64层螺旋CT冠状动脉成像在冠心病诊断中的初步应用

目的 评价64层螺旋CT冠状动脉成像（coronary 64-slice computed tomographic angiography,64S-CCTA）在诊断冠状动脉疾病（CAD）中的临床应用价值.方法 回顾性分析92例行64S-CCTA患者完整资料,并以近期（2周之内）实施的X线冠状动脉造影检查（coronary artery disease,CAG）结果为金标准进行对比.结果 所有可用于评估1,129段冠脉中,64S-CCTA显示轻度和明显狭窄病变各为122、231段,其中各有61、198段得到CAG证实;64S-CCTA判断冠状动脉明显狭窄的灵敏度、特异度、阳性预测值、阴性预测值、阳性似然比、阴性似然比分别为88.39%、96.35%、85.71%、97.10%及24.22、0.12;在CAG确诊狭窄节段中,64S-CCTA在轻度狭窄和明显狭窄中分别检测出非钙化性斑块、钙化斑块各为32、65 和154、53个.结论 64S-CCTA是一种简便、可靠的无创性检查方法,对病变血管管腔狭窄及不同性质粥样硬化斑块与狭窄关系的评价有一定价值,可作为临床拟诊冠心病患者筛查的有效手段.     

冠周脂肪影像组学鉴别冠状动脉狭窄程度初探

目的 初步探讨基于冠脉CTA(CCTA)图像上冠状动脉周围脂肪(PCAT)的影像组学模型对冠状动脉狭窄程度的鉴别诊断.方法 回顾性分析319例接受CCTA检查者的临床、影像资料,分为三组,包括正常组(101例202支经CCTA评估为正常者),轻中度组[74例74支经数字减影血管造影(DSA)评估为轻中度狭窄者],重度组...     

Prognostic value of coronary CT angiography on long-term follow-up of 6.9 years

Long term follow-up of coronary CT angiography (CCTA) is scarce. The aim of the present study was to assess the prognostic value of CCTA over a follow-up period of more than 6 years. 218 Patients were included undergoing 64-slice CCTA. Images were analysed with regard to the presence of nonobstructive (<50 %) or obstructive (50 % stenosis) coronary artery disease (CAD). Major adverse cardiovascular events (MACE) were defined as death, nonfatal myocardial infarction or urgent coronary revascularization. CCTA revealed normal coronaries in 49, nonobstructive lesions in 94, and obstructive CAD in 75 patients. During a median follow-up period of 6.9 years, MACE occurred in 45 patients (21 %). Annual MACE rates were 0.3, 2.7, and 6.0 % (p = 0.001), for patients with normal CCTA, nonobstructive, and obstructive CAD, respectively. Multivariate Cox regression analysis identified the number of segments with plaques [hazard ratio (HR) 1.18, p = 0.002] as well as the presence of obstructive lesions (HR 2.28, p = 0.036) as independent predictors of MACE. The present study extends the predictive value of CCTA over more than 6 years. Patients with normal coronary arteries of CCTA continue to have an excellent cardiac prognosis, while outcome is progressively worse in patients with nonobstructive and obstructive CAD.     

Coronary CT angiography in patients with high calcium score: evaluation of plaque characteristics and diagnostic accuracy

Our aim was to evaluate the plaque characteristics of coronary arteries related to significant stenosis with coronary CT angiography (CCTA) and to discuss the diagnostic accuracy of CCTA in patients with high calcium scores. After institutional review board approval, 110 patients (63 men; mean age: 67.1 ± 7.9 years) with Agatston scores >400 were retrospectively reviewed. Patients underwent Agatston calcium scoring and 64-slice CCTA, in addition to invasive coronary angiography (CAG). The composition (calcified, mixed, and non-calcified) and configuration (concentric, eccentric) of coronary artery plaques were analyzed on a per-segment basis by CCTA. We analyzed the differences in plaque composition and configuration between significant (≥ 50%) and non-significant (<50%) stenosis. Additionally, the diagnostic accuracy of stenosis according to plaque composition was evaluated by CCTA, using CAG as a reference method. Significant differences in plaque composition and configurations were observed between the two groups. In cases of significant stenosis, the proportions of concentric, mixed, and non-calcified plaques were significantly higher than those of eccentric and calcified plaques (P < 0.001). The sensitivity and positive predictive value of mixed (97.4, 87.6%) and non-calcified plaques (97.8, 95.7%) were significantly higher than those of calcified plaques (87.6, 67.2%). Although CCTA has limited value due to low diagnostic accuracy of calcified plaques, knowledge about the high frequencies of mixed and non-calcified plaques in significant stenosis help to make an accurate assessment of CAD with CCTA in patients with high calcium scores.     

