vs. 241.8 ± 240.6 mGy; p = 0.01, Figure 4B). Additionally, fluoroscopy dose was less variable between patients in the VLA group compared to the needle group (F-test, p ≤ 0.0001) ( Figure 4B). There were no significant differences in contrast use between the large access sheath workflow and the needle workflow (53.8 ± 20.7 ml vs. 64.0 ± 22.9 ml, respectively; p = 0.16, Table 2). the use of the VLA RF-wire based workflow was shown to streamline LAAC procedures, enabling overall 5.6 min faster procedures compared to the previous standard-of-practice using the RF needle ( Figure 3F). Although not significant, TSP times were numerically faster using the RF-wire based workflow compared to RF needle ( Figure 3A). There were no intraprocedural complications in either group indicating that the RF-wire system improves LAAC procedural efficiency without compromising safety.

| DISCUSSION
The RF wire was used to directly access the LAA to optimize WATCHMAN sheath trajectory into the LAA ostium, estimate LAA size based on the 24-mm pigtail and allow for LAA angiograms to be performed directly through the WATCHMAN sheath without the need for a pigtail catheter (Figure 2). These improvements using sheath, which can potentially reduce the crossing force, risk of septal tearing and tissue injury. 12 In this study, the use of the 12.5 Fr VLA sheath-dilator system, in addition to the VersaCross RF wire, allowed for pre-dilation of the septum to enable faster and more smooth WATCHMAN delivery sheath LA access than the standard needle and sheath group ( Figure 3B).
Compared to mechanical needles, RF needles have been previously shown to reduce fluoroscopy use. 13 We found that the VLA system led to further reduction in fluoroscopy usage over the RF needle, whereby the VLA system was associated with 25% less  (Figure 4). This is likely due to direct WATCHMAN sheath delivery into the LAA, fewer device recaptures, and better visualization of the RF-wire system without the need for higher magnification. 14 By reducing radiation exposure, this provides safety benefits to the patients, as well as to clinicians.
Furthermore, although it did not reach statistical significance, there was a 20% reduction in cases requiring device recapture, and lower number of recaptures overall using the VLA workflow (Table 2).
While design improvements have simplified the process for implant recapture to adjust position, additional imaging and assessment may cause significant delays to the overall procedure. The lower recapture rate observed in our study further supports the premise that improved coaxiality and accuracy of LAA assessment can improve LAAC efficiency and acute success, thereby, reducing safety risks associated with excess device and catheter manipulation. [9][10][11] Moreover, it is important to note that at our institution, LAAC Similarly, in our study the additional benefit of the RF-wire based approach was the optimized and direct access to the LAA, likely accounting for the overall procedural efficiency. investigation is required to confirm these findings.

| CONCLUSION
Purpose-built RF puncture technologies have been shown to be safer, efficient, and more effective tools for TSP. 6,12 The dedicated RF transseptal needle and RF wire are both similar in effectiveness and safety, however; the wire-based system eliminates device exchanges which may lead to further time savings. Use of a 12.5 Fr seamless sheath-dilator transseptal assembly allowed for faster LA catheterization using the large WATCHMAN delivery sheath, without compromising transseptal site specificity. The VLA system eliminated several procedural steps and reduced the number of device exchanges, which may lead to lower risk of perforation, tissue injury, and air embolism.
LAAC procedural time savings, consistency, and predictability may lead to improved catheterization lab efficiency and operational cost savings, without compromising safety.

ACKNOWLEDGMENTS
We acknowledge Rhodaba Ebady and Saja Al-Dujaili (Boston Scientific, Scientific Affairs) for their assistance in manuscript preparation.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.