CT-Based Coronary Plaque Feature Detection for Predicting Myocardial Ischemia

描述(由申请人提供)：医生在推荐血管成形术或外科搭桥手术治疗冠状动脉阻塞时，通常依赖两项诊断测试信息：冠状动脉因斑块(斑块是细胞、胆固醇和碎片的堆积)而变窄的程度，以及这种狭窄导致心肌血流量减少(“心肌低灌流”)的程度。1有证据表明，即使严重堵塞的冠状动脉通常也不会产生显著的心肌低灌流，2表明除了堵塞严重之外，还有其他过程在起作用。一种可能的致病过程阻碍了冠状动脉对血流的正常扩张能力。这一过程的触发因素还会在冠状动脉计算机断层血管成像(CCTA)3-11--一种直接成像冠状动脉斑块的非侵入性、低风险测试中可见的斑块外观(称为“不良特征”)中产生某些变化。该项目的目的是评估在导致严重阻塞的斑块中发现不良特征是否会增加患者出现明显心肌低灌注率的机会。我们的假设是，CCTA发现任何不良斑块特征将预示更大的心肌低灌注率。我们将研究56名非糖尿病患者，他们刚刚在CCTA上被诊断为严重的冠状动脉阻塞，并将继续进行基于导管的冠状动脉造影术，以可能进行血管成形术。CCTA上的斑块发现将把人群分成两组：28组将没有不良特征，28组将显示至少一种不良特征。在基于导管的血管造影术之前，每个患者都将接受正电子发射断层扫描的心脏成像，以测量受影响的冠状动脉在静息和药物诱导的“应激”期间供应给心肌的血流量。在进行基于导管的血管造影术时，每个患者都将接受直接测量斑块引起的液体压降。正电子发射断层扫描结果和压降测量结果将在两组患者之间进行比较，以确定不良特征的存在与心肌低灌注量之间的关系。该项目的实施旨在扩大目前对如何识别重要冠状动脉阻塞的理解，探索为什么某些斑块比其他斑块导致更多的心肌低灌流，并改善CCTA的临床和研究应用。 公共卫生相关性：项目叙述(相关性)在严重的慢性冠状动脉疾病的治疗中，血管成形术和外科搭桥手术的最大好处是那些动脉粥样硬化斑块积聚导致心肌血流显著受限的患者。虽然当冠状动脉严重阻塞时，通常认为血流减少，但许多严重的阻塞实际上并不会造成明显的血流限制，原因尚不清楚。一种可能的解释是动脉壁的损伤量，这可能会阻碍冠状动脉维持血流的能力。该项目将评估非侵入性和安全的冠状动脉扫描检测到的与动脉壁损伤相关的斑块外观的某些变化是否有助于识别导致血流量显著减少的冠状动脉阻塞。提高我们对这种关系的理解将有助于指导未来研究导致心肌血流量减少的机制，并提高冠心病患者诊断测试的效率。

DESCRIPTION (provided by applicant): Doctors often rely on two pieces of diagnostic testing information when making recommendations regarding angioplasty or surgical bypass to treat coronary artery blockage: How severely a coronary artery is narrowed by plaque (plaque is a build-up of cells, cholesterol, and debris), and how much reduction in blood flow to the heart muscle ("myocardial hypoperfusion") is caused by this narrowing.1 There is evidence showing that even severely blocked coronary arteries frequently do not produce significant myocardial hypoperfusion,2 indicating that processes other than blockage severity are at work. One possible contributing process handicaps the normal ability of the coronary artery to dilate in response to blood flow. Triggers for this process also create certain changes in plaque appearance (termed "adverse features") visible on coronary computed tomographic angiography (CCTA)3-11 - a noninvasive, low-risk test that directly images coronary arterial plaque. The objective of this project is to evaluate whether finding adverse features in plaques causing severe blockage increases the patient's chances of having significant myocardial hypoperfusion. Our hypothesis is that finding any adverse plaque feature by CCTA will predict greater myocardial hypoperfusion. We will study 56 non-diabetic patients who have just been diagnosed with severe coronary artery blockage on CCTA and will be proceeding to catheter-based coronary angiography for possible angioplasty. Plaque findings on CCTA will separate the population into 2 groups: 28 will show no adverse features, and 28 will show at least 1 adverse feature. Prior to catheter-based angiography, each patient will undergo heart imaging with positron-emission tomography to measure blood flow to the heart muscle supplied by the affected coronary artery at rest and during medication-induced "stress". At the time of catheter-based angiography, each patient will undergo direct measurement of fluid pressure drop caused by the plaque. Positron-emission tomography results and pressure drop measurements will be compared between the 2 patient groups to determine the relationship between presence of adverse features and myocardial hypoperfusion. Performance of this project is intended to expand the current understanding of how to identify important coronary artery blockages, explore why certain plaques cause more myocardial hypoperfusion than others, and improve both clinical and research use of CCTA. PUBLIC HEALTH RELEVANCE: PROJECT NARRATIVE (RELEVANCE) In the treatment of severe chronic coronary artery disease, the greatest benefit for angioplasty and surgical bypass are in patients whose atherosclerotic plaque build-up causes significant limitation of blood flow to the heart muscle. Although reduced blood flow is often assumed when coronary artery blockage is severe, many severe blockages do not actually cause demonstrable blood flow limitation, and the reason is not known. One potential explanation is the amount of damage to the arterial wall, which can handicap the coronary artery's ability to maintain blood flow. This project will evaluate whether certain changes in plaque appearance related to arterial wall injury, as detected by a noninvasive and safe coronary artery scan, enhance the identification of coronary artery blockages that cause significant reduction in blood flow. Improving our understanding of this relationship will help direct future efforts in researching mechanisms that cause reduced blood flow to the heart muscle and increase the efficiency of diagnostic testing for patients with coronary artery disease.