Prognostic value of CT myocardial perfusion imaging and CT-derived fractional flow reserve for major adverse cardiac events in patients with coronary artery disease

ObjectivesThe purpose of this study was to analyze the prognostic value of dynamic CT perfusion imaging (CTP) and CT derived fractional flow reserve (CT-FFR) for major adverse cardiac events (MACE).Methods81 patients from 4 institutions underwent coronary computed tomography angiography (CCTA) with dynamic CTP imaging and CT-FFR analysis. Patients were followed-up at 6, 12, and 18 months after imaging. MACE were defined as cardiac death, nonfatal myocardial infarction, unstable angina requiring hospitalization, or revascularization. CT-FFR was computed for each major coronary artery using an artificial intelligence-based application. CTP studies were analyzed per vessel territory using an index myocardial blood flow, the ratio between territory and global MBF. The prognostic value of CCTA, CT-FFR, and CTP was investigated with a univariate and multivariate Cox proportional hazards regression model.Results243 vessels in 81 patients were interrogated by CCTA with CT-FFR and 243 vessel territories (1296 segments) were evaluated with dynamic CTP imaging. Of the 81 patients, 25 (31%) experienced MACE during follow-up. In univariate analysis, a positive index-MBF resulted in the largest risk for MACE (HR 11.4) compared to CCTA (HR 2.6) and CT-FFR (HR 4.6). In multivariate analysis, including clinical factors, CCTA, CT-FFR, and index-MBF, only index-MBF significantly contributed to the risk of MACE (HR 10.1), unlike CCTA (HR 1.2) and CT-FFR (HR 2.2).ConclusionOur study provides initial evidence that dynamic CTP alone has the highest prognostic value for MACE compared to CCTA and CT-FFR individually or a combination of the three, independent of clinical risk factors.     

冠状动脉CT血管成像在引导冠心病介入治疗中的应用及进展

冠状动脉CT血管成像(CCTA)在经皮冠状动脉介入术(PCI)术前可以明确病人是否需要进入导管室检查或治疗,可视化斑块特征及预测PCI术后风险;术中可以提供精确的冠状动脉解剖特征和病变特征,协助选择PCI器材和手术方式;PCI术后利用CCTA可以检测支架内再狭窄。就CCTA在PCI术前、术中和术后的应用价值及研究进展予以综述。     

CT-SYNTAX评分在复杂冠状动脉疾病心肌血运重建决策中的应用进展

复杂冠状动脉疾病（CAD）心肌血运重建治疗策略的选择是临床医师关注的问题,基于有创冠状动脉造影（ICA）的SYNTAX评分是当前重要的临床指导依据。随着冠状动脉CT血管成像（CCTA）的普及,基于CCTA的SYNTAX评分（CT-SYNTAX）成为研究热点。基于CCTA的血流储备分数（FFR_CT）可提供CAD的功能学信息,实现了CT-SYNTAX评分从解剖学向功能学的提升。就CT-SYNTAX评分在复杂CAD病人治疗策略中应用的研究进展予以综述。     

CT Fractional Flow Reserve for the Diagnosis of Myocardial Bridging-Related Ischemia: A Study Using Dynamic CT Myocardial Perfusion Imaging as a Reference Standard

ObjectiveTo investigate the diagnostic performance of CT fractional flow reserve (CT-FFR) for myocardial bridging-related ischemia using dynamic CT myocardial perfusion imaging (CT-MPI) as a reference standard.Materials and MethodsDynamic CT-MPI and coronary CT angiography (CCTA) data obtained from 498 symptomatic patients were retrospectively reviewed. Seventy-five patients (mean age ± standard deviation, 62.7 ± 13.2 years; 48 males) who showed myocardial bridging in the left anterior descending artery without concomitant obstructive stenosis on the imaging were included. The change in CT-FFR across myocardial bridging (ΔCT-FFR, defined as the difference in CT-FFR values between the proximal and distal ends of the myocardial bridging) in different cardiac phases, as well as other anatomical parameters, were measured to evaluate their performance for diagnosing myocardial bridging-related myocardial ischemia using dynamic CT-MPI as the reference standard (myocardial blood flow < 100 mL/100 mL/min or myocardial blood flow ratio ≤ 0.8).ResultsΔCT-FFR_systolic (ΔCT-FFR calculated in the best systolic phase) was higher in patients with vs. without myocardial bridging-related myocardial ischemia (median [interquartile range], 0.12 [0.08–0.17] vs. 0.04 [0.01–0.07], p < 0.001), while CT-FFR_systolic (CT-FFR distal to the myocardial bridging calculated in the best systolic phase) was lower (0.85 [0.81–0.89] vs. 0.91 [0.88–0.96], p = 0.043). In contrast, ΔCT-FFR_diastolic (ΔCT-FFR calculated in the best diastolic phase) and CT-FFR_diastolic (CT-FFR distal to the myocardial bridging calculated in the best diastolic phase) did not differ significantly. Receiver operating characteristic curve analysis showed that ΔCT-FFR_systolic had largest area under the curve (0.822; 95% confidence interval, 0.717–0.901) for identifying myocardial bridging-related ischemia. ΔCT-FFR_systolic had the highest sensitivity (91.7%) and negative predictive value (NPV) (97.8%). ΔCT-FFR_diastolic had the highest specificity (85.7%) for diagnosing myocardial bridging-related ischemia. The positive predictive values of all CT-related parameters were low.ConclusionΔCT-FFR_systolic reliably excluded myocardial bridging-related ischemia with high sensitivity and NPV. Myocardial bridging showing positive CT-FFR results requires further evaluation.     

