Abstract and Introduction
Stroke is the most feared complication of atrial fibrillation (AF). Although oral anticoagulation with non-vitamin K antagonist and non-vitamin K antagonist oral anticoagulants (NOACs) have been established to significantly reduce risk of stroke, real-world use of these agents are often suboptimal due to concerns for adverse events including bleeding from both patients and clinicians. Particularly in patients with previous serious bleeding, oral anticoagulation may be contraindicated. Left atrial appendage occlusion (LAAO), mechanically targeting the source of most of the thrombi in AF, holds an immense potential as an alternative to OAC in management of stroke prophylaxis. In this focused review, we describe the available evidence of various LAAO devices, detailing data regarding their use in patients with a contraindication for oral anticoagulation. Although some questions of safety and appropriate use of these new devices in patients who cannot tolerate anticoagulation remain, LAAO devices offer a significant step forward in the management of patients with AF, including those patients who may not be able to be prescribed OAC at all. Future studies involving patients fully contraindicated to OAC are warranted in the era of LAAO devices for stroke risk reduction.
Atrial fibrillation (AF) is the most common cardiac arrhythmia, and the lifetime risk of AF is estimated to be one in six. Stroke is the most feared complication, and AF raises the risk of stroke five-fold.[2,3] Moreover, strokes associated with AF have worse clinical outcomes and result in significant morbidity and mortality. Therefore, stroke prophylaxis is a critical component in the management of patients with AF. Warfarin, a vitamin K antagonist, effectively reduces risk of stroke by 60%. Non-vitamin K antagonist oral anticoagulants (NOACs) have been shown to have further reduction in stroke, intracranial haemorrhage, and mortality compared with warfarin therapy.
Nonetheless, it has been widely established that the real-world use of oral anticoagulants (OAC) is often suboptimal, falling short of guideline-based recommendations.[6–8] Multiple studies report appropriate use of OAC in only one-half to two-thirds of patients with AF for a variety of reasons including patient refusal due to risks from anticoagulation and clinician reluctance from perceived contraindications to anticoagulation.[6–9] Non-vitamin K antagonist oral anticoagulants also showed significant rates of discontinuation: 21% for dabigatran, 23.7% for rivaroxaban, and 25.3% for apixaban in their respective randomized controlled trials (RCTs).[10–12] In specific patient populations, such as those patients who have had a near-fatal bleeding event, administration of an oral anticoagulant may be deemed a contraindication. Therefore, there exists an intense need for an alternative method of stroke prophylaxis, particularly in patients with AF who have contraindications to anticoagulation. One such alternative is left atrial appendage occlusion (LAAO).
The left atrial appendage (LAA) is a remnant of the primordial left atrium. Although its function in an adult heart is largely unknown, studies implicate about 90% of thrombi formation in non-valvular AF to the LAA.[13,14] Consequently, the LAA is an attractive target for mechanical means of preventing stroke in non-valvular AF. Left atrial appendage occlusion as a target for stroke prophylaxis is not a new concept in the surgical arena, and surgical LAA occlusion at the time of cardiac surgery has been in practice for more than a half century.[13,15] More recently, however, several minimally invasive, percutaneous LAAO devices have been introduced and have attracted attention as an alternative to chronic anticoagulation. In the studies of LAAO devices, post-procedural anticoagulation was often administered to avoid residual thrombus formation and thromboembolism risk; hence, patients with a contraindication to anticoagulation were not included in most of the pivotal studies. In this review, we aim to provide a focused review of contemporary percutaneous modalities of LAAO and the evidence for their use in the presence of contraindications to oral anticoagulation.
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.