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First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure
Cardiovascular Revascularization Medicine xxx (2017) xxx–xxx
Contents lists available at ScienceDirect
Cardiovascular Revascularization Medicine
First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure☆ Julia Seeger a, Ralf Birkemeyer b, Wolfgang Rottbauer a, Jochen Wöhrle a,⁎ a b
Department of Internal Medicine II, Cardiology, University of Ulm, Ulm, Germany Herzklinik Ulm, Ulm, Germany
a r t i c l e
i n f o
Article history: Received 5 November 2016 Received in revised form 17 April 2017 Accepted 26 April 2017 Available online xxxx Keywords: Left atrial appendage Transcatheter closure Watchman FLX Compression
a b s t r a c t Background: We aimed to evaluate efficacy and safety of left atrial appendage (LAA) closure with the new Watchman FLX and analyze procedural features in a consecutive series of high risk non-valvular atrial fibrillation patients. Methods and results: Twelve consecutive non-valvular atrial fibrillation patients (age 76.6 ± 7.8 years) at high risk for stroke (CHA2DS2-VASc-Score 5.5 ± 0.9) and bleeding (HAS-BLED-Score 3.8 ± 0.9), received LAA closure with the Watchman FLX. Bench testing demonstrated easy repositioning as well as optimized sealing and anchoring. Follow-up was done at 30 days, and at 3 and 6 months including transesophageal echocardiography after 3 months. Compression was calculated as occluder size to diameter at shoulder in final position. The device was successfully implanted in all patients. Partial recapture was necessary in 6 (50%) of cases, and full recapture in one (8.3%). There were no procedure-related complications. In 83.3% of cases (N = 10/12) compression was between 10 and 27%, and mean compression was 24.0 ± 11.1%. Mean implantation depth was 4.0 ± 4.4 mm distal of LAA ostium. There was no residual flow. Proximal shift in device position was noticed in 2 patients. One device was embolized at 30 day follow-up, and another device showed thrombus formation. There was no disabling or non-disabling stroke through 6 months of follow-up with dual antiplatelet therapy for 3 months. Conclusion: LAA closure with the new Watchman FLX is associated with a good periprocedural safety, complete sealing of the LAA and simple repositioning. Summary: We evaluated the efficacy and safety of left atrial appendage (LAA) closure with the new Watchman FLX and analyzed procedural features in a consecutive series of high risk non-valvular atrial fibrillation patients. This is a first observational study demonstrating procedural safety, complete sealing of the LAA and simple technique for repositioning. There was no stroke within a 6 month follow-up. © 2017 Elsevier Inc. All rights reserved.
1. Introduction Left atrial appendage (LAA) closure has been established as an alternative to oral anticoagulation in non-valvular atrial fibrillation (AF) patients at high stroke and bleeding risk [1]. The Watchman Left Atrial Appendage System for Embolic Protection in Patients with AF (PROTECT AF) [2] trial demonstrated non-inferiority to warfarin for a combined endpoint in non-valvular atrial fibrillation (AF) patients. In the prospective randomized evaluation of the Watchman Left Atrial Appendage Closure device in patients with atrial fibrillation versus long-term warfarin
Abbreviations: AF, atrial fibrillation; LAA, left atrial appendage; TEE, transesophageal echocardiography. ☆ Conflict of interest: None declared. ⁎ Corresponding author at: Department of Internal Medicine II, University of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany. Tel.: +49 731 500 45001; fax: +49 731 500 45029. E-mail address: [email protected] (J. Wöhrle).
therapy (PREVAIL) trial [3] non-inferiority was confirmed while procedural safety was improved. The Watchman FLX (Boston Scientific Corp., Marlborough; MA, USA) is a second generation LAA closure device optimized regarding exact positioning and effective sealing of the LAA, featuring an option to be fully recaptured, re-maneuvered and redeployed to achieve optimal positioning even in demanding LAA anatomies. We evaluated in a first consecutive series of high risk non-valvular AF patients the safety and efficacy of LAA closure with focus on procedural techniques and patient outcome during 6 months of follow-up with the new Watchman FLX LAA closure device. 2. Methods From November 2015 on, consecutive patients (N = 12) with nonvalvular atrial fibrillation and a high risk for stroke with a CHA2DS2VASc Score ≥ 1 and high bleeding risk (HAS-BLED Score N 3) were treated with Watchman FLX left atrial appendage closure system (Boston
http://dx.doi.org/10.1016/j.carrev.2017.04.018 1553-8389/© 2017 Elsevier Inc. All rights reserved.
Please cite this article as: Seeger J, et al, First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure, Cardiovasc Revasc Med (2017), http://dx.doi.org/10.1016/j.carrev.2017.04.018
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J. Seeger et al. / Cardiovascular Revascularization Medicine xxx (2017) xxx–xxx
Scientific Corp., Marlborough; MA, USA) for LAA closure. Patients had contraindications for long-term oral anticoagulation, had bleeding events during oral anticoagulation or were difficult to treat with warfarin and not eligible for new oral anticoagulants. Written informed consent was obtained from all patients before procedure. All patients underwent diagnostic evaluation with routine laboratory testing, medical history with current medication and calculation of CHA2DS2-VASc and HAS-BLED Scores as well as electrocardiography (ECG). Transthoracic and transesophageal echocardiography was done to evaluate the left atrium and to exclude thrombus in the LAA. TEE was performed with a multiplane, phased-array 4- to 7-MHz transesophageal echocardiography probe with a CX50 (Philips Medical Systems, Best, the Netherlands). Size and morphology of the LAA were assessed by TEE. Patients with intracardial thrombus were not included. Transthoracic control echocardiography was performed immediately post-procedure, on days one and two post procedure. Patients were followed up by assessing their clinical history at scheduled outpatient controls or through telephone contacts after one, three and 6 months. At each contact the same questionnaire (stroke, transient ischemic attack, bleeding, endocarditis, device dislocation, and other complications) was used. Patients were scheduled for control TEE at 3 months after device implantation for exclusion of device or procedure-related adverse events. Position of occluder device in LAA, residual flow (b5 mm or ≥5 mm) and possible thrombus formation on device were evaluated.