Myocardial ischemia detection with single-phase CT perfusion in symptomatic patients using high-pitch helical image acquisition technique

Coronary CT angiography (CCTA) suffers from a reduced diagnostic accuracy in patients with heavily calcified coronary arteries or prior myocardial revascularisation due to artefacts caused by calcifications and stent material. CT myocardial perfusion imaging (CTMPI) yields high potential for the detection of myocardial ischemia and might help to overcome the above mentioned limitations. We analysed CT single-phase perfusion using high-pitch helical image acquisition technique in patients with prior myocardial revascularisation. Thirty-six patients with an indication for invasive coronary angiography (28 with coronary stents, 2 with coronary artery bypass grafts and 6 with both) were included in this prospective study at two study sites. All patients were examined on a 2nd generation dual-source CT system. Stress CT images were obtained using a prospectively ECG-triggered single-phase high-pitch helical image acquisition technique. During stress the tracer for myocardial perfusion (MP) SPECT imaging was administered. Rest CT images were acquired using prospectively ECG-triggered sequential CT. MP-SPECT imaging and invasive coronary angiography served as standard of reference. In this heavily diseased patient cohort CCTA alone showed a low overall diagnostic accuracy for detection of hemodynamically relevant coronary artery stenosis of only 31% on a per-patient base and 60% on a per-vessel base. Combining CCTA and CTMPI allowed for a significantly higher overall diagnostic accuracy of 78% on a per-patient base and 92% on a per-vessel base (p?<?0.001). Mean radiation dose for stress CT scans was 0.9 mSv, mean radiation dose for rest CT scans was 5.0 mSv. In symptomatic patients with known coronary artery disease and prior myocardial revascularization combining CCTA and CTMPI showed significantly higher diagnostic accuracy in detection of hemodynamically significant coronary artery stenosis when compared to CCTA alone.     

The prognostic value of multidetector coronary CT angiography for the prediction of major adverse cardiovascular events: a multicenter observational cohort study

To assess the prognostic value of coronary artery stenosis identification by coronary computed tomographic angiography (CCTA) for the prediction of major adverse cardiac events (MACE) in a multicenter prospective cohort study. We performed a prospective multicenter observational cohort study of symptomatic patients with suspected or known coronary artery disease (CAD) (n = 172; 57% male) undergoing CCTA in accordance to ACC/AHA Appropriateness Criteria from 4 sites in and around Paris, France, and followed for a mean duration of 22.0 ± 4.5 months (interquartile range 18–26 months). Coronary arteries by CCTA were interpreted by physicians blinded to the patient characteristics for the presence or absence obstructive (≥70% luminal diameter stenosis), as well as for plaque composition categorized as non-calcified, calcified or “mixed.” MACE was defined as death, non-fatal myocardial infarction, unstable angina or target vessel revascularization. MACE event rates were compared between patients with or without obstructive plaque and with differing plaque compositions. MACE event rates were significantly higher in patients with obstructive coronary artery stenosis by CCTA compared to those without (61.1% vs. 3.9%, P < 0.01). In patients with obstructive stenosis, mixed (83.3% vs. 25.3%, P < 0.01) and calcified (94.4% vs. 50.7%, P < 0.01) plaque presence was significantly higher than in patients without obstructive stenosis, with no differences in prevalence of non-calcified plaque (27.8% vs. 20.8%, P = NS). For MACE, the negative predictive value of no observed coronary artery plaque was 100% in the follow-up period. In this prospective multicenter study of symptomatic patients with suspected or known CAD undergoing CCTAs interpreted by imagers blinded to patient characteristics, CCTA presence of plaque severity and composition successfully identifies patients at risk for incident MACE events. Importantly, a negative CCTA portends an extremely low risk for incidence MACE.     

