Predicting coronary events with coronary calcium: pathophysiologic and clinical problems

Prognostic implications of myocardial perfusion imaging and coronary calcium score in a Macedonian cohort of asymptomatic patients with type 2 diabetes

AIM

Type 2 diabetes is a risk factor for coronary artery disease; however, a number of studies have shown that patients are asymptomatic for coronary artery disease. The presence of coronary artery disease in asymptomatic patients with type 2 diabetes was evaluated to determine its impact on management decision and prognosis.

METHODS

A total of 75 patients underwent single-photon emission computed tomography myocardial perfusion imaging for detection of suspected coronary artery disease. We used 17-segment model for perfusion and function analysis. Multislice computed tomography was performed in 45 patients to assess coronary artery calcium. Complete laboratory analyses with lipid values and standard risk factors were analysed. Forward logistic regression analysis was used to assess predictive parameters for myocardial ischaemia during the follow-up period of 20 ± 4 months.

RESULTS AND CONCLUSION

Silent myocardial ischaemia and subclinical coronary artery disease can be detected in a significant proportion of asymptomatic patients with type 2 diabetes. Diabetic patients with normal myocardial perfusion imaging had an excellent 2-year prognosis with optimal medical therapy and intensive risk factor control. In comparison, an abnormal myocardial perfusion imaging led to an increased risk of cardiovascular events. Myocardial perfusion imaging and coronary artery calcium are valuable tools for risk stratification and optimal treatment decision in this asymptomatic diabetic cohort of Macedonian patients.

Serum Alkaline Phosphatase and Risk of Incident Cardiovascular Disease: Interrelationship with High Sensitivity C-Reactive Protein

Background

Alkaline phosphatase (ALP) has been suggested to be associated with cardiovascular disease (CVD) risk, however, important aspects of the association, such as shape and independence from established risk factors, have yet to be characterized in detail. We assessed the association of ALP with CVD risk and determined its utility for CVD risk prediction.

Methods

Alkaline phosphatase activity was measured at baseline in the PREVEND prospective cohort involving 6,974 participants aged 28-75 years without pre-existing CVD. Hazard ratios (95% confidence intervals [CI]) and measures of risk discrimination and reclassification were assessed.

Results

During a median follow-up of 10.5 years, 737 participants developed CVD. Serum ALP was correlated with several risk markers for CVD, with strongest correlations for age (r = 0.30; P < 0.001), gamma-glutamyltransferase (r = 0.26; P < 0.001), and C-reactive protein (CRP) (r = 0.25; P < 0.001). There was a non-linear “J-shaped” relationship between ALP and CVD risk. In analyses adjusted for conventional risk factors, the hazard ratio (95% CI) for CVD in a comparison of the top quintile versus bottom quintiles 1-4 of ALP values was 1.34 (1.14 to 1.56; P<0.001), which persisted after additional adjustment for potential confounders 1.33 (1.13 to 1.55; P<0.001). However, the association was somewhat attenuated after adjustment for CRP 1.24 (1.05 to 1.45; P=0.009). Addition of information on ALP to a CVD risk prediction model containing established risk factors did not improve the C-index or net reclassification.

Conclusions

Available evidence suggests a non-linear association between ALP activity and CVD risk, which is partly dependent on CRP. Taking account of conventional risk factors, additional information on ALP does not improve CVD risk assessment.

Amyloidosis, inflammation, and oxidative stress in the heart of an alkaptonuric patient

Background. Alkaptonuria, a rare autosomal recessive metabolic disorder caused by deficiency in homogentisate 1,2-dioxygenase activity, leads to accumulation of oxidised homogentisic acid in cartilage and collagenous structures present in all organs and tissues, especially joints and heart, causing a pigmentation called ochronosis. A secondary amyloidosis is associated with AKU. Here we report a study of an aortic valve from an AKU patient. Results. Congo Red birefringence, Th-T fluorescence, and biochemical assays demonstrated the presence of SAA-amyloid deposits in AKU stenotic aortic valve. Light and electron microscopy assessed the colocalization of ochronotic pigment and SAA-amyloid, the presence of calcified areas in the valve. Immunofluorescence detected lipid peroxidation of the tissue and lymphocyte/macrophage infiltration causing inflammation. High SAA plasma levels and proinflammatory cytokines levels comparable to those from rheumatoid arthritis patients were found in AKU patient. Conclusions. SAA-amyloidosis was present in the aortic valve from an AKU patient and colocalized with ochronotic pigment as well as with tissue calcification, lipid oxidation, macrophages infiltration, cell death, and tissue degeneration. A local HGD expression in human cardiac tissue has also been ascertained suggesting a consequent local production of ochronotic pigment in AKU heart.

