Coronary artery CTA: imaging of atherosclerosis in the coronary arteries and reporting of coronary artery CTA findings

Invasive coronary angiography remains the standard for assessment of coronary anatomy and pathology, and for determining the extent and severity of coronary lumen obstruction in coronary artery disease. Recent advances in multidetector row computed tomography (MDCT) technology allowing noninvasive imaging of the coronary arteries has led to widespread enthusiasm for the use of noninvasive coronary angiography. A comprehensive and clinically useful MDCT study should incorporate an understanding of the patient history and reason for performance of the test, an overall assessment of study quality, and a complete description of pertinent findings. Because the majority of cardiac computed tomography (CT) studies are now being performed for the evaluation of the coronary arteries and obstructive coronary disease, a clear understanding of what the clinician wants to know from a CTA is critical to its comprehensive interpretation. In this manuscript, we provide an overview of the necessary components of CT coronary angiogram interpretation, from the point of view of the practicing invasive cardiologist.

Multifocal ischemic necroses of varying age (MINOVA): A distinctive form of atherosclerotic heart disease

While reviewing the cardiac histopathology and the postmortem arteriography of patients studied at autopsy, a collection of findings was identified in a small proportion of those with ischemic heart disease. These included varying degrees of hypertrophy and left ventricular dilation and severe multifocal atherosclerotic obstruction of the coronary arteries by gross examination. Histology showed multiple small foci of coagulation or contraction-band necrosis in a circumferential, subendocardial pattern; focal replacement fibrosis of varying ages and size; focal atrophy or vacuolization (a marker of chronic ischemia) of surviving myocytes; and marked dilation of the subendocardial vasculature. This collection of findings described here is termed multifocal ischemic necroses of varying age (MINOVA). Review of patient histories showed that the clinical suspicion for the degree of ischemic heart disease did not correlate well with the severity of the pathological findings.

Support vector machines classification for discriminating coronary heart disease patients from non-coronary heart disease

OBJECTIVE

The present contribution concentrates on the application of support vector machines (SVM) for coronary heart disease and non-coronary heart disease classification.

METHODS

We conducted many experiments with support vector machine and different variables of low-density lipoprotein cholesterol (LDLC), high-density lipoprotein cholesterol (HDLC), total cholesterol (TC), triglycerides (TG), glucose and age (dataset 346 patients with completed diagnostic procedures). Linear and non-linear classifiers were compared: linear discriminant analysis (LDA) and SVM with a radial basis function (RBF) kernel as a non-linear technique.

RESULTS

The prediction accuracy of training and test sets of SVM were 96.86% and 78.18% respectively, while the prediction accuracy of training and test sets of LDA were 90.57% and 72.73% respectively. The cross-validated prediction accuracy of SVM and LDA were 92.67% and 85.4%.

CONCLUSION

Support vector machine can be used as a valid way for assisting diagnosis of coronary heart disease.

Artery-Related Differences in Atherosclerosis Expression

Background and Purpose— Information about the expression of atherosclerosis in different arteries is important. The impact of cardiovascular risk factors is artery-related, and the assessment of arterial structure and function in peripheral arteries are increasingly used as surrogate markers for coronary atherosclerosis and the risk of developing heart attack.

Methods— In an autopsy study, we analyzed the coronary, carotid and superficial femoral arteries from 100 individuals (70 men; 20 to 82 years of age) of which 27 died from coronary atherosclerosis. Microscopic sections (n=4756) were analyzed blindly using a modification of the histological classification endorsed by the American Heart Association (AHA).

Results— We found distinct artery-dependent patterns of atherosclerosis with a high prevalence of foam cell lesions and lipid core plaques in the carotid arteries. The femoral arteries were least affected by atherosclerosis, foam cell lesions were rare, and the development of advanced atherosclerosis was strongly age-dependent and dominated by fibrous plaques. Plaques were most common in the left anterior descending coronary artery and the carotid bifurcation. In coronary (versus noncoronary) death, lipid core plaques were more prevalent in all arteries.

