Cover Story

Case Study: Utilizing the WATCHMAN Device

Senthil Thambidorai, MD, FHRS, Heart Center of North Texas, Fort Worth, Texas

Senthil Thambidorai, MD, FHRS, Heart Center of North Texas, Fort Worth, Texas

Atrial fibrillation (AF) is a leading cause of stroke. Around 90% of thrombus in patients with AF originates in the left atrial appendage (LAA). The WATCHMAN Left Atrial Appendage Closure Device (Boston Scientific) is indicated to reduce the risk of thromboembolism from the LAA in patients with non-valvular AF who are at increased risk for stroke and systemic embolism based on CHADS2 or CHA2DS2-VASc scores and are recommended for anticoagulation therapy, are deemed by their physicians to be suitable for warfarin and have an appropriate rationale to seek a non-pharmacologic alternative to warfarin, taking into account the safety and effectiveness of the device compared to warfarin.1 The WATCHMAN implant procedure was first approved for use in Europe in 2005. The U.S. Food and Drug Administration (FDA) approved the WATCHMAN device in March 2015. 

Plaza Medical Center of Fort Worth was the first hospital in Dallas-Fort Worth (and North Texas) to implant this device since its FDA approval. Plaza Medical Center of Fort Worth, established in 1974, is a 320-bed facility offering comprehensive diagnostic and treatment services. Located in the heart of the medical district, Plaza Medical Center of Fort Worth serves as a tertiary referral center not only for Tarrant County, but also numerous counties within a 90-mile radius, and offers cutting-edge diagnostic treatment services in a wide range of specialties and subspecialties. 

The EP program at Plaza Medical Center of Fort Worth formally started in 2003, and there are now two electrophysiology labs. There is a dedicated EP lab team comprised of two nurses, two radiation technologists, and two scrub technicians. Since the introduction of our WATCHMAN implant program, we have designated two days each month to perform multiple WATCHMAN implants; this helps ensure the presence of all members of the implanting team. This article highlights a recent case implanting the WATCHMAN as well as provides a review of the literature. 

Case Description

Our first patient was an 80-year-old male with persistent atrial fibrillation s/p AV nodal ablation and pacemaker four years ago. His CHA2DS2-VASc score was 4 (hypertension, age >75 years, and coronary artery disease). He had been on warfarin but was complicated by hemorrhoids and external bleeding episodes, making his use of warfarin intermittent in the past four years. He was interested in coming off oral anticoagulation and was seeking an alternative.

After a discussion of the benefits/risks and medication regimen for the WATCHMAN device, the patient consented to the procedure. INR was maintained between 2-3, and on the day of procedure, the INR was 2.2.

We performed this procedure in the cardiac catheterization laboratory under general anesthesia. The implanting team included an electrophysiologist, an interventional cardiologist, and an imaging cardiologist (Figure 1). Percutaneous LAA occlusion is usually performed under general anesthesia, with transesophageal echocardiography (TEE) and fluoroscopic guidance and additional intracardiac echocardiography (ICE) if needed. Antibiotic prophylaxis is administered prior to the procedure. Vascular access through a femoral vein is obtained, and the delivery system is introduced by transseptal puncture using a standard transseptal needle and sheath. We obtained transseptal access using the standard technique utilizing fluoroscopy and ICE. Device sizing and placement is performed using TEE. Ideal transseptal puncture is done in the posterior and inferior portion of the septum to optimize alignment with the LAA. Different curves of sheaths are available to access the LAA. After the puncture, a bolus of unfractionated heparin is given to achieve an activated clotting time (ACT) >250 s. TEE and contrast angiography are used to measure the LAA dimensions (ostium, neck width, depth), and based on these measurements, the size of the device is chosen. The positioning of the device in the LAA cavity is ensured by TEE/ICE and fluoroscopy (Figure 2). The device is deployed by withdrawing the sheath over the device, to reduce the risk of perforation. Once in position, the device stability is confirmed by a ‘tug test’, and complete sealing is verified by color Doppler imaging by TEE. Finally, the device is released from the delivery cable and possible complications such as pericardial effusion are ruled out.2

 After the WATCHMAN device was placed in this case, the patient was extubated and monitored in the hospital overnight and discharged without any complications. We usually hold manual pressure with purse-string suture of the venous access to assure hemostasis. At two-week follow-up, the patient was doing well. TEE at 45 days noted good device placement (with no leak) and warfarin was stopped. The patient will continue aspirin and clopidogrel for six months.

