Exploring the dark side of left atrial appendage closure devices
Imaging studies have shown that the majority of AF‐associated intracardiac thrombi are located within the left atrial appendage (LAA),5 a finding that has provided the basis and justification for the development of mechanical catheter‐based technologies for left atrial appendage occlusion (LAAO) as an alternative to oral anticoagulant therapy. Currently, three LAAO devices are in use in the United States: two of these devices (WATCHMAN™ [Boston Scientific, Natick, MA, USA], and AMPLATZER™AMULET™ [St Jude Medical/Abbott, St. Paul, MN, USA) are for endocardial LAAO, whereas the LARIAT® (SentreHEART, Redwood City, CA, USA) is used for epicardial LAAO. The WATCHMAN™ is the only device that has been approved by the Food and Drug Administration (FDA) as an alternative to warfarin for stroke prevention in nonvalvular AF. The clinical evaluation of the WATCHMAN™ device has followed a rigorous process that included two multicenter randomized trials against dose‐adjusted warfarin and two prospective registries.7 Overall, the available data show substantial equivalence of WATCHMAN™ compared with warfarin for all‐cause stroke, and a significant reduction of serious intracranial bleeding events, disabling/fatal strokes and cardiovascular death with WATCHMAN™.7 The safety of the device has also been thoroughly investigated in the setting of randomized controlled trials and, more recently, within post‐approval registries. The most recent assessment of the safety of WATCHMAN™ included 3,822 cases of device implant within a national U.S. registry.11 Notably, 71% of the operators who performed 50% of the procedures were new implanters not participating to the prior clinical trials. The procedure was successfully completed in more than 95% of cases, and the overall rate of periprocedural complications was 2.75%, which included pericardial tamponade (1.02%), procedure‐related stroke (0.078%), device embolization (0.24%), and periprocedural death (0.078%). These figures were similar to those reported in the randomized PREVAIL study, in which the primary safety endpoint (composite of all‐cause death, ischemic stroke, systemic embolism, need for emergent surgery or major endovascular intervention) occurred in 2.2% of the patients randomized to WATCHMAN™.7 Whether the efficacy and safety of LAAO with WATCHMAN™ can be generalized to other types of LAAO devices needs to be evaluated in similarly designed randomized controlled trials. In this regard, a randomized trial comparing the AMULET™ device with the WATCHMAN™ for endocardial LAAO is underway and will formally evaluate whether the two devices perform similarly in terms of efficacy and safety.12
The bulk of the evidence supporting the clinical use of the LARIAT® device for LAAO is substantially different from what is already available for WATCHMAN™ or will soon be available for AMULET™. The LARIAT® is a suture delivery device that has received a 510(k) class II device approval by FDA to deliver a pretied stich for soft tissue approximation during surgery. The approval process was facilitated by the substantial similarities between the LARIAT® system and other FDA‐approved suture systems such as the Ethicon Endosuture System (Ethicon US LLC, Somerville, NJ, USA) that are typically used during laparoscopic surgeries.