Percutaneous Closure of the Left Atrial Appendage: Initial Experience With the LARIAT System at The Valley Hospital

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Atrial fibrillation is the most common arrhythmia seen in clinical practice. The most feared complication is stroke. To compound matters, these strokes are in general more debilitating than ischemic strokes resulting from cerebrovascular disease, i.e. larger, less recovery and not heralded by transient ischemic attack (TIA).

Risk stratification schemes such as CHADS₂ or CHA₂DS₂-VASc can be used to determine which patient is at risk for stroke. In these patients, chronic oral anticoagulation is recommended with either warfarin or one of the three novel FDA-approved oral anticoagulants (apixaban [Eliquis], dabigatran [Pradaxa], or rivaroxaban [Xarelto]). 

Chronic therapeutic anticoagulation is associated with a marked reduction in the likelihood of stroke. However, chronic oral anticoagulation, using any of the approved oral agents, is associated with a small but definite serious bleeding risk. Thus, there are patients in whom anticoagulation cannot be instituted because their co-morbidities place them at high risk for bleeding, and other patients in whom institution of anticoagulation has already resulted in an episode of major bleeding. Should serious bleeding occur, it is most often managed by temporary discontinuation and/or reversal of the anticoagulant along with treatment of the bleeding source. If the bleeding source can be permanently eliminated, many patients can safely resume oral anticoagulant therapy. However, in a finite subset of patients who have experienced bleeding complications with oral anticoagulants, there is a chronic and/or recurring risk of serious or life-threatening bleeding if anticoagulation is resumed. Despite the long-term risk of stroke, these patients cannot receive anticoagulant therapy and are chronically exposed to the risk of debilitating stroke.

The recent large-scale randomized clinical trials of the novel oral anticoagulants indicate a major bleeding risk of approximately 2%–3.5%.^1-3 Some of these patients are candidates for alternative interventions to mitigate long-term risk of stroke when anticoagulant therapy cannot be used. Specifically, these patients are candidates to undergo procedures that are designed to prevent embolization of atrial thrombus in the setting of atrial fibrillation. It is well established that more than 90% of emboli that occur in the setting of non-valvular atrial fibrillation have their origin within the left atrial appendage (LAA). If the LAA can be excluded from the arterial circulation in a definitive manner, cardioembolic stroke in the setting of atrial fibrillation can be prevented. 

This is the rationale for the long-used surgical procedure of resection of the LAA. The procedure originated in 1947 and more recently has evolved to appendage ligation using a variety of apparatuses. Generally, surgical intervention is performed in patients undergoing other cardiac surgical procedures, most commonly mitral valve repair or replacement. Surgical procedures solely designed to resect or ligate the LAA are infrequently performed because of the morbidity involved. More so, patients are typically reluctant to undergo a stand-alone LAA surgical ligation procedure. 

Alternative nonsurgical techniques have been developed, including transvenous placement of a left atrial occlusion device after transseptal access to the LAA. The rationale is to prevent egress of clot from the appendage to the arterial circulation. The WATCHMAN^™ left atrial appendage closure device (Boston Scientific) has the largest experience to date, but has not yet been FDA approved.⁴ Thus, there remains a clinical need for a technique that consistently and permanently closes the LAA, utilizing a procedure with acceptable morbidity. In order to accomplish this treatment goal, a new system has been developed for nonsurgical closure of the appendage, and the results have been extremely favorable.

The system we have chosen to incorporate into our practice at The Valley Hospital is called the LARIAT^® Suture Delivery Device, developed by SentreHEART. This system was developed to achieve the following technical goals: (1) complete and immediate anatomic closure; (2) no requirement for short-term post-procedure anticoagulation to allow for endothelialization or other tissue growth over an implanted occlusion device; (3) absence of foreign bodies or implants left in the patient; and (4) a non-surgical, minimally invasive procedure.

Case Vignettes

Case 1: A 79-year-old female with paroxysmal atrial fibrillation (CHADS₂ = 1; CHA₂DS₂-VASc = 3) suffered from severe orthostatic hypotension. Despite aggressive volume repletion and daily treatment with midodrine, the patient experienced recurrent falls; several of these falls resulted in trauma. Thus, anticoagulation was never initiated in this patient. A cardiac CT scan showed a LAA orifice of 45 mm.

Case 2: A 72-year-old male with hypertension and coronary artery disease (s/p percutaneous coronary intervention with stent implantation to the left anterior descending and left circumflex arteries) suffered from permanent atrial fibrillation (CHADS₂= 1; CHA₂DS₂-VASc = 3). Although he had been anticoagulated with warfarin for years, he recently suffered a massive lower GI bleed. During this event, he lost 9 units of blood. He was successfully resuscitated with blood products; however, a discrete source of GI bleeding could not be identified despite extensive evaluation. Several cecal AV malformations were clipped empirically. He was deemed a poor candidate for repeat attempt at anticoagulation. 

