Left Atrial Appendage Exclusion Using the Lariat Suture Ligation Device

Disclosure: Dr. Amico, Dr. Varghese, and Dr. George report no conflicts of interest regarding the content herein. 

The authors can be contacted via Dr. Jon George at georgej@deborah.org.

Abstract 

A 48-year-old male with paroxysmal atrial fibrillation presented for a left atrial appendage closure secondary to contraindication to oral anticoagulation. The closure was performed successfully using the Lariat suture-based closure system and the procedure described herein. 

Case 

A 48-year-old male with a past medical history of coronary artery disease, paroxysmal atrial fibrillation, hypertension, and dyslipidemia presented for left atrial appendage (LAA) closure. The patient had a CHADS score of 2 and was unable to take anticoagulation secondary to his job as a construction worker and multiple recurrent work-related bleeding injuries. The patient was evaluated and scheduled for percutaneous LAA exclusion and ligation.  

The procedure was performed under general anesthesia using transesophageal echocardiography (TEE). Access was obtained in the right femoral vein using a 6 French sheath. A pigtail catheter was advanced into the right ventricle and a selective right ventriculogram was performed in a left lateral projection to demonstrate the anterior border of the pericardium at the RV apex (Figure 1). Pericardial access was then obtained using a subxiphoid approach with a 17-gauge, 150mm upward-beveled needle (Pajunk GmbH) confirmed by simultaneous injection of dilute contrast into the pericardium (Figure 2). A trans-septal puncture was performed under TEE imaging, and a magnet-tipped endocardial guide wire with occlusion balloon (EndoCath, SentreHeart) was positioned within the most anterior lobe of the LAA utilizing an inflated balloon in order to identify the LAA ostium. A second opposing polarity magnet-tipped pericardial guide wire (FindrWirz, SentreHeart) was advanced from the trans-septal access sheath to attract the endocardial guidewire and enable an end-to-end alignment for creating a railing (Figure 3). The Lariat suture delivery system (SentreHeart) was then advanced over this railing from the pericardial sheath to capture the LAA (Figure 4). After confirmation of the position around the ostium of the LAA, the suture was delivered to completely ligate the LAA. The entire system was then withdrawn and a pigtail pericardial drain catheter was positioned within the pericardium to drain any residual fluid within the space. Final TEE imaging confirmed complete ligation of the LAA with no residual flow. Selective angiogram of the left atrium also confirmed complete ligation of the LAA (Figure 5). 

Discussion

Histologic anatomy of the left atrial appendage (LAA) changes significantly in chronic atrial fibrillation (AF). There is initial smoothening of the endocardial surface, which later becomes thickened and fibrotic. With dilation of the left atrium, the volume of the LAA increases in AF, and low-flow hemodynamics contribute to thrombus formation in the LAA.¹ Additionally, the pectinate muscles within the LAA create a nidus for blood stasis and thrombus formation.

Approximately 90% of strokes in patients with AF not associated with valvular heart disease are attributed to a thrombus originating from the LAA.² In patients with AF and valvular heart disease, thrombus in LAA occurs in 50% of those patients that suffer a stroke. The two main goals of therapy in patients with AF are to alleviate symptoms and to reduce the rate of systemic thromboembolism. The overall risk for thrombotic stroke in a patient with AF is five times greater than in patients without AF. Furthermore, embolic strokes caused by AF are typically larger and more disabling compared with strokes occurring in sinus rhythm. In nonvalvular AF, the annual stroke risk on aspirin is similar for paroxysmal (3.2%) and permanent AF (3.3%). Currently, the American College of Cardiology and American Heart Association recommend that patients undergoing mitral valve surgery also undergo LAA obliteration.³ 

The rationale behind the closure of the LAA is due to the limitations of oral anticoagulants (OAC).⁴ These limitations include, but are not limited to, a high risk of bleeding, important interactions with food and medications, as well as the need for frequent laboratory testing to check the efficiency of anticoagulation by measuring the international normalized ratio (INR). Despite the known benefits of anticoagulation, only 40-55% of patients receive warfarin. Furthermore, certain patient populations have contraindications for lifelong use of any OAC. Gastrointestinal bleeding is the most common type of extracranial bleeding in AF patients on OAC. When evaluating neurological patients, a Canadian registry showed that only 12% of patients had an INR within the therapeutic range.⁵ A Danish stroke registry found that among patients without contraindications, 30% of males ≤65 years of age to 70% of females >80 years of age were not treated with OAC at 6 months after diagnosis.⁶ Hemorrhagic complications of OAC therapy remain a significant clinical problem, especially in the elderly. Patients that suffer from a warfarin-associated intracerebral hemorrhage have a high mortality rate versus those that suffer an ischemic stroke (50% vs. 10%). 

