Abstract
Background
Concomitant atrial fibrillation ablation and left atrial appendage (LAA) occlusion are increasingly considered in patients with elevated thromboembolism and bleeding risk. Emerging data suggest a higher incidence of peridevice leak with pulsed field ablation (PFA).
Case Summary
Two patients underwent concomitant PFA with the Sphere-9 catheter (Affera/Medtronic) and Watchman FLX Pro (Boston Scientific); postablation LAA changes were managed with tailored upsizing in one case and standard sizing in the other. At 6 months, both maintained sinus rhythm on antiplatelet therapy with no thromboembolic or bleeding events, and cardiac computed tomography confirmed well-seated devices with peridevice leak ≤2 mm.
Discussion
These are the first reported cases of concomitant LAA occlusion with Watchman FLX Pro and Sphere-9 PFA. Postablation LAA anatomical changes influenced device selection, and larger studies are needed to validate these findings.
Take-Home Messages
Focal PFA led to specific, observable changes in LAA anatomy, directly affecting device sizing decisions. Tailoring device sizing to account for postablation LAA remodeling—using standard sizing or upsizing—may optimize device seal and compression.
Key Words: atrial fibrillation, LAAO, pulsed field ablation, watchman FLX Pro
Visual Summary
Catheter ablation is evolving as the standard of care for patients with symptomatic atrial fibrillation (AF).1 However, long-term anticoagulation after the procedure remains a challenge for many patients and may reduce quality of life.2 This is attributable to several factors including financial burden and increased bleeding risk, especially in patients with a history of clinically relevant bleeding and high HAS-BLED scores.3 Recently, concomitant left atrial appendage occlusion (LAAO) and catheter ablation using radiofrequency energy have been shown as a safe and noninferior alternative to anticoagulation after catheter ablation for AF in patients at lower risk of bleeding.4
Pulsed field ablation (PFA) has emerged as a novel energy source with greater selectivity for myocardial tissue compared with conventional radiofrequency ablation modalities.5 Emerging multicenter data recently reported a higher incidence of clinically significant peridevice leak (PDL) with PFA, but the overall experience remains limited.3,6,7
Given the focal geometry of the Sphere-9 catheter, use in concomitant procedures may facilitate favorable postablation anatomy and device-tissue interaction. However, the extent of pulmonary ridge edema associated with the Sphere-9 catheter (Affera/Medtronic) compared with other PFA form factors is unknown. In one case, a tailored upsizing approach was used to account for transient postablation LAA changes. In this report, "tailored upsizing" refers to increasing the device size by 40% to 50% beyond the LAA orifice when LAA width decreases significantly after ablation, thereby achieving a 20% to 30% compression at the upper limit of the acceptable range. This case report aims to illustrate how dynamic changes in the LAA anatomy after PFA may influence device sizing during a concomitant procedure.
Case Presentation
Case 1
A 76-year-old woman presented with symptomatic, recurrent paroxysmal AF, interfering with her quality of life. She had a medical history of obesity, hypertension, and obstructive sleep apnea. She also had a previous incident of significant hemarthrosis that led to the replacement of her right knee (CHA2DS2-VASc score of 3, HAS-BLED score of 2) (Table 1). She presented in 2015 with paroxysmal AF and was prescribed rivaroxaban, which contributed to the development of right hemarthrosis 1 year later. After her index catheter ablation in May 2016 and intolerance to alternate oral anticoagulation, she has been maintained on antiplatelet monotherapy. In April 2025, she underwent a combined procedure for recurrent AF using the Sphere-9 catheter and Watchman FLX Pro (Boston Scientific). A preablation transesophageal echocardiogram revealed a single-lobed LAA with an orifice width of 2.0 to 2.2 cm and a depth of 1.7 to 2.6 cm with no thrombus present (Figure 1). After pulmonary vein reisolation, an upsized 31-mm Watchman FLX Pro device (41% larger than the LAA orifice) was implanted to meet the PASS criteria8 with no PDL. The final device compression percentage in this patient was 25.8%. The extent of device upsizing was calculated and compared with the standard upsizing measurements provided by Boston Scientific's device size chart, which includes overlapping device profiles. The procedure was performed under general anesthesia, with a duration of 96 minutes, a fluoroscopy dose of 132 mGy, and a fluoroscopy time of 12.9 minutes. Notably, LAA width decreased after ablation compared with preprocedure measurements across multiple angles, suggesting significant lateral ridge edema (Table 2).
Table 1.
