Anatomic and Physiologic Determinants of Vessel-Specific Ischemia by Coronary CT

描述（由申请人提供）：本提案的总体目标是整合计算机断层扫描血管造影片的解剖和生理信息，以精确识别导致缺血的冠状动脉病变。本提案是ISCHEMIA试验的伴随研究。对于稳定性缺血性心脏病患者，心肌缺血可能是阻塞性冠状动脉疾病（CAD）的结果，并可用于指导血运重建的决策。迄今为止，非侵入性负荷试验已成为确定缺血的主要手段;这些试验包括超声心动图、磁共振和心肌灌注断层扫描（MPS）。其中，MPS是最常见的，因为它能够识别阻塞性CAD，重新分类CAD可能性，并预测不良事件。CT已成为一种非侵入性方法，可直接显示CAD，与侵入性冠状动脉造影（伊卡）相比，对阻塞性CAD表现出更高的性能，并可预测不良预后。除狭窄外，CT还可评价其他动脉粥样硬化斑块特征（APC），这些特征与侵入性方法高度一致，并可增强对导致缺血的冠状动脉病变的确定。CT的最新发展还允许通过将计算流体动力学应用于通常采集的CT扫描来计算冠状动脉压力和流量，从而实现血流储备分数（FFRCT）的非侵入性计算，这是血管特异性缺血的量度。该提案的总体假设是，将解剖APC与生理FFRCT相结合将优化缺血引起的冠状动脉病变的识别。我们提出了3个具体目标：目的1：通过CT评估解剖APC诊断血管特异性缺血的性能。目的2：评价生理性FFRCT诊断血管特异性缺血的性能。目的3：直接比较综合解剖-生理（APC-FFRCT）CT测量与MPS用于诊断病变特异性缺血。本提案中的工作将为一种新的诊断范式提供理论基础，该范式比传统的应力成像测试更准确，可用于识别表现出缺血的患者并精确定位病因的冠状动脉病变;因此，可以更好地选择进行血运重建的个体并消除不必要的侵入性手术。

DESCRIPTION (provided by applicant): The OVERALL OBJECTIVE of this proposal is to integrate the anatomic and physiologic information derived from computed tomographic angiograms for the precise identification of coronary artery lesions that cause ischemia. This proposal is a companion study to ISCHEMIA Trial. For patients with stable ischemic heart disease, myocardial ischemia may arise as a consequence of obstructive coronary artery disease (CAD) and is useful for guiding decisions of revascularization. To date, non-invasive stress tests have served as a mainstay for identifying ischemia; these tests include echocardiography, magnetic resonance and myocardial perfusion scintigraphy (MPS). Among these, MPS is performed most commonly due to its ability to identify obstructive CAD, reclassify CAD likelihood, and predict adverse events. CT has emerged as a non-invasive method that permits direct visualization of CAD, demonstrates high performance for obstructive CAD compared to invasive coronary angiography (ICA), and predicts adverse prognosis. Beyond stenosis, CT enables evaluation of additional atherosclerotic plaque characteristics (APCs) that demonstrate high agreement to invasive methods and may augment determination of coronary lesions that cause ischemia. Recent developments in CT also permit physiologic assessment of CAD by applying computational fluid dynamics to typically- acquired CT scans for calculation of coronary artery pressure and flow, thus enabling the non-invasive calculation of fractional flow reserve (FFRCT), a measure of vessel-specific ischemia. The OVERALL HYPOTHESIS of this proposal is that integrating anatomic APCs with physiologic FFRCT will optimize identification of coronary lesions that are ischemia-causing. We propose 3 specific aims: AIM 1: To assess performance of anatomic APCs by CT for diagnosis of vessel-specific ischemia. AIM 2: To assess performance of physiologic FFRCT for diagnosis of vessel-specific ischemia. AIM 3: To directly compare an integrated anatomic-physiologic (APC-FFRCT) CT measure to MPS for diagnosis of lesion-specific ischemia. The work in this proposal will provide the rationale for a novel diagnostic paradigm that is more accurate than conventional stress imaging testing for identifying patients who manifest ischemia and pinpointing the coronary lesions that are the cause; thus, allowing for better selection of individuals for revascularization and eliminating unnecessary invasive procedures.