Dose-Finding Study of Landiolol Hydrochloride: A Short-Acting β1-Blocker for Controlling Heart Rate During Coronary Computed-Tomography Angiography in Japan

Introduction

Coronary computed-tomography angiography (CCTA) has high diagnostic performance, but it sometimes does not allow evaluation because of artifacts. Currently, the use of a β-blocker is recommended to prevent motion artifacts, but the β-blocker (metoprolol, propranolol, etc.) commonly used has a slow onset and long duration of action. Landiolol hydrochloride is an intravenous β₁-blocker with a very short half-life. We investigated the efficacy and optimal dose of this drug for reduction of heart rate in patients undergoing CCTA.

Methods

Eighty-seven subjects with ischemic heart disease were divided into three groups to receive landiolol hydrochloride at a dose of 0.125 (Group L), 0.25 (Group M), or 0.5 mg/kg (Group H). CCTA was performed at 3–7 min after administration, and heart rate, blood pressure, and image quality were assessed.

Results

Heart rate decreased rapidly after completion of landiolol hydrochloride administration in all groups, with a heart rate reduction of 15.55 ± 6.56% in Group L, 16.48 ± 7.80% in Group M, and 21.49 ± 6.13% in Group H (Group L vs Group H, P = 0.0008; Group M vs Group H, P = 0.0109). Since there was no significant difference in heart rate during imaging among the three groups, although there was a significant difference between groups L and H and groups M and H in terms of percent change in heart rate, coronary stenosis was diagnosable in all groups with no significant difference.

Conclusion

Landiolol hydrochloride showed a rapid onset and short β-blocking effect, and was most effective at a dose of 0.5 mg/kg. However, the diagnosable proportion had no significant differences among the three groups in CCTA. Therefore, the clinically recommended dose was 0.125 mg/kg or less, considering the heart rate of patients with suspected coronary stenosis during CCTA.     

CT-based myocardial ischemia evaluation: quantitative angiography,transluminal attenuation gradient,myocardial perfusion,and CT-derived fractional flow reserve

The detection of hemodynamically significant stenosis is important because ischemia-guided revascularization improves overall patient outcomes. Fractional flow reserve (FFR), which is measured during invasive coronary angiography, is regarded as the gold standard for determining hemodynamically significant coronary stenosis. Although coronary computed tomography angiography (CCTA) has been widely used to exclude significant coronary artery disease in patients with low to intermediate pretest probability, anatomic assessment by CCTA using diameter stenosis ≥50 % does not correlate well with the functional assessment of FFR. To overcome the weaknesses of conventional CCTA, such as its low specificity and positive predictive value, especially in patients with a small-diameter artery, poor image quality, or high calcium score, more sophisticated CCTA analysis methods have been developed to detect hemodynamically significant coronary stenosis. Studies that use the quantification of coronary plaque, transluminal attenuation gradient (TAG), CT myocardial perfusion (CTP), and CT-derived FFR have been conducted to validate their diagnostic performances, though each method has its pros and cons. This review provides details on the quantification of coronary plaque, TAG, CTP, and CT-derived FFR, including a definition of each, how to gather and interpret data, and the strengths and limitations of each. Further, we provide an overview of recent clinical studies.     

Cardiac CT for acute chest pain in the emergency department: advantages of prospective triggering

Coronary CT angiography (CCTA) is emerging as a powerful tool for the diagnosis and characterization of coronary artery disease. In the emergency department (ED) setting, the high negative predictive value of CCTA has been shown to reduce the length of stay and the cost of care in the evaluation of patients at low and intermediate risk for an acute coronary syndrome (ACS). In addition, CCTA and triple-rule-out protocol CT examinations which simultaneously evaluate the coronary arteries, aorta and pulmonary arteries, have the potential to diagnose not only significant atherosclerotic coronary artery disease (CAD) and coronary artery anomalies, but noncoronary etiologies of chest pain, including pulmonary embolism, aortic dissection, infection, pleural and pericardial disease. Caution has been raised about the widespread use of CCTA in this setting, particularly given the prevalence of repeat ED visits for chest pain, due to the radiation exposure associated with retrospectively-gated CCTA. However, the recent development of prospectively-triggered coronary artery CTA makes the ED evaluation possible with a substantially lower radiation exposure to the patient. Although most studies of CCTA to date are performed with retrospective ECG gating, early reports on prospectively triggered CCTA demonstrate equivalent image quality and accuracy when compared to studies acquired with retrospective ECG gating.     