Dynamic CT Myocardial Perfusion Imaging in Patients without Obstructive Coronary Artery Disease: Quantification of Myocardial Blood Flow according to Varied Heart Rate Increments after Stress

ObjectiveThe present study aimed to investigate the association between myocardial blood flow (MBF) quantified by dynamic CT myocardial perfusion imaging (CT-MPI) and the increments in heart rate (HR) after stress in patients without obstructive coronary artery disease.Materials and MethodsWe retrospectively included 204 subjects who underwent both dynamic CT-MPI and coronary CT angiography (CCTA). Patients with more than minimal coronary stenosis (diameter ≥ 25%), history of myocardial infarction/revascularization, cardiomyopathy, and microvascular dysfunction were excluded. Global MBF at stress was measured using hybrid deconvolution and maximum slope model. Furthermore, the HR increments after stress were recorded.ResultsThe median radiation dose of dynamic CT-MPI plus CCTA was 5.5 (4.5–6.8) mSv. The median global MBF of all subjects was 156.4 (139.8–180.4) mL/100 mL/min. In subjects with HR increment between 10 to 19 beats per minute (bpm), the global MBF was significantly lower than that of subjects with increment between 20 to 29 bpm (153.3 mL/100 mL/min vs. 171.3 mL/100 mL/min, p = 0.027). This difference became insignificant when the HR increment further increased to ≥ 30 bpm.ConclusionThe global MBF value was associated with the extent of increase in HR after stress. Significantly higher global MBF was seen in subjects with HR increment of ≥ 20 bpm.     

Coronary Artery Disease in Asymptomatic Young Adults: Its Prevalence According to Coronary Artery Disease Risk Stratification and the CT Characteristics

Objective

We aimed at evaluating the prevalence and CT characteristics of occult coronary artery disease (CAD) in young Korean adults under 40 years of age by performing coronary CT angiography (CCTA).

Materials and Methods

We retrospectively enrolled 112 consecutive asymptomatic subjects (90 men, mean age: 35.6 ± 3.7 years) who underwent CCTA as part of a general health evaluation. We classified the subjects into three National Cholesterol Education Program risk categories and we assessed the plaque characteristics on CCTA according to the number of involved vessels, the location and type of plaques and vascular remodeling.

Results

Twelve individuals had CAD (11%, 11 men). The prevalence of CAD was significantly higher in the subgroups with moderate (22%) or high (25%) risk than that in the low risk subgroup (5%) (p < 0.05). Nine patients had single-vessel disease and three patients had two-vessel disease. The most common location for plaque was the proximal left anterior descending coronary artery (60%). All the patients had non-significant stenosis and plaque, including the non-calcified (27%), mixed (47%) and calcified (27%) types. Positive vascular remodeling was identified in all the patients with non-calcified or mixed plaques.

Conclusion

The prevalence of occult CAD was not negligible in the asymptomatic young adults with moderate to high risk, and this suggests the importance of management and risk factor modification in this population. All the patients had non-significant stenosis, and one fourth of the plaques did not show calcification.     

