Abstract 16758: Presence of Left Atrial Fibrosis Contributes to Aberrant Hemodynamics and Increased Risk of Stroke in Atrial Fibrillation Patients

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Nikhil Paliwal ◽  
Matteo Salvador ◽  
Ryan Ohara ◽  
Rheeda Ali ◽  
Rebecca Yu ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrial ◽  
Stroke Risk ◽  
Fluid Dynamic ◽  
Blood Pool ◽  
Clot Formation ◽  
Low Flow ◽  
Dynamic Simulations ◽  
Normal Region ◽  
Increased Risk

Introduction: Atrial fibrillation (AF) patients are at high risk of stroke, with the left atrial appendage (LAA) found to be the most common site of clot formation. Left atrial (LA) fibrosis is also associated with higher stroke risk. However, the mechanisms for increased stroke risk in patients with atrial fibrotic remodeling are poorly understood. We sought to explore these specific mechanisms using fluid dynamics analysis. Hypothesis: The presence of LA fibrosis leads to aberrant hemodynamics in the atria, contributing to increased stroke risk in AF patients. Methods: We retrospectively collected LGE-MRI images of 3 AF patients and reconstructed their 3D LA endocardial surfaces. Fibrotic regions were identified as those with intensity 3 standard deviations greater than the mean LA blood-pool intensity. Personalized computational fluid dynamic simulations were performed, and hemodynamics at the LA wall were quantified by wall shear stress (WSS, friction of blood) and oscillatory shear index (OSI, temporal directional change of WSS). For each case, WSS and OSI were compared between fibrotic and normal regions. Results: WSS was significantly lower in the fibrotic region as compared to normal region for all 3 cases. Additionally, OSI was higher in the fibrotic region as compared to normal region for all 3 cases. However, this different was statistically significant for cases 1 and 3; case 2 was not statistically significantly different. Low WSS and high OSI in the vicinity of the fibrotic wall suggest that local blood-flow was slow and oscillating, enabling pro-thrombotic conditions for circulating blood. Conclusion: LA fibrosis correlates with regions of aberrant hemodynamics, which renders it susceptible to blood thrombosis. AF patients with high LA fibrosis burden will have more pro-thrombotic regions, in addition to low flow in the LAA, providing more sites for a potential clot formation. These conditions might get exacerbated during an AF event and cause stroke.

scholarly journals Presence of Left Atrial Fibrosis May Contribute to Aberrant Hemodynamics and Increased Risk of Stroke in Atrial Fibrillation Patients

2021 ◽  
Vol 12 ◽  
Author(s):  
Nikhil Paliwal ◽  
Rheeda L. Ali ◽  
Matteo Salvador ◽  
Ryan O’Hara ◽  
Rebecca Yu ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Residence Time ◽  
Left Atrial ◽  
Cell Activation ◽  
Stroke Risk ◽  
Fluid Dynamic ◽  
Clot Formation ◽  
Endothelial Cell Activation ◽  
Relative Residence Time ◽  
Increased Risk

Atrial fibrillation (AF) patients are at high risk of stroke, with the left atrial appendage (LAA) found to be the most common site of clot formation. Presence of left atrial (LA) fibrosis has also been associated with higher stroke risk. However, the mechanisms for increased stroke risk in patients with atrial fibrotic remodeling are poorly understood. We sought to explore these mechanisms using fluid dynamic analysis and to test the hypothesis that the presence of LA fibrosis leads to aberrant hemodynamics in the LA, contributing to increased stroke risk in AF patients. We retrospectively collected late-gadolinium-enhanced MRI (LGE-MRI) images of eight AF patients (four persistent and four paroxysmal) and reconstructed their 3D LA surfaces. Personalized computational fluid dynamic simulations were performed, and hemodynamics at the LA wall were quantified by wall shear stress (WSS, friction of blood), oscillatory shear index (OSI, temporal directional change of WSS), endothelial cell activation potential (ECAP, ratio of OSI and WSS), and relative residence time (RRT, residence time of blood near the LA wall). For each case, these hemodynamic metrics were compared between fibrotic and non-fibrotic portions of the wall. Our results showed that WSS was lower, and OSI, ECAP, and RRT was higher in the fibrotic region as compared to the non-fibrotic region, with ECAP (p = 0.001) and RRT (p = 0.002) having significant differences. Case-wise analysis showed that these differences in hemodynamics were statistically significant for seven cases. Furthermore, patients with higher fibrotic burden were exposed to larger regions of high ECAP, which represents regions of low WSS and high OSI. Consistently, high ECAP in the vicinity of the fibrotic wall suggest that local blood flow was slow and oscillating that represents aberrant hemodynamic conditions, thus enabling prothrombotic conditions for circulating blood. AF patients with high LA fibrotic burden had more prothrombotic regions, providing more sites for potential clot formation, thus increasing their risk of stroke.

