Coronary artery calcium and its relationship to coronary artery disease

Photon-Counting Detector Computed Tomography Versus Energy-Integrating Detector Computed Tomography for Coronary Artery Calcium Quantitation

OBJECTIVES

Photon-counting detector (PCD) computed tomography (CT) offers improved spatial and contrast resolution, which can impact quantitative measurements. This work aims to determine in human subjects the effect of dual-source PCD-CT on the quantitation of coronary artery calcification (CAC) compared with dual-source energy-integrating detector (EID) CT in both 1- and 3-mm images.

METHODS

This prospective study enrolled patients receiving a clinical EID-CT CAC examination to undergo a research PCD-CT CAC examination. Axial images were reconstructed with a 512 × 512 matrix, 200-mm field of view, 3-mm section thickness/1.5-mm interval using a quantitative kernel (Qr36). Sharper kernels (Qr56/QIR strength 4 for PCD and Qr49/ADMIRE strength 5 for EID) were used to reconstruct images with 1-mm section thickness/0.5-mm interval. Pooled analysis was performed for all calcifications with nonzero values, and volume and Agatston scores were compared between EID-CT and PCD-CT. A Wilcoxon signed-rank test was performed with P < 0.05 considered statistically significant.

RESULTS

In 21 subjects (median age, 58 years; range, 50-75 years; 13 male [62%]) with a total of 42 calcified arteries detected at 3 mm and 46 calcified arteries at 1-mm images, EID-CT CAC volume and Agatston scores were significantly lower than those of PCD-CT ( P ≤ 0.001). At 3-mm thickness, the mean (standard deviation) volume and Agatston score for EID-CT were 55.5 (63.4) mm 3 and 63.8 (76.9), respectively, and 61.5 (69.4) mm 3 and 70.4 (85.3) for PCD-CT ( P = 0.0001 and P = 0.0013). At 1-mm thickness, the mean (standard deviation) volume and score for EID-CT were 50.0 (56.3) mm 3 and 61.1 (69.3), respectively, and 59.5 (63.9) mm 3 and 72.5 (79.9) for PCD-CT ( P < 0.0001 for both). The applied radiation dose (volume CT dose index) for the PCD-CT scan was 2.1 ± 0.6 mGy, which was 13% lower than for the EID-CT scan (2.4 ± 0.7 mGy, P < 0.001).

CONCLUSIONS

Relative to EID-CT, PCD-CT demonstrated a small but significant increase in coronary artery calcium volume and Agatston score.

Association of cardiometabolic and vascular atherosclerosis phenotypes on non-contrast chest CT with incident heart failure in patients with severe hypercholesterolemia

BACKGROUND

Coronary artery calcium (CAC), thoracic aorta calcification (TAC), non-alcoholic fatty liver disease (NAFLD), and epicardial adipose tissue (EAT) are associated with atherosclerotic cardiovascular disease (ASCVD) and heart failure (HF).

OBJECTIVES

We aimed to determine whether these cardiometabolic and atherosclerotic risk factors identified by non-contrast chest computed tomography (CT) are associated with HF hospitalizations in patients with LDL-C≥ 190 mg/dL.

METHODS

We conducted a retrospective cohort analysis of patients with LDL-C ≥190 mg/dL, aged ≥40 years without established ASCVD or HF, who had a non-contrast chest CT within 3 years of LDL-C measurement. Ordinal CAC, ordinal TAC, EAT, and NAFLD were measured. Kaplan-Meier curves and multivariable Cox regression models were built to ascertain the association with HF hospitalization.

RESULTS

We included 762 patients with median age 60 (53-68) years, 68% (n=520) female, and median LDL-C level of 203 (194-216) mg/dL. Patients were followed for 4.7 (IQR 2.75-6.16) years, and 107 (14%) had a HF hospitalization. Overall, 355 (47%) patients had CAC=0, 210 (28%) had TAC=0, 116 (15%) had NAFLD, and median EAT was 79 mL (49-114). Moderate-Severe CAC (log-rank p<0.001) and TAC (log-rank p=0.006) groups were associated with increased HF hospitalizations. This association persisted when considering myocardial infarction (MI) as a competing risk. NAFLD and EAT volume were not associated with HF.