Cardiac CT for acute chest pain in the emergency department: advantages of prospective triggering

Coronary CT angiography (CCTA) is emerging as a powerful tool for the diagnosis and characterization of coronary artery disease. In the emergency department (ED) setting, the high negative predictive value of CCTA has been shown to reduce the length of stay and the cost of care in the evaluation of patients at low and intermediate risk for an acute coronary syndrome (ACS). In addition, CCTA and triple-rule-out protocol CT examinations which simultaneously evaluate the coronary arteries, aorta and pulmonary arteries, have the potential to diagnose not only significant atherosclerotic coronary artery disease (CAD) and coronary artery anomalies, but noncoronary etiologies of chest pain, including pulmonary embolism, aortic dissection, infection, pleural and pericardial disease. Caution has been raised about the widespread use of CCTA in this setting, particularly given the prevalence of repeat ED visits for chest pain, due to the radiation exposure associated with retrospectively-gated CCTA. However, the recent development of prospectively-triggered coronary artery CTA makes the ED evaluation possible with a substantially lower radiation exposure to the patient. Although most studies of CCTA to date are performed with retrospective ECG gating, early reports on prospectively triggered CCTA demonstrate equivalent image quality and accuracy when compared to studies acquired with retrospective ECG gating.     

一日法多巴酚丁胺负荷/静息SPECT心肌灌注显像指导治疗冠心病的临床价值

目的 研究一日法多巴酚丁胺负荷/静息单光子发射计算机断层扫描（SPECT）心肌灌注显像指导治疗冠心病的临床应用价值。 方法 回顾性收集我院2019年5月~2021年7月因胸闷、胸痛就诊的冠心病患者68例,常规行冠状动脉CT血管造影（CCTA）,将患者分为两组：研究组（n = 34）,同期行一日法多巴酚丁胺负荷/静息SPECT心肌灌注显像并依据SPECT结果选择治疗方案;对照组（n = 34）,依据CCTA结果选择治疗方案。确定治疗方案后随诊,比较两组症状缓解率及心血管不良事件发生率,分析SPECT及CCTA推荐的治疗方案差异及原因。 结果 两组间临床病情、冠脉狭窄程度、病变部位及数量差异无统计学意义（P>0.05）。研究组中血运重建治疗3%（1/34）,单纯药物治疗97%（33/34）,症状缓解率100%;对照组中血运重建治疗50%（17/ 34）,单纯药物治疗50%（17/34）,症状缓解率100%。研究组血运重建率低于对照组（χ² = 19.342,P < 0.05）。随诊7~33月（中位数28月）,心血管不良事件发生率对照组3%（1/34）,研究组为0。研究组有14例患者SPECT的治疗建议与CCTA的治疗建议不同,最终这14例患者均依据SPECT结果选择了单纯药物治疗,比依据CCTA结果做决策的冠脉造影率减少约41%（14/34）,单次住院诊疗费用节省约50%。 结论 一日法多巴酚丁胺负荷/静息SPECT心肌灌注显像有利于筛选出不需介入治疗的冠心病患者,其采用单纯药物治疗方案安全有效,相较于目前常用的CCTA筛查,可减少不必要的有创检查及介入手术,降低医疗总费用,缩短住院时间。     

Low-dose prospectively gated 256-slice coronary computed tomographic angiography

Since the introduction of 64-slice scanners, multidetector computed tomography (MDCT) has experienced a marked increase in adoption for the noninvasive assessment of coronary artery disease, although radiation dose concerns remain. The recent introduction of prospective coronary CT angiography (CCTA) has begun to address these concerns; however, its applicability with existing scanners remains limited to cohorts defined by heart rate, heart rate variability, and body mass index. This paper reviews prospective CCTA, the effect of heart rate and heart rate variability on image quality, and the physiologic basis for selection of optimal prospective imaging windows. We then discuss 256-slice technology and our first 4 months of clinical experience with 256-slice prospective CCTA. Our early clinical results indicate that high-quality, low-dose prospective coronary CTA may be applied to patients with higher heart rates, higher BMI, and with less sensitivity to heart rate variability using 256-slice MDCT.     