scholarly journals Effect of the Alterations in Contractility and Morphology Produced by Atrial Fibrillation on the Thrombosis Potential of the Left Atrial Appendage

2021 ◽  
Vol 9 ◽  
Author(s):  
Danila Vella ◽  
Alessandra Monteleone ◽  
Giulio Musotto ◽  
Giorgia Maria Bosi ◽  
Gaetano Burriesci
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrium ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Thrombus Formation ◽  
Fluid Dynamic ◽  
Atrial Appendage ◽  
Primary Role ◽  
Shear Strain Rate ◽  
Increased Risk

Atrial fibrillation (AF) is a common arrhythmia mainly affecting the elderly population, which can lead to serious complications such as stroke, ischaemic attack and vascular dementia. These problems are caused by thrombi which mostly originate in the left atrial appendage (LAA), a small muscular sac protruding from left atrium. The abnormal heart rhythm associated with AF results in alterations in the heart muscle contractions and in some reshaping of the cardiac chambers. This study aims to verify if and how these physiological changes can establish hemodynamic conditions in the LAA promoting thrombus formation, by means of computational fluid dynamic (CFD) analyses. In particular, sinus and fibrillation contractility was replicated by applying wall velocity/motion to models based on healthy and dilated idealized shapes of the left atrium with a common LAA morphology. The models were analyzed and compared in terms of shear strain rate (SSR) and vorticity, which are hemodynamic parameters directly associated with thrombogenicity. The study clearly indicates that the alterations in contractility and morphology associated with AF pathologies play a primary role in establishing hemodynamic conditions which promote higher incidence of ischaemic events, consistently with the clinical evidence. In particular, in the analyzed models, the impairment in contractility determined a decrease in SSR of about 50%, whilst the chamber pathological dilatation contributed to a 30% reduction, indicating increased risk of clot formation. The equivalent rigid wall model was characterized by SSR values about one order of magnitude smaller than in the contractile models, and substantially different vortical behavior, suggesting that analyses based on rigid chambers, although common in the literature, are inadequate to provide realistic results on the LAA hemodynamics.

scholarly journals Addressing Stroke Risk in a Patient with CREST Syndrome and Atrial Fibrillation with Left Atrial appendage Occluder Device (WATCHMAN)

2021 ◽  
Vol 4 (1) ◽  
pp. 01-04
Author(s):  
Ali Alkhayru
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrial ◽  
Stroke Risk ◽  
Left Atrial Appendage ◽  
Bleeding Risk ◽  
Atrial Appendage ◽  
Crest Syndrome ◽  
Increased Risk ◽  
Occluder Device ◽  
One Year

CREST syndrome is rare autoimmune disease causing calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly and telangiectasias. We present a case of an eighty-two year old female with CREST syndrome who presented to our clinic with atrial fibrillation and prohibitive bleeding risk. Managing stroke risk in atrial fibrillation is essential to minimize the morbidity and mortality of the condition. Those with CREST syndrome presenting with recurrent gastrointestinal bleeding may require alternatives to anticoagulation. Recently, the left atrial appendage occluder device became widely used to manage patients at increased risk for bleeding. The device provides a safe and efficacious alternative in lowering atrial fibrillation associated stroke risk. Our patient underwent uncomplicated implantation of the left atrial appendage occluder device. She was closely monitored for one year where she remained stroke free and had one minor episode of gastrointestinal hemorrhage.