guidance transesophageal echocardiography was used. After obtaining femoral venous access, transseptal puncture at the posterior–inferior portion of the fossa ovalis was performed under echocardiographic and fluoroscopic guidance to optimize proper orientation of the delivery system. After transseptal puncture heparin was administered with an activated clotting time of N300 s. A 5 French pigtail marker catheter was inserted in the LAA through the transseptal sheath. Selective angiography was done in the 20° right oblique–20° cranial and 20° right oblique–20° caudal view to evaluate LAA anatomy and dimensions. TEE views were obtained at 0°, 45°, 90° and 135° for multimodality sizing of LAA ostia and landing zone with maximum and minimum diameters. 2.3. Sizing The Watchman FLX device was available in 5 sizes. Oversizing was calculated in dimension to the LAA landing zone with minimum and maximum diameters to allow accurate sizing even in oval anatomies. Compression was calculated as given occluder size at shoulder of occluder to diameter at occluder shoulder in final position. Relation of oversizing to compression level and depth of implantation distal to LAA ostium was calculated. Oversizing with the Watchman FLX is intended to achieve a final range of compression between 10 and 27% according to instructions for use. 2.4. Anticoagulation
2.1. The Watchman FLX LAA closure device The Watchman FLX LAA closure device (Boston Scientific Corp., Marlborough; MA, USA) consists of a self-expandable 18 struts nitinol frame with a polyethylenterephtalate membrane. Twelve “J” shaped fixation barbs arranged in two rows are designed to reduce the risk of dislocation and embolization. The occluder features an atraumatic closed distal end, enabling atraumatic advancement even when partially deployed. With the second generation Watchman FLX device profile is 10–20% shortened compared with its predecessor to be available for shallow appendages also (Fig. 1). The proximal flat surface is designed with a recessed screw to reduce risk of thrombus formation and facilitate endothelialization. The occluder is introduced via a 14 French femoral venous access single or double curve sheath. Available occluder sizes were 20, 24, 27, 31 and 35 mm to treat ostia from 15 mm to 32 mm. The distal point is featured by a fluoroscopic marker to visualize device position. In case of unproper placement, the Watchman FLX can be fully or partially recaptured and remaneuvered to optimize position and compression in the LAA. 2.2. Procedure Procedures were performed in the catheterization laboratory under conscious sedation as described elsewhere [4,5]. For intraprocedural
Oral anticoagulation, if present, was discontinued ≥48 h prior to procedure. Dual antiplatelet therapy with aspirin 100 mg and clopidogrel 75 mg was recommended for 3 months after device implantation, followed by long-term antiplatelet therapy with aspirin 100 mg daily [4]. No oral anticoagulation was recommended after device implantation. 2.5. Statistical analysis Categorical parameters are presented as counts and percentages. Continuous variables are presented as mean ± standard deviation (SD). Statistical analysis was performed using Statistica release 7.1 (StatSoft, Tulsa, Oklahoma). 3. Results 3.1. Patient selection A series of 12 consecutive patients were enrolled (Table 1). Mean age was 76.6 ± 7.8 years (range 61–86 years). All patients had nonvalvular AF (33% paroxysmal, 8.3% persistent, 58.3% permanent). CHA2DS2-VASc Score was 5.2 ± 0.9 (range 4–7) and HAS-BLED Score 3.8 ± 0.9. Coronary artery disease was present in 33.3% of patients and reduced renal function in 58.3%. Half of patients had a history of
Fig. 1. With the second generation Watchman FLX device profile is 10–20% shortened compared with its predecessor to be available for shallow appendages also.
Please cite this article as: Seeger J, et al, First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure, Cardiovasc Revasc Med (2017), http://dx.doi.org/10.1016/j.carrev.2017.04.018
J. Seeger et al. / Cardiovascular Revascularization Medicine xxx (2017) xxx–xxx Table 1 Patient baseline characteristics. Patients, n Mean age, years Atrial fibrillation, n (%) CHA2DS2-VASc-Score HAS-BLED-Score Diabetes mellitus, n (%) History of TIA/ischemic stroke, n (%) Female gender, n (%) Renal insufficiency, n (%) Coronary artery disease, n (%) Arterial hypertension, n (%) History of smoking, n (%) Body mass index, kg/m2
12 76.6 ± 7.8 12 (100%) 5.2 ± 0.9 3.8 ± 0.9 5 (41.7%) 6 (50%) 6 (50%) 7 (58.3%) 4 (33.3%) 9 (75%) 1 (8.3%) 26.6 ± 3.8
Numbers are mean ± standard deviation; TIA = transient ischemic attack.
stroke or transient ischemic attack prior to the procedure. Clinical indication for LAA closure and contraindication for long-term oral anticoagulation were gastrointestinal bleeding (91.6%), epistaxis with syncopes and need for transfusion (8.3%). 3.2. Procedure Implantation success was 100%. Average size of the LAA closure device was 24.9 ± 3.9 mm (range 20–31 mm) (Table 2). There were no procedure related serious complications. In 83.3% of cases (N = 10/ 12) compression of occluder was between 10 and 27% (Fig. 2) with a mean compression of 24.0 ± 11.1%. Mean oversizing was 36.3 ± 12.9%. Partial recapture to achieve an optimal device position with the shoulder at the LAA landing zone was performed in 50% of patients in the present series. Reasons for recapture were positioning of the device too far distal of the ostium in two cases and too far proximal of the intended landing zone with insufficient compression and positive tug test in four cases. Change to a different device size was necessary in one patient (8.3%). Mean implantation depth was 4 ± 4.4 mm (range − 11 to 1 mm) distal of LAA ostium (Table 3). Transesophageal echocardiography was done 3 months after LAA closure. Neither post-procedural nor in follow-up echocardiographic controls there was residual flow ≥5 mm. Proximal shift in device position was noticed in 2 patients. One shift appeared directly after device release, and the other one was noticed at 30 day follow-up. In the first patient a 27 mm occluder was implanted with 36.7% oversizing. Final compression was 17.4%. In the second patient a 20 mm occluder was used with 30.7% oversizing, leading to a final compression of 17.6%. Shift in position did not lead to residual flow. In one patient a 27 mm occluder was embolized to the aortic arch documented at 30 day follow-up and needed to be percutaneously salvaged. Initial implantation depth was 11 mm distal of LAA ostium with an oversizing of 42.1%, resulting in a final compression of 52.5%. One patient presented with thrombus formation on the device adherent to the screw
Table 2 Procedural data. Minimal LAA diameter angio, mm Maximum LAA diameter angio, mm Minimal LAA diameter TEE, mm Maximum LAA diameter TEE, mm Oversizing/Mean LAA diameter angio, (%) Oversizing/Mean LAA diameter TEE, (%) Compression, (%) Occluder size, mm 20 mm, n 24 mm, n 27 mm, n 31 mm, n Pericardial effusion, n Numbers are mean ± standard deviation.