The concept of percutaneous closure of the LAA to prevent stroke was birthed from the inadequacy and limitations of OAC, and technical success of early surgical attempts for ligation of the LAA.  

The PROTECT AF trial was a multicenter prospective randomized clinical trial that enrolled 707 patients with AF comparing the Watchman device (Boston Scientific) to long-term warfarin therapy, designed to demonstrate that device treatment arm was non-inferior to the medical therapy arm.⁷ The Watchman device is a self-expanding nitinol frame covered with a porous filtering PET membrane. The PET membrane acts as a filter, preventing the outflow of the thrombi, and promotes endothelialization. The primary efficacy endpoints were all stroke (ischemic and hemorrhagic), cardiovascular death (limited to any cardiovascular and unexplained death), and systemic embolism. The primary safety endpoints included life-threatening events such as device embolization requiring retrieval and bleeding events such as pericardial effusion requiring drainage, cranial bleeding events due to any source, gastrointestinal bleeds requiring transfusion, or any bleeding related to the device or procedure that necessitated an intervention. In this trial, over 80% of the patients had a CHADS2 score of 3 or lower. Furthermore, paroxysmal AF was the most common presenting rhythm. The demonstration of non-inferiority in the PROTECT AF trial of the LAA implant compared to warfarin provided proof that exclusion of the LAA is beneficial in preventing cardioembolic events and bleeding consequences related to oral anticoagulation therapy.⁸ The Watchman device was recently FDA-approved and is in the process of being adopted into clinical practice. 

Based on the results of the PROTECT-AF trial, various endocardial and epicardial approaches have been developed for the exclusion of the LAA. The most recent technique has been a catheter-based ligation procedure utilizing pericardial and transseptal access.⁹ After access has been gained, a magnet-tipped guide wire is connected to an epicardial magnet-tipped guide wire to stabilize the LAA. Once the suture delivery device is properly situated over the LAA, the device is closed with a suture. In a single-site study, 89 patients with AF underwent percutaneous closure of the LAA with the Lariat device.¹⁰ The closure was confirmed with TEE and contrast fluoroscopy. Subsequently, these patients had repeat TEE at 1 day, 30 days, 90 days, and 1 year post-ligation. Results showed that 98% of these patients had successful and sustained closure of the LAA after 1 year.

There are other devices that have undergone investigation and are currently being studied. The Plaato device (Covidien) consists of a self-expanding nitinol cage with three anchors on each strut and is covered with non-thrombogenic PTFE membrane.¹¹ LAA closure was technically feasible using the Plaato device; however, this device was withdrawn by the manufacturer due to the insurmountable investment projected to obtain clinical approval. The Amplatzer cardiac plug (St. Jude Medical) is a combination of nitinol frame with polyester patch to seal the orifice of the LAA.¹² This device functions differently from the previously mentioned LAA closure devices, since it is not dependent on the anatomy of the LAA. The most important difference between the Amplatzer and Watchman device is the regimen of antiplatelet and anticoagulant therapy after successful implantation. The Amplatzer cardiac plug requires no anticoagulants and the long-term use of dual antiplatelet therapy is not necessary. More commonly, 6 months of aspirin and 1 month of clopidogrel is prescribed. The Watchman filter necessitates at least 45 days of oral anticoagulation with a goal INR of 2.0-3.0 based on the initial trial.⁷ After 45 days, long-term aspirin is recommended. 

Complications of percutaneous LAA closure can be significant.⁴ Some of these complications are access site complications (hematoma, bleeding), cardiac perforation associated with cardiac tamponade, pericarditis, device migration and embolization, and incomplete closure with thrombus formation. Contraindications for percutaneous LAA closure include AF in patients with valvular heart disease (i.e. mitral stenosis).

Percutaneous LAA occlusion or exclusion offers physicians an alternative treatment option for patients with AF that are unable to tolerate anticoagulation. Herein, we describe a patient that was high risk for OAC and underwent successful percutaneous ligation of the LAA using the Lariat device.

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