Coronary Calcium Measurements Research Articles

Abstract 269: Coronary Artery Calcium As A Predictor For Stenting Outcomes: A Meta-analytic Comparison

Abstract: Coronary Artery Calcium (CAC) measurement and its usefulness to stratify patients by CAD risk remains an area of controversy. Current AHA/ACC guidelines recommend using CAC to guide management on patients with risk factors for CAD but not on optimal medical treatment. The purpose of this study is to investigate the impact of CAC on stenting outcomes. Methods: A systematic review of MEDLINE using PRISMA guidelines was conducted using the search terms CAC, Calcium, Coronary, and Stent. Studies were included if they had an appropriate control group and subdivided high coronary calcium and low coronary calcium measured using an approved imaging modality. Clinical characteristics of patients and outcomes were aggregated according to the Cochrane Manual. A random effects model was used to retrieve odds ratio values. Revman 5.3 was used to aggregate outcomes. Results: A total of 11 studies with 56,725 patients were included. The high CAC cohort included 14,390 patients and Low/No CAC included 42,335 patients. TLR was significantly higher in the high CAC cohort: Odds Ratio: 1.82 [1.37, 2.43], Test for overall effect: Z = 4.08 (P < 0.0001). Heterogeneity was significant amongst the studies for TLR but not amongst TVR or Stent Thrombosis outcomes (Heterogeneity: Tau 2 = 0.14; Chi 2 = 84.08, df = 10 (P < 0.00001); I 2 = 88%). TVR and Stent Thrombosis was significantly higher in the high CAC cohort: Odds Ratio 1.20 [1.14, 1.26] and Odds Ratio 1.42 [1.24, 1.62] Test for overall effect: Z = 5.01 (P < 0.00001) respectively. Conclusion: TLR, TVR, and Stent Thrombosis were all significantly higher in the high CAC cohort as compared to control. Elevated CAC not only provides a description of coronary plaque morphology but also can be used to predict adverse interventional outcomes. Further prospective studies with standard imaging techniques are needed to eliminate any inter-imaging modality differences in CAC characterization.

On the association between circulating biomarkers and atherosclerotic calcification in a cohort of arterial disease participants

Background and aimsAtherosclerotic calcification is a powerful predictor of cardiovascular disease. This study aims to determine whether circulating levels of a local/systemic calcification inhibitor or a marker of bone formation correlate with measures of coronary or extracoronary calcification. Methods and resultsClinical computed tomography (CT) was performed on 64 arterial disease participants undergoing carotid and lower extremity endarterectomy. Coronary artery calcium (CAC) scores and volumes were acquired from the CT scans (n = 42). CAC scores and volumes were used to derive CAC density scores. Micro-CT was performed on excised carotid (n = 36) and lower extremity (n = 31) plaques to quantify the volume and volume fraction of extracoronary calcification. Circulating levels of dephospho-uncarboxylated Matrix Gla Protein (dp-ucMGP), fetuin-A, carboxylated and uncarboxylated osteocalcin (ucOC) were quantified using commercial immunoassays. Carotid participant CAC density scores were moderately negatively correlated with plasma dp-ucMGP (rs = −0.592, P = 0.008). A weak negative association was found between CAC scores and %ucOC for all participants (rs = −0.335, P = 0.040). Another weak negative correlation was observed between fetuin-A and the volume of calcification within excised carotid specimens (rs = −0.366, P = 0.031). Despite substantial differences in coronary and extracoronary calcium measurements, the levels of circulating biomarkers did not vary significantly between carotid and lower extremity subgroups. ConclusionCorrelations identified between circulating biomarkers and measures of coronary and extracoronary calcium were not consistent among participant subgroups. Further research is required to determine the association between circulating biomarkers, coronary and extracoronary calcium.