Coronary artery ectasia diagnosed using multidetector computed tomography: morphology and relation to coronary artery calcification

Coronary artery ectasia (CAE) is usually considered a variant of coronary artery atherosclerosis; however, a definite link has not yet been confirmed. As not all patients with CAE are symptomatic, the real incidence is unknown. The aim of this study was to evaluate the prevalence of CAE and its clinical and angiographic characteristics as well as its relation to coronary artery calcification and any associated vascular abnormality by using multidetector computed tomography (MDCT). We prospectively enrolled 2,600 patients (mean age 55 ± 10 years) who were scheduled for computed tomography coronary angiography (CTCA). CTCA was performed using 64-MDCT with dedicated software for calcium measurement. CAE was defined as an arterial segment with a diameter of >1.5 times the diameter of the adjacent normal segment. The presence of ≥70 % diameter stenosis of any major epicardial vessel was considered an obstructive lesion. CAE was encountered in 192 (7.4 %) patients and showed gender predominance in men (88 %). Patients with CAE were more hypertensive but less diabetic. Left anterior descending artery was the most commonly affected vessel. Only 16 % of CAE patients had no atherosclerotic lesion. Coronary artery calcium score (CACS) and prevalence of ascending aorta aneurysm were shown to be significantly higher in CAE patients compared to patients having no ectasia. A significant negative correlation was noted between CACS and Markis classification. CTCA is a feasible technique to identify and evaluate morphology of CAE. The link between CACS and CAE may favor the consideration that ectasia is an advanced form of atherosclerosis.

Current techniques for MR imaging of atherosclerosis

Vessel wall imaging of large vessels has the potential to identify culprit atherosclerotic plaques that lead to cardiovascular events. Comprehensive assessment of atherosclerotic plaque size, composition, and biological activity is possible with magnetic resonance imaging (MRI). Magnetic resonance imaging of the atherosclerotic plaque has demonstrated high accuracy and measurement reproducibility for plaque size. The accuracy of in vivo multicontrast MRI for identification of plaque composition has been validated against histological findings. Magnetic resonance imaging markers of plaque biological activity such as neovasculature and inflammation have been demonstrated. In contrast to other plaque imaging modalities, MRI can be used to study multiple vascular beds noninvasively over time. In this review, we compare the status of in vivo plaque imaging by MRI to competing imaging modalities. Recent MR technological improvements allow fast, accurate, and reproducible plaque imaging. An overview of current MRI techniques required for carotid plaque imaging including hardware, specialized pulse sequences, and processing algorithms are presented. In addition, the application of these techniques to coronary, aortic, and peripheral vascular beds is reviewed.

Carbonic anhydrases II and XII are up-regulated in osteoclast-like cells in advanced human atherosclerotic plaques-Tampere Vascular Study

BACKGROUND AND AIMS

Carbonic anhydrases (CA) play a central role in osteoclast function and bone remodeling by catalyzing the formation of bicarbonate and proton from carbon dioxide. According to previous histochemical studies, advanced atherosclerotic plaques share similarities with bone. However, whether CAs are expressed in plaques is not known.

METHODS AND RESULTS

Whole genome expression array of arterial samples (n = 24) confirmed that several genes indicating osteoblastogenesis and osteoclastogenesis were up-regulated in plaques when compared to control vessel samples from internal thoracic arteries (n = 6), including CA2 and CA12, expression of which was also verified with quantitative reverse transcription polymerase chain reaction (RT-PCR). In atherosclerotic plaques there was 11.6-fold (P < 0.0001) and 11.4-fold (P < 0.0001) up-regulation of CA2 and CA12, compared to controls, respectively. According to quantitative PCR, CA2 expression was elevated in carotid (12.3-fold, P < 0.0001), femoral (13.2-fold, P < 0.01), and aortic plaques (7.5-fold, P < 0.0001). CA12 expression was elevated in carotid (11.6-fold, P < 0.0001), femoral (11.5-fold, P < 0.01), and aortic plaques (9.7-fold, P < 0.0001). CAII, CAXII, and CD68 and tartrate-resistant acid phosphatase (TRAP), a marker of osteoclast-like cells, were found to be co-localized in multinucleated giant cells in the atherosclerotic plaques using immunohistochemistry and double-staining immunofluorescence analysis.