18.1 ± 3.9 19.9 ± 4.3 16.8 ± 4.6 21.0 ± 4.8 34.6 ± 10.7 36.4 ± 12.9 24.0 ± 11.1 24.9 ± 3.9 3 (25%) 4 (33.3%) 3 (25%) 2 (16.7%) 0 (0%)
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3 months after implantation at routine scheduled TEE while on dual antiplatelet therapy. The patient had a CHA2DS2-VASc score of 6 and HASBLED score of 3 and was treated with a 24 mm device. Oral anticoagulation was started for a period of 4 weeks and discontinued after proof of resolution in TEE control. 3.3. Clinical follow-up There was no disabling or non-disabling stroke through 6 months of follow-up (Table 4). The expected annual stroke rate according to CHA2DS2-VASc Score would have been 5.0 to 6.7% [6]. While on recommended antiplatelet therapy non-fatal gastrointestinal bleeding occurred in 2/12 patients (16.7%) within 30 days of follow-up, and none in the period from 30 days to 6 months. The expected annual bleeding rate according to HAS-BLED-score ranged between 8.7 and 12.5% [7]. One patient died 4 months post-procedure for new diagnosed hepatic cancer. 4. Discussion We are demonstrating in a first consecutive series of 12 high risk non-valvular AF patients the efficacy and safety of the new generation Watchman FLX left atrial appendage occluder device and its procedural features. The randomized PROTECT AF trial [2] and the randomized multicentre PREVAIL trial [3] showed non-inferiority of left atrial appendage closure with the last generation Watchman device to oral anticoagulation with warfarin for a combined endpoint in nonvalvular AF patients. However there were several limitations of the first generation device such as difficult positioning in shallow appendages and a limited number of available occluder sizes. The Watchman FLX is a second-generation repositionable and retrievable LAA occluder device designed to optimize positioning even in shallow and anatomically complex appendages where its predecessor the Watchman encountered limitations. In the presented first series of patients treated with the new Watchman FLX there were no serious procedure related events and no peri- or postprocedural pericardial effusion, compared to 5% in PROTECT-AF [2] in 463 patients and 2% in the Continued Access registry (CAP) in 437 patients [8]. There was no ischemic stroke within 6 months of follow-up after LAA closure compared to 1.1% in PROTECT-AF [2], 1.9% in the PREVAIL trial [3] in 269 patients and 1.7% in the ASA Plavix Feasibility Study With Watchman Left Atrial Appendage Closure Technology (ASAP trial) [9] including 142 patients. CHA2DS2-VASc Score was high in our population (5.2 ± 0.9) compared to 2.2 ± 1.2 in PROTECT AF, corresponding to an expected annual stroke rate of 5.0 to 6.7% [6,10–12]. Fifty percent of patients had a history of stroke or TIA prior to LAA closure. There were 2 (16.7%) non-fatal bleedings on recommended antiplatelet therapy within the first 30 days of follow-up in 2 patients with a HAS-BLED score of N3, corresponding to a high bleeding risk. No hemorrhagic stroke was seen within the follow-up of 6 months. With the last generation Watchman device implantation was recommended with a final compression of around 30%. The Watchman FLX features two rows of anchors which, combined with a higher radial strength, should allow safe anchoring in the LAA even with less compression to enable positioning proximal to the interlobular LAA ridge. Recommended compression ranges from 10 to 27%. Dependent on degree of compression the device changes in shape from a “ball-like” shape to its known “hut-shape” (Fig. 1). In 10 out of 12 patients in this first series, final compression was in the intended range between 10 and 27%, with a mean of 24.0 ± 11.1%. However, there were 2 cases wwere a shift in position was noted, one immediately after release and the other one at follow-up, with no residual flow in both cases. Compression in both cases was 17.4% and 17.6%. Recommended position ranges from 5 mm distal of LAA ostium to 3.5 mm proximal. One of the shifted cases was implanted 7 mm proximal of LAA ostium, and
Please cite this article as: Seeger J, et al, First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure, Cardiovasc Revasc Med (2017), http://dx.doi.org/10.1016/j.carrev.2017.04.018
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J. Seeger et al. / Cardiovascular Revascularization Medicine xxx (2017) xxx–xxx
Fig. 2. Deployment map, showing compression relative to oversizing of the LAA occluder for the 12 implanted cases and shape of occluder dependent on level of compression. Recommended compression (10–27%) is marked in green.
the other one 1 mm proximal. Both devices remained in their final shifted position, as documented in follow-up imaging. There was one device embolization (8.3%), compared to 3 in PROTECT AF (0.6%) and none in the CAP registry. The embolized 27 mm device was implanted with an oversizing of 42.1% leading to a final compression of 52.5%. Final position was 11 mm proximal of LAA ostium, showing stability in performed tugtest. An attempt to explain embolization might be to look at shape of occluder relative to compression as shown in Fig. 2. Other than its predecessor, the Watchman FLX has 12 “J” shaped anchors in 2 rows, compared to 10 in one row with the last generation device. With a final compression of around 50% the occluder still is in a “ball-like” shape, where the distal row of anchors might not be able to hold onto the LAA. On the one hand because of the lack of contact and on the other hand because the “J” shape does not enable grasping when the occluder is still “ballshaped”. Hence, extensive compression might lead to improper stability within the LAA and a smaller occluder size as well as an implantation less proximal of the LAA ostium should be attempted, using the new
feature of repositionabilty and retrievability. With an increased number of struts design was also optimized for complete sealing of the LAA. Immediately post-procedure as well as at 30 day follow-up successful sealing was proven without residual flow ≥5 mm in all cases. The new generation Watchman FLX was designed with a flat proximal screw hub, to reduce thrombus formation on the device. In this first series there was one case (N = 1/12; 8.3%) of device-associated thrombus compared to 4.2% in PROTECT AF (N = 20/478). There was however no associated stroke in this patient and the thrombotic material was completely resolved by 4 weeks of oral anticoagulation. 5. Limitation This is a first observational registry including a limited number of patients. Larger randomized multicentre trials would be needed to underline safety and efficacy and to better understand implantation features of this new device, which is presently re-designed.