Conclusions— The initiation, speed of development, and phenotypic expression of atherosclerotic plaques are artery-related. Foam cell lesions are frequent in the carotid arteries, probably explaining the dynamics in carotid intima-media thickness. Atherosclerosis develops slowly in femoral arteries, and severe atherosclerosis is dominated by fibrous plaques. The higher prevalence of lipid core plaques in all arteries in coronary death indicates a systemically more vulnerable expression of atherosclerosis in these individuals.

Soft and Intermediate Plaques in Coronary Arteries: How Accurately Can We Measure CT Attenuation Using 64-MDCT?

OBJECTIVE

The objective of this study was to validate the accuracy of 64-MDCT densitometry of soft and intermediate plaques.

MATERIALS AND METHODS

Acrylonitrile-butadiene-styrene resin (47 H) and acrylic (110 H) were used to simulate soft and intermediate plaques, respectively, in coronary artery models (diameters of 3 and 4 mm). The variable parameters were heart rate (50, 65, 80, and 95 beats per minute), reconstruction algorithm (half and segmentation), coronary artery enhancement (150, 250, 350, and 450 H), CT densitometry site (arterial lumen or center), shape of plaque (D-shaped, centric, and eccentric), and level of stenosis due to plaque (25%, 50%, and 75% of arterial diameter). Measured CT attenuation values of soft and intermediate plaques were compared for different combinations of parameters. Repeated measures analysis of variance, Wilcoxon's signed rank, Mann-Whitney U, and Kruskal-Wallis tests were used for statistical analyses.

RESULTS

For measuring soft plaque, CT densitometry was accurate at low heart rates with the use of a half reconstruction algorithm (p < 0.01) on intracoronary artery enhancement of 250 H (p < 0.01). For both soft and intermediate plaques, the densitometry measurements near the arterial lumen were overestimated and higher than those at the center (p < 0.01). For plaques that were 50% or more of the arterial diameter, accurate CT densitometry was possible.

CONCLUSION

Coronary artery enhancement has a significant impact on 64-MDCT densitometry measurements of coronary artery plaques, especially of soft plaques. A large plaque size, densitometry performed not near the arterial lumen but at the center of the plaque, intracoronary enhancement of 250 H, and a low heart rate increase the accuracy of plaque densitometry.

An objective method for grading of distal disease in the grafted coronary arteries

The impact of diffuseness of coronary artery disease on the outcome of coronary bypass grafting remains unclear due to the absence of an objective grading system for diffuseness. This study proposes a system and validates it by transit time flow measurements. All patients operated upon by the author from July 2004 to August 2006 were enrolled in the study. The patients who had procedures other than isolated coronary bypass grafting were excluded. This resulted in a set of 186 (151 male and 35 female) patients with a mean age of 59.55 years. Those vessels which had endarterectomies, on-lay patches, multiple/sequential grafts to a single artery were removed from analysis. The diffuseness of distal disease was graded from 0 to 3 on the basis of (i) the size of vessel and (ii) the number as well as significance of atheromatous lesions distal to the graft. The correlation analysis showed a moderate positive correlation between pulsitility index and grade of diffuseness and a moderate negative correlation between graft flow and grade of diffuseness (P<0.0001). This study shows that the proposed method of grading provides an objective and reliable system for the assessment of severity of distal disease in the grafted coronary arteries.

Detection and characterization of coronary bifurcation lesions with 64-slice computed tomography coronary angiography

AIMS

To compare the performance of 64-slice computed tomography coronary angiography (CTCA) and invasive coronary angiography (ICA) in the detection and classification (according to the Medina system) of bifurcation lesions (BLs).