Case 3: An 84-year-old female with hypertension and prior TIA suffered from paroxysmal atrial fibrillation (CHADS₂ = 4; CHA₂DS₂-VASc = 6). Although she too suffered from frequent falls, she was begun on rivaroxaban 20 mg daily. She presented with a complaint of shortness of breath, and was found to have a massive and spontaneous right-sided hemothorax. She required a chest tube for drainage. Following recovery, her physician instituted warfarin. However, the INR reached as high as 10. Thus, she was finally deemed an unacceptable candidate for long-term anticoagulation. 

The first step is to identify the proper patient for the procedure. To date, the ideal patient is one who requires lifelong anticoagulation for prevention of stroke but has an absolute contraindication for anticoagulants or has already demonstrated a life-threatening bleeding complication when exposed to an anticoagulant. Patients who have had prior open-heart surgery cannot be treated with this approach. Additionally, a cardiac CT scan is necessary to identify the size, shape, and location of the LAA. Approximately 1 in 4 patients do not have an anatomy that is suitable for this technique. For example, in case #1, the CT scan showed a left atrial appendage orifice of 45 mm, which exceeded the maximal 40 mm orifice that can currently be accommodated by the LARIAT suture. In her case, a cardiothoracic surgeon performed a successful robotic-assisted ligation of the appendage. Intra-operative transesophageal echocardiogram (TEE) showed no residual flow between the left atrium and LAA; however, a follow-up TEE examination has not been performed. For the remainder, this new procedure offers a great deal of hope. 

The LARIAT procedure begins with the patient undergoing a TEE, which allows one to confirm the size and shape of the appendage, identify the anterior and posterior lobes of the appendage, and exclude the presence of any preexisting thrombi (Figure 1). The pericardial space is then accessed via subxiphoid puncture using techniques commonly employed for performing epicardial ablation; a guidewire is advanced into the pericardial space. Next, left atrial access is obtained via standard transseptal puncture under TEE guidance to visualize the fossa ovalis. Angiography of the LAA is performed to identify its orientation (Figure 2; online video #1). A specially designed magnetic catheter is then advanced into the most anterior lobe of the LAA, where it makes contact with a second magnetic wire advanced within the pericardial space. A collapsible snare with a retained suture is then advanced to the base of the LAA (Figure 3). Once the LARIAT is advanced over the appendage, it is closed and complete obliteration of the appendage is confirmed by TEE and angiography (Figure 4). The suture is then tightened and cut, with closure verified by TEE, and the procedure is completed. In experienced hands, the procedure is performed in under an hour. Hospital stay is generally only one or two nights.

Both case #2 and #3 underwent successful ligation of the LAA using the LARIAT system. No peri-procedural complications were observed. In case #2, a residual 3.7 mm orifice with a high velocity jet was observed immediately upon closure (Figure 5). However, a follow-up TEE performed a month later showed no residual defect (online video #2). Neither patient was discharged home on anticoagulant therapy. 

In the initial series of patients treated with this technique, it was demonstrated that complete ligation of the LAA was accomplished immediately in 96% of patients; a TEE performed at one-year follow-up showed complete ligation in 98% of patients.⁵ Complications from the procedure were infrequent and the median procedural time was only 45 minutes. It appeared that the LARIAT Suture Delivery Device could be successfully deployed with a high rate of closure and a low rate of complications. The only retained material is a small remnant of suture.

Conclusion

In summary, this novel technological advance provides an option for left atrial appendage closure in patients who are unable to use chronic anticoagulation in the setting of atrial fibrillation. However, more data are needed to establish the long-term safety and efficacy of this procedure. In particular, it needs to be established whether closure by this technique can immediately obviate the need for continued anticoagulation and whether closure translates into reduction in stroke events. Finally, the comparative safety and efficacy of this approach versus other percutaneous left atrial appendage closure techniques needs to be evaluated. n

Disclosure: Drs. Mittal, Musat, and Steinberg have no conflicts of interest to report. 

References

1. Connolly SJ, Ezekowitz MD, Yusuf S, et al. Dabigatran versus warfarin in patients with atrial fibrillation. N Engl J Med. 2009;361:1139-1151.
2. Patel MR, Mahaffey KW, Garg J, et al. Rivaroxaban versus warfarin in nonvalvular atrial fibrillation. N Engl J Med. 2011;365:883-891.
3. Granger CB, Alexander JH, McMurray JJV, et al. Apixaban versus warfarin in patients with atrial fibrillation. N Engl J Med. 2011;365:981-992. 
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;127:720-729. 
5. Bartus K, Han FT, Bednarek J, et al. Percutaneous left atrial appendage suture ligation using the LARIAT device in patients with atrial fibrillation: Initial clinical experience. J Am Coll Cardiol. 2012 Sept 28.