CONCLUSIONS

The present findings provide evidence for the involvement of CAs in advanced atherosclerosis in osteoclast-like cells of monocyte-macrophage lineage.

Feasibility of 18F-sodium fluoride PET/CT for imaging of atherosclerotic plaque

The aim of this study was to examine the prevalence, distribution, and topographic relationship of vascular (18)F-sodium fluoride uptake and arterial calcification in major arteries.

METHODS

Image data obtained from 75 patients undergoing whole-body (18)F-sodium fluoride PET/CT were evaluated retrospectively. Arterial radiotracer uptake and calcification were analyzed qualitatively and semiquantitatively.

RESULTS

(18)F-sodium fluoride uptake was observed at 254 sites in 57 (76%) of the 75 study patients, and calcification was observed at 1,930 sites in 63 (84%) of the patients. Colocalization of radiotracer accumulation and calcification could be observed in 223 areas of uptake (88%). However, only 12% of all arterial calcification sites showed increased radiotracer uptake.

CONCLUSION

Our data indicate the feasibility of (18)F-sodium fluoride PET/CT for the imaging of mineral deposition in arterial wall alterations. (18)F-sodium fluoride PET/CT may provide relevant information about the morphologic and functional properties of calcified plaque.

The immune response is involved in atherosclerotic plaque calcification: could the RANKL/RANK/OPG system be a marker of plaque instability?

Atherogenesis is characterized by an intense inflammatory process, involving immune and vascular cells. These cells play a crucial role in all phases of atherosclerotic plaque formation and complication through cytokine, protease, and prothrombotic factor secretion. The accumulation of inflammatory cells and thus high amounts of soluble mediators are responsible for the evolution of some plaques to instable phenotype which may lead to rupture. One condition strongly associated with plaque rupture is calcification, a physiopathological process orchestrated by several soluble factors, including the receptor activator of nuclear factor (NF)κB ligand (RANKL)/receptor activator of nuclear factor (NF)κB (RANK)/osteoprotegerin (OPG) system. Although some studies showed some interesting correlations with acute ischemic events, at present, more evidences are needed to evaluate the predictive and diagnostic value of serum sRANKL and OPG levels for clinical use. The major limitation is probably the poor specificity of these factors for cardiovascular disease. The identification of tissue-specific isoforms could increase the importance of sRANKL and OPG in predicting calcified plaque rupture and the dramatic ischemic consequences in the brain and the heart.

Novel inhibitors of alkaline phosphatase suppress vascular smooth muscle cell calcification

We report three novel inhibitors of the physiological pyrophosphatase activity of alkaline phosphatase and show that these compounds are capable of reducing calcification in two models of vascular calcification (i.e., they suppress in vitro calcification by cultured Enpp1(-/-) VSMCs and they inhibit the increased pyrophosphatase activity in a rat aortic model).

INTRODUCTION

Genetic ablation of tissue-nonspecific alkaline phosphatase (TNALP) leads to accumulation of the calcification inhibitor inorganic pyrophosphate (PP(i)). TNALP deficiency ameliorates the hypermineralization phenotype in Enpp1(-/-) and ank/ank mice, two models of osteoarthritis and soft tissue calcification. We surmised that the pharmacological inhibition of TNALP pyrophosphatase activity could be used to prevent/suppress vascular calcification.

MATERIALS AND METHODS

Comprehensive chemical libraries were screened to identify novel drug-like compounds that could inhibit TNALP pyrophosphatase function at physiological pH. We used these novel compounds to block calcification by cultured vascular smooth muscle cells (VSMCs) and to inhibit the upregulated pyrophosphatase activity in a rat aortic calcification model.

