A Guide to Left Atrial Appendage Occlusion Devices in Patients with Contraindication to Anticoagulation
Accumulating experience with the percutaneous LAAO devices has demonstrated their exciting promise as a practice changing alternative to OAC in the management of patients with AF. Of the devices currently available, the efficacy and safety of the WATCHMAN device have been evaluated with two RCTs and were shown to be non-inferior to warfarin in terms of prevention of stroke and systemic embolism in AF. Longer follow-up of the WATCHMAN device has demonstrated a declining trend in procedure-related adverse events and non-inferiority in efficacy of stroke prevention as well as improvement in cardiac mortality compared with conventional warfarin therapy. Safety and efficacy of the ACP and Amulet device have been evaluated by numerous observational studies, with as many as 1047 patients with median follow-up of 13 months. The Lariat system has also been evaluated with numerous observational studies, which showed improvement in procedural complication with time and operator experience.
Nonetheless, there are no randomized data available on LAAO in patients with strict contraindication to anticoagulation to date. The two WATCHMAN RCTs necessitated periprocedural anticoagulation in order to prevent thrombus formation during device endothelialization. Hence, extrapolation of the findings from the RCTs to these patients at high risk for bleed is not straightforward, although these are the very patients who would derive the most benefit from LAAO if shown to be efficacious and safe.
To address the use of the Watchman device in patients with contraindication to anticoagulation, the ASAP study demonstrated the safety of the device without initial anticoagulation in the immediate post-procedural time period and in long-term follow-up. The incidence of stroke in the ASAP study cohort was also lower than predicted by patient clinical risk factors; however, there was no control group for direct comparison. More recently, in the large EWOLUTION registry that included real-world patients with contraindication to anticoagulation, the Watchman device was shown to have a large success rate with low periprocedural risk even in a population with high risk of stroke. Importantly, 6% of patients did not undergo any form of anticoagulation or antiplatelet therapy without an apparent increase in adverse events related to thromboembolism. Regardless, antiplatelet therapy with aspirin, Clopidogrel, or both were more commonly used in these studies. Safety of the device in patients at a profound risk of bleeding who cannot safely tolerate these antiplatelet therapies also remains unclear.
On the other hand, the observational studies of ACP or Amulet were largely conducted in patients with contraindication to anticoagulation. The post-procedural antiplatelet therapy varied widely depending on the study. Although these were not RCTs, several studies have demonstrated lower incidence of stroke than predicted by their clinical risk factors. Santoro et al. in their observational study of 134 patients with mean follow-up 680 days reported 2.5% annual risk of any thromboembolic event compared with 7.7% predicted by clinical risk factors. Similarly, Tzikas et al. in a large multicentre registry (n = 1047) reported annual stroke rate of 2.3% vs. 5.6% as predicted by risk factors.
The striking benefit of the Lariat system is that no device is left behind in the LAA circumventing the potential need for periprocedural anticoagulation, important for LAAO endocardial counterparts which require device endothelialization. In fact, in the most recent multicentre registry (n = 712), OAC was discontinued in approximately 80% of the patients prior to LAAO due to prohibitive risks of anticoagulation. Despite the initial concern with periprocedural complications, the experience with the Lariat system also showed decline in adverse events with time and operator experience as seen by later studies.
Currently, the most recent AHA/ACC/HRS AF guideline published in 2014 does not mention percutaneous LAAO as it predated the FDA approval of the Watchman device; an update to this guideline is being developed at this time. It does make Class IIb Level C recommendation stating surgical excision of LAA closure may be considered in patients undergoing cardiac surgery. The most recent ESC recommendation in management of AF published in 2016 states LAAO may be considered for stroke prevention in patients with AF and contraindication for long-term anticoagulant treatment (Class IIb, Level B recommendation). The 2014 EHRA/EAPCI exert consensus statement on catheter-based LAAO reports that although their data are based on several observational studies and registries, these studies suggest that LAAO is safe and effective despite absence of even temporary OAC.
Europace. 2018;20(9):1412-1419. © 2018 Oxford University Press
Copyright 2007 European Heart Rhythm Association of the European Society of Cardiology (ESC). Published by Oxford University Press. All rights reserved.