scholarly journals Double-blind, placebo-controlled randomised clinical trial to evaluate the effect of ASPIRIN discontinuation after left atrial appendage occlusion in atrial fibrillation: protocol of the ASPIRIN LAAO trial

BMJ Open ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. e044695
Author(s):  
Mu Chen ◽  
Qunshan Wang ◽  
Jian Sun ◽  
Peng-Pai Zhang ◽  
Wei Li ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Ethics Committee ◽  
Aspirin Therapy ◽  
Atrial Appendage ◽  
Control Group ◽  
Coronary Syndrome ◽  
Left Atrial Appendage Occlusion ◽  
Increased Risk

IntroductionIt is the common clinical practice to prescribe indefinite aspirin for patients with non-valvular atrial fibrillation (NVAF) post left atrial appendage occlusion (LAAO). However, aspirin as a primary prevention strategy for cardiovascular diseases has recently been challenged due to increased risk of bleeding. Therefore, aspirin discontinuation after LAAO in atrial fibrillation (ASPIRIN LAAO) trial is designed to assess the uncertainty about the risks and benefits of discontinuing aspirin therapy at 6 months postimplantation with a Watchman LAAO device in NVAF patients.Methods and analysisThe ASPIRIN LAAO study is a prospective, multicentre, randomised, double-blinded, placebo-controlled non-inferiority trial. Patients implanted with a Watchman device within 6 months prior to enrollment and without pre-existing conditions requiring long-term aspirin therapy according to current guidelines are eligible for participating the trial. Subjects will be randomised in a 1:1 allocation ratio to either the Aspirin group (aspirin 100 mg/day) or the control group (placebo) at 6 months postimplantation. A total of 1120 subjects will be enrolled from 12 investigational sites in China. The primary composite endpoint is stroke, systemic embolism, cardiovascular/unexplained death, major bleeding, acute coronary syndrome and coronary or periphery artery disease requiring revascularisation at 24 months. Follow-up visits are scheduled at 6 and 12 months and then every 12 months until 24 months after the last patient recruitment.Ethics and disseminationEthics approval was obtained from the Ethics Committee of Xinhua Hospital, Shanghai, China (reference number XHEC-C-2018-065-5). The protocol is also submitted and approved by the institutional Ethics Committee at each participating centre. Results are expected in 2024 and will be disseminated through peer-reviewed journals and presentations at national and international conferences.Trial registration numberNCT03821883.

Abstract 18516: Regional Dysfunction of Left Atrial Appendage and its Association with Stroke in Atrial Fibrillation

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Abdullah A Alissa ◽  
Yuko Inoue ◽  
Jochen Cammin ◽  
Qiulin Tang ◽  
Elliot Fishman ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Atrial Appendage ◽  
Control Group ◽  
Prior History ◽  
Area Change ◽  
Increased Risk ◽  
History Of ◽  
Regional Dysfunction

Background: Atrial Fibrillation (AF) is associated with an increased risk of cardioembolic stroke. Previous studies demonstrate that the Left atrial appendage (LAA) is the most common site of intracardiac thrombus, and the LAA morphology alone may determine the risk of stroke. We aimed to determine the association between LAA regional dysfunction using novel, noninvasive, image-based motion-estimation CT (iME) and prior history of stroke in patients with AF. Methods: Among the patients with history of AF referred for ablation who underwent pre-ablation CT with retrospective ECG gating, we identified 18 patients with a prior history of stroke or TIA, and 18 age- and gender-matched controls. The patients in AF at the time of CT were excluded. Four-dimensional motion vector field was estimated from reconstructed CT images using iME at every 5% RR interval. To assess myocardial deformation, area change ratio and area change rate were calculated over the endocardial surface of the LA and LAA. Univariate and multivariate comparisons were made by using binary logistic regression model. Results: A total of 36 patients (mean age 67.6 ± 8.1 years, 66.7% male, 16.7% persistent AF) were included in the study. Univariate analysis showed that the LA pre-atrial contraction area change ratio and LAA maximum area change ratio were significantly lower (P= 0.02 and 0.04, respectively) in the stroke/TIA group compared to the control group. These changes remained statistically significant in multivariate analysis (P=0.03 and 0.04, respectively) after adjusting for age, sex, body mass index, LV ejection fraction, type of AF, and CHADS score. Conclusions: LAA regional dysfunction is associated with stroke/TIA in patients with AF. LAA regional dysfunction detected by iME could represent a marker for stroke and a possible therapeutic target.

