Is the Site of Thrombus Formation in the Left Atrial Appendage Associated with the Risk of Cerebral Embolism?

Abstract

Atrial fibrillation (AF) is a risk factor for cerebral embolism, with the left atrial appendage (LAA) being considered as the source of emboli. However, the relationship between the histologic properties of LAA thrombi and the occurrence of cerebral embolism is not known. Seventy-six hearts from patients who died within 1 month after cerebral embolism were studied at autopsy. Patients were grouped according to the presence of AF and the presence of valvular disease (VD). We determined whether the LAA thrombi adhered to the trabecular region or the remainder of the LAA. LAA thrombi were grouped into three stages: a fresh stage in which thrombi consisted of fibrin and platelets, an organizing stage in which angiogenesis was observed in the thrombi, and an organized stage in which endothelial cells covered the surface of the thrombi. The AF+/VD– group included 19 patients (25.0%), the AF+/VD+ group 8 (10.5%), the AF–/ VD– group 37 (48.7%), and the AF–/VD+ group included 12 patients (15.8%). LAA thrombi were observed in 15 patients (78.9%) in the AF+/VD– group, and all of the thrombi adhered to the trabecular region. Thrombi in the fresh and the organizing stages were observed in 10 patients (66.7%). Patients in the AF+/VD– group accounted for about 25% of the cases of cerebral embolism. All of these thrombi were attached to the trabecular region, and about 70% of them could represent an embolic source.

Structural Comparison between the Right and Left Atrial Appendages Using Multidetector Computed Tomography

“…Yamaji et al [20] reported that all thrombi are adhered to PMs. The results of this study revealed a lower incidence of PMs in RAA, indicating that the inner surface area of RAA is smaller than that of LAA.…”

Video-assisted minimally invasive surgery for lone atrial fibrillation: A clinical report of 81 cases

“…Thrombotic material associated with AF arises most frequently in trabeculated portions, such as the LAA. 7,18 According to the study of Odell and associates, 19 the thrombus was localized to the LAA in 91% of patients with nonrheumatic AF, including patients with lone AF. When combined with amputation or obliteration of the LAA, postoperative thromboembolic events are substantially reduced.…”

Early neurological deterioration in cardiogenic cerebral embolism due to nonvalvular atrial fibrillation: Predisposing factors and clinical implications

“…The mechanism underlying cerebral embolism in patients with AF is complex. The main mechanism of pathogenesis involves a change in the structure and function of the left atrial appendage (LAA), which leads to blood stasis and induction of LAA thrombosis(Yamaji et al., 2002). The embolus then falls off and embolizes the intracranial artery.…”