Table 3 Procedural characteristics and outcome. Pat no.
Mean LAA diameter angio, mm
Mean LAA diameter TEE, mm
Oversizing, (%)
Compression (%)
Occluder size, mm
Implantation depth, mm
Partial recapture, no.
2nd device
Shift
Residual flow ≥5 mm
Late Embolization
Bleeding
1 2 3 4 5 6 7 8 9 10 11 12
19.7 16.7 19.2 14.2 26.4 20.2 15.7 19.3 25.5 14.1 17.8 16.0
19.5 17.0 19.75 15.3 22.5 15.25 19.25 19 21.5 15.5 18.5 16.5
38.5 41.2 36.7 30.7 37.8 57.4 4,9 42.1 44.2 29.0 29.7 45.5
39.9 18.5 17.4 17.6 23.0 12.9 19.8 52.5 22.7 19.4 21.5 23.1
27 24 27 20 31 24 20 27 31 20 24 24
−10 −8 −7 −1 0 1 −5 −11 0 −1 0 −6,5
5 0 2 1 0 2 0 1 0 0 0 1
Yes No No No No No No No No No No No
No No Yes Yes No No No No No No No No
No No No No No No No No No No No No
No No No No No No No Yes No No No No
Yes No No No No No Yes No No No No No
Please cite this article as: Seeger J, et al, First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure, Cardiovasc Revasc Med (2017), http://dx.doi.org/10.1016/j.carrev.2017.04.018
J. Seeger et al. / Cardiovascular Revascularization Medicine xxx (2017) xxx–xxx Table 4 Clinical follow-up.
Follow-up rate Occluder in situ, n (%) MACE, n (%) Mortality, n (%) Disabling/non-disabling stroke, n (%) Bleeding, n (%) Residual flow ≥5 mm, n (%)
30 days
3 months
6 months
100% 11 (91.6%) 3 (25%) 0 (0%) 0 (0%) 2 (16.7%) –
100% 11 (91.6%) 3 (25%) 0 (0%) 0 (0%) 2 (16.7%) 0 (0%)
100% 11 (91.6%) 4 (33.3%) 1 (8.3%) 0 (0%) 2 (16.7%) –
MACE = major adverse cardiac events.
6. Conclusion Left atrial appendage closure with the new Watchman FLX device in patients with non-valvular atrial fibrillation and high risk for stroke and bleeding events was associated with a good periprocedural safety, complete sealing of the LAA and simple technique for repositioning. There was no stroke within a 6 month follow-up. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. References [1] Blackshear JL, Odell JA. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thorac Surg 1996;61(2):755–9.
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[2] Reddy VY, Sievert H, Halperin J, Doshi SK, Buchbinder M, Neuzil P, et al. Percutaneous left atrial appendage closure vs warfarin for atrial fibrillation: a randomized clinical trial. JAMA 2014;312(19):1988–98. [3] Holmes Jr DR, Kar S, Price MJ, Whisenant B, Sievert H, Doshi SK, et al. Prospective randomized evaluation of the Watchman Left Atrial Appendage Closure device in patients with atrial fibrillation versus long-term warfarin therapy: the PREVAIL trial. J Am Coll Cardiol 2014;64(1):1–12. [4] Seeger J, Bothner C, Dahme T, Gonska B, Scharnbeck D, Markovic S, et al. Efficacy and safety of percutaneous left atrial appendage closure to prevent thromboembolic events in atrial fibrillation patients with high stroke and bleeding risk. Clin Res Cardiol 2016;105(3):225–9. [5] Saw J, Lempereur M. Percutaneous left atrial appendage closure: procedural techniques and outcomes. JACC Cardiovasc Interv 2014;7(11):1205–20. [6] Gage BF, van Walraven C, Pearce L, Hart RG, Koudstaal PJ, Boode BS, et al. Selecting patients with atrial fibrillation for anticoagulation: stroke risk stratification in patients taking aspirin. Circulation 2004;110:2287–92. [7] Roldán V, Marín F, Manzano-Fernández S, Gallego P, Vílchez JA, Valdés M, et al. The HAS-BLED score has better prediction accuracy for major bleeding than CHADS2 or CHA2DS2-VASc scores in anticoagulated patients with atrial fibrillation. J Am Coll Cardiol 2013;62(23):2199–204. [8] Reddy VY, Holmes D, Doshi SK, Neuzil P, Kar S. Safety of percutaneous left atrial appendage closure: results from the Watchman Left Atrial Appendage System for Embolic Protection in Patients with AF (PROTECT AF) clinical trial and the Continued Access Registry. Circulation 2011;23(4):417–24. [9] Reddy VY, Möbius-Winkler S, Miller MA, Neuzil P, Schuler G, Wiebe J, et al. Left atrial appendage closure with the Watchman device in patients with a contraindication for oral anticoagulation: the ASAP study (ASA Plavix Feasibility Study With Watchman Left Atrial Appendage Closure Technology). J Am Coll Cardiol 2013;61(25):2551–6. [10] Tzikas A, Shakir S, Gafoor S, Omran H, Berti S, Santoro G, et al. Left atrial appendage occlusion for stroke prevention in atrial fibrillation: multicentre experience with the AMPLATZER Cardiac Plug. EuroIntervention 2015;11(10):1170–9. [11] Lip GY, Nieuwlaat R, Pisters R, Lane DA, Crijns HJ. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the Euro Heart Survey on Atrial Fibrillation. Chest 2010; 137:263–72. [12] Poli D, Lip GY, Antonucci E, Grifoni E, Lane D. Stroke risk stratification in a “realworld” elderly anticoagulated atrial fibrillation population. J Cardiovasc Electrophysiol 2010;22:25–30.