Progression of coronary calcium burden and carotid stiffness in patients with essential thrombocythemia associated with JAK2 V617F mutation

Background and aimsPatients with myeloproliferative neoplasms often succumb to cardiovascular events, but little is known on the early stages of their vascular disease. We studied how patients with JAK2 V617F positive essential thrombocythemia (ET) without overt atherosclerotic disease differed from control subjects in the progression of carotid artery stiffness and preclinical atherosclerosis. MethodsThirty-six patients with JAK2 V617F positive ET and 38 age-, gender- and Framingham coronary heart disease (CHD) -matched control subjects were examined twice within 4 years. Clinical and laboratory testing, echo-tracking ultrasound of carotid arteries, coronary calcium measurement and digital plethysmography were performed (ClinTrials.gov NCT03828422). ResultsCoronary calcium correlated with the Framingham CHD risk score at the first examination in the control group (rs = 0.410), but not among the ET patients (rs = 0.116). Both groups progressed in coronary calcium, but the outliers were more prominent among ET patients. Carotid artery stiffness increased with time in the ET patients much more than in the control group: the increase in β-index 1.95 (SD 2.18) vs. 0.22 (SD 1.99), p < 0.001, and the increase in carotid pulse wave velocity 0.72 (SD 0.92) vs. 0.08 (SD 0.72) m/s, p = 0.001. There was no correlation between carotid stiffness and Framingham CHD risk in either group. Digital endothelial function did not change. ConclusionCarotid artery stiffness progressed faster in patients with JAK2 V617F positive ET than in control subjects. Coronary calcium correlated with the Framingham CHD risk only in control subjects. This indicates that JAK2 V617F positive ET acted as a non-classical risk factor for vascular disease.

Detection of coronary artery calcification with nontriggered computed tomography of the chest.

Objective To evaluate the accuracy of visual analysis and of the coronary artery calcium (CAC) score in nontriggered computed tomography (CT), in comparison with that of the CAC score in electrocardiogram-triggered CT, in identifying coronary calcification.Materials and Methods A total of 174 patients for whom CT was indicated for CAC scoring underwent nontriggered and triggered CT in a 64-channel multislice scanner, in a single session without a change in position. The images were interpreted by a radiologist with seven years of experience in thoracic and cardiovascular radiology. The measurement of coronary calcium was carried out by three methods: CAC score with dedicated software in nontriggered CT, CAC score with dedicated software in triggered CT, and visual analysis without dedicated software in nontriggered CT.Results In nontriggered CT, the CAC score presented an accuracy of 95.98% (95% CI: 91.93-98.04). The visual analysis showed an accuracy of 97.13% (95% CI: 93.45-98.77).Conclusion Nontriggered CT showed excellent accuracy in the identification and exclusion of coronary calcification, either the CAC score was determined with dedicated software or through visual analysis.

Coronary age, based on coronary calcium measurement, is increased in patients with morbid obesity.

PurposeObesity is a well-known of risk factor for atherosclerosis. However, recently an “obesity paradox” has been discussed, which is considered as a protective effect of obesity on the development coronary artery disease (CAD). An aim of the study was to investigate the risk of CAD in morbidly obese patients using coronary artery calcium measurement.Material and methodsFifty-one patients with morbid obesity (BMI ≥ 40 kg/m2) and thirty controls were scanned to determine the amount of coronary artery calcification (CAC), which was expressed as calcium score (CS) and coronary age (CA). The control group consisted of patients scanned for the clinical suspicion of CAD, who did not fulfil the criteria of obesity.ResultsMean BMI of obese patients and controls was 47.3 and 26.5, respectively (p < 0.0001). Arterial hypertension, dyslipidaemia, and smoking were more frequent in the control group than in the obesity group (p < 0.02). The prevalence of CAC was higher in the obesity group (53% vs. 23%, p < 0.01). The groups did not differ regarding CS and CA. However, the difference between coronary age and metrical age was higher in obese patients than in controls (+5.6 vs. –4.8 years, respectively, p < 0.005).ConclusionsPatients with morbid obesity present an increased risk of CAD that is reflected by the difference between their coronary age and metrical age.

The association between coronary calcification and adenomatous polyps of colon in Korean adults

