Left Atrial Appendage: Physiology, Pathology, and Role as a Therapeutic Target

Abstract

Atrial fibrillation (AF) is the most common clinically relevant cardiac arrhythmia. AF poses patients at increased risk of thromboembolism, in particular ischemic stroke. The CHADS2 and CHA2DS2-VASc scores are useful in the assessment of thromboembolic risk in nonvalvular AF and are utilized in decision-making about treatment with oral anticoagulation (OAC). However, OAC is underutilized due to poor patient compliance and contraindications, especially major bleedings. The Virchow triad synthesizes the pathogenesis of thrombogenesis in AF: endocardial dysfunction, abnormal blood stasis, and altered hemostasis. This is especially prominent in the left atrial appendage (LAA), where the low flow reaches its minimum. The LAA is the remnant of the embryonic left atrium, with a complex and variable morphology predisposing to stasis, especially during AF. In patients with nonvalvular AF, 90% of thrombi are located in the LAA. So, left atrial appendage occlusion could be an interesting and effective procedure in thromboembolism prevention in AF. After exclusion of LAA as an embolic source, the remaining risk of thromboembolism does not longer justify the use of oral anticoagulants. Various surgical and catheter-based methods have been developed to exclude the LAA. This paper reviews the physiological and pathophysiological role of the LAA and catheter-based methods of LAA exclusion.

Durability of cryoballoon left atrial appendage isolation: Acute and invasive remapping electrophysiological findings

“…As a result, LAA isolation can reduce LAA blood flow velocity despite sinus rhythm. According to the Virchow's triad, a reduced blood flow increases the risk of thrombus formation and potentially enhances embolic stroke risk . This topic remains controversial: two different meta‐analyses of published data reported no increased rate of thromboembolic events in patients treated with an LAA isolation; however, in these studies, a subset of patients were treated with LAAC.…”

Left atrial appendage closure: A single center experience and comparison of two contemporary devices

“…Over the last years, percutaneous left atrial appendage (LAA) closure has emerged as a possible alternative to anticoagulation , which is particularly attractive in individuals with a relative contraindication to warfarin . In this category of patients, percutaneous LAA closure has been included in the European Society of Cardiology (ESC) guidelines as a IIb class indication .…”

Prolonged transesophageal echocardiography during percutaneous closure of the left atrial appendage without general anesthesia: the utility of the Janus mask

“…To perform such an interventional procedure, the patient must remain immobile throughout the entire procedure. 2 For this reason, as well as the need for continuous and prolonged TEE, LAA closure is mainly performed under general anesthesia, which itself is burdened by an increased risk of pulmonary complications. 4,9 The possibility of substituting general anesthesia with sedation while keeping the patient spontaneously breathing is debatable.…”

“…The patient must be immobile during all these phases, as a sudden movement can increase the risk of significant complications, including atrial perforation and pericardial tamponade. 2 To keep patients immobile and allow a prolonged three-dimensional transesophageal echocardiography (3D-TEE) examination, percutaneous LAA is usually performed under general anesthesia. The risk of general anesthesia in the elderly is associated not only with challenges of airway control, potential for residual neuromuscular block, and an increased risk of perioperative pulmonary complications 3,4 but also with the risk of cognitive decline.…”