CONCLUSIONS

In patients without established ASCVD and LDL-C≥190 mg/dL, CAC was independently associated with increased HF hospitalizations while TAC, NAFLD and EAT were not.

Serum Thyrotropin Elevation and Coronary Artery Calcification in Hemodialysis Patients

INTRODUCTION

Hypothyroidism is highly prevalent in end-stage kidney disease patients, and emerging data show that lower circulating thyroid hormone levels lead to downregulation of vascular calcification inhibitors and coronary artery calcification (CAC) in this population. To date, no studies have examined the association of serum thyrotropin (TSH), the most sensitive and specific single biochemical metric of thyroid function, with CAC risk in hemodialysis patients.

METHODS

In secondary analyses of patients from the Anti-Inflammatory and Anti-Oxidative Nutrition in Hypoalbuminemic Dialysis Patients trial, we examined serum TSH levels and CAC risk assessed by cardiac computed tomography scans collected within a 90-day period. We evaluated the relationship between serum TSH with CAC Volume (VS) and Agatston score (AS) (defined as >100 mm3 and >100 Houndsfield Units, respectively) using multivariable logistic regression.

RESULTS

Among 104 patients who met eligibility criteria, higher TSH levels in the highest tertile were associated with moderately elevated CAC VS and AS in case-mix-adjusted analyses (ref: lowest tertile): adjusted ORs (95% CIs) 4.26 (1.18, 15.40) and 5.53 (1.44, 21.30), respectively. TSH levels >3.0 mIU/L (ref: ≤3.0 mIU/L) were also associated with moderately elevated CAC VS and AS. In secondary analyses, point estimates of incrementally lower direct free thyroxine levels trended toward elevated CAC VS and AS, although associations did not achieve statistical significance.

CONCLUSIONS

In hemodialysis patients, higher serum TSH was associated with elevated CAC VS and AS. Further studies are needed to determine if thyroid hormone supplementation can attenuate CAC burden in this population.

Magnesium Citrate Protects Against Vascular Calcification in an Adenine-induced Chronic Renal Failure Rat Model

BACKGROUND

Hypomagnesemia was identified as a strong risk factor for cardiovascular disease in patients with chronic renal failure (CRF). However, the effects of magnesium (Mg) on vascular calcification (VC) have not been fully elucidated. Thus, we aim to determine the effects of Mg citrate (MgCit) on VC in CRF rats.

METHODS

Rats were divided into 5 groups: group 1 (normal diet), group 2 (normal diet with MgCit), group 3 (the VC model of CRF induced by 0.75% adenine and 0.9% phosphorus diet from day 1 to day 28), group 4 (group 3 treated with low-dose MgCit from day 1 to day 42), and group 5 (same as group 3 except the high-dose MgCit). All rats were killed at day 43 with collection of blood and aortas. Then, serum biochemical parameters, VC-related staining, calcium and P contents, alkaline phosphatase contents and activity, expression of alpha smooth muscle actin, and runt-related transcription factor 2 (RUNX2) in aortas were assessed.

RESULTS

Group 3 had extensive VC. The VC degree decreased in groups 4 and 5 in a dose-depended manner with reduced calcium content, P levels, alkaline phosphatase content and activity, and protein levels of RUNX2 and increased protein levels of alpha smooth muscle actin in aortas.

CONCLUSIONS

MgCit exerted a protective role in VC in adenine-induced CRF rats; thus, it may be a potential drug for the prevention of VC in patients with CRF.