METHODS AND RESULTS

We studied 323 consecutive patients undergoing 64-slice CTCA prior to ICA. All coronary segments >or=2 mm in diameter were evaluated for the presence of a significant (>or=50% diameter reduction on quantitative coronary angiography) BL. Evaluation of BL by CTCA included the assessment of significant lumen obstruction in both main and side branch vessels. Forty-one out of 43 patients (46/48 lesions) with significant BL were identified by CTCA. Excluding coronary segments with non-diagnostic image quality (5%), the sensitivity, specificity, and positive and negative predictive values of CTCA for detecting significant BL were 96, 99, and 85 and 99%, respectively. In 39 of these 41 patients, CTCA assessment was concordant with the Medina lesion classification on ICA.

CONCLUSION

Sixty-four-slice CTCA allows accurate assessment of complex BL.

Coronary calcification in patients with end-stage renal disease: a novel endocrine disorder?

Cardiovascular mortality is significantly increased among patients with end-stage renal disease. The commonly observed vascular calcification in such patients has been considered as one of the causative factors. In patients undergoing dialysis, the incidence of coronary artery calcification is 2-5 times higher compared to patients with normal renal function and angiographically demonstrated coronary artery disease. Moreover, epidemiological studies have revealed a significant correlation of the extent of coronary artery calcification with the severity of underlying atherosclerotic lesions. Vascular calcification was initially considered as a passive process of hydroxyapatite deposition due to elevated plasma concentrations of calcium and phosphate. Nevertheless, there is a growing body of evidence that vascular calcification is an actively regulated and cell-mediated process. This phenomenon includes phenotypic alterations of vascular smooth muscle cells mainly resulting from an imbalance between promoters (such as increased Ca x P product) and inhibitors (fetuin-A, GLA protein, osteoprotegerin) of mineral deposition. With regard to the therapeutic approach, despite the evident effectiveness of both traditional and innovative remedies in the management of metabolic and electrolytic abnormalities of patients with end-stage renal disease, an individualized intervention based on etiopathogenesis is really required.

Relationship between arterial distensibility and coronary atherosclerosis in angina patients

OBJECTIVE

Arterial stiffening is associated with an increased risk of cardiovascular disease. However, limited evidence exists on whether it also relates to subclinical atherosclerosis, thereby providing a non-invasive marker of the overall cardiovascular status. The aim of the present study was to provide information on arterial stiffening in angina patients in whom angiographic evaluation allowed quantification of coronary atherosclerosis.

METHODS

We studied 101 patients with angina from a large number admitted to our hospital for coronary angiography. In each patient, radial (RA), subdiaphragmatic aorta (AO) and carotid (CA) distensibility (Dist) were measured by an ultrasonic device, following ultrasonic exclusion of atherosclerotic lesions at these specific sites. Patients were classified into three groups according to the angiographic findings: (i) no significant coronary lesions (lumen obstruction < 50%, group A); (ii) one (group B); and (iii) two or three (group C) coronary vessels with hemodynamic significant plaques (lumen obstruction > 50%).

RESULTS

Age, male prevalence, previous cardiovascular disease and interventions were progressively greater or more common from group A to C, whereas several other risk factors (plasma glucose, serum cholesterol, smoking, history of hypertension, etc.) did not differ between the three groups or between the group with single vessel (B) versus the group with multivessel disease (C). CA and AO Dist decreased progressively from group A to C with a significant relationship in the group as a whole between distensibility values and the number of diseased vessels. The progressive decrease in AO Dist from group A to C remained significant after adjustment for variables that showed between-group differences (such as gender, age and systolic blood pressure) and the ROC curve showed it to be a more sensitive and specific marker of coronary atherosclerosis than CA Dist. RA Dist was similar in the three groups and showed no relationship with the number of diseased vessels in the group as a whole.

CONCLUSION

In patients with angina, AO and CA Dist are related to the severity of coronary atherosclerosis, with the relationship being better for alterations in aortic than in carotid mechanical properties. Large elastic artery (and in particular aortic) stiffening can thus be considered as a marker of the severity of coronary atherosclerosis, providing non-invasive obtainable information on the need to proceed with further clinical examinations.

