Early Experience With the WATCHMAN Device

Introduction

Atrial fibrillation (AF) is the most common cardiac arrhythmia, associated with a rising incidence in the general population, and portends substantial morbidity and mortality. It is a major risk factor for embolic stroke and accounts for at least 15%-20% of all cardiovascular accidents (CVA), and as much as 30% in patients over the age of 80.^1,2

Oral anticoagulation (OAC) is the standard treatment to prevent embolic events in AF; however, adherence rates are low and bleeding complications are common. It is estimated that greater than 50% of OAC-eligible patients are not on adequate treatment.³

The left atrial appendage (LAA) has been identified as the dominant source of emboli in AF. A review of 23 studies revealed that when the LAA was examined by autopsy, TEE, or direct intraoperative visualization, intracardiac thrombi were identified in 10%-15% of patients. Approximately 91% of these thrombi were localized to the LAA in nonvalvular AF.^4,5 It is with this background that rationale for the occlusion, exclusion, or removal of the LAA has been studied to prevent stroke.

With 5 published trials and multicenter registries, almost 2400 patients and 6000 patient-years of follow-up, the WATCHMAN Left Atrial Appendage Closure Device (Boston Scientific) was approved by the FDA in March 2015 and approved for use in Europe in 2005. It has been proven to be superior to warfarin in preventing hemorrhagic strokes. Additionally, a reduction of the rate of death was observed in the device arm. However, it did not meet prespecified criteria for noninferior therapy to warfarin.^6-9

The device is designed with a compressible nitinol frame, 10 fixation anchors, and a 160 micron cap to block thrombus formation. It is available in various sizes to accommodate unique LAA anatomy. The FDA approval specified indications for use in patients with nonvalvular AF who are at increased risk of stroke and systemic embolism based upon CHADS₂ or CHA₂DS₂-VASc scores, deemed by their physicians to be suitable for warfarin therapy; and have an appropriate rationale to seek a non-pharmacologic alternative to warfarin, taking into account the safety and efficacy of the device compared with warfarin. 

Bryn Mawr Hospital was the first hospital in the state of Pennsylvania to implant this device and has the highest volume in the state since the device was given FDA approval. In this article, we describe our early experience of LAA closure with the WATCHMAN device. 

Case Study

An 81-year-old male with a history of multiple falls and recurrent syncope with associated head injury over the past few years presented for evaluation for LAA closure. He has persistent AF and CHA2DS2-VASc score of 5 with hypertension and prior transient ischemic attack (TIA). He was deemed high risk for embolic complications, with an estimated stroke rate of 7.2% and systemic embolization rate of 10%. He was not a suitable candidate for anticoagulation in light of frequent falls, some resulting in head trauma and intracerebral bleeding. His HAS-BLED score was 4, predicting a 9% yearly risk of major bleeding. He was considered for and underwent WATCHMAN device implantation.

Prior to the procedure, transesophageal echo (TEE) was performed to analyze the LAA in detail, document absence of thrombus, and obtain pre-procedural measurements. (Figure 1)

Procedure

The procedure was performed under general anesthesia. Intraoperative TEE was performed by an assisting cardiologist. Arterial and venous access were obtained. IV heparin was administered to maintain ACT >300 seconds. Single transseptal puncture was performed in the inferior/posterior aspect of the fossa ovalis using an SL1 sheath and an electrocautery transseptal needle (Figure 2). The SL1 sheath was wire-exchanged using an Amplatz Super Stiff Guidewire (Boston Scientific) to a 14 French (Fr) double curve WATCHMAN Access Sheath. This was directed to the LAA using a pigtail catheter. The WATCHMAN Access Sheath was advanced into position using fluoroscopy, IV contrast, and TEE (Figures 3A and B). A 27 mm WATCHMAN device was deployed by withdrawing the sheath over the device to prevent LAA perforation (Figure 4). Final release criteria were assessed, including seal of appendage, adequate compression of device in LAA, “tug” test, and final position at ostium of LAA. Procedure time was 91 minutes. Protamine was administered to aid in vascular closure. Perclose venous closure (Abbott Vascular) was used in this patient. The patient was observed overnight, and discharged within 24 hours on warfarin and aspirin (81 mg).

Six weeks later, a TEE performed showed no LAA leaks, no change in position or compression of device (Figure 5). Warfarin was discontinued, aspirin was changed to 325 mg, and clopidogrel (75 mg) was added. In 6 months, the clopidogrel will be discontinued.

Watchman Experience

To date, 7 male patients (age 82±6; CHA2DS2-VASc score = 4±2) have undergone the WATCHMAN procedure at Bryn Mawr Hospital. One procedure was aborted secondary to LAA anatomy. A cactus-shaped LAA with a broad base and early branching and numerous pectinate muscles prohibited full closure of the ostium of the LAA, and we opted not to leave the LAA partially closed. That patient was referred for a mitral valve repair and concomitant LAA closure. Two patients presented with IVC filters, and this did not prohibit LAA closure. A 16 Fr venous access sheath was used to stabilize the WATCHMAN Access Sheath for these and all subsequent procedures. Silk mattress sutures have recently been used to close the venous access sites immediately post procedure instead of the Perclose system. All 6 remaining patients have been able to stop warfarin after their 6-week follow-up TEEs. Average procedure time is 75 ± 28 minutes. No immediate procedural complications have been observed; however, 2 patients developed bleeding on warfarin within 3 weeks of initiation post operatively. In both of these patients, warfarin was discontinued and 6-week TEE did not reveal thrombus on the device, or any other adverse sequelae.

Conclusion

In this early experience of LAA closure with the WATCHMAN device, we experienced no complications and one procedure was aborted. Procedure times have continued to decline as we gain increasing experience. All LAAs remain occluded and in all patients, warfarin was able to be discontinued by 6 weeks. IVC filters were not a hindrance to successful closure of the LAA. We believe the WATCHMAN device can be used to safely close the LAA in high-risk patients.

Disclosure: The authors have no conflicts of interest to report regarding the content herein. 

References

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3. Onalan O, Crystal E. Left atrial appendage exclusion for stroke prevention in patients with nonrheumatic atrial fibrillation. Stroke. 2007;38:624-630.
4. Patel TK, Yancy CW, Knight BP. Left atrial appendage exclusion for stroke prevention in atrial fibrillation. Cardiol Res Pract. 2012;2012:610827.
5. Blackshear JL, Odell JA. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thorac Surg. 1996;61:755-759.
6. Holmes DR, Reddy VY, Turi ZG, et al. Percutaneous closure of the left atrial appendage versus warfarin therapy for prevention of stroke in patients with atrial fibrillation: a randomized non-inferiority trial. Lancet. 2009;374:534-542.
7. Reddy VY, Doshi SK, Sievert H, et al. Percutaneous left atrial appendage closure for stroke prophylaxis in patients with atrial fibrillation: 2.3-year follow-up of the PROTECT AF (Watchman Left Atrial Appendage System for Embolic Protection in Patients with Atrial Fibrillation) trial. Circulation. 2013;127(6):720-729.
8. Holmes DR Jr, Kar S, Price MJ, 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. 
9. Reddy VY, Möbius-Winkler S, Miller MA, 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):2551-2556.