Left atrial appendage (LAA) amputation for stroke prevention in atrial fibrillation (AF) was initially described by Madden et al. in 1948. Since then, surgeons have used different approaches to deal with the LAA over time. However, it was not until the early 2000s that a team at the Cleveland Clinic developed an epicardial device specifically for mechanical closure of the LAA, a device that was initially known as the CG-Clip. This clip went through several changes during its development phase, eventually evolving into the AtriClip device (AtriCure, Inc., Mason, OH).
The complete LAA Clip System includes a self-closing, implantable clip and a disposable measuring guide to determine the optimal clip size to use clinically from a choice of four options (35, 40, 45, or 50 mm). When deployed in its fully closed position, the epicardial AtriClip applies uniform and continuous pressure to the LAA throughout its length to ensure consistent, reproducible, secure occlusion of the base of the LAA ( Fig. 44.1 ). Because the AtriClip is applied epicardially, it devascularizes the myocardium of the LAA and therefore accomplishes not only mechanical closure of the LAA but also electrical isolation of the LAA from the remainder of the heart. The AtriClip can be applied during open cardiac surgery via a median sternotomy, thoracotomy, or thoracoscopically during minimally invasive cardiac surgery ( Fig. 44.2 ).
AtriClip construction. The AtriClip consists of two rigid components facing each other that are kept closed by continuous dynamic inward pressure caused by a nitinol spring mechanism and the elastomeric pressure components. The encompassed rigid beams and the rigid elastomeric beams combine to aid in the remodeling of the closed left atrial appendage orifice inside the left atrium. Additionally, the external polyester covering adds friction and promotes full encapsulation by the surrounding structures to ensure that the AtriClip stays anchored at its original implantation site and does not migrate over time.
An AtriClip properly deployed across the base of the left atrial appendage.
Long-Term Results of AtriClip Closure of the Left Atrial Appendage
Extensive preclinical evaluation showed that the AtriClip device was safe and effective for LAA occlusion (LAAO), and this led to the first human application of the AtriClip device, which we performed in Zurich in 2009. , The AtriClip device was subsequently deployed successfully as a concomitant procedure in our series of 34 patients undergoing elective open cardiac surgery who had a prior history of AF and ongoing stroke prevention treatment with oral anticoagulants. Serial 3-month computed tomography (CT) scans after LAAO with the AtriClip confirmed that the LAA was completely closed in all patients with no evidence of residual reperfusion of the LAA. In addition, all AtriClips remained at their original site of implantation with no interim migration, and no patient had a stroke or transient ischemic attack (TIA) during or after LAA closure.
In 2011, Ailawadi et al. reported a multicenter US Food and Drug Administration trial to determine the safety and efficacy of the AtriClip device in 71 patients undergoing elective cardiac surgery. At 3-month follow-up, no adverse events or device-related perioperative deaths had occurred. Complete closure of the LAA, confirmed by either CT angiography (CTA) or transesophageal echocardiography, was accomplished in 98.4% (60 of 61) of patients with the AtriClip device. This study again showed that the AtriClip device was safe and atraumatic with a greater than 95% successful closure rate and excellent short-term durability.
In 2018, our group reported the long-term AtriClip data on 251 consecutive patients, including all patients from our first-in-human prospective trial and our institutional registry. We used CT scans to assess the safety, efficacy, and long-term durability of epicardial AtriClip LAA closure and its subsequent impact on stroke prevention in patients with AF undergoing cardiac surgery. The LAA was successfully excluded in all patients during a mean follow-up of 36 ± 23 months. No device-related complications occurred, and CT imaging in patients 5 years or more after implant revealed complete LAAO with no signs of residual reperfusion or significant residual LAA pouches. Patients with discontinued oral anticoagulation ( n = 166) experienced a relative risk reduction of 87.5% with an observed ischemic stroke rate of 0.5 per 100 patient-years compared with an expected ischemic stroke rate of 4.0 per 100 patient-years in patients with similar CHA 2 DS 2 -VASc scores. In a subsequent retrospective analysis of 291 patients from this study cohort, 43 patients had available postoperative short-term and long-term follow-up by CTA. Both residual LAA patency and the presence of residual LAA pouches were assessed by two-dimensional multiplanar reconstructions, maximum intensity projection images, and volume as determined by three-dimensional CT reconstructions. At a mean follow-up period of 7.1 ± 0.8 years after AtriClip LAAO, there was no residual connection between the left atrium and the LAA in any patient. CTA revealed no residual LAA pouch in 72% (31 of 43) of patients, insignificant (<10 mm) residual pouches in 26% (11 of 43) of patients, and a significant residual pouch (>10 mm) in one patient (2%) with a residual pouch that measured 12 mm in depth.
Ellis et al. used CTA to assess long-term outcomes when the AtriClip was applied via a totally thoracoscopic approach. They reported a complete occlusion rate of 93.9% and no major complications during a mean follow-up period of 34.3 months after thoracoscopic AtriClip closure of the LAA. Kurfirst et al. reported a successful AtriClip LAA closure rate of 98% in 101 patients over a follow-up period of 18 ± 11 months. In that series, the AtriClip was applied via a sternotomy, thoracotomy, or thoracoscopically. There were no clip migration, no leakage around the clip, and no thrombus formation near any small remnant pouch. Toale et al. performed a metaanalysis of 11 studies that included 922 patients who underwent LAA closure with an AtriClip device. Successful closure was accomplished in 97.8% (902 of 922) of patients with no device-related adverse events. The incidence of stroke or TIA after AtriClip LAA closure ranged from 0.2 to 1.5 per 100 patient-years. The authors concluded that the concomitant or stand-alone application of an AtriClip device is safe and effective for the management of patients with AF undergoing cardiac surgery. In 2012, Starck et al. reported that epicardial LAAO with an AtriClip device leads to the acute electrical isolation of the LAA and suggested additionally that it may reduce the recurrence of AF.
The AtriClip device has now been successfully deployed in more than 500,000 patients worldwide. However, the largest cohort yet published consisted of only 291 patients, reflecting the problematic lack of available long-term data in large patient cohorts. Unfortunately, the largest randomized controlled trial assessing surgical LAA closure to date, the LAAOS III trial, did not include detailed information on the deployment rate of the AtriClip device within the surgical arm of the study, so its long-term outcomes could not be compared with other LAAO strategies. ,
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