Coronary artery calcification, common carotid artery intima-media thickness and aortic pulse wave velocity in patients on peritoneal dialysis

An increasing body of evidence suggests that atherosclerosis in patients with uremia differs from that found in general population in terms of advancement and localization of vascular lesions. It has also been suggested that different non-invasive techniques of vascular system evaluation are designed to show different types of lesions (i.e. vascular calcification, stiffness or 'classical' atherosclerosis). The aim of the study was to search for possible associations between results obtained with three different non-invasive methods of vascular system assessment in three different vascular sites in patients treated with peritoneal dialysis (PD). 61 patients (28 F, 33 M), mean age of 50.4+/-13.6 years, on maintenance PD for a median period of 10 months (range 1-96 months) were included. Coronary artery disease (CAD) was present in 21 subjects. In all subjects coronary artery calcification score (CaSc) using multi-row spiral computed tomography (MSCT), aortic pulse wave velocity (AoPWV) and ultrasound-based common carotid artery intima-media thickness (CCA-IMT) were performed as methods for assessing coronary calcium burden, arterial stiffness and atherosclerosis, respectively. Median value of CaSc equaled 11.5 Agatston units (range 0-5502.8 units). Median AoPWV was 10.4 m/s (range 7.56-18.1 m/s), and median CCA-IMT-0.6 mm (range 0.3-1.0 mm). In 16 patients (26.2%) at least one plaque in at least one common carotid artery was found on ultrasound. CaSc correlated with AoPWV (R=0.32, p<0.01) and with CCA-IMT (R=0.35, p<0.005), whereas no association was found between AoPWV and CCA-IMT. AoPWV, but not CaSc nor IMT correlated with blood pressure. The values of CCA-IMT and AoPWV increased together with consecutive Agatston categories (with p<0.001 for differences in AoPWV and p<0.05 for CCA-IMT). Patients with at least one plaque found in at least one CCA and patients with CAD were characterized with significantly higher values of CaSc, IMT and PWV, when compared to plaque-free and CAD- negative subjects, respectively. Association between CaSc and both IMT and PWV may suggest that the mechanism of three assessed vascular pathologies may be based, to some extent, on the process of pathologic calcium-phosphate deposition. Lack of correlation found between PWV and IMT may suggest that aortic stiffness and carotid atherosclerosis may partially differ in their pathologic background and/or are dissociated in time.

Pregnancy-associated plasma protein A and proform eosinophilic major basic protein in the detection of different types of coronary artery disease

Kryptor system was proven to be a rapid, standard method for pregnancy-associated plasma protein A and proform eosinophilic major basic protein (PAPP-A/proMBP) complex detection in coronary artery disease (CAD). No age and/or gender differences in 51 controls and 110 stable coronary artery disease (SCAD) patients were found. SCAD patients did not differ from controls and no difference in PAPP-A/proMBP levels with regards to the number of affected vessels was found. In 21 unstable angina pectoris (UAP), in 35 without and 66 with ST elevation acute myocardial infarctions (NSTEMI, STEMI respectively) patients PAPP-A/proMBP levels were increased (P=0.004 and P<0.0005, respectively). PAPP-A/proMBP levels did not correlate with cardiac troponin I (cTnI) in STEMI and NSTEMI patients. PAPP-A/ proMBP increase was more frequent than cTnI (P=0.036) within the early phase of STEMI. In NSTEMI patients PAPP-A/proMBP positivity was present in 50% of cTnI negative cases. Receiver operating characteristic (ROC) analysis revealed the highest diagnostic accuracy of PAPP-A/proMBP (0.919) in STEMI cTnI positive cases. The highest specificity/sensitivity PAPP-A/proMBP levels for particular acute coronary syndrome (ACS) types were 10.65-14.75 mIU/l. Combination of PAPP-A/proMBP with cTnI increases their diagnostic efficacy within the early phase of ACS. Our results suggest that PAPP-A/proMBP complex is involved in processes preceding vulnerable plaque development in ACS.