RESULTS

Using VSMC cultures, we determined that Enpp1(-/-) and ank/ank VSMCs express higher TNALP levels and enhanced in vitro calcification compared with wildtype cells. By high-throughput screening, three novel compounds, 5,361,418, 5,923,412, and 5,804,079, were identified that inhibit TNALP pyrophosphatase function through an uncompetitive mechanism, with high affinity and specificity when measured at both pH 9.8 and 7.5. These compounds were shown to reduce the calcification by Enpp1(-/-) VSMCs. Furthermore, using an ex vivo rat whole aorta PP(i) hydrolysis assay, we showed that pyrophosphatase activity was inhibited by all three lead compounds, with compound 5,804,079 being the most potent at pH 7.5.

CONCLUSIONS

We conclude that TNALP is a druggable target for the treatment and/or prevention of ectopic calcification. The lead compounds identified in this study will serve as scaffolds for medicinal chemistry efforts to develop drugs for the treatment of soft tissue calcification.

Coronary artery calcification, serum lipids, lipoproteins, and peripheral inflammatory markers in adolescents and young adults with type 1 diabetes

OBJECTIVE

To determine whether coronary artery calcification (CAC), elevated fasting lipids, and lipoproteins and peripheral inflammatory markers are present in insulin-dependent diabetic adolescents and young adults several years after diagnosis.

STUDY DESIGN

Hispanic insulin-dependent diabetics (n = 32) diagnosed a mean of 7.8 +/- 4.5 years ago (range, 3 to 16 years), with a mean glycosylated hemoglobin concentration at the time of the study of 8.8% +/- 2.3% and a mean chronological age of 16.1 +/- 4.4 years, were evaluated. Healthy patients (n = 15) with a chronological age (CA) of 15.2 +/- 2.2 years served as control subjects. CAC was assessed by multiple slice computed tomography, and total CAC score in Agatston units was calculated. Fasting lipids, C-reactive protein, apolipoprotein (Apo) A, Apo B, and metalloproteinase-9 (MMP-9) concentrations were measured in all subjects.

RESULTS

Neither adolescents with type 1 diabetes nor healthy control subjects presented with evidence of CAC. Fasting lipids, Apo A, Apo B, CRP, and MMP-9 concentrations were similar between diabetic subjects and control subjects. However, 34.4% and 25.0% of our type 1 diabetic subjects had elevated total and LDL cholesterol levels (>200 and >130 mg/dL, respectively), whereas 15.6% and 28.1% had elevated triglyceride and Apo B concentrations (>150 mg/dL and >100 mg/dL, respectively). In addition, 28.1% and 34.4% presented with elevated CRP and MMP-9 levels (>2 mg/L and >80 ng/mL, respectively). Total, LDL and HDL cholesterol, triglycerides, Apo B, CRP, and MMP-9 concentrations correlated positively with duration of the disease and with glycosylated hemoglobin levels.

CONCLUSIONS

Although the study adolescents with type 1 diabetes did not present any radiologic evidence of CAC at this stage of the disease, they remain a high-risk group for the development of microvascular and macrovascular artery disease, as risk factors such as elevated lipoproteins and proinflammatory markers are already present in a significant percentage of patients studied.

Calcium Deposition and Associated Chronic Diseases (Atherosclerosis, Diffuse Idiopathic Skeletal Hyperostosis, and Others)

Extracellular matrix mineralization or calcification occurs in many pathologic conditions, including atherosclerosis, medial wall calcification, diffuse idiopathic skeletal hyperostosis, and chondrocalcinosis. Vascular wall calcification is the most common and involves two mechanisms: passive calcification resulting from breakdown of the protection system and active calcification resulting from transdifferentiation of mesenchymal cells in the vascular wall to bone. Although reports are conflicting, several matrix proteins are identified as protective factors against dystrophic calcification in nonosseous tissues. Serum matrix Gla protein may be a marker of osteometabolic syndromes that cause hyperostosis and plays a role in Milwaukee shoulder syndrome.

Cardiovascular calcification in Hispanic Americans (HA) with chronic kidney disease (CKD) due to type 2 diabetes

BACKGROUND

Cardiovascular calcification (CVC) is common and severe in patients with end-stage renal disease on dialysis. However, the prevalence and severity of CVC is less well documented in patients with chronic kidney disease (CKD) not yet on dialysis.

METHODS

Fifty-eight nondialyzed HA with type 2 diabetes and CKD were enrolled. They comprise 29 patients with stages 1 and 2 CKD (early CKD group) and 26 patients with stages 4 and 5 CKD (advanced CKD group). Coronary artery calcification (CAC) was measured by ultrafast spiral computed tomography, while peripheral artery calcification (PAC) was evaluated by plain x-ray of the chest, pelvis, thighs, and lower extremities.