CT-FFR对冠状动脉狭窄功能评价的临床价值

CT冠状动脉血流储备分数(CT-FFR)可无创性检查冠状动脉粥样硬化性心脏病(冠心病),是一种结合了解剖与功能的检查方法。CT-FFR是基于冠状动脉CT血管成像(CCTA)的影像数据测得的,具有CCTA和冠状动脉血流储备分数(FFR)的优势。CT-FFR从解剖学方面评估病变的狭窄程度,同时可以从血流动力学方面测定狭窄冠状动脉是否存在缺血及缺血的严重程度。综述总结了CT-FFR的优势、诊段效能及其临床应用。     

动态容积320排冠状动脉CT血管成像诊断冠状动脉疾病的意义

目的：研究320排动态容积冠状动脉CT成像（CCTA）诊断冠状动脉疾病（CAD）的可行性。方法：5961例临床诊断CAD的患者进行CCTA检查,其中186例接受常规X线冠状动脉造影术（CAG）,对照分析其检查结果。1490例接受CCTA检查的健康查体者作为对照。结果：成像质量均在I～III级,无呼吸伪影图像。在186例CAD患者中,CCTA诊断冠状动脉狭窄（狭窄度≥50％）的敏感性为96．72％,特异性98．95％,阳性预测值95．16％,阴性预测值99．30％,准确度98．56％。结论：320排动态容积CT冠状动脉成像图像清晰,对诊断CAD具有重要的临床价值。     

CT血管造影在诊断功能相关性冠状动脉狭窄中的应用

目的以 SPECT 心肌灌注显像(MPI)为参考,评价 CT 血管造影检测功能相关性冠状动脉狭窄(FRCS)的诊断效能.资料与方法2005-11~2011-03在天津医科大学心血管病临床学院同期(30d 内)行冠状动脉 CT血管造影(CCTA)和 MPI 的504例可疑或确诊冠状动脉疾病患者,以 CCTA冠状动脉狭窄≥50%并伴有相应血管支配区域 MPI 灌注缺损作为诊断 FRCS的参考标准.以病例或血管为观察对象,分别计算 CCTA 冠状动脉狭窄≥50%或≥75%时检测 FRCS 的诊断效能.结果以病例为观察对象,CCTA 冠状动脉狭窄≥50%或≥75%检测 FRCS 的灵敏度、特异性、阳性预测值和阴性,预测值分别为67.2%和35.8%、84.7%和97.3%、40.2%和66.7%、94.4%和90.8%,差异均有统计学意义(P<0.05);以血管为观察对象,CCTA 冠状动脉狭窄≥50%或≥75%检测 FRCS 的灵敏度、特异性、阳性预测值和阴性预测值分别为70.2%和33.7%、95.4%和99.0%、42.9%和60.0%、98.5%和97.0%,差异均有统计学意义(P<0.05).结论 CCTA 具有较佳的排除 FRCS 的能力.当冠脉狭窄≥50%时,CCTA 虽然对 FRCS 检测灵敏度较高,但其阳性预测值相对较差.当冠脉狭窄≥75%时,CCTA 检测 FRCS 的阳性预测值有一定的提高.     

CT imaging of myocardial perfusion: Possibilities and perspectives

Functional imaging in patients with suspected or known coronary artery disease (CAD) is crucial for the identification of patients who could benefit from coronary revascularization. Several studies demonstrated the high diagnostic accuracy of Single-photon-emission computed tomography myocardial perfusion imaging, stress perfusion magnetic resonance imaging, and of invasive FFR measurements for the detection of hemodynamic relevant stenosis. Cardiac computed tomography (CT) used to be limited to coronary angiography (CTA); current guidelines recommend CTA only for the exclusion of CAD. Technological advances now offer the possibility to assess myocardial perfusion by computed tomography (CT-MPI). Though different acquisition protocols and post-processing algorithms still have to be evaluated, initial clinical studies could already show a diagnostic accuracy comparable to the established imaging modalities. Thus, cardiac CT may offer a combined approach of anatomical and functional imaging. Beside the need for further studies, especially on the prognostic value of CT-MPI to stratify future cardiovascular events, the comparatively high radiation exposure and additional administration of contrast agent has to be taken in account.     