Trifurcating coronary artery disease: a proposed classification and treatment methodology

Trifurcating coronary artery disease is a complex atherosclerotic process involving the origin of one or more of three side branches arising from a main coronary artery vessel or trunk (MT), with or without involvement of the MT itself. To date, there is no classification or standardized methodology to treat trifurcation disease. In this report, we propose a new, simplified classification system for trifurcation coronary artery disease and describe various methodologies to treat the various types.

Variable ECG signs of ischemia during controlled occlusion of the left and right coronary artery in humans

Infarct size (IS) increases with vascular occlusion time, area at risk for infarction, lack of collateral supply, absence of preconditioning, and myocardial demand for O2 supply. ECG S-T segment elevation is used as a measure of severity of ischemia and a surrogate for IS. This study in 50 patients with coronary artery disease undergoing a first 120-s balloon occlusion of a stenosis sought to determine whether S-T segment elevation, corrected for the above-mentioned variables, in the left coronary artery (LCA group, n = 36) is different from that in the right coronary artery (RCA group, n = 14) territory. After consideration of all known determinants of IS, particularly mass at risk and collateral supply, the LCA territory is more sensitive than the RCA region to a 2-min period of myocardial ischemia.

[Management of the acute coronary syndrome under German diagnosis related groups in 2005/2006]

In Germany, patients with acute coronary syndromes are often primarily admitted to hospitals without PCI (percutaneous coronary intervention) facilities. It is known, that this leads to considerable delays in contact-to-balloon time, which may trigger enhanced mortality and morbidity of these coronary events. The new German hospital reimbursement system, which is based on Diagnosis Related Groups, may contribute by different incentives to this unadverted result. Hospitals gain more money, if patients remain longer, and admitting patients by transfer from other hospitals is less profitable than primary admittance. Transport reimbursement back to basic hospitals is not provided by public insurance. The German Cardiac Society has submitted proposals to recalculate the transfer cases of patients with acute coronary syndromes for several years without success. The present paper discusses possible and necessary changes in the reimbursement system. As a main result, the system will not be changed as proposed. The reason is, that-compared to the whole volume of hospital treatment cases-the volume of transfer cases with acute coronary syndromes is not large enough to justify changes in the reimbursement rules by economic considerations. The paper discusses the consequences of a hospital reimbursement system that can only be adapted to changed conditions by economic but not by medical reasons.

Method to correct intensity inhomogeneity in MR images for atherosclerosis characterization

We are developing methods to characterize atherosclerotic disease in human carotid arteries using multiple MR images having different contrast mechanisms (T1W, T2W, PDW). To enable the use of voxel gray values for interpretation of disease, we created a new method, local entropy minimization with a bicubic spline model (LEMS), to correct the severe (approximately 80%) intensity inhomogeneity that arises from the surface coil array. This entropy-based method does not require classification and robustly addresses some problems that are more severe than those found in brain imaging, including noise, steep bias field, sensitivity of artery wall voxels to edge artifacts, and signal voids near the artery wall. Validation studies were performed on a synthetic digital phantom with realistic intensity inhomogeneity, a physical phantom roughly mimicking the neck, and patient carotid artery images. We compared LEMS to a modified fuzzy c-means segmentation based method (mAFCM), and a linear filtering method (LINF). Following LEMS correction, skeletal muscles in patient images were relatively isointense across the field of view. In the physical phantom, LEMS reduced the variation in the image to 1.9% and across the vessel wall region to 2.5%, a value which should be sufficient to distinguish plaque tissue types, based on literature measurements. In conclusion, we believe that the correction method shows promise for aiding human and computerized tissue classification from MR signal intensities.