RESULTS

The prevalence of CAC and PAC were significantly higher in the advanced CKD group compared to the early CKD group (73% vs. 38%; P < 0.01 and 85% vs. 35%; P < 0.0001, respectively). The median CAC scores were 18-fold greater in the advanced CKD group (138.9 vs. 7.8, respectively). By linear regression analysis, a strong association was found between the level of renal function and ln total volume of CAC.

CONCLUSION

Our data indicate that CAC and PAC are common and severe in HA diabetic patients with CKD not previously treated with dialysis, calcium-based phosphate binders, or vitamin D analogues. Lower level of renal function is associated with increased burden of vascular calcification in predialysis patients with CKD.

Dyslipidemia and progression of cardiovascular calcification (CVC) in patients with end-stage renal disease (ESRD)

Dyslipidemia and progression of cardiovascular calcification (CVC) in patients with end-stage renal disease (ESRD). Cardiovascular calcification (CVC) is commonly encountered both in the general population as well as in patients with end-stage renal disease (ESRD). The etiology of CVC in patients with ESRD is multifactorial. Despite that, current debate remains narrowly focused on the role of calcium loading from calcium-based phosphate binders (CBPB) in the pathogenesis and progression of CVC. Yet, the alleged link between these binders and CVC has not been substantiated in well-designed controlled trials. In contrast, the purported role of sevelamer, a non-calcium-based phosphate binder, in slowing the progression of CVC in dialysis patients has attracted widespread attention. The beneficial effect of sevelamer on progression of calcification was thought to be due to lower calcium loading during its use. However, an alternative and possibly more likely mechanism involves sevelamer-induced lowering of LDL cholesterol. In this context, previous studies in individuals with normal renal function have documented amelioration of coronary artery calcification (CAC) with reduction of LDL-cholesterol by treatment with HMG-CoA reductase inhibitors (statins). Given that CAC is a well-accepted marker of atherosclerosis, and that high plasma cholesterol concentration is one of the main risk factors for atherosclerosis, then it is not unreasonable to suspect that CAC may be halted or even reversed by lowering of LDL cholesterol level with statin therapy. Unfortunately, the effect of lowering the LDL-cholesterol level on CAC has not been studied in patients with ESRD. Therefore, conclusions about this important topic should await the results of well-designed clinical studies that control for all factors potentially implicated in the CVC burden of patients with ESRD. In this review, I will discuss the role of various potential mechanisms involved in the pathogenesis of CVC in patients with ESRD, and emphasize the role of dyslipidemia and its treatment in this important clinical entity.

Visualising noncalcified coronary plaques by CT

Due to a rapid improvement of the new generation submillimetre multislice CT-technology noninvasive tomographic imaging of the coronary vessel wall has become reality. First clinical studies have shown the ability in particular of 16-slice CT to determine plaque burden, plaque composition and compensatory vessel-wall remodelling. These novel findings already constitute an important step forward to assess coronary atherosclerosis noninvasively in a detailed manner which opens promising new opportunities for a better understanding and riskstratification of coronary atherosclerosis. Current limitations, mainly the insufficient accuracy to detect small lesions in distal coronary segments, might be overcome by improved spatial and temporal resolution of the new generation scanners operating with 64 and more detectors.

The pathogenesis of atherosclerosis

Worldwide, more people die of the complications of atherosclerosis than of any other cause. It is not surprising, therefore, that enormous resources have been devoted to studying the pathogenesis of this condition. This article attempts to summarize present knowledge on the events that take place within the arterial wall during atherogenesis. Classical risk factors are not dealt with as they are the subjects of other parts of this book. First, we deal with the role of endothelial dysfunction and infection in initiating the atherosclerotic lesion. Then we describe the development of the lesion itself, with particular emphasis on the cell types involved and the interactions between them. The next section of the chapter deals with the events leading to thrombotic occlusion of the atherosclerotic vessel, the cause of heart attack and stroke. Finally, we describe the advantages--and limitations--of current animal models as they contribute to our understanding of atherosclerosis and its complications.

