Page 9 - Journal of Structural Heart Disease Volume 2, Issue 1

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Review Article
Surgical Closure
less-invasive nature compared to surgical techniques has resulted in signi cant enthusiasm for transcath- eter LAA closure as possible alternative to anticoag- ulation in patients with nonvalvular AF at high risk for stroke especially among patients with absolute or relative contraindications to long-term anticoag- ulation. A variety of devices and techniques have been developed with individual development his- tories and studies which dictate individual e cacy and safety outcomes. Below we discuss, the most fre- quently studied devices.
PLAATO
The PLAATO device was the rst transcatheter LAA occlusion system developed and implanted in hu- mans [31]. The device was a self-expanding nitinol cage covered with an occlusive expanded polytetra- uoroethylene membrane. It was delivered through a trans-septal access into the left atrium via femoral vein. Initial studies demonstrated that transcatheter closure of the LAA with the PLAATO device was feasi- ble and safe in a nonrandomized study of patients at high risk for thromboembolism who were not able to receive warfarin therapy. When compared to expect- ed event rates based on CHADS2 score, the PLAATO device decrease events by 42–65% [32, 33]. The PLAA- TO system was withdrawn from the market in 2006 due to commercial reasons.
Amplatzer Cardiac Plug
The Amplatzer cardiac plug (St. Jude Medical, Min- neapolis, Minnesota, USA) also known as ACP device was developed speci cally for LAA closure. The ACP device is a self-expanding nitinol mesh connected to a polyester disk through a central waist (Figure 1). The soft lobe mesh is deformable and deploys distally with anchors that insert into the LAA. This maintains device stability within the LAA. The disk covers the ostium of the LAA sealing it. The development of this device followed the success of the AMPLATZER sep- tal occluder device for patent formen ovale and atrial septal defects. The ACP device is delivered through the femoral vein into the left atrium via transseptal access and requires uoroscopy and TEE guidance. Patients with the ACP device are maintained on dual
Surgical closure of the LAA has been performed for many years with mixed results. The rst reported cases of LAA exclusion in the surgical literature was in 1949, in two patients with recurrent arterial emboli [23]. Since that time, surgical ligation has fallen in and out of favor. TEE assessment has shown surgical tech- niques to have a high occurrence of unsuccessful clo- sure. Success is dependent on the surgical technique utilized with excision providing the best results [24]. Currently, LAA excision is performed usually as an ad- ditional procedure with cardiac surgery or as part of a surgical MAZE procedure. Thoracoscopic LAA exci- sion is mainly performed with thoracoscopic surgical pulmonary vein isolation [25], though stand-alone procedures have been reported [26, 27]. There has been a lack of large, randomized, controlled trials with evaluation of long-term stroke risk after surgical LAA closure. Currently, the Left Atrial appendage Occlu- sion Study (LAAOS III) is being conducted to evaluate LAA occlusion during on-pump cardiac surgical pro- cedures. It is a large-scale randomized controlled trial with an enrollment goal of 4,700 patients with AF. The end-point will be rst occurrence of stroke or systemic arterial embolism over a mean follow up of 4 years.
Surgical clip devices have been developed in order to more predictably close the LAA during cardiac surgi- cal procedures. The AtriClip system (AtriCure-USA, West Chester, Ohio, USA) and the Tigerpaw system (Maquet, Rastatt, Germany) are available in the United States [28, 29]. Advantages of use include utilization with live TEE guidance to evaluate position of the clip prior to nal closure. While observational studies have demonstrat- ed safety and feasibility of clip based LAA closure, there are no randomized, controlled trial data demonstrating e cacy with regard to stroke prevention. These devices are usually utilized in patients undergoing cardiac sur- gery, though stand-alone thoracoscopic implantation has been reported with the AtriClip [30]. Further data should help further delineate the e ect on clinical out- come of surgical closure with these novel devices.
Transcatheter Closure
Percutaneous transcatheter approaches have been developed to close the LAA. The inherently
Sánchez, J.M. et al.
Where Do We Stand Now?