Characterization of Atherosclerosis Formation in a Murine Model of Type IIa Human Familial Hypercholesterolemia

A murine genetic model of LDL-cholesterol- (LDL-C-) driven atherosclerosis, based on complete deficiencies of both the LDL-receptor (Ldlr^-/-) and key catalytic component of an apolipoprotein B-edisome complex (Apobec1^-/-), which converts apoB-100 to apoB-48, has been extensively characterized. These gene deficiencies allow high levels of apoB-100 to be present and inefficiently cleared, thus leading to very high levels of LDL-C in mice on a normal diet. Many key features of atherosclerotic plaques observed in human familial hypercholesterolemia are found in these mice as they are allowed to age through 72 weeks. The general characteristics include the presence of high levels of LDL-C in plasma and macrophage-related fatty streak formation in the aortic tree, which progressively worsens with age. More specifically, plaque found in the aortic sinuses contains a lipid core with relatively high numbers of macrophages and a smooth muscle cell α-actin- and collagen-containing cap, which thins with age. These critical features of plaque progression suggest that the Ldlr^-/-/Apobec1^-/- mouse line presents a superior model of LDL-C-driven atherosclerosis.

CT calcium scoring. History, current status and outlook

Cardiovascular risk assessment has assumed a prominent role in the course of preventive care of all adults. Traditionally cardiovascular risk assessment has been performed using risk factors including gender, age, smoking history, lipid status, diabetes status, and family history. Increasingly, imaging has been deployed to directly detect coronary atherosclerotic disease. Quantification of coronary calcium (e.g., Agatston method, calcium mass and volume) is readily detected using helical CT scanners. Large multicenter cohort studies have enabled a better understanding of the relevance of coronary calcium detection. The purpose of this review is to review the methods for quantification of coronary artery calcium, as well as to present current and future perspectives on calcium scoring for cardiovascular risk stratification.

Vascular Calcification in Uremia: New-Age Concepts about an Old-Age Problem

A hallmark of aging, and major contributor to the increased prevalence of cardiovascular disease in patients with chronic kidney disease (CKD), is the progressive structural and functional deterioration of the arteries and concomitant accrual of mineral. Vascular calcification (VC) was long viewed as a degenerative age-related pathology that resulted from the passive deposition of mineral in the extracellular matrix; however, since the discovery of "bone-related" protein expression in calcified atherosclerotic plaques over 20 years ago, a plethora of studies have evoked the now widely accepted view that VC is a highly regulated and principally cell-mediated phenomenon that recapitulates many features of physiologic ossification. Central to this theory are changes in vascular smooth muscle cell (VSMC) phenotype and viability, thought to be driven by chronic exposure to a number of dystrophic stimuli characteristics of the uremic state. Here, dedifferentiated synthetic VSMCs are seen to spawn calcifying matrix vesicles that actively seed mineralization of the arterial matrix. This review provides an overview of the major epidemiological, histological, and molecular aspects of VC in the context of CKD, and a counterpoint to the prevailing paradigm that emphasizes the primacy of VSMC-mediated mechanisms. Particular focus is given to the import of protein and small molecule inhibitors in regulating physiologic and pathological mineralization and the emerging role of mineral nanoparticles and their interplay with proinflammatory processes.

Relationship between erectile dysfunction and silent coronary artery disease: detection with multidetector computed tomography coronary angiography

AIM

Our aim was to determine the relationship between erectile dysfunction (ED) and silent coronary artery disease (CAD) by multidetector computed tomography (MDCT) coronary angiography.

METHODS

Thirty consecutive men with nonhormonal and nonpsychogenic ED and with no cardiac symptoms were evaluated. Medical history, physical examination and laboratory investigation were performed. The five-item brief form of the International Index of Erectile Function (IIEF-5) was performed for evaluation of ED. The Agatston score (AS) was determined from MDCT images under beta blockade to induce bradycardia. The MDCT coronary angiography findings were evaluated by two radiologists blinded to the clinical findings. Patients were classified into three categories (mild, moderate and severe ED) according to IIEF-5 scores and into five categories (very low, low, moderate, moderately high and high CAD risk) according to the AS.