Inhibitory effects of etidronate on the progression of vascular calcification in hemodialysis patients

The present study was designed to determine if etidronate inhibits the development of aortic calcification in hemodialysis (HD) patients. Eighteen Japanese HD patients were divided randomly into etidronate-treated or control groups. Etidronate was given orally at the dose of 200 mg just before sleep on the day of dialysis, which was performed three times per week. In the control group, the aortic calcification area (ACA) increased after 6 months. In the patients who received etidronate, however, when compared to the control group, increases in ACA were significantly suppressed. Serum Ca, P, and the Ca x P product did not change during etidronate treatment. These results suggest that etidronate inhibits the progression of vascular calcification without changes in serum Ca and P levels.

Accuracy of multidetector spiral computed tomography in identifying and differentiating the composition of coronary atherosclerotic plaques

OBJECTIVES

We evaluated the accuracy of contrast-enhanced multidetector spiral computed tomography (MDCT) for the noninvasive detection and classification of coronary plaques and compared it with intracoronary ultrasound (ICUS).

BACKGROUND

Noninvasive determination of plaque composition and plaque burden may be important to improve risk stratification and to monitor progression of coronary atherosclerosis.

METHODS

We included 46 consecutive patients with a distinctive risk profile, who were investigated by ICUS (Goldvision, 20 MHz, Jomed Inc., Rancho Cordova, California). Due to the inability to slow the heart rate below 65 beats/min (n = 7) and due to renal insufficiency (n = 2), nine of 46 consecutive patients could not be studied by MDCT (Sensation 16, Siemens, Forchheim, Germany).

RESULTS

In the remaining 37 patients, 68 vessels were investigated by ICUS, and 58 of these vessels were visualized by MDCT with image quality sufficient for analysis. In these vessels that were divided in 3-mm sections, MDCT correctly classified 62 of 80 (78%) sections containing hypoechoic plaque areas, 87 of 112 (78%) sections containing hyperechoic plaque areas, and 150 of 158 (95%) sections containing calcified plaque tissue. In 484 of 525 (92%) sections, atherosclerotic lesions were correctly excluded. The MDCT-derived density measurements within coronary lesions revealed significantly different values for hypoechoic (49 HU [Hounsfield Units] +/- 22), hyperechoic (91 HU +/- 22), and calcified plaques (391 HU +/- 156, p < 0.02).

CONCLUSIONS

This study demonstrates that, in the case of diagnostic image quality, contrast-enhanced MDCT permits an accurate identification of coronary plaques and that computed tomography density values measured within plaques reflect echogenity and plaque composition.

Genetic determinants of arterial calcification associated with atherosclerosis

Increasing research interest has focused on arterial calcification in the setting of atherosclerosis. Many features of atherosclerosis-related calcification provide useful clinical information. For example, calcium mineral deposits frequently form in atherosclerotic plaque, and intimal arterial calcification can be used as a surrogate marker for atherosclerosis; also, calcium deposits are readily and noninvasively quantified, which is useful because greater amounts of coronary calcification predict a higher risk of myocardial infarction and death. Several mechanisms leading to calcification associated with atherosclerosis have been proposed; however, no direct testing of proposed mechanisms has yet been reported. Studies in genetically altered animals and in humans have shed light on potential genetic determinants, which in turn could form the basis for a more comprehensive understanding of the factors affecting calcification within plaque and the associated pathobiologic implications. We review proposed molecular and cellular mechanisms of atherosclerosis-associated arterial calcification, summarize genetic influences, and suggest areas in which further investigation is needed. Understanding the molecular and genetic determinants of specific structural plaque components such as calcification can provide a solid foundation for the development of novel therapeutic approaches to favorably alter plaque structure and minimize vulnerability to arterial rupture.