Adenomatous polyps of colon is a precancerous lesion. Many studies have shown that the adenomatous polyps of colon and cardiovascular disease share several common risk factors. This cross-sectional study aimed to investigate whether coronary calcification is associated with the adenomatous polyps of colon. Among 1637 Korean adults, we examined the association between coronary calcium score (CCS) as a measurement of coronary calcification and the presence of adenomatous polyps of colon via multi-detected row computed tomography (MDCT) and colonoscopy, respectively. CCS values were categorized as follows: 0, 1-17, 18-105, or≥106. The odds ratios (ORs) and 95% confidence intervals (CIs) for the presence of adenomatous polyps of colon were calculated across CCS groups. After adjusting for confounding variables, the adjusted ORs (95% CIs) for the presence of adenomatous polyps of colon in each of the four CCS groups were 1.00 (reference), 1.44 (0.91-2.33), 1.88 (1.15-3.01) and 3.61 (2.23-5.74). And higher CCS values were associated with multiple polyps (P≤0.001), villous histologic features or high-grade dysplasia (P=0.02), and advanced adenomatous polyps (P≤0.001). A higher level of CCS was found to be strongly and independently associated with the presence of adenomatous polyps of colon in Korean adults. This finding suggests that people at high risk for coronary atherosclerosis through MDCT should be considered for further evaluation of adenomatous polyps.

Abstract W MP66: Are Carotid Artery Stenosis-Isolated and Carotid Artery-Plus Two Distinct Entities?

Objective: To test the hypothesis that isolated carotid artery stenosis (CAS-isolated) and CAS as part of concurrent coronary artery disease (CAD) and/or peripheral arterial disease (PAD) are two distinct entities. Methods: We used the data from Multi-Ethnic Study of Atherosclerosis (MESA) which is a population-based sample of 6,814 men and women aged 44-84 years recruited from six US field centers. Baseline measurements include measurement of coronary calcium using computed tomography; carotid intimal-medial wall thickness and stenosis severity using ultrasonography; and measurement of peripheral vascular disease using ankle and brachial blood pressures. Participants were followed for identification and characterization of cardiovascular events. We defined CAS-isolated based on presence of CAS without any CAD (calcium score of 0 with no history of angina/myocardial infarction) or PAD (arm-brachial index 1.0-1.4). Results: Of the 858 persons with CAS ranging in severity from 25 to 100%, 155 (18%) and 703 (82%) were classified as CAS-isolated and CAS-plus, respectively. Persons with CAS-isolated were younger (mean age ±SD; 61±8 versus 70±8, p=0.001) and more likely to be women (63.2% versus 41.8%, p=&lt;.0001). The proportion of persons with hypertension (51.6% versus 66.3%, p=0.0006) and family history of heart attack (37.2% versus 51.1%, p=0.003) were lower among those with CAS-isolated. The proportion of persons with current cigarette smoking (19.6% versus 14.5%, p=0.01) and current alcohol abuse (73.4% versus 62.8%, p=0.03) were higher among CAS-isolated. Persons with CAS-isolated were more likely to have smooth carotid lesions (80.6% versus 69.3%, p=0.004). The relative risk for ischemic stroke was similar among patients with CAS-plus compared with CAS-isolated (RR, 1.1 95% CI 0.3-4.1) after adjustment for age and gender. Conclusions: CAS-isolated and CAS-plus appear to be two distinct entities with unique demographic and clinical attributes.

Relation of Thoracic Aortic Distensibility to Left Ventricular Area (from the Multi-Ethnic Study of Atherosclerosis [MESA

Decreased arterial compliance is an early manifestation of adverse structural and functional changes within the vessel wall. Its correlation with left ventricular (LV) area on computed tomography, a marker of LV remodeling, has not been well demonstrated. The aim of this study was to test the hypothesis that decreasing aortic compliance and increasing arterial stiffness are independently associated with increased LV area. The study population consisted of 3,540 patients (mean age 61 ± 10 years, 46% men) from the Multi-Ethnic Study of Atherosclerosis (MESA) who underwent aortic distensibility (AD) assessment on magnetic resonance imaging and LV area measurement on computed tomography (adjusted to body surface area). Multivariate logistic regression was performed to assess the association between body surface area-normalized LV area >75th percentile and AD after adjusting for baseline clinical, historical, and imaging covariates. Mean LV area index was 2,153 cm(2), and mean AD was 1.84 × 10(3) mm Hg(-1). Subjects in the lowest AD quartile were older, with higher prevalence rates of hypertension, diabetes, and hypercholesterolemia (p <0.05 for all comparisons). Using multivariate linear regression adjusting for demographics, traditional risk factors, coronary artery calcium, and C-reactive protein, each SD decrease was associated with an 18-cm(2) increase in LV area. In addition, decreasing AD quartiles were independently associated with increasing LV area index, defined as >75th percentile. In conclusion, in this multiethnic cohort, reduced AD was associated with increased LV area. Longitudinal studies are needed to determine if decreased distensibility precedes and directly influences increased LV area.