Economic Considerations for Coronary CT Angiography

In recent years, coronary CT angiography (CCTA) has emerged has a noninvasive anatomic imaging modality that demonstrates high diagnostic performance to detect and exclude high-grade coronary artery stenosis. Proponents of CCTA have advocated its use as an effective alternative to functional stress imaging, while critics have maintained that the benefits of CCTA use remain unproven and may promote unnecessary “layering” of imaging studies on top of conventional stress testing. In this review, we consider the clinical and economic data related to CCTA to date, and suggest future studies that may clarify the role of CCTA in daily clinical evaluation of patients with suspected or known coronary artery disease.     

Low-dose prospectively gated 256-slice coronary computed tomographic angiography

Since the introduction of 64-slice scanners, multidetector computed tomography (MDCT) has experienced a marked increase in adoption for the noninvasive assessment of coronary artery disease, although radiation dose concerns remain. The recent introduction of prospective coronary CT angiography (CCTA) has begun to address these concerns; however, its applicability with existing scanners remains limited to cohorts defined by heart rate, heart rate variability, and body mass index. This paper reviews prospective CCTA, the effect of heart rate and heart rate variability on image quality, and the physiologic basis for selection of optimal prospective imaging windows. We then discuss 256-slice technology and our first 4 months of clinical experience with 256-slice prospective CCTA. Our early clinical results indicate that high-quality, low-dose prospective coronary CTA may be applied to patients with higher heart rates, higher BMI, and with less sensitivity to heart rate variability using 256-slice MDCT.     

ba-PWV、ABI及IMT和冠心病的相关性研究

目的评价肱-踝脉搏波传导速度(ba-PWV)、踝臂指数(ABI)、颈动脉内中膜厚度(IMT)与冠心病冠状动脉狭窄严重程度之间的相关性。方法收集冠心病及可疑冠心病患者167例,结合冠状动脉造影结果,分析ba-PWV、IMT、ABI与冠脉狭窄程度的相关性。结果 ABII、MT、ba-PWV 3个检测指标单一应用时,冠脉单支病变组与非冠心病组相比无显著性差异,双支和多支病变组与非冠心病组相比有显著差异(P<0.01);当ABI、IMT、ba-PWV均异常或任意2个指标为异常与非冠心病组相比,单支病变组亦有显著性差异。结论 ba-PWV、ABI、IMT与冠状动脉病变狭窄程度具有明显相关性。联合应用ba-PWV、ABI和IMT,可用于评价冠状动脉粥样硬化性心脏病的严重程度。     

心包脂肪组织体积与冠状动脉斑块组成的相关性研究

目的：本研究的目的是评估心包脂肪组织（PAT）体积与320排冠状动脉CT造影（CCTA）动脉硬化斑块组成的关系。方法本研究纳入1597例因可疑冠心病而接受320排 CCTA 检查的患者（男1090例,女507例,年龄35～71岁）。其中382例发现存在动脉斑块。我们比较了冠心病和斑块组成[存在斑块、钙化斑块（CP）、非钙化斑块（NCP）、混合斑块（MP）、多支病变和梗阻性狭窄]与无冠心病者的PAT体积。结果单因素分析显示存在CP、NCP、MP及多支血管病变者的PAT体积大于无斑块者[分别为（211.4±93.6）cm3、（233.2±95.0）cm3、（257.3±82.1）cm3及（261.5±101.7）cm3 vs.（173.7±98.1） cm3,P值分别为0.012、0.008、0.004及0.002]。存在梗阻性狭窄者的PAT体积明显大于无斑块者[（279.2±99.81）cm3 vs.（173.7±98.1）cm3,P＜0.001]。在多因素Cox比例风险回归模型分析中,只有MP、多支血管病变和梗阻性狭窄者的PAT体积明显大于无斑块者（P＜0.001）。结论存在冠状动脉斑块、CP、NCP、MP、多支血管病变和梗阻性狭窄患者的PAT体积大于无斑块者,PAT体积是冠心病重要的危险因素之一。     