About the WATCHMAN Device

The WATCHMAN device has been studied in two randomized clinical trials and multiple clinical registries. The WATCHMAN Left Atrial Appendage Closure (LAAC) Device for Embolic PROTECTion in Patients with Atrial Fibrillation (PROTECT AF) trial3 was a multicenter, prospective trial designed to demonstrate that WATCHMAN is non-inferior to warfarin for the combined endpoint of stroke, systemic embolism and cardiovascular or unexplained death in patients with non-valvular AF who were eligible for warfarin therapy and had a CHADS2 score of ≥1. A total of 707 patients from 59 centers were randomized 2:1 device vs warfarin control. All randomized study patients completed follow-up assessments at post-randomization intervals of 45 days, 6 months, 9 months, 12 months, and annual office visits thereafter, with semi-annual telephone visits for up to 5 years.7

PROTECT AF trial data demonstrated that the WATCHMAN LAAC device was non-inferior to warfarin control for the primary endpoint of all stroke, cardiovascular or unexplained death, and systemic embolism. In the post-hoc four-year follow-up, WATCHMAN group was superior to warfarin: 2.3% for WATCHMAN and 3.8% for warfarin annually, demonstrating a 40% relative risk reduction for the composite endpoint of all stroke, cardiovascular or unexplained death, and systemic embolism.4,7

As a follow-up, the PREVAIL trial was designed to confirm the results of the PROTECT AF trial and validate the safety of the implant procedure, including a minimum of 20% of randomized patients enrolled at institutions that did not participate in a previous WATCHMAN study (PROTECT AF or CAP Registry) and a minimum of 25% of randomized patients enrolled by new operators at any institution.5 A total of 407 patients were randomized 2:1 device vs warfarin control in the PREVAIL trial. Patients enrolled in PREVAIL were warfarin eligible and had a means CHADS2 score of 2.6 ± 1.0. Non-inferiority was not achieved for the pre-specified criteria for the primary efficacy endpoint (composite of all stroke, systemic embolism, and cardiovascular/unexplained death at 18 months). The PREVAIL treatment group performed similarly to prior WATCHMAN studies; however, the observed rate of stroke and systemic embolism (0.7 per 100 patient-years) in the PREVAIL Control group was lower than warfarin control groups in recently published studies (1.6-2.2 per 100 patient-years), explaining the lack of primary endpoint.8

In the PROTECT AF trial, oral anticoagulation (OAC) was given for 45 days and patients discontinued OAC if the 45-day TEE control showed either complete closure of the LAA or if the jet width of the residual peri-device flow was <5 mm. After stopping OAC therapy, patients were given dual antiplatelet therapy (DAPT) with aspirin (ASA) and clopidogrel until completion of the 6-month TEE control, after which ASA monotherapy was continued indefinitely. In 14% of patients, OAC was continued beyond 45 days, and in 8% of patients, OAC was continued beyond 6 months because of incomplete LAA closure or device thrombosis. A more recent study (ASAP registry) of 150 patients receiving the WATCHMAN device reported that implantation can be safely performed without OAC transition and that DAPT prescribed for 6 months followed by ASA alone may be an adequate antithrombotic regimen.

Disclosure: The author has no conflicts of interest to report regarding the content herein. 

References

  1. WATCHMAN LAA Closure Technology – P130013. FDA. Published April 2, 2015. Available online at http://tinyurl.com/ovbecrq. Accessed August 10, 2015. 
  2. De Backer O, Arnous S, Ihlemann N, et al. Percutaneous left atrial appendage occlusion for stroke prevention in atrial fibrillation: an update. Open Heart. 2014;1(1):e000020.
  3. 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 randomised non-inferiority trial. Lancet. 2009;374(9689):534-542.
  4. 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.
  5. 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. 
  6. 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.
  7. PREVAIL Study. Boston Scientific. Available online at http://bit.ly/1htb2v8. Accessed August 20, 2015. 
  8. PREVAIL Study. Boston Scientific. Available online at http://bit.ly/1LlJ0Lz. Accessed August 20, 2015.