RESULTS

Mean age was 58.3 ± 8.7 years (46-79). 6 patients had hypertriglyceridemia, 4 had hypercholesterolemia and 4 had hyperglycemia. All patients had normal early morning testosterone levels. Regarding IIEF-5 scores, none of them had mild ED, 14 had moderate ED and 16 had severe ED. Of the 14 patients with moderate ED, 21.4% had low and 28.5% had moderate CAD risk regarding AS. Of the 16 patients with severe ED, 25% had moderate, 31.2% had moderately high and 25% had high CAD risk regarding AS. Increasing age was a risk factor for high AS (p = 0.045). There was a significant correlation between AS and ED severity (p = 0.01).

CONCLUSIONS

ED and CAD often coexist. MDCT coronary angiography can detect coronary lesions and allow appropriate medical intervention.

Coronary calcium quantification using contrast-enhanced dual-energy computed tomography scans

The purpose of this study is to evaluate a direct measure of calcium burden by using dual-energy computed tomography (DECT) during contrast-enhanced coronary imaging, potentially eliminating the need for an extra noncontrast X-ray acquisition. The ambiguity of separation of calcium from contrast material on contrast-enhanced images was solved by using virtual noncontrast images obtained by DECT. A new threshold CT number was required to detect the calcium carrying potential risk for adverse coronary events on virtual noncontrast images. Two methods were investigated to determine the 130 HU threshold for DECT scoring. An in vitro anthropomorphic phantom with 29 excised patient calcium plaques inserted was used for both a linear and a logistic regression analysis. An IRB approved in vivo prospective study of six patients was also performed to be used for logistic regression analysis. The threshold found by logistic regression model to define the calcium burden on virtual noncontrast images detects the calcium carrying potential risk for adverse coronary events correctly (2.45% error rate). DECT calcium mass and volume scores obtained by using the threshold correlates with both conventional Agatston and volume scores (r = 0.98, p &lt; 0.001). A conventional CT cardiac exam requires two scans, including a noncontrast scan for calcium quantification and a contrast-enhanced scan for coronary angiography. With the ability to quantify calcium on DECT contrast-enhanced images, a DECT cardiac exam could be accomplished with one contrast-enhanced scan for both calcium quantification and coronary angiography. 

Potential beneficial role of sevelamer hydrochloride in diabetic retinopathy

Patients with chronic kidney disease (CKD) experience co-morbid illnesses, including cardiovascular disease and retinopathy. Sevelamer hydrochloride (Renagel®); a non-calcium phosphate binder reduces coronary artery and aortic calcification as compared to calcium containing phosphate binders and additionally effects inflammatory biomarkers such as C-reactive protein (CRP), and lowers LDL cholesterol in patients with CKD. Since retinopathy is proven to be associated with increased coronary calcification, shared pathophysiological processes may contribute to both microvascular and macrovascular disease. We here suggest three different mechanisms of possible sevelamer's influence on the retinopathy: (1) by direct effect on the microvasculature through lowering CRP and LDL, involved in endothelial dysfunction and atherogenesis, (2) indirectly by attenuation of vascular calcification of aorta and carotid internal artery, it reduces ischaemia and improves circulation in the opthalmic artery and hence postponing retinopathy, (3) through hypertension by reducing atherosclerosis and calcification of carotid arteries, sevelamer decreases stiffness and intima-media wall thickness, therefore lowering blood pressure, which is well known to increase progression of diabetic retinopathy. So far no studies have yet been published on the direct influence of sevelamer on the retinopathy which we believe has good theoretical background. With its combined macrovascular and microvascular effect, sevelamer could potentially postpone and/or decrease retinopathy in diabetic patients with hypertension, and that are on hemodialysis or even predialysis patients.

Comparison of dual-source and electron-beam CT for the assessment of coronary artery calcium scoring

OBJECTIVE

Cardiac CT allows the detection and quantification of coronary artery calcification (CAC). Electron-beam CT (EBCT) has been widely replaced by high-end CT generations in the assessment of CAC. The aim of this study was to compare the CAC scores derived from an EBCT with those from a dual-source CT (DSCT).