Case 1: Demographic Information and Highlights of the Most Significant Clinical Events in Her Medical History
| Demographics | Details |
|---|---|
| Sex | Female |
| Age (y) at initial presentation | 66 |
| Date of initial presentation | 2015 |
| Presenting arrhythmia at her first clinical encounter | Paroxysmal atrial fibrillation |
| Timelines | Significant clinical events |
| 2015 | Diagnosed with paroxysmal atrial fibrillation and was prescribed rivaroxaban. After a short period of time, the patient developed hemarthrosis of the right knee that required knee replacement and rivaroxaban discontinuation. |
| May 2016 | Radiofrequency ablation for paroxysmal atrial fibrillation and typical atrial flutter. The patient was maintained on apixaban after the procedure. |
| June 2016 | Development of knee swelling and discontinuation of apixaban. She has been maintained on antiplatelet monotherapy since then. |
| April 2025 | Pulsed field ablation using Sphere-9 catheter (Affera/Medtronic) with concomitant Watchman FLX Pro implantation. |
| May 2025 | Cardiac computed tomography scan showed a well-seated Watchman device with no evidence of peridevice leak or device-related thrombus. |
Figure 1.
Transesophageal Echocardiography Image for Case 1
Image demonstrating left atrial appendage width measurements before ablation indicated by the white arrow.
Table 3.
Case 2: Demographic Information and Highlights of the Most Significant Clinical Events in Her Medical History
| Demographics | Details |
|---|---|
| Sex | Female |
| Age (y) at initial presentation | 59 |
| Date of initial presentation | 2015 |
| Presenting arrhythmia at her first clinical encounter | Paroxysmal atrial fibrillation |
| Timelines | Significant clinical events |
| 2015 | Diagnosed with paroxysmal atrial fibrillation. |
| August 2021 | She had an ischemic stroke in the occipital lobe. She was prescribed flecainide and rivaroxaban at the time. |
| July 2024 | She was hospitalized due to severe iron deficiency (hemoglobin = 4.6 g/dL and MCV = 64 fL). The patient received 3 packed red blood cell transfusions, and symptomatic improvement was witnessed. Rivaroxaban was discontinued due to gastrointestinal bleeding concerns. |
| March 2025 | Pulsed field ablation using Sphere-9 catheter (Affera/Medtronic) with concomitant Watchman FLX Pro implantation. |
| May 2025 | Computed tomography scan revealed that the device was well seated, with a 2-mm inferior peridevice leak and no evidence of an atrial thrombus or pericardial effusion. |
MCV = mean corpuscular volume.
The patient was maintained on anticoagulation therapy and then transitioned to antiplatelet monotherapy. At 45 days after the procedure, cardiac computed tomography showed a well-seated Watchman device with no evidence of PDL or device-related thrombus (Figure 2). In addition, there was no decrease in the left pulmonary vein dimensions when compared with the preablation measurements (Table 2). During the 6-month follow-up, the patient remained in sinus rhythm with no thromboembolic or bleeding events while on antiplatelet monotherapy.
Figure 2.
Computed Tomography Image for Case 1 at 45 Days After the Procedure
Image demonstrating a well-seated 31-mm Watchman FLX Pro device with no peridevice leak or device-related thrombus.
Table 2.
Pre- and Postablation Measurements of LAA Width at Various Angles, LAA Ridge Width and LPV Width
| LAA Width (mm) | Case 1 |
Case 2 |
||
|---|---|---|---|---|
| Preablation | Postablation | Preablation | Postablation | |
| 0 | 20 | 15 | 16 | 19 |
| 45 | 21 | 15 | 17 | 16 |
| 90 | 19 | 16 | 17 | 18 |
| 135 | 22 | 17 | 19 | 17 |
| LAA ridge width (mm) | 3.0 | 4.6 | 3.0 | 4.8 |
| Left upper pulmonary vein width (mm) | 17 | 17 | ||
| Left lower pulmonary vein width (mm) | 17 | 17 | ||
| Left common pulmonary vein width (mm) | 31 | 31 | ||
| Device compression (%) | 25.8 | 16.7 | ||
LAA = left atrial appendage; LPV = left pulmonary vein.
Case 2
A 69-year-old woman with a medical history of paroxysmal AF while on antiarrhythmic drug therapy and significant gastrointestinal bleeding in 2024 presented for ablation and LAAO using the Sphere-9 catheter and Watchman FLX Pro. Despite having a history of prior occipital embolic stroke and a CHA2DS2-VASc score of 5, she was maintained on aspirin before the procedure given her high bleeding risk (HAS-BLED score of 4) (Table 3). A preablation transesophageal echocardiogram showed an orifice width of 1.6 to 1.9 cm and a depth of 1.4 cm (Figure 3).