Early detection of premature subclinical coronary atherosclerosis in systemic lupus erythematosus patients

Abstract Objective To elucidate early coronary atherosclerotic changes in premenopausal systemic lupus erythematosus (SLE) female patients without clinical cardiovascular manifestation using a 64-slice Multi-detector computed tomography (MDCT) scan to detect coronary calcification and measure coronary calcium score (CCS), and to find out its correlation to some traditional and non-traditional risk factors. Methodology Sixty consecutive premenopausal SLE female patients, and sixty age and sex matched healthy subjects without known systemic, immunological, or cardiovascular disease (served as a control group) underwent clinical examination, serological analysis, and 64-slice MDCT-based coronary calcium scoring. All the clinical, serological, and MDCT parameters of the patients were correlated. Results Coronary calcification (CC) was seen in 21 patients (35%), the number of atherosclerotic calcified plaques ranged from 0 to 19. Calcium scores ranged from 0 to 843. In contrast to control subjects, SLE patients had significantly higher erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), total cholesterol level, low-density lipoprotein (LDL), immunoglobulin G (IgG) and IgM anti-cardiolipin antibodies, serum intracellular adhesion molecule (sICAM) and E-selectin levels. SLE patients had highly significantly more atherosclerotic plaques (3 ± 0.66 compared to 0.1 ± 0.07, p p p Conclusion Pre-menopausal SLE female patients free from clinical atherosclerotic vascular disease have an increased number of atherosclerotic plaques and CCS, which correlate positively with SLEDAI disease activity score, serum CRP, anticardiolipin antibodies, sICAM-1, E-Selectin, LDL level, total cholesterol level, and cumulative prednisone dose. In addition, we conclude that MDCT is a non-invasive, sensitive, reproducible, and reliable tool for accurate measurement of coronary calcification.

The Women on the Move Through Activity and Nutrition (WOMAN) Study: Final 48‐Month Results

The Women on the Move through Activity and Nutrition (WOMAN) study was designed to test whether a nonpharmacological intervention including qualitative and quantitative dietary changes to induce weight loss and increased physical activity levels would reduce blood triglyceride levels and number of low-density lipoprotein particles (LDL-P). Such decreases in lipoproteins and other risk factors could reduce or slow progression of subclinical cardiovascular disease (CVD). Study participants were randomized to either the intervention (Lifestyle Change) or assessment (Health Education) group. Most of the intervention ended at the 30-month visit. The last 48-month examination was completed in 9/2008. There was very substantial weight loss and increased exercise during the first 30 months of the trial resulting in significant decreases in CV risk factors. Most of the intervention effect was lost through 48 months. Weight loss was 3.4kg in Lifestyle Intervention and 0.2kg in the Health Education at 48 months (P = 0.000). There were no significant changes at 48 months in lipid levels, blood pressure (BP), glucose, insulin, or in the subclinical measures of coronary calcium, carotid intima media thickness, or plaque. There was a significant decrease in long-distance corridor walk time in the Lifestyle vs. Health Education groups. Significant lifestyle changes can be achieved that result in decreases in CV risk factors. Whether such changes reduce CV outcomes is still untested in clinical trials of weight loss or exercise. Long-term maintenance of successful lifestyle changes, weight loss and reduced risk factors is the hurdle for lifestyle interventions attempting to prevent CV and other chronic diseases.

Subclinical atherosclerosis in northern and southern China: the Chinese paradox

BackgroundThe incidence of coronary heart disease (CHD) is higher in Northern than that in Southern China, however differences in traditional CHD risk factors do not fully explain this. No study has examined the differences in subclinical atherosclerosis that may help explain the differences in incidence. This study examined these differences in subclinical atherosclerosis using coronary computed tomography (CT) for calcification between the Northern and Southern China.MethodsWe selected a random sample of participants in a large multi-center ongoing epidemiologic study for coronary calcium scanning in one northern city (North) (Beijing, n = 49) and in two southern cities (South) (Shanghai, n = 50, and Guangzhou, n = 50). Participants from the three field centers (mean age 67 years) underwent coronary risk factor evaluation and cardiac CT scanning for coronary calcium measurement using the Multi-Ethnic Study of Atherosclerosis scanning protocol.ResultsAdjusted log-transformed coronary artery calcium score in North China (Beijing) was 3.1 ± 0.4 and in South China (Shanghai and Guangzhou) was 2.2 ± 0.3 (P = 0.04). Mean calcium score for the northern city of Beijing was three times higher than that of the southern city of Guangzhou (P = 0.01) and 2.5 times higher than for the southern city of Shanghai (P = 0.03).ConclusionsThe extent of subclinical atherosclerosis is significantly higher in the northern city of Beijing than that in the two southern cities of Guangzhou and Shanghai, even after adjusting for standard cardiac risk factors. This finding suggests that standard risk factors do not fully explain north south differences in clinical CHD incidence.