METHODS

We retrospectively selected 92 patients (61 males; mean age, 60.7 ± 12 years) from our database, who underwent both EBCT and DSCT. CAC was assessed using the Agatston score by two independent readers (replicates: 1, 2; 3=mean of reading 1 and 2).

RESULTS

EBCT scores were on average slightly higher than DSCT scores (281 ± 569 vs 241 ± 502; p<0.05). In regression analysis R(2)-values vary from 0.956 (1) to 0.966 (3). We calculated a correction factor as EBCT=(DSCT+1)(1.026)-1. When stratifying into CAC categories (0, 1-99, 100-399, 400-999 and ≥1000), 79 (86%) were correctly classified. From those with positive CAC scores, 7 out of 61 cases (11%, κ=0.81) were classified in different categories. Using the corrected DSCT CAC score, linear regression analysis for the comparison to the EBCT results were r=0.971 (p<0.001), with a mean difference of 6.4 ± 147.8. Five subjects (5.4%) were still classified in different categories (κ=0.84).

CONCLUSION

CAC obtained from DSCT is highly correlated with the EBCT measures. Using the calculated correction factor, agreement only marginally improved the clinical interpretation of results. Overall, for clinical purposes, face value use of DSCT-derived values appears as useful as EBCT for CAC scoring.

Subclinical atherosclerosis: what it is, what it means and what we can do about it

Atherosclerosis is a chronic, progressive, inflammatory disease with a long asymptomatic phase. Disease progression can lead eventually to the occurrence of acute cardiovascular events such as myocardial infarction, unstable angina pectoris and sudden cardiac death. While the disease is still in a subclinical stage, however, the presence of atherosclerosis can be identified by several methods, including coronary angiography, intravascular ultrasonography, B-mode ultrasonography, computed tomography and magnetic resonance imaging. Based on the results of imaging studies, statin therapy can slow, halt or even reverse the progression of atherosclerotic disease, depending on the intensity of treatment. Whether to screen and treat patients for subclinical atherosclerosis remains controversial. Although atheromatous plaque burden reduction has not yet been definitively correlated with significant decreases in risk for acute coronary events in asymptomatic patients, statin therapy contributes significantly to the risk reduction observed in clinical trials in patients with and without overt coronary disease.

Interrelation of coronary calcification, myocardial ischemia, and outcomes in patients with intermediate likelihood of coronary artery disease: a combined positron emission tomography/computed tomography study

BACKGROUND

Although the value of coronary artery calcium (CAC) for atherosclerosis screening is gaining acceptance, its efficacy in predicting flow-limiting coronary artery disease remains controversial, and its incremental prognostic value over myocardial perfusion is not well established.

METHODS AND RESULTS

We evaluated 695 consecutive intermediate-risk patients undergoing combined rest-stress rubidium 82 positron emission tomography (PET) perfusion imaging and CAC scoring on a hybrid PET-computed tomography (CT) scanner. The frequency of abnormal scans among patients with a CAC score > or = 400 was higher than that in patients with a CAC score of 1 to 399 (48.5% versus 21.7%, P<0.001). Multivariate logistic regression supported the concept of a threshold CAC score > or = 400 governing this relationship (odds ratio 2.91, P<0.001); however, the frequency of ischemia among patients with no CAC was 16.0%, and its absence only afforded a negative predictive value of 84.0%. Risk-adjusted survival analysis demonstrated a stepwise increase in event rates (death and myocardial infarction) with increasing CAC scores in patients with and without ischemia on PET myocardial perfusion imaging. Among patients with normal PET myocardial perfusion imaging, the annualized event rate in patients with no CAC was lower than in those with a CAC score > or = 1000 (2.6% versus 12.3%, respectively). Likewise, in patients with ischemia on PET myocardial perfusion imaging, the annualized event rate in those with no CAC was lower than among patients with a CAC score > or = 1000 (8.2% versus 22.1%).