Please cite this article as: Seeger J, et al, First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure, Cardiovasc Revasc Med (2017), http://dx.doi.org/10.1016/j.carrev.2017.04.018
Contents lists available at ScienceDirect
Cardiovascular Revascularization Medicine
First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure☆ Julia Seeger a, Ralf Birkemeyer b, Wolfgang Rottbauer a, Jochen Wöhrle a,⁎ a b
Department of Internal Medicine II, Cardiology, University of Ulm, Ulm, Germany Herzklinik Ulm, Ulm, Germany
a r t i c l e
i n f o
Article history: Received 5 November 2016 Received in revised form 17 April 2017 Accepted 26 April 2017 Available online xxxx Keywords: Left atrial appendage Transcatheter closure Watchman FLX Compression
a b s t r a c t Background: We aimed to evaluate efficacy and safety of left atrial appendage (LAA) closure with the new Watchman FLX and analyze procedural features in a consecutive series of high risk non-valvular atrial fibrillation patients. Methods and results: Twelve consecutive non-valvular atrial fibrillation patients (age 76.6 ± 7.8 years) at high risk for stroke (CHA2DS2-VASc-Score 5.5 ± 0.9) and bleeding (HAS-BLED-Score 3.8 ± 0.9), received LAA closure with the Watchman FLX. Bench testing demonstrated easy repositioning as well as optimized sealing and anchoring. Follow-up was done at 30 days, and at 3 and 6 months including transesophageal echocardiography after 3 months. Compression was calculated as occluder size to diameter at shoulder in final position. The device was successfully implanted in all patients. Partial recapture was necessary in 6 (50%) of cases, and full recapture in one (8.3%). There were no procedure-related complications. In 83.3% of cases (N = 10/12) compression was between 10 and 27%, and mean compression was 24.0 ± 11.1%. Mean implantation depth was 4.0 ± 4.4 mm distal of LAA ostium. There was no residual flow. Proximal shift in device position was noticed in 2 patients. One device was embolized at 30 day follow-up, and another device showed thrombus formation. There was no disabling or non-disabling stroke through 6 months of follow-up with dual antiplatelet therapy for 3 months. Conclusion: LAA closure with the new Watchman FLX is associated with a good periprocedural safety, complete sealing of the LAA and simple repositioning. Summary: We evaluated the efficacy and safety of left atrial appendage (LAA) closure with the new Watchman FLX and analyzed procedural features in a consecutive series of high risk non-valvular atrial fibrillation patients. This is a first observational study demonstrating procedural safety, complete sealing of the LAA and simple technique for repositioning. There was no stroke within a 6 month follow-up. © 2017 Elsevier Inc. All rights reserved.
1. Introduction Left atrial appendage (LAA) closure has been established as an alternative to oral anticoagulation in non-valvular atrial fibrillation (AF) patients at high stroke and bleeding risk [1]. The Watchman Left Atrial Appendage System for Embolic Protection in Patients with AF (PROTECT AF) [2] trial demonstrated non-inferiority to warfarin for a combined endpoint in non-valvular atrial fibrillation (AF) patients. In the prospective randomized evaluation of the Watchman Left Atrial Appendage Closure device in patients with atrial fibrillation versus long-term warfarin
Abbreviations: AF, atrial fibrillation; LAA, left atrial appendage; TEE, transesophageal echocardiography. ☆ Conflict of interest: None declared. ⁎ Corresponding author at: Department of Internal Medicine II, University of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany. Tel.: +49 731 500 45001; fax: +49 731 500 45029. E-mail address: [email protected] (J. Wöhrle).
therapy (PREVAIL) trial [3] non-inferiority was confirmed while procedural safety was improved. The Watchman FLX (Boston Scientific Corp., Marlborough; MA, USA) is a second generation LAA closure device optimized regarding exact positioning and effective sealing of the LAA, featuring an option to be fully recaptured, re-maneuvered and redeployed to achieve optimal positioning even in demanding LAA anatomies. We evaluated in a first consecutive series of high risk non-valvular AF patients the safety and efficacy of LAA closure with focus on procedural techniques and patient outcome during 6 months of follow-up with the new Watchman FLX LAA closure device. 2. Methods From November 2015 on, consecutive patients (N = 12) with nonvalvular atrial fibrillation and a high risk for stroke with a CHA2DS2VASc Score ≥ 1 and high bleeding risk (HAS-BLED Score N 3) were treated with Watchman FLX left atrial appendage closure system (Boston
http://dx.doi.org/10.1016/j.carrev.2017.04.018 1553-8389/© 2017 Elsevier Inc. All rights reserved.
Please cite this article as: Seeger J, et al, First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure, Cardiovasc Revasc Med (2017), http://dx.doi.org/10.1016/j.carrev.2017.04.018
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J. Seeger et al. / Cardiovascular Revascularization Medicine xxx (2017) xxx–xxx
Scientific Corp., Marlborough; MA, USA) for LAA closure. Patients had contraindications for long-term oral anticoagulation, had bleeding events during oral anticoagulation or were difficult to treat with warfarin and not eligible for new oral anticoagulants. Written informed consent was obtained from all patients before procedure. All patients underwent diagnostic evaluation with routine laboratory testing, medical history with current medication and calculation of CHA2DS2-VASc and HAS-BLED Scores as well as electrocardiography (ECG). Transthoracic and transesophageal echocardiography was done to evaluate the left atrium and to exclude thrombus in the LAA. TEE was performed with a multiplane, phased-array 4- to 7-MHz transesophageal echocardiography probe with a CX50 (Philips Medical Systems, Best, the Netherlands). Size and morphology of the LAA were assessed by TEE. Patients with intracardial thrombus were not included. Transthoracic control echocardiography was performed immediately post-procedure, on days one and two post procedure. Patients were followed up by assessing their clinical history at scheduled outpatient controls or through telephone contacts after one, three and 6 months. At each contact the same questionnaire (stroke, transient ischemic attack, bleeding, endocarditis, device dislocation, and other complications) was used. Patients were scheduled for control TEE at 3 months after device implantation for exclusion of device or procedure-related adverse events. Position of occluder device in LAA, residual flow (b5 mm or ≥5 mm) and possible thrombus formation on device were evaluated.