Evaluating the Clinical Utility of a Biomarker

Biomarkers, broadly defined, are markers of a biological process or state.1 Biomarkers are often used in research studies, but they may also be useful for clinicians and patients if they provide information about current status or future risk of disease. It is not always clear, however, when a novel biomarker provides enough useful information to justify measuring it in the context of clinical care. Evaluating the clinical utility of a novel biomarker requires a phased approach.2 Early-phase studies must prove that the biomarker is associated statistically with the clinical state of interest and adds information about presence or risk of disease above and beyond established markers. Midphase studies describe how often this incremental information might alter physician prescribing decisions. Early- and mid-phase studies are useful because they help investigators compare biomarker performance in terms that are generic (ie, not dependent on the specifics of the disease state being studied). Generic measures of biomarker performance have been reviewed previously2,–,16 and are described in Table 1 along with relevant published examples.17,–,32 View this table: Table 1. Generic Measures of Biomarker Performance Measuring biomarker performance in generic terms, however, is not sufficient for demonstrating clinical utility.6 The decision to use a biomarker in clinical practice should be based on an expectation that it will have a positive net health impact, and measuring health impact, by definition, requires use of measurements that consider the specific disease state being studied and its consequences. The goal of this review is to describe the methods by which evidence about the health impact of measuring a biomarker may be generated (late-phase evidence2) using examples relevant to cardiovascular disease and with a focus on the use of randomized clinical trials and modeling for estimating health impact. ### Mechanisms by Which Biomarker Measurement Can Impact Health There are 3 fundamental …

Circulating lymphotoxin β receptor and atherosclerosis: Observations from the Dallas Heart Study

Objective Lymphotoxin β receptor (LTβR), a member of the tumor necrosis factor superfamily, binds ligands expressed by activated lymphocytes. Interruption of LTβR signaling improves autoimmune diseases and alters lipid homeostasis. We assayed circulating LTβR and examined its association with atherosclerosis phenotypes in a population-based sample. Methods and results Plasma LTβR was measured by ELISA in 3215 subjects enrolled in the Dallas Heart Study. Atherosclerosis was assessed using CT measurements of coronary calcium (CAC) and abdominal MRI measurements of aortic plaque (AP) ( n = 2252) and aortic wall thickness (AWT) ( n = 2265). We analyzed associations between LTβR and atherosclerosis using multivariable logistic and linear regression methods. Higher levels of LTβR associated with most traditional cardiovascular risk factors, multiple inflammatory markers, and markers of cardiac injury. Univariable analyses demonstrated significant associations of LTβR with CAC, AP, and AWT ( p < 0.0001 for each). In multivariable models adjusted for traditional risk factors, the 4th vs. the 1st quartile of LTβR remained associated with prevalent CAC, AP, and increased AWT (all p < 0.05). Similar associations were observed when LTβR was modeled as a log-transformed continuous variable. Conclusion LTβR levels are independently associated with atherosclerosis in multiple vascular beds. These findings support further investigation of the lymphotoxin/LTβR pathway in atherosclerosis.

Coronary Computed Tomography Angiography for Screening of an Asymptomatic Population: Too Much or Too Soon?

Coronary Computed Tomography Angiography for Screening of an Asymptomatic Population: Too Much or Too Soon?

