4D Magnetic Resonance Imaging for Atrial Flow Assessment in Atrial Fibrillation

4D 磁共振成像用于心房颤动心房血流评估

基本信息

批准号：
8605912
负责人：
JEFFREY J GOLDBERGER
金额：
$ 21.62万
依托单位：
NORTHWESTERN UNIVERSITY AT CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-01-16 至 2015-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8605912
关键词：
Affect Age American Anatomy Anticoagulant therapy Anticoagulants Anticoagulation Area Arrhythmia Atrial Fibrillation Blood Blood Vessels Brain Cardiac Cardiovascular system Characteristics Chest Cicatrix Clinical Coagulation Process Complement Complication Development Diabetes Mellitus Embolism Evaluation Evaluation Indexes Event Future Glean Goals Heart Heart Atrium Hemorrhage Hypertension Imagery Imaging Techniques Individual Interobserver Variability Intraobserver Variability Left Left atrial structure Length Link Magnetic Resonance Imaging Maps Measurement Methods Patients Pattern Performance Physicians Physiological Predictive Value Prevention therapy Protocols documentation Pulmonary Embolism Recording of previous events Reporting Right atrial structure Risk Risk Factors Role Scanning Side Sinus Stratification Stroke Stroke prevention Surveys Techniques Testing Therapeutic Embolization Thromboembolism Thrombophilia Thrombus Time Ultrasonography Ventricular Warfarin auricular appendage base clinical practice clinical risk college high risk improved indexing insight migration novel population based public health relevance residence screening statistics tool

项目摘要

DESCRIPTION (provided by applicant): Atrial fibrillation (AF) affects over 2.2 million Americans, with projections of 12 million people by 2050. Stroke is the most serious complication of AF -15-20% of all strokes occurring in patients with AF - and results from thrombus formation in the left atrium (LA) and subsequent embolization. Stroke prevention in AF focuses on inhibiting thrombus formation with the use of warfarin in selected high risk patients. Although warfarin is effective at reducing stroke risk, it is also associated with a 3.4% annual risk of major bleeding. Clinicians utilize risk scores to identify patients who benefit from warfarn. However, an expert panel of the American College of Chest Physicians recently reported that the predictive value of these scores is mediocre, at best. This means that many patients who are not receiving warfarin will suffer a stroke while many patients who are treated with warfarin are being unnecessarily exposed to the risk of major bleeding. One reason for the subpar performance of these scores is that they are comprised of clinical risk factors (e.g. age > 75 years, high blood pressure) that are associated with stroke on a population basis but are not specifically related to thrombus formation in an individual based on physiologic principles. One of the key factors responsible for thrombus formation is blood stasis in the LA. Studies using ultrasound have linked markers of low flow in the LA to risk of stroke. However, this technique is not suitable for widespread screening and is unable to map 3D flow. The novel technique of functional 4D cardiovascular magnetic resonance imaging (4DcMRI) incorporating time- resolved 3D anatomy and 3D blood velocity information can assess 3D flow characteristics and is uniquely suited to evaluate blood stasis within the LA and right atrium (RA). We will apply thi technique to evaluate whether differences in stasis or flow patterns in the LA and RA appendages explain the approximately 10-fold greater risk of LA versus RA appendage thrombus formation and the 10-fold greater risk of systemic versus pulmonary embolism in AF. We hypothesize that stasis and regions with altered flow patterns are more common in the LA versus RA appendage in patients with AF at risk for intraatrial thrombus formation. We will a) optimize the 4DcMRI settings for flow characterization in AF patients; b) develop semi-automated analysis tools to calculate indices of stasis and assess 3D flow patterns; and c) compare flow patterns in two groups: 1) patients with persistent AF and documented prior atrial thrombus or thromboembolic stroke; 2) patients with persistent AF for >4 years not treated with warfarin and without history of LA thrombus or thromboembolic event. The hypothesis is that indices of stasis and flow pattern alterations will be significantly different in the LA versus RA appendage in Group 1 versus 2. This project will help determine whether 4DcMRI can be used to provide physiologic information regarding the risk for thrombus formation. The long-term goal is to evaluate whether individualized evaluation of indices of stasis can provide additional valuable information to advise which AF patients require warfarin therapy, thereby reducing both strokes and bleeding complications.

描述（由申请人提供）：心房颤动 (AF) 影响着超过 220 万美国人，预计到 2050 年这一数字将达到 1200 万。中风是 AF 最严重的并发症 - 占 AF 患者发生的所有中风的 15-20% - 并且左心房 (LA) 血栓形成和随后的栓塞的结果。房颤的中风预防重点是在选定的高危患者中使用华法林来抑制血栓形成。尽管华法林可有效降低中风风险，但它也与每年 3.4% 的大出血风险相关。临床医生利用风险评分来识别从华法恩中受益的患者。然而，美国胸科医师学会的一个专家小组最近报告称，这些分数的预测价值充其量是平庸的。这意味着许多未接受华法林治疗的患者将遭受中风，而许多接受华法林治疗的患者则不必要地面临大出血的风险。这些评分表现不佳的原因之一是，它们由临床危险因素（例如年龄 > 75 岁、高血压）组成，这些因素与人群中的中风相关，但与个体中的血栓形成没有特定关系。就生理原理而言。血栓形成的关键因素之一是洛杉矶的血瘀。使用超声波的研究已将洛杉矶低流量标记与中风风险联系起来。然而，该技术不适合广泛筛查，并且无法绘制 3D 血流图。功能性 4D 心血管磁共振成像 (4DcMRI) 新技术结合了时间分辨 3D 解剖结构和 3D 血流速度信息，可以评估 3D 血流特征，并且特别适合评估 LA 和右心房 (RA) 内的血流淤滞。我们将应用这项技术来评估左心耳和右耳肢的瘀滞或血流模式的差异是否解释了左心耳血栓形成风险比右耳肢血栓形成高约 10 倍，以及 AF 中全身栓塞风险比肺栓塞风险高出 10 倍。我们假设，对于有房内血栓形成风险的 AF 患者，左心耳与右心耳相比，瘀滞和血流模式改变的区域更常见。我们将 a) 优化 4DcMRI 设置以用于 AF 患者的血流表征； b) 开发半自动分析工具来计算停滞指数并评估 3D 流动模式； c) 比较两组血流模式：1) 患有持续性房颤且有既往心房血栓或血栓栓塞性中风记录的患者； 2) 持续性房颤超过 4 年且未接受华法林治疗且无 LA 血栓或血栓栓塞事件病史的患者。假设第 1 组和第 2 组的左心耳和右心耳的瘀滞指数和血流模式改变将显着不同。该项目将有助于确定 4DcMRI 是否可用于提供有关血栓形成风险的生理信息。长期目标是评估瘀滞指数的个体化评估是否可以提供额外的有价值的信息，以建议哪些房颤患者需要华法林治疗，从而减少中风和出血并发症。