guidance transesophageal echocardiography was used. After obtaining femoral venous access, transseptal puncture at the posterior–inferior portion of the fossa ovalis was performed under echocardiographic and fluoroscopic guidance to optimize proper orientation of the delivery system. After transseptal puncture heparin was administered with an activated clotting time of N300 s. A 5 French pigtail marker catheter was inserted in the LAA through the transseptal sheath. Selective angiography was done in the 20° right oblique–20° cranial and 20° right oblique–20° caudal view to evaluate LAA anatomy and dimensions. TEE views were obtained at 0°, 45°, 90° and 135° for multimodality sizing of LAA ostia and landing zone with maximum and minimum diameters. 2.3. Sizing The Watchman FLX device was available in 5 sizes. Oversizing was calculated in dimension to the LAA landing zone with minimum and maximum diameters to allow accurate sizing even in oval anatomies. Compression was calculated as given occluder size at shoulder of occluder to diameter at occluder shoulder in final position. Relation of oversizing to compression level and depth of implantation distal to LAA ostium was calculated. Oversizing with the Watchman FLX is intended to achieve a final range of compression between 10 and 27% according to instructions for use. 2.4. Anticoagulation
2.1. The Watchman FLX LAA closure device The Watchman FLX LAA closure device (Boston Scientific Corp., Marlborough; MA, USA) consists of a self-expandable 18 struts nitinol frame with a polyethylenterephtalate membrane. Twelve “J” shaped fixation barbs arranged in two rows are designed to reduce the risk of dislocation and embolization. The occluder features an atraumatic closed distal end, enabling atraumatic advancement even when partially deployed. With the second generation Watchman FLX device profile is 10–20% shortened compared with its predecessor to be available for shallow appendages also (Fig. 1). The proximal flat surface is designed with a recessed screw to reduce risk of thrombus formation and facilitate endothelialization. The occluder is introduced via a 14 French femoral venous access single or double curve sheath. Available occluder sizes were 20, 24, 27, 31 and 35 mm to treat ostia from 15 mm to 32 mm. The distal point is featured by a fluoroscopic marker to visualize device position. In case of unproper placement, the Watchman FLX can be fully or partially recaptured and remaneuvered to optimize position and compression in the LAA. 2.2. Procedure Procedures were performed in the catheterization laboratory under conscious sedation as described elsewhere [4,5]. For intraprocedural
Oral anticoagulation, if present, was discontinued ≥48 h prior to procedure. Dual antiplatelet therapy with aspirin 100 mg and clopidogrel 75 mg was recommended for 3 months after device implantation, followed by long-term antiplatelet therapy with aspirin 100 mg daily [4]. No oral anticoagulation was recommended after device implantation. 2.5. Statistical analysis Categorical parameters are presented as counts and percentages. Continuous variables are presented as mean ± standard deviation (SD). Statistical analysis was performed using Statistica release 7.1 (StatSoft, Tulsa, Oklahoma). 3. Results 3.1. Patient selection A series of 12 consecutive patients were enrolled (Table 1). Mean age was 76.6 ± 7.8 years (range 61–86 years). All patients had nonvalvular AF (33% paroxysmal, 8.3% persistent, 58.3% permanent). CHA2DS2-VASc Score was 5.2 ± 0.9 (range 4–7) and HAS-BLED Score 3.8 ± 0.9. Coronary artery disease was present in 33.3% of patients and reduced renal function in 58.3%. Half of patients had a history of
Fig. 1. With the second generation Watchman FLX device profile is 10–20% shortened compared with its predecessor to be available for shallow appendages also.
Please cite this article as: Seeger J, et al, First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure, Cardiovasc Revasc Med (2017), http://dx.doi.org/10.1016/j.carrev.2017.04.018
J. Seeger et al. / Cardiovascular Revascularization Medicine xxx (2017) xxx–xxx Table 1 Patient baseline characteristics. Patients, n Mean age, years Atrial fibrillation, n (%) CHA2DS2-VASc-Score HAS-BLED-Score Diabetes mellitus, n (%) History of TIA/ischemic stroke, n (%) Female gender, n (%) Renal insufficiency, n (%) Coronary artery disease, n (%) Arterial hypertension, n (%) History of smoking, n (%) Body mass index, kg/m2
12 76.6 ± 7.8 12 (100%) 5.2 ± 0.9 3.8 ± 0.9 5 (41.7%) 6 (50%) 6 (50%) 7 (58.3%) 4 (33.3%) 9 (75%) 1 (8.3%) 26.6 ± 3.8
Numbers are mean ± standard deviation; TIA = transient ischemic attack.
stroke or transient ischemic attack prior to the procedure. Clinical indication for LAA closure and contraindication for long-term oral anticoagulation were gastrointestinal bleeding (91.6%), epistaxis with syncopes and need for transfusion (8.3%). 3.2. Procedure Implantation success was 100%. Average size of the LAA closure device was 24.9 ± 3.9 mm (range 20–31 mm) (Table 2). There were no procedure related serious complications. In 83.3% of cases (N = 10/ 12) compression of occluder was between 10 and 27% (Fig. 2) with a mean compression of 24.0 ± 11.1%. Mean oversizing was 36.3 ± 12.9%. Partial recapture to achieve an optimal device position with the shoulder at the LAA landing zone was performed in 50% of patients in the present series. Reasons for recapture were positioning of the device too far distal of the ostium in two cases and too far proximal of the intended landing zone with insufficient compression and positive tug test in four cases. Change to a different device size was necessary in one patient (8.3%). Mean implantation depth was 4 ± 4.4 mm (range − 11 to 1 mm) distal of LAA ostium (Table 3). Transesophageal echocardiography was done 3 months after LAA closure. Neither post-procedural nor in follow-up echocardiographic controls there was residual flow ≥5 mm. Proximal shift in device position was noticed in 2 patients. One shift appeared directly after device release, and the other one was noticed at 30 day follow-up. In the first patient a 27 mm occluder was implanted with 36.7% oversizing. Final compression was 17.4%. In the second patient a 20 mm occluder was used with 30.7% oversizing, leading to a final compression of 17.6%. Shift in position did not lead to residual flow. In one patient a 27 mm occluder was embolized to the aortic arch documented at 30 day follow-up and needed to be percutaneously salvaged. Initial implantation depth was 11 mm distal of LAA ostium with an oversizing of 42.1%, resulting in a final compression of 52.5%. One patient presented with thrombus formation on the device adherent to the screw
Table 2 Procedural data. Minimal LAA diameter angio, mm Maximum LAA diameter angio, mm Minimal LAA diameter TEE, mm Maximum LAA diameter TEE, mm Oversizing/Mean LAA diameter angio, (%) Oversizing/Mean LAA diameter TEE, (%) Compression, (%) Occluder size, mm 20 mm, n 24 mm, n 27 mm, n 31 mm, n Pericardial effusion, n Numbers are mean ± standard deviation.