Figure 3.
Transesophageal Echocardiography Image for Case 2
Image demonstrating left atrial appendage width measurements before ablation indicated by the white arrow.
After catheter ablation, a 24-mm Watchman FLX Pro device, selected to be 26% larger than the measured LAA orifice, was deployed. This size provided an excellent seal and stability. The final device compression percentage in this patient was 16.7%. The procedure was performed under general anesthesia with a duration of 85 minutes, a fluoroscopy dose of 176 mGy, and a fluoroscopy time of 7.1 minutes. Notably, LAA width dimensions did not show a significant decrease after ablation compared with preprocedure measurements across multiple angles (Table 2).
The patient was maintained on anticoagulation therapy and then transitioned to dual antiplatelet therapy. At 45 days after the procedure, a computed tomography scan revealed the device to be well seated with a 2-mm inferior PDL and no evidence of device-related thrombus or pericardial effusion (Figure 4). In addition, there was no decrease in the left pulmonary vein dimensions compared with the preablation measurements (Table 2). At the 6-month follow-up, the patient remained in sinus rhythm, with no recurrence of gastrointestinal bleeding or thromboembolism, despite continued antiplatelet therapy.
Figure 4.
Computed Tomography Image for Case 2 at 45 Days After the Procedure
Image demonstrating a well-seated 24-mm Watchman FLX Pro device with a 2-mm inferior peridevice leak and no device-related thrombus
Discussion
To our knowledge, these patients represent the first 2 reported cases of successful concomitant PFA using the Sphere-9 catheter and the Watchman FLX Pro implant with specific emphasis on dynamic LAA dimensions, compression rate, and tailored upsizing. No clinically significant PDL or major cardiovascular or cerebrovascular adverse events were observed over 6 months.
Technical insight
PFA has been shown to produce less global atrial edema on acute postprocedural cardiac magnetic resonance compared with radiofrequency ablation.9 Separately, Szegedi et al10 demonstrated measurable changes in pulmonary vein and LAA ridge dimensions after PFA.
A recently published multicenter comparative study reported a 69.4% increase in pulmonary ridge thickness after PFA with a large-footprint pentaspline catheter and 20% clinically significant PDL.4 The combined approach had a higher incidence of clinically significant PDL of 3 mm or greater compared with standalone Watchman FLX, possibly due to dynamic pulmonary ridge edema. In contrast, our case report demonstrated a nonsignificant, stable PDL of ≤2 mm at follow-up. Given the smaller focal footprint of the Sphere-9 catheter, focal PFA delivery might interact differently with the pulmonary ridge compared with larger, “one-shot” PFA catheter form factors. However, case 1 demonstrated significant pulmonary ridge edema despite using the focal Sphere-9 form factor.
Thus, our findings highlight that tissue response at the ridge remains highly variable and may depend more on local anatomy and catheter-tissue contact dynamics than on a catheter form factor. Regardless of the PFA-tissue coupling, tailored upsizing of the Watchman profile may ensure durable device compression that accounts for changes in pulmonary ridge edema and could impact the development of PDL.
Clinical implications
Concomitant AF ablation and LAAO require careful attention to postablation anatomy. These cases highlight that dynamic changes in LAA dimensions associated with PFA may influence device sizing despite using a focal form factor. Measurement of LAA dimensions in pre- and postablation imaging and considering Watchman dimensions that optimize compression may help improve outcomes.
Limitations and future directions
Although the tailored upsizing approach has yielded good clinical outcomes in the patient reported in our case report, its long-term efficacy remains unknown. The potential negative clinical impact of oversizing may include device embolization, LAA perforation, and impingement on adjacent structures. Moreover, the influence on pulmonary vein dynamics is still undetermined. Hence, future studies with larger cohorts and special imaging are necessary to investigate the safety and long-term efficacy of this approach.
Conclusions
Concomitant AF ablation and LAAO were successfully performed with Sphere-9 and Watchman FLX Pro; one patient was managed with tailored upsizing and the other with standard device sizing. No thromboembolic or bleeding complications were reported at 6-month follow-up. These cases suggest how PFA delivery with a focal form factor may be associated with dynamic postablation anatomical changes that influence LAAO device sizing and may impact remodeling and PDL after concomitant procedures.
Take-Home Messages
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•
Focal pulsed field ablation used in both cases was associated with dynamic postablation changes in LAA anatomy that influenced device sizing.
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Postablation LAA remodeling in concomitant procedures may necessitate either standard or tailored upsizing to optimize the device seal and to achieve optimal compression rates.
Funding Support and Author Disclosures
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
References
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