scholarly journals CHA2DS2-VASc score, left atrial size and atrial fibrillation as stroke risk factors in the Tromsø Study

Open Heart ◽  
2016 ◽  
Vol 3 (2) ◽  
pp. e000439 ◽  
Author(s):  
Sweta Tiwari ◽  
Maja-Lisa Løchen ◽  
Bjarne K Jacobsen ◽  
Laila A Hopstock ◽  
Audhild Nyrnes ◽  
...  
Keyword(s):  
Risk Factors ◽  
Atrial Fibrillation ◽  
Left Atrial ◽  
Stroke Risk ◽  
Left Atrial Size ◽  
Stroke Risk Factors ◽  
Atrial Size

A Proof of Concept for Computational Fluid Dynamic Analysis of the Left Atrium in Atrial Fibrillation on a Patient-Specific Basis

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Alessandro Masci ◽  
Martino Alessandrini ◽  
Davide Forti ◽  
Filippo Menghini ◽  
Luca Dedé ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Risk Stratification ◽  
Left Atrium ◽  
Stroke Risk ◽  
Fluid Dynamic ◽  
Blood Stasis ◽  
Patient Specific ◽  
Computational Fluid Dynamic Analysis ◽  
Cerebrovascular Events ◽  
Hemodynamic Information

Abstract Atrial fibrillation (AF) is associated with a fivefold increase in the risk of cerebrovascular events, being responsible of 15–18% of all strokes. The morphological and functional remodeling of the left atrium (LA) caused by AF favors blood stasis and, consequently, stroke risk. In this context, several clinical studies suggest that the stroke risk stratification could be improved by using hemodynamic information on the LA and the left atrial appendage (LAA). The goal of this study was to develop a personalized computational fluid dynamics (CFD) model of the LA which could clarify the hemodynamic implications of AF on a patient-specific basis. In this paper, we present the developed model and its application to two AF patients as a preliminary advancement toward an optimized stroke risk stratification pipeline.

scholarly journals Subclinical and Device-Detected Atrial Fibrillation: Pondering the Knowledge Gap: A Scientific Statement From the American Heart Association

Circulation ◽  
2019 ◽  
Vol 140 (25) ◽  
Author(s):  
Peter A. Noseworthy ◽  
Elizabeth S. Kaufman ◽  
Lin Y. Chen ◽  
Mina K. Chung ◽  
Mitchell S.V. Elkind ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Stroke Risk ◽  
American Heart ◽  
Electronic Devices ◽  
Heart Association ◽  
Cardiac Implantable Electronic Devices ◽  
Increased Risk ◽  
Scientific Statement ◽  
Existing Data

The widespread use of cardiac implantable electronic devices and wearable monitors has led to the detection of subclinical atrial fibrillation in a substantial proportion of patients. There is evidence that these asymptomatic arrhythmias are associated with increased risk of stroke. Thus, detection of subclinical atrial fibrillation may offer an opportunity to reduce stroke risk by initiating anticoagulation. However, it is unknown whether long-term anticoagulation is warranted and in what populations. This scientific statement explores the existing data on the prevalence, clinical significance, and management of subclinical atrial fibrillation and identifies current gaps in knowledge and areas of controversy and consensus.

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