CONCLUSIONS

Although increasing CAC content is generally predictive of a higher likelihood of ischemia, its absence does not completely eliminate the possibility of flow-limiting coronary artery disease. Importantly, a stepwise increase occurs in the risk of adverse events with increasing CAC scores in patients with and without ischemia on PET myocardial perfusion imaging.

Mechanisms of vascular calcification in chronic kidney disease

Vascular calcification is common in chronic kidney disease and associated with increased morbidity and mortality. Its mechanism is multifactorial and incompletely understood. Patients with chronic kidney disease are at risk for vascular calcification because of multiple risk factors that induce vascular smooth muscle cells to change into a chondrocyte or osteoblast-like cell; high total body burden of calcium and phosphorus due to abnormal bone metabolism; low levels of circulating and locally produced inhibitors; impaired renal excretion; and current therapies. Together these factors increase risk and complicate the management of vascular calcification.

Calcium scoring using 64-slice MDCT, dual source CT and EBT: a comparative phantom study

Purpose Assessment of calcium scoring (Ca-scoring) on a 64-slice multi-detector computed tomography (MDCT) scanner, a dual-source computed tomography (DSCT) scanner and an electron beam tomography (EBT) scanner with a moving cardiac phantom as a function of heart rate, slice thickness and calcium density. Methods and materials Three artificial arteries with inserted calcifications of different sizes and densities were scanned at rest (0 beats per minute) and at 50–110 beats per minute (bpm) with an interval of 10 bpm using 64-slice MDCT, DSCT and EBT. Images were reconstructed with a slice thickness of 0.6 and 3.0 mm. Agatston score, volume score and equivalent mass score were determined for each artery. A cardiac motion susceptibility (CMS) index was introduced to assess the susceptibility of Ca-scoring to heart rate. In addition, a difference (Δ) index was introduced to assess the difference of absolute Ca-scoring on MDCT and DSCT with EBT. Results Ca-score is relatively constant up to 60 bpm and starts to decrease or increase above 70 bpm, depending on scoring method, calcification density and slice thickness. EBT showed the least susceptibility to cardiac motion with the smallest average CMS-index (2.5). The average CMS-index of 64-slice MDCT (9.0) is approximately 2.5 times the average CMS-index of DSCT (3.6). The use of a smaller slice thickness decreases the CMS-index for both CT-modalities. The Δ-index for DSCT at 0.6 mm (53.2) is approximately 30% lower than the Δ-index for 64-slice MDCT at 0.6 mm (72.0). The Δ-indexes at 3.0 mm are approximately equal for both modalities (96.9 and 102.0 for 64-slice MDCT and DSCT respectively). Conclusion Ca-scoring is influenced by heart rate, slice thickness and modality used. Ca-scoring on DSCT is approximately 50% less susceptible to cardiac motion as 64-slice MDCT. DSCT offers a better approximation of absolute calcium score on EBT than 64-slice MDCT when using a smaller slice thickness. A smaller slice thickness reduces the susceptibility to cardiac motion and reduces the difference between CT-data and EBT-data. The best approximation of EBT on CT is found for DSCT with a slice thickness of 0.6 mm.

Relations between bone status and glucose metabolism with progression of insulin resistance