Induced Cardiovascular Procedural Costs and Resource Consumption Patterns After Coronary Artery Calcium Screening: Results From the EISNER (Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research) Study

We prospectively evaluated procedural costs and resource consumption patterns in the EISNER (Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research) study after coronary calcium (CAC) measurements.Controversy surrounds expansion of cardiovascular disease (CVD) screening to include atherosclerosis imaging as the result of concern whether induced costs will outweigh any benefit.Detailed risk factor and CAC measurements with 4-year follow-up for CVD death or myocardial infarction and procedures were performed. Costs were estimated with the use of Medicare reimbursement rates (discounted and inflation corrected). Cox survival analysis was used to estimate procedures and events.CAC scores varied widely but were skewed toward low scores with 56.7% of screened subjects having CAC scores<or=10 and only 8.2% having CAC scores>or=400. Noninvasive testing was infrequent and medical costs were low among subjects with low CAC scores, both rising progressively with increasing CAC scores (p<0.001), particularly in the 31 (2.2% of subjects) that had CAC scores>or=1,000. Similarly, invasive coronary angiography rose progressively with increasing scores (p<0.001) but occurred exclusively among subjects first undergoing noninvasive testing and overall, was performed in only 19.4% of subjects with CAC scores>or=1,000.CAC scanning is associated with a marked differential in downstream frequency of medical tests and costs, ranging from a very low frequency of testing and invasive procedures among a predominantly large percentage of subjects with low CAC scores, to selectively concentrated testing and procedures among a small number of subjects with CAC scores>400. Thus, CAC scanning appears to foster efficient selective testing patterns among asymptomatic individuals at risk for CVD.

Coronary artery calcium distribution and interscan measurement variability in end-stage renal and coronary heart disease patients

Coronary heart disease patients and end-stage renal disease patients have been documented to have an increased amount of coronary artery calcifications (CAC). To evaluate the distribution of CAC and its influence on interscan variability of measurement in end-stage renal disease and coronary heart disease patients, proven to have calcifications. 69 patients having CAC, including 34 with coronary heart disease and 35 with end-stage renal disease, were scanned twice with multidetector-row computed tomography (MDCT). Amount of CAC was determined as the number of calcified lesions (CN), total calcium score (CS), calcium volume (CV), and calcium mass (CM). Distribution of CAC was evaluated on a per-patient basis as the median CS and CM of a single lesion. Density of the calcifications was calculated as the patient's CM divided by CV. The overall median CS was 457.2, and the median CM was 75.6 mg. There were no significant differences in the number of calcified lesions, CS, or CM between the two groups. Both CS and CM of a single lesion, as well as the mean calcium density were lower in renal disease patients (P<0.05) than in coronary heart disease subjects. The relative interscan variability of coronary calcium measurement was higher in the renal disease group (P<0.05). There was a negative correlation between the calcium concentration and the relative interscan variability. The results indicate that the coronary calcium distribution influences the measurement interscan reproducibility, and the distribution may differ between end-stage renal disease patients and coronary heart disease patients, reflecting the dissimilar nature of coronary calcifications in those groups.

The association between plasma caspase-3, atherosclerosis, and vascular function in the Dallas Heart Study

Caspase-3, an apoptosis protease, is expressed in atherosclerotic plaques. We examined the relationship between plasma caspase-3 levels, aortic compliance, and atherosclerosis. Caspase-3 was measured in 3,221 subjects from the Dallas Heart Study. Electron beam computed tomography measures of coronary calcium (CAC) (n = 2,404) and magnetic resonance imaging (MRI) measures of abdominal aortic wall thickness (AWT) (n = 2,208) and aortic compliance (AC) (n = 2,328) were obtained. Multivariate analyses were performed, adjusting for age, sex, ethnicity, body mass index (BMI), traditional cardiovascular risk factors, and cardiac medications. In univariable analysis, caspase-3 associated with CAC (P < 0.0001), AWT (P = 0.002), and AC (P < 0.0001). After multivariable adjustment, 4th quartile caspase-3 (compared to 1st quartile) was significantly associated with CAC (P = 0.004), AWT (P = 0.02), and AC (P < 0.0001) with similar findings for caspase-3 as a continuous variable. Caspase-3 independently associates with CAC, AWT, and AC, suggesting a link between apoptosis and atherosclerosis.