Effect of type 1 diabetes on the gender difference in coronary artery calcification: a role for insulin resistance? The Coronary Artery Calcification in Type 1 Diabetes (CACTI) Study

The objective of this is study was to examine whether estimated insulin resistance and insulin resistance-related factors are associated with coronary artery calcification (CAC) in 1,420 asymptomatic participants in the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study. A total of 656 patients with type 1 diabetes and 764 control subjects aged 20-55 years were examined. CAC was assessed by electron-beam computed tomography. Insulin resistance was computed with linear regression based on an equation previously validated in clamp studies on type 1 diabetic adults. Insulin resistance was associated with CAC (OR 1.6 in type 1 diabetes and 1.4 in control subjects, P < 0.001), independent of coronary artery disease risk factors. There was a male excess of CAC in control subjects (OR 2.7, adjusted for age, smoking, and LDL and HDL cholesterol levels) and in type 1 diabetic patients (OR 2.2, adjusted for the same factors and diabetes duration). After adjusting for insulin resistance, the CAC male excess in diabetic patients decreased from OR 2.2 (P < 0.001) to 1.8 (P = 0.04). After adjustment for waist-to-hip ratio, waist circumference, or visceral fat, the gender difference in CAC was not significant in diabetic subjects. In conclusion, gender differences in insulin resistance-associated fat distribution may explain why type 1 diabetes increases coronary calcification in women relatively more than in men.

Ethnic differences in the presentation, treatment strategy, and outcomes of percutaneous coronary intervention (a report from the National Heart, Lung, and Blood Institute Dynamic Registry)

Information about the impact of race/ethnicity on adverse outcomes after percutaneous coronary intervention (PCI) in the modern era is limited. Using consecutive patients from the National Heart, Lung, and Blood Institute Dynamic Registry, this study investigated differences in clinical presentation, treatment strategy, and acute and long-term outcomes in 3,669 white, 446 black, 301 Hispanic, and 201 Asian patients who underwent PCI. All comparisons were made to whites. Blacks were more likely than whites to be younger, women, and to present with a higher prevalence of cardiovascular risk factors (hypertension, diabetes, and smoking). Hispanics tended to be younger, hypertensive, diabetic, and to be undergoing their first cardiovascular procedure. Asians were, on average, younger, men, and presented more often with hypertension and diabetes than whites. Although the rate of stent implantation was significantly lower in blacks compared with whites (63% vs 74%, p <0.001), angiographic and procedural success rates were high (> or =95%) and did not differ by race/ethnicity. In-hospital mortality (0.2% vs 1.7%, p <0.05) and death/myocardial infarction (MI)/coronary artery bypass grafting (CABG) (3.1% vs 5.5%, p <0.05) were lower in blacks. All other in-hospital complications were similar to whites. At 1 year, there were no statistical differences in cumulative adverse event rates by ethnicity; however by 2 years there was a modestly higher mortality rate (adjusted RR 1.87; 95% confidence interval 1.15 to 3.04) and adverse event rate (death/MI, death/MI/CABG) among black patients. Thus, although differences in patient demographics, clinical presentation, angiographic characteristics and treatment strategies did not impact the incidence of acute and 1-year adverse outcomes of non-whites, there appears to be a significant reduction in event-free survival among blacks by 2 years.

Calcification in atherosclerosis: bone biology and chronic inflammation at the arterial crossroads

Dystrophic or ectopic mineral deposition occurs in many pathologic conditions, including atherosclerosis. Calcium mineral deposits that frequently accompany atherosclerosis are readily quantifiable radiographically, serve as a surrogate marker for the disease, and predict a higher risk of myocardial infarction and death. Accelerating research interest has been propelled by a clear need to understand how plaque structure, composition, and stability lead to devastating cardiovascular events. In atherosclerotic plaque, accumulating evidence is consistent with the notion that calcification involves the participation of arterial osteoblasts and osteoclasts. Here we summarize current models of intimal arterial plaque calcification and highlight intriguing questions that require further investigation. Because atherosclerosis is a chronic vascular inflammation, we propose that arterial plaque calcification is best conceptualized as a convergence of bone biology with vascular inflammatory pathobiology.

Prognostic value of cardiac risk factors and coronary artery calcium screening for all-cause mortality

PURPOSE

To develop risk-adjusted multivariable models that included risk factors and coronary calcium scores determined with electron-beam computed tomography (CT) in asymptomatic patients for the prediction of all-cause mortality.

MATERIALS AND METHODS

We followed up a cohort of 10,377 asymptomatic individuals undergoing cardiac risk factor evaluation and coronary calcium screening with electron-beam CT. Multivariable Cox proportional hazards models were developed to predict all-cause mortality. Risk-adjusted models incorporated traditional risk factors for coronary disease and coronary calcium scores.