18.1 ± 3.9 19.9 ± 4.3 16.8 ± 4.6 21.0 ± 4.8 34.6 ± 10.7 36.4 ± 12.9 24.0 ± 11.1 24.9 ± 3.9 3 (25%) 4 (33.3%) 3 (25%) 2 (16.7%) 0 (0%)
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3 months after implantation at routine scheduled TEE while on dual antiplatelet therapy. The patient had a CHA2DS2-VASc score of 6 and HASBLED score of 3 and was treated with a 24 mm device. Oral anticoagulation was started for a period of 4 weeks and discontinued after proof of resolution in TEE control. 3.3. Clinical follow-up There was no disabling or non-disabling stroke through 6 months of follow-up (Table 4). The expected annual stroke rate according to CHA2DS2-VASc Score would have been 5.0 to 6.7% [6]. While on recommended antiplatelet therapy non-fatal gastrointestinal bleeding occurred in 2/12 patients (16.7%) within 30 days of follow-up, and none in the period from 30 days to 6 months. The expected annual bleeding rate according to HAS-BLED-score ranged between 8.7 and 12.5% [7]. One patient died 4 months post-procedure for new diagnosed hepatic cancer. 4. Discussion We are demonstrating in a first consecutive series of 12 high risk non-valvular AF patients the efficacy and safety of the new generation Watchman FLX left atrial appendage occluder device and its procedural features. The randomized PROTECT AF trial [2] and the randomized multicentre PREVAIL trial [3] showed non-inferiority of left atrial appendage closure with the last generation Watchman device to oral anticoagulation with warfarin for a combined endpoint in nonvalvular AF patients. However there were several limitations of the first generation device such as difficult positioning in shallow appendages and a limited number of available occluder sizes. The Watchman FLX is a second-generation repositionable and retrievable LAA occluder device designed to optimize positioning even in shallow and anatomically complex appendages where its predecessor the Watchman encountered limitations. In the presented first series of patients treated with the new Watchman FLX there were no serious procedure related events and no peri- or postprocedural pericardial effusion, compared to 5% in PROTECT-AF [2] in 463 patients and 2% in the Continued Access registry (CAP) in 437 patients [8]. There was no ischemic stroke within 6 months of follow-up after LAA closure compared to 1.1% in PROTECT-AF [2], 1.9% in the PREVAIL trial [3] in 269 patients and 1.7% in the ASA Plavix Feasibility Study With Watchman Left Atrial Appendage Closure Technology (ASAP trial) [9] including 142 patients. CHA2DS2-VASc Score was high in our population (5.2 ± 0.9) compared to 2.2 ± 1.2 in PROTECT AF, corresponding to an expected annual stroke rate of 5.0 to 6.7% [6,10–12]. Fifty percent of patients had a history of stroke or TIA prior to LAA closure. There were 2 (16.7%) non-fatal bleedings on recommended antiplatelet therapy within the first 30 days of follow-up in 2 patients with a HAS-BLED score of N3, corresponding to a high bleeding risk. No hemorrhagic stroke was seen within the follow-up of 6 months. With the last generation Watchman device implantation was recommended with a final compression of around 30%. The Watchman FLX features two rows of anchors which, combined with a higher radial strength, should allow safe anchoring in the LAA even with less compression to enable positioning proximal to the interlobular LAA ridge. Recommended compression ranges from 10 to 27%. Dependent on degree of compression the device changes in shape from a “ball-like” shape to its known “hut-shape” (Fig. 1). In 10 out of 12 patients in this first series, final compression was in the intended range between 10 and 27%, with a mean of 24.0 ± 11.1%. However, there were 2 cases wwere a shift in position was noted, one immediately after release and the other one at follow-up, with no residual flow in both cases. Compression in both cases was 17.4% and 17.6%. Recommended position ranges from 5 mm distal of LAA ostium to 3.5 mm proximal. One of the shifted cases was implanted 7 mm proximal of LAA ostium, and
Please cite this article as: Seeger J, et al, First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure, Cardiovasc Revasc Med (2017), http://dx.doi.org/10.1016/j.carrev.2017.04.018
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J. Seeger et al. / Cardiovascular Revascularization Medicine xxx (2017) xxx–xxx
Fig. 2. Deployment map, showing compression relative to oversizing of the LAA occluder for the 12 implanted cases and shape of occluder dependent on level of compression. Recommended compression (10–27%) is marked in green.
the other one 1 mm proximal. Both devices remained in their final shifted position, as documented in follow-up imaging. There was one device embolization (8.3%), compared to 3 in PROTECT AF (0.6%) and none in the CAP registry. The embolized 27 mm device was implanted with an oversizing of 42.1% leading to a final compression of 52.5%. Final position was 11 mm proximal of LAA ostium, showing stability in performed tugtest. An attempt to explain embolization might be to look at shape of occluder relative to compression as shown in Fig. 2. Other than its predecessor, the Watchman FLX has 12 “J” shaped anchors in 2 rows, compared to 10 in one row with the last generation device. With a final compression of around 50% the occluder still is in a “ball-like” shape, where the distal row of anchors might not be able to hold onto the LAA. On the one hand because of the lack of contact and on the other hand because the “J” shape does not enable grasping when the occluder is still “ballshaped”. Hence, extensive compression might lead to improper stability within the LAA and a smaller occluder size as well as an implantation less proximal of the LAA ostium should be attempted, using the new
feature of repositionabilty and retrievability. With an increased number of struts design was also optimized for complete sealing of the LAA. Immediately post-procedure as well as at 30 day follow-up successful sealing was proven without residual flow ≥5 mm in all cases. The new generation Watchman FLX was designed with a flat proximal screw hub, to reduce thrombus formation on the device. In this first series there was one case (N = 1/12; 8.3%) of device-associated thrombus compared to 4.2% in PROTECT AF (N = 20/478). There was however no associated stroke in this patient and the thrombotic material was completely resolved by 4 weeks of oral anticoagulation. 5. Limitation This is a first observational registry including a limited number of patients. Larger randomized multicentre trials would be needed to underline safety and efficacy and to better understand implantation features of this new device, which is presently re-designed.