CCTA技术对冠状动脉狭窄及其钙化斑块的评估

冠状动脉CT血管成像（CCTA）是一种可无创检测冠状动脉粥样硬化性疾病的成像手段,已成为临床筛查及诊断冠心病的首要检查方法。但对于钙化严重的冠状动脉节段,CCTA的特异性及阳性预测值偏低,可导致病人过度治疗,因此限制了CCTA的临床应用。综述钙化斑块伪影对CCTA的影响,并就CCTA对冠状动脉狭窄准确评估的相关技术进展进行分析,以利于临床诊断中提高CCTA对冠状动脉狭窄率的评估。     

Coronary 64-slice CT angiography predicts outcome in patients with known or suspected coronary artery disease

The aim of this study was to assess the prognostic value of 64-slice CT angiography (CTA) in patients with known or suspected coronary artery disease (CAD). Sixty-four-slice coronary CTA was performed in 220 patients [mean age 63 ± 11 years, 77 (35%) female] with known or suspected CAD. CTA images were analyzed with regard to the presence and number of coronary lesions. Patients were followed-up for the occurrence of the following clinical endpoints: death, nonfatal myocardial infarction, unstable angina, and coronary revascularization. During a mean follow-up of 14 ± 4 months, 59 patients (27%) reached at least one of the predefined clinical endpoints. Patients with abnormal coronary arteries on CTA (i.e., presence of coronary plaques) had a 1st-year event rate of 34%, whereas in patients with normal coronary arteries no events occurred (event rate, 0%, p < 0.001). Similarly, obstructive lesions (≥50% luminal narrowing) on CTA were associated with a high first-year event rate (59%) compared to patients without stenoses (3%, p < 0.001). The presence of obstructive lesions was a significant independent predictor of an adverse cardiac outcome. Sixty-four-slice CTA predicts cardiac events in patients with known or suspected CAD. Conversely, patients with normal coronary arteries on CTA have an excellent mid-term prognosis.     

Accuracy of 64-slice CT angiography for the detection of functionally relevant coronary stenoses as assessed with myocardial perfusion SPECT

Purpose CT angiography (CTA) offers a valuable alternative for the diagnosis of CAD but its value in the detection of functionally relevant coronary stenoses remains uncertain. We prospectively compared the accuracy of 64-slice CTA with that of myocardial perfusion imaging (MPI) using ^99mTc-tetrofosmin-SPECT as the gold standard for the detection of functionally relevant coronary artery disease (CAD). Methods MPI and 64-slice CT were performed in 100 consecutive patients. CTA lesions were analysed quantitatively and area stenoses ≥50% and ≥75% were compared with the MPI findings. Results In 23 patients, MPI perfusion defects were found (12 reversible, 13 fixed). A total of 399 coronary arteries and 1,386 segments was analysed. Eighty-four segments (6.1%) in 23 coronary arteries (5.8%) of nine patients (9.0%) were excluded owing to insufficient image quality. In the remaining 1,302 segments, quantitative CTA revealed stenoses ≥50% in 57 of 376 coronary arteries (15.2%) and stenoses ≥75% in 32 (8.5%) coronary arteries. Using a cut-off at ≥75% area stenosis, CTA yielded the following sensitivity, specificity, negative (NPV) and positive predictive value (PPV), and accuracy for the detection of any (fixed and reversible) MPI defect: by patient, 75%, 90%, 93%, 68% and 87%, respectively; by artery, 76%, 95%, 99%, 50% and 94%, respectively. Conclusion Sixty-four-slice CTA is a reliable tool to rule out functionally relevant CAD in a non-selected population with an intermediate pretest likelihood of disease. However, an abnormal CTA is a poor predictor of ischaemia.     

64层CT评价冠脉粥样斑块性质与狭窄程度的相关性

目的：探讨64层CT评价冠状动脉粥样硬化斑块性质与冠脉狭窄程度之间的相关性。方法：36例疑诊为冠心病患者行64层冠状动脉CT血管成像（CCTA）及冠状动脉血管造影（CAG）检查,以CAG为标准评价CCTA诊断冠脉狭窄程度的准确性,并诊断冠状动脉粥样硬化斑块性质,分析其与经CAG确诊的冠脉狭窄程度之间有无统计学意义。结果：36例患者中共检出105个斑块。冠脉轻度狭窄以钙化斑块引起为主,冠脉中度狭窄和重度狭窄以混合斑块引起为主。CCTA诊断冠状动脉钙化斑块与管腔轻度狭窄、混合斑块与中重度管腔狭窄存在相关性。结论：64层CCTA可在诊断冠脉狭窄的同时无创性评价斑块性质,可及时发现冠脉中脂质成分丰富的斑块,以便尽早及时给予临床干预,可降低急性冠脉综合征发生率。     

Applications of multislice computed tomography in coronary artery disease

Multislice computed tomography (MSCT) provides high accuracy for noninvasive assessment of coronary artery disease (CAD). The introduction of the latest computed tomography (CT) technology allows comprehensive evaluation of various aspects of CAD, including the coronary calcium score, coronary artery stenoses, bypass patency, and myocardial function. Other applications, such as plaque characterization, first-pass perfusion imaging, and viability imaging using delayed contrast enhancement, are still under development and may demonstrate clinical utility in the future. Further improvements in CT hardware and imaging protocols are expected that may result in improved coronary artery imaging, new applications, and a significant reduction of radiation dose.     