Az elhízás, a metabolikus szindróma, a 2-es típusú cukorbetegség és a csontritkulás előfordulása világszerte növekszik, vagyis a világméretű diabéteszjárványt az az elhízás „hajtja”, amely nők esetében erősebb csontokat eredményez. Vizsgálatunk során a glükózanyagcsere-zavar korai időszakában kerestük a csontállapot és a metabolikus paraméterek közötti összefüggéseket. A vizsgálatban 20 egészséges és 51 glükózintoleráns (49 ± 9 év) nőbeteg vett részt. Mértük a szénhidrát-, lipid- és csontanyagcsere paramétereit, a csontok denzitását (lumbális 1–4 csigolyákon és a femur nyakon); cukorterheléses és hyperinsulinaemiás-normoglykaemiás klamp vizsgálatot végeztünk. A csontok denzitása a két csoport között nem különbözött. Az egészségesek denzitása szoros kapcsolatban volt az egésztest-cukorfelhasználással (inzulinérzékenység) (gerinc r = –0,4921, p < 0,05, femur: r = –0,4972, p < 0,05), de a romló glükóztoleranciával ez a kapcsolat megszűnt (gerinc: r = –0,022, ns; femur: r = –0,3136, ns). Az adipokinek közül csak az adiponectin korrelált a denzitással, amíg ez a kapcsolat a cukoranyagcsere romlásával megmaradt a gerincen ( r = –0,5081, p < 0,05; –0,2804, p < 0,05), eltűnt a femuron ( r = –0,6742, p < 0,01; –0,1723, ns). A formációs és reszorpciós markerből képzett „reszorpciós hányados” növekedése a glükózanyagcsere romlásával csökkenő csontreszorpciót jelezte. Adataink az inzulinrezisztencia „gold standard” mérőmódszerét használva szoros kapcsolatot igazoltak a glükózanyagcsere, inzulinérzékenység és a csontok állapota között az egészséges, változó korban lévő nőkben, mely a glükóztolerancia romlásával és az inzulinrezisztencia kialakulásával megbomlik. Az egészségesekben észlelhető, de az inzulinrezisztencia kialakulásával romló, negatív adiponectin-csont kapcsolat értelmezése további vizsgálatokat igényel.

Indications for Coronary and Cardiac Computed Tomographic Angiography

Cardiovascular disease remains the leading cause of death and disability in the developed world. Over the last several years, many noninvasive imaging techniques have been used to enhance the diagnosis of cardiac disease. One of these advances, multidetector computed tomographic angiography (CTA), has transformed computed tomography from a single-slice transaxial imaging modality to a true 3-dimensional imaging technique with the ability to acquire submillimeter volumetric data. These benefits enable novel applications of CTA for the assessment of cardiac and coronary anatomy that were not previously possible. In this report, we discuss evolving indications for coronary CTA, noncoronary cardiac CTA, and several potential future indications for cardiac CTA.

Accuracy of 64-row multidetector computed tomography in detecting coronary artery disease in 134 symptomatic patients: influence of calcification

BACKGROUND

The new 64-row multidetector computed tomography (CT)-assisted angiography can now detect coronary artery disease with shorter breath-hold time and at faster heart rates for symptomatic patients. We aim to determine if the 64-row scanner can also overcome limitations due to mild to moderate calcification.

METHODS

Scheduled for conventional coronary angiography, 134 symptomatic patients underwent multidetector CT-assisted angiography within 3 months. Patients were divided into those with low or high calcium score (median score 142) by modified Agatston formula: group A calcium score <142 Agatston score (68 patients, mean age 53 years, heart rate 62 beat/min) and group B calcium score > or = 142 Agatston score (66 patients, mean age 57 years, heart rate 62 beat/min). Eleven major coronary segments were evaluated.

RESULTS

In group A, 93.6% of segments were evaluable with 97.3% correlation. Segment-by-segment analyses for sensitivity, specificity, and positive and negative predictive values were 85.4%, 98.1%, 76.7%, and 99.2%, respectively. For group B, 86.9% of segments were evaluable with 90.5% correlation. Sensitivity, specificity, and positive and negative predictive values were 79.9%, 92.8%, 78.8%, and 93.5%, respectively.

CONCLUSIONS

The 64-slice multidetector CT coronary angiography can reliably detect the presence of significant coronary stenosis in symptomatic patients with mild calcification, but remains limited by moderate to heavy calcification.

Noninvasive diagnosis of coronary artery disease in women

Cardiovascular disease is the leading cause of mortality and significant morbidly among women in the United States. The frequent absence of antecedent symptoms, the potential for an initial fatal cardiac event and the limitations of currently available noninvasive diagnostic tests pose challenges to healthcare practitioners as they try to optimally risk stratify patients. Therefore, the purpose of this article is to discuss the accuracy of noninvasive tests for CAD diagnosis in women.