Table 3 Procedural characteristics and outcome. Pat no.
Mean LAA diameter angio, mm
Mean LAA diameter TEE, mm
Oversizing, (%)
Compression (%)
Occluder size, mm
Implantation depth, mm
Partial recapture, no.
2nd device
Shift
Residual flow ≥5 mm
Late Embolization
Bleeding
1 2 3 4 5 6 7 8 9 10 11 12
19.7 16.7 19.2 14.2 26.4 20.2 15.7 19.3 25.5 14.1 17.8 16.0
19.5 17.0 19.75 15.3 22.5 15.25 19.25 19 21.5 15.5 18.5 16.5
38.5 41.2 36.7 30.7 37.8 57.4 4,9 42.1 44.2 29.0 29.7 45.5
39.9 18.5 17.4 17.6 23.0 12.9 19.8 52.5 22.7 19.4 21.5 23.1
27 24 27 20 31 24 20 27 31 20 24 24
−10 −8 −7 −1 0 1 −5 −11 0 −1 0 −6,5
5 0 2 1 0 2 0 1 0 0 0 1
Yes No No No No No No No No No No No
No No Yes Yes No No No No No No No No
No No No No No No No No No No No No
No No No No No No No Yes No No No No
Yes No No No No No Yes No No No No No
Please cite this article as: Seeger J, et al, First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure, Cardiovasc Revasc Med (2017), http://dx.doi.org/10.1016/j.carrev.2017.04.018
J. Seeger et al. / Cardiovascular Revascularization Medicine xxx (2017) xxx–xxx Table 4 Clinical follow-up.
Follow-up rate Occluder in situ, n (%) MACE, n (%) Mortality, n (%) Disabling/non-disabling stroke, n (%) Bleeding, n (%) Residual flow ≥5 mm, n (%)
30 days
3 months
6 months
100% 11 (91.6%) 3 (25%) 0 (0%) 0 (0%) 2 (16.7%) –
100% 11 (91.6%) 3 (25%) 0 (0%) 0 (0%) 2 (16.7%) 0 (0%)
100% 11 (91.6%) 4 (33.3%) 1 (8.3%) 0 (0%) 2 (16.7%) –
MACE = major adverse cardiac events.
6. Conclusion Left atrial appendage closure with the new Watchman FLX device in patients with non-valvular atrial fibrillation and high risk for stroke and bleeding events was associated with a good periprocedural safety, complete sealing of the LAA and simple technique for repositioning. There was no stroke within a 6 month follow-up. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. References [1] Blackshear JL, Odell JA. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thorac Surg 1996;61(2):755–9.
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[2] Reddy VY, Sievert H, Halperin J, Doshi SK, Buchbinder M, Neuzil P, et al. Percutaneous left atrial appendage closure vs warfarin for atrial fibrillation: a randomized clinical trial. JAMA 2014;312(19):1988–98. [3] Holmes Jr DR, Kar S, Price MJ, Whisenant B, Sievert H, Doshi SK, et al. Prospective randomized evaluation of the Watchman Left Atrial Appendage Closure device in patients with atrial fibrillation versus long-term warfarin therapy: the PREVAIL trial. J Am Coll Cardiol 2014;64(1):1–12. [4] Seeger J, Bothner C, Dahme T, Gonska B, Scharnbeck D, Markovic S, et al. Efficacy and safety of percutaneous left atrial appendage closure to prevent thromboembolic events in atrial fibrillation patients with high stroke and bleeding risk. Clin Res Cardiol 2016;105(3):225–9. [5] Saw J, Lempereur M. Percutaneous left atrial appendage closure: procedural techniques and outcomes. JACC Cardiovasc Interv 2014;7(11):1205–20. [6] Gage BF, van Walraven C, Pearce L, Hart RG, Koudstaal PJ, Boode BS, et al. Selecting patients with atrial fibrillation for anticoagulation: stroke risk stratification in patients taking aspirin. Circulation 2004;110:2287–92. [7] Roldán V, Marín F, Manzano-Fernández S, Gallego P, Vílchez JA, Valdés M, et al. The HAS-BLED score has better prediction accuracy for major bleeding than CHADS2 or CHA2DS2-VASc scores in anticoagulated patients with atrial fibrillation. J Am Coll Cardiol 2013;62(23):2199–204. [8] Reddy VY, Holmes D, Doshi SK, Neuzil P, Kar S. Safety of percutaneous left atrial appendage closure: results from the Watchman Left Atrial Appendage System for Embolic Protection in Patients with AF (PROTECT AF) clinical trial and the Continued Access Registry. Circulation 2011;23(4):417–24. [9] Reddy VY, Möbius-Winkler S, Miller MA, Neuzil P, Schuler G, Wiebe J, et al. Left atrial appendage closure with the Watchman device in patients with a contraindication for oral anticoagulation: the ASAP study (ASA Plavix Feasibility Study With Watchman Left Atrial Appendage Closure Technology). J Am Coll Cardiol 2013;61(25):2551–6. [10] Tzikas A, Shakir S, Gafoor S, Omran H, Berti S, Santoro G, et al. Left atrial appendage occlusion for stroke prevention in atrial fibrillation: multicentre experience with the AMPLATZER Cardiac Plug. EuroIntervention 2015;11(10):1170–9. [11] Lip GY, Nieuwlaat R, Pisters R, Lane DA, Crijns HJ. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the Euro Heart Survey on Atrial Fibrillation. Chest 2010; 137:263–72. [12] Poli D, Lip GY, Antonucci E, Grifoni E, Lane D. Stroke risk stratification in a “realworld” elderly anticoagulated atrial fibrillation population. J Cardiovasc Electrophysiol 2010;22:25–30.
Please cite this article as: Seeger J, et al, First experience with the Watchman FLX occluder for percutaneous left atrial appendage closure, Cardiovasc Revasc Med (2017), http://dx.doi.org/10.1016/j.carrev.2017.04.018