Machine-learning integration of CT histogram analysis to evaluate the composition of atherosclerotic plaques: Validation with IB-IVUS

BackgroundTo determine whether machine learning with histogram analysis of coronary CT angiography (CCTA) yields higher diagnostic performance for coronary plaque characterization than the conventional cut-off method using the median CT number.MethodsWe included 78 patients with 78 coronary plaques who had undergone CCTA and integrated backscatter intravascular ultrasound (IB-IVUS) studies. IB-IVUS diagnosed 32 as fibrous- and 46 as fatty or fibro-fatty plaques. We recorded the coronary CT number and 7 histogram parameters (minimum and mean value, standard deviation (SD), maximum value, skewness, kurtosis, and entropy) of the plaque CT number. We also evaluated the importance of each feature using the Gini index which rates the importance of individual features. For calculations we used XGBoost. Using 5-fold cross validation of the plaque CT number, the area under the receiver operating characteristic curve of the machine learning- (extreme gradient boosting) and the conventional cut-off method was compared.ResultsThe median CT number was 56.38 Hounsfield units (HU, 8.00–95.90) for fibrous- and 1.15 HU (−35.8–113.30) for fatty- or fibro-fatty plaques. The calculated optimal threshold for the plaque CT number was 36.1 ± 2.8 HU. The highest Gini index was the coronary CT number (0.19) followed by the minimum value (0.17), kurtosis (0.17), entropy (0.14), skewness (0.11), the mean value (0.11), the standard deviation (0.06), and the maximum value (0.05), and energy (0.00). By validation analysis, the machine learning-yielded a significantly higher area under the curve than the conventional method (area under the curve 0.92 and 95%, confidence interval 0.86–0.92 vs 0.83 and 0.75–0.92, p = 0.001).ConclusionThe machine learning-was superior the conventional cut-off method for coronary plaque characterization using the plaque CT number on CCTA images.     

Prognostic value of coronary computed tomography angiography in patients with prior percutaneous coronary intervention

ObjectiveWe sought to determine the prognostic value of coronary computed tomography angiography (CCTA) in patients with a history of percutaneous coronary intervention (PCI).BackgroundAlthough the prognostic value of CCTA has been well studied, its incremental value in patients with previous PCI has not been robustly investigated.MethodsConsecutive patients with previous PCI were prospectively enrolled and CCTA images were evaluated for coronary artery disease (CAD) severity. Patients were followed for major adverse cardiovascular events (MACE) which was a composite of cardiac death and non-fatal myocardial infarction. All-cause death was assessed as a secondary endpoint.ResultsA total of 501 patients were analyzed with a mean follow-up time of 59.5 ± 32.0 months and 52 patients (10.4%) experienced MACE. Multivariable Cox regression analysis showed that CAD severity was a predictor of MACE with 0, 1, 2, and 3 vessel disease having annual rates of 1.3%, 2.2%, 2.2%, and 5.3%, respectively. All-cause death was similar in all categories of CAD.ConclusionsIn patients with previous PCI, CAD severity as measured with CCTA has independent and incremental prognostic value.     

Coronary plaque imaging by coronary computed tomography angiography

Coronary computed tomography angiography (CTA) has become the useful noninvasive imaging modality alternative to the invasive coronary angiography for detecting coronary artery stenoses in patients with suspected coronary artery disease (CAD). With the development of technical aspects of coronary CTA, clinical practice and research are increasingly shifting toward defining the clinical implication of plaque morphology and patients outcomes by coronary CTA. In this review we discuss the coronary plaque morphology estimated by CTA beyond coronary angiography including the comparison to the currently available other imaging modalities used to examine morphological characteristics of the atherosclerotic plaque. Furthermore, this review underlies the value of a combined assessment of coronary anatomy and myocardial perfusion in patients with CAD, and adds to an increasing body of evidence suggesting an added diagnostic value when combining both modalities. We hope that an integrated, multi-modality imaging approach will become the gold standard for noninvasive evaluation of coronary plaque morphology and outcome data in clinical practice.