冠状动脉CT血管造影对先天性右冠状动脉缺如的评价价值

目的总结先天性右冠状动脉缺如患者的临床和冠状动脉CT血管造影（CCTA）影像表现。方法回顾性分析2014年1月~2019年6月于本院行CCTA检查并经选择性冠状动脉造影（SCA）确诊的13例先天性右冠状动脉缺如患者的临床资料和CCTA影像表现。结果13例先天性右冠状动脉缺如患者的临床表现缺乏特异性,大多表现为心血管疾病的临床症状。CCTA平扫显示左主干、左前降支和（或）左回旋支走行区内数量不等、形态各异的高密度钙化斑块形成;增强扫描显示左主干、左前降支和（或）左回旋支不同程度变窄,升主动脉和右冠状窦区均未见右冠状动脉发出,左主干、左前降支和左回旋支均不同程度增粗,并左回旋支延伸至右心室背面,进而发出分支供应右心房和右心室。CCTA与SCA表现基本一致。结论先天性右冠状动脉缺如罕见,其临床表现缺乏特异性,仅凭临床表现往往难以诊断,CCTA联合SCA检查常可用于确诊。     

Coronary Artery Disease Progression: Insights from Cardiac CT

Coronary plaque progression is a multi-faceted process influenced by cardiovascular risk factors, as well as the presence, extent, stenosis, morphology, and vulnerability of plaque, which may ultimately result in myocardial infarction or death. Traditionally, intravascular ultrasound (IVUS) has been the primary modality to study atherosclerosis progression. However, it is invasive and impractical for screening or monitoring. While coronary artery calcium (CAC) scoring has been widely studied as a non-invasive method to measure plaque progression, it is limited to visualization of stenosis and non-calcified plaque. Coronary computed tomographic angiography (CCTA) allows for visualization of the severity of stenosis, plaque burden, plaque morphology, and ability to differentiate between plaque types. Furthermore, certain CCTA plaque features are useful in identifying vulnerable plaque including low attenuation plaque, positive remodeling, spotty calcification, and napkin-ring sign. This review covers multiple aspects of plaque progression—its pathophysiology, clinical implications, and use of novel non-invasive technology for the assessment of plaque progression over time.     

冠状动脉CTA对冠状动脉粥样硬化性心脏病高危人群的随访观察价值

目的 探讨冠状动脉CT血管成像（CCTA）对冠状动脉粥样硬化性心脏病（简称冠心病）高危险因素人群（简称高危人群）的随访观察价值。方法 选取于我院接受CCTA检查且空腹血糖、血脂（甘油三酯、总胆固醇、高密度脂蛋白及低密度脂蛋白）等生化指标及体质量指数有2项或2项以上异常的80例患者,经临床干预后,间隔2年再次行CCTA检查,同时行上述生化指标及体质量指数检测,根据两次CCTA检查结果分为稳定组和进展组,并对2组两次生化指标、体质量指数及其变化率进行统计学分析。结果 稳定组60例,进展组20例。进展组第1次与第2次检查高密度脂蛋白水平差异有统计学意义（t=2.64,P=0.02）;稳定组第2次检查体质量指数、血糖、甘油三酯、总胆固醇及低密度脂蛋白明显小于第1次检查（t=2.10、2.68、3.45、4.26、5.90,P=0.04、0.01、0.001、0.000 1、0.000 1）;进展组第2次检查甘油三酯（t=2.39,P=0.02）和低密度脂蛋白高于稳定组第2次检查（t=3.98,P<0.000 1）;进展组血糖变化率高于稳定组（t=-2.04,P=0.045）。结论 CCTA对于随访观察高危人群冠心病有积极的指导意义,通过加强对冠心病危险因素的积极干预,改变不良生活习惯,可以有效延缓或阻止冠心病的发生及发展。     

ba—PWV、ABI及IMT和冠心病的相关性研究

目的评价肱-踝脉搏波传导速度（ba—PWV）、踝臂指数（ABI）、颈动脉内中膜厚度（IMT）与冠心病冠状动脉狭窄严重程度之间的相关性。方法收集冠心病及可疑冠心病患者167例,结合冠状动脉造影结果,分析ba—PWV、IMT、ABI与冠脉狭窄程度的相关性。结果ABI、IMT、ha—PWV3个检测指标单一应用时,冠脉单支病变组与非冠心病组相比无显著性差异,双支和多支病变组与非冠心病组相比有显著差异（P〈0．01）;当ABI、IMT、ba—PwV均异常或任意2个指标为异常与非冠心病组相比,单支病变组亦有显著性差异。结论ba—PWV、ABI、IMT与冠状动脉病变狭窄程度具有明显相关性。联合应用ba—PWV、ABI和IMT,可用于评价冠状动脉粥样硬化性心脏病的严重程度。