27-Hydroxycholesterol causes remodeling in endothelial cell membrane lipid composition comparable to remodeling in the failed vein grafts of CABG patients

Our objective is to determine if vascular remodeling in CABG patients is related to oxysterols, therefore, we compared failed vein grafts from 18 patients, available after a second coronary artery bypass grafting (CABG), with human endothelial cells (ECs). The ECs were cultured in minimum essential medium (MEM) with or without 27-hydroxycholesterol (27OHC), one of the oxysterol products of oxidatively modified low density lipoproteins (ox-LDL), as an agent to alter molecular mechanisms in vascular cells. Significant changes in phospholipid composition, in fatty acid profile and in calcium concentration were found in the failed vein compared to the native saphenous vein from the same (CABG) patient. The failed vein contained significantly less phosphatidylethanolamine, more sphingomyelin, less arachidonic acid, more linoleic acid and more calcium than the native saphenous vein. Comparable changes in phospholipid composition, in fatty acid profile and increased calcium influx were reproduced in ECs cultured in medium containing 27OHC indicating that an oxysterol is an agent that can alter the lipid composition of vascular cell membranes. Our study indicates that a lipid agent, as well as protein agents that have previously been linked to the process of vascular remodeling, may be fundamental to many vascular diseases.

Population-based assessment of subclinical coronary atherosclerosis using electron-beam computed tomography

AIMS

Coronary artery calcification (CAC) is determined as a measure of the extent of coronary atherosclerosis and can be used for expanded cardiovascular risk stratification. It was our aim to establish reference CAC scores in a population-based unselected European cohort.

METHODS AND RESULTS

The Heinz Nixdorf Recall study (HNR) recruited a total of 4814 participants aged 45-74 years. Cardiovascular risk factors and medications were recorded, and CAC was measured using electron-beam CT (EBCT). CAC score distribution was compared with previous studies in subjects who were self-referred, volunteered, or were physician-referred. Of the 4472 (92.9%) subjects free of clinical coronary artery disease, the CAC score was available in 4275 (95.3%) (2027 men, 2248 women). CAC scores were lower in particular in the higher age groups (> or = 60 years) in men than in the previous studies. Also, in most age groups (except the highest, 70-74 years), subjects with no cardiovascular medications had significantly lower CAC scores than subjects using cardiovascular medications.

CONCLUSIONS

The current report characterises the distribution of EBCT-derived CAC scores in a European unselected population. Compared with previous reports, CAC scores were lower in our cohort, in particular in subjects not receiving cardiovascular medications. Classification of the CAC score may underestimate true risk if previously published referral cohorts are used as the reference.

Natural history of vascular calcification in dialysis and transplant patients

BACKGROUND

The purpose of the present study was to determine the natural history of coronary artery and aorta calcification by spiral computed tomography (CT) in patients who undergo a renal transplant and patients on haemodialysis.

METHODS

Two cohorts were evaluated for the natural history of vascular calcification: (i) 23 patients who underwent a baseline CT scan at the time of renal transplant and a repeat evaluation 15-20 months later; and (ii) 33 chronic kidney disease, stage 5 haemodialysis subjects who underwent a baseline CT scan, all followed for a minimum of 15 months, and 17 of whom underwent a second CT scan.

RESULTS

In the patients undergoing a renal transplant, there was no net change in CAC with time, suggesting stabilization of calcification. In the haemodialysis patients, the median CAC increased by 1.27+/-1.88 score/days, P = 0.013. There was a trend towards increasing AoC score in both groups. All patients without calcification at baseline remained calcification free at follow-up. In the 15 months following baseline, the six dialysis patients who died had a significantly greater CAC score at baseline compared with the 24 patients who remained alive. Similarly, those patients who were hospitalized had a greater baseline CAC than patients who were not hospitalized.

CONCLUSION

In this preliminary study, renal transplantation appears to slow down or arrest CAC, whereas CAC progresses in haemodialysis patients. In haemodialysis patients, CAC was greater in patients who died or were hospitalized compared with those who remained alive or were not hospitalized.