Selective use of coronary calcification measurements in an expanded intermediate risk group

Risk assessment is an imperative initial step in the clinical management of cardiovascular risk factors. On the basis of the estimation of the 10-year absolute risk of manifesting coronary heart disease (myocardial infarction or coronary heart disease death), risk categories are conventionally divided into low, intermediate, and high. The most widely used quantitative risk assessment algorithm, the Framingham risk score for hard events, is based on traditional risk factors, but it does not fully account for all available cardiovascular risk factors. Current national guidelines defining coronary heart disease risk categories based on the Framingham risk score may inaccurately assign persons with a high burden of subclinical coronary atherosclerosis to a low-risk group (<10% risk), failing to predict the true risk of a cardiovascular event. Coronary artery calcification as a measure of subclinical atherosclerosis has already established itself as a useful adjunct for refining the broad intermediate risk category of adults, leading to more decisive management strategies. In a point-counterpoint format this article argues for the improved accuracy of coronary calcium scoring in predicting the risk of future cardiac events in persons with a low Framingham risk score (including women and different ethnic groups). To better incorporate recent scientific findings into cardiovascular assessment and to refine stratification in those with a low Framingham risk score, we therefore propose a timely algorithm supporting coronary calcium screening in a selected group of low-risk persons.

Coronary calcium measurement improves prediction of cardiovascular events in asymptomatic patients with type 2 diabetes: the PREDICT study

The PREDICT Study is a prospective cohort study designed to evaluate coronary artery calcification score (CACS) as a predictor of cardiovascular events in type 2 diabetes (T2DM). A total of 589 patients with no history of cardiovascular disease and with established T2DM had CACS measured, as well as risk factors, including plasma lipoprotein, apolipoprotein, homocysteine and C-reactive protein concentrations, homeostasis model assessment insulin resistance (HOMA-IR), and urine albumin creatinine ratio. Participants were followed for a median of 4 years and first coronary heart disease (CHD) and stroke events were identified as primary endpoints. There were 66 first cardiovascular events (including 10 strokes). CACS was a highly significant, independent predictor of events (P < 0.001), with a doubling in CACS being associated with a 32% increase in risk of events (29% after adjustment). Hazard ratios relative to CACS in the range 0-10 Agatston units (AU) were: CACS 11-100 AU, 5.4 (P = 0.02); 101-400 AU 10.5 (P = 0.001); 401-1000 AU, 11.9 (P = 0.001), and >1000 AU, 19.8 (P < 0.001). Only HOMA-IR predicted primary endpoints independently of CACS (P = 0.01). The areas under the receiver operator characteristic curve for United Kingdom Prospective Diabetes Study (UKPDS) risk engine primary endpoint risk and for UKPDS risk plus CACS were 0.63 and 0.73, respectively (P = 0.03). Measurement of CACS is a powerful predictor of cardiovascular events in asymptomatic patients with T2DM and can further enhance prediction provided by established risk models.

Aortic Size Assessment by Noncontrast Cardiac Computed Tomography: Normal Limits by Age, Gender, and Body Surface Area

To determine normal limits for ascending and descending thoracic aorta diameters in a large population of asymptomatic, low-risk adult subjects. Assessment of aortic size is possible from gated noncontrast computed tomography (CT) scans obtained for coronary calcium measurements. However, normal limits for aortic size by these studies have yet to be defined. In 4,039 adult patients undergoing coronary artery calcium (CAC) scanning, systematic measurements of the ascending and descending thoracic aorta diameters were made at the level of the pulmonary artery bifurcation. Multiple linear regression analysis was used to detect risk factors independently associated with ascending and descending thoracic aorta diameter and exclude subjects with these parameters from the final analysis. The final analysis groups for ascending and descending thoracic aorta included 2,952 and 1,931 subjects, respectively. Subjects were then regrouped by gender, age, and body surface area (BSA) for ascending and descending aorta, separately, and for each group, the mean, standard deviation, and upper normal limit were calculated for aortic diameter as well as for the calculated cross-sectional aortic area. Also, linear regression models were used to create BSA versus aortic diameter nomograms by age groups, and a formula for calculating predicted aortic size by age, gender, and BSA was created. Age, BSA, gender, and hypertension were directly associated with thoracic aorta dimensions. Additionally, diabetes was associated with ascending aorta diameter, and smoking was associated with descending aorta diameter. The mean diameters for the final analysis group were 33 +/- 4 mm for the ascending and 24 +/- 3 mm for the descending thoracic aorta, respectively. The corresponding upper limits of normal diameters were 41 and 30 mm, respectively. Normal limits of ascending and descending aortic dimensions by noncontrast gated cardiac CT have been defined by age, gender, and BSA in a large, low-risk population of subjects undergoing CAC scanning.