RESULTS

Cardiac risk factors such as family history of coronary disease (69%), hypercholesterolemia (62%), hypertension (44%), smoking (40%), and diabetes (9%) were prevalent. The frequency of coronary calcium scores was 57%, 20%, 14%, 6%, and 3% for scores of 10 or less, 11-100, 101-400, 401-1,000, and greater than 1,000, respectively. During a mean follow-up of 5.0 years +/- 0.0086 (standard error of the mean), the death rate was 2.4%. In a risk-adjusted model (model chi2 = 388.2, P <.001), coronary calcium was an independent predictor of mortality (P <.001). Risk-adjusted relative risk values for coronary calcium were 1.64, 1.74, 2.54, and 4.03 for scores of 11-100, 101-400, 401-1,000, and greater than 1,000, respectively (P <.001 for all values), as compared with that for a score of 10 or less. Five-year risk-adjusted survival was 99.0% for a calcium score of 10 or less and 95.0% for a score of greater than 1,000 (P <.001). With a receiver operating characteristic curve, the concordance index increased from 0.72 for cardiac risk factors alone to 0.78 (P <.001) when the calcium score was added to a multivariable model for prediction of death.

CONCLUSION

This large observational data series shows that coronary calcium provides independent incremental information in addition to traditional risk factors in the prediction of all-cause mortality.

Value of coronary artery calcium scanning by computed tomography for predicting coronary heart disease in diabetic subjects

OBJECTIVE

The South Bay Heart Watch is a cohort study designed to determine the significance of coronary calcium in high-risk asymptomatic patients. This is a report of the relative risk (RR) for outcomes of coronary artery calcium in diabetic and nondiabetic subjects.

RESEARCH DESIGN AND METHODS

A total of 1312 diabetic and nondiabetic subjects underwent risk factor screening and computed tomography testing for coronary calcium at baseline and were followed clinically for 6.3 +/- 1.4 years. End points were either 1). hard events of nonfatal myocardial infarction (MI) or coronary death or 2). any cardiovascular event (nonfatal MI, coronary death, coronary revascularization, or stroke).

RESULTS

The incidence rates of a hard event and any cardiovascular event for diabetic and nondiabetic subjects were 14.5 and 6.1% and 23.8 and 12.2%, respectively (P < 0.001). Cox regression analyses of the combined risk relationship of diabetes status and calcium score demonstrated that relative to nondiabetic subjects with low calcium scores (<2.8), diabetic subjects with calcium scores >or=2.8 exhibited at least a fourfold increase in the risk of either a hard or any cardiovascular event (P < 0.001). Cox regression analyses conducted separately for nondiabetic and diabetic subjects revealed that coronary calcium score risk groups were significantly associated with events in nondiabetic subjects (RR >or= 2.6, P <or= 0.01), but not in diabetic subjects (RR <or= 1.7, P > 0.05).

CONCLUSIONS

The risk of coronary heart disease increases with increasing calcium scores and diabetes status. Calcium scores have less prognostic value in diabetic subjects.

Rationale for the role of osteoclast-like cells in arterial calcification

Atherosclerotic arteries frequently become calcified, and these calcium deposits are associated with a high risk of adverse clinical events. Descriptive studies suggest calcification is an organized and regulated process with many similarities to osteogenesis, yet the mechanism and its relationship to atherosclerosis remain largely unknown. In bone development and homeostasis, mineral deposition by osteoblasts and mineral resorption by osteoclasts are delicately balanced such that there is no overall gain or loss in bone mass. We hypothesize that there exists in arteries a mechanism that similarly balances mineral deposition with resorption. We propose that the cellular mediators of arterial mineral resorption are osteoclast-like cells (OLCs) derived from hematopoietic precursors of the mononuclear phagocytic lineage. In arterial microenvironments, mononuclear precursors are induced to differentiate toward OLCs by macrophage-colony stimulating factor and receptor activator of NF-kappaB ligand, both of which are necessary and sufficient for osteoclastogenesis and mineral resorption in bone. OLCs may participate in normal mineral homeostasis within the arterial wall or, alternatively, may be recruited to specific sites within developing plaque. Net calcium deposition occurs as a result of focal perturbation of the balance between the activity of osteoblast-like cells and OLCs. Our proposed mechanism thus views arterial mineral deposition not so much as an active pathological process, but as a localized failure of protective mechanisms that actively oppose mineral deposition within the disordered metabolic milieu of developing atherosclerotic plaque.