Electron Beam Computed Tomography Research Articles

The epidemiology of abdominal aortic diameter

The diameter of the abdominal aorta is central to the diagnosis of abdominal aortic aneurysm. This study aimed to determine the associations between the diameter of the abdominal aorta at three distinct locations and the traditional cardiovascular disease risk factors as well as calcified atherosclerosis. A total of 504 patients (41% women) underwent whole body scanning by electron beam computed tomography (EBCT) and a standardized assessment for cardiovascular disease risk factors. The resulting EBCT images were retrospectively interrogated for the diameter of the abdominal aorta just inferior to the superior mesenteric artery (SMA), just superior to the aortic bifurcation, and at the midpoint between the SMA and bifurcation. Mean patient age was 57.8 years. The mean (SD) diameter was 21.3 (2.9) mm at the SMA, 19.3 (2.5) mm at the midpoint, and 18.6 (2.2) mm at the bifurcation. In a model containing the traditional cardiovascular disease risk factors, age (standardized beta = 0.96), male sex (beta = 3.06), and body mass index (standardized beta = 0.68) were significantly associated with increasing aortic diameter at the SMA (P < .01 for all). The significance of the associations for these variables was the same for aortic diameter at the midpoint and bifurcation. Furthermore, a 1-unit increment in the calcium score in the abdominal aorta and iliac arteries was associated with 0.13-mm (P < .01) and 0.09-mm (P = .02) increases, respectively, in aortic diameter at the SMA. The results were similar for the midpoint (beta = 0.19, P < .01; beta = 0.12, P = .01, respectively) and bifurcation (beta = 0.09, P < .04; beta = 0.09, P = .03, respectively). Age, sex, body mass index, and the presence and extent of calcified atherosclerosis in both the abdominal aorta and iliac arteries are significantly associated with increasing aortic diameter independent of the other cardiovascular disease risk factors.

The Added Value of a Dedicated Cardiac CT Scanner for the Assessment of Coronary Calcium

SummaryThe amount of coronary calcium is generally used as an indicator for risk stratification of patients with (suspected) coronary artery disease. Orginally, electron beam tomography (EBT) was used to image the amount of coronary calcium and quantification was performed by the Agatston score. Risk stratification has been validated on large patients populations using the EBT scanner in combination with this scoring method. While EBT scanners become more and more obsolete nowadays, these scanners are being replaced by multi‐detector computer tomography (MDCT) systems and dedicated cardio scanners like dual source computer tomography (DSCT). However, in order to used the calcium score obtained from a patient scan on these systems, it must be demonstrated to be accurate, clinically relevant and reproducible. In this study we compared the infiuence of cardiac motion on the calcium score for a 64‐slice MDCT scanner and for an EBT and a DSCT systems. A moving cardiac phantom was used and the measured Agatston scores were compared on these three systems as a function of heart rate, calcification density and slice thickness. The results show that DSCT is approximately 50% less susceptible to cardiac motion than 64‐slice MDCT and that the susceptibility is further reduced by using a smaller slice thickness. At a slice thickness of 3.0 mm DSCT and 64‐slice MDCT show similar results, however, at a slice thickness of 0.6 mm DSCT gives the best approximation of the calcium score on EBT in comparison to 64‐slice MDCT.

Considerations in Calcium Scoring Using Multi‐Detector Computed Tomography

SummaryCalcium scoring is a promising tool for acquiring insight in the amount of coronary calcium present in the coronary arteries. Using electron beam tomography in the past, and multi‐detector computed tomography (MDCT) nowadays, calcium scoring can be performed within minutes. However, MDCT offers a large scale of possibilities in data acquisition and reconstruction. In this article, a short overview is given on the influence of different parameters on the outcome of calcium scoring in terms of absolute score and variability. In a short study, the influence of two highly influencing parameters is investigated in more detail. The study shows that at higher heart rates the calcium score of high‐density calcifications are increased. The opposite behaviour is observed for low‐density calcifications. In addition, calcium scores are increased with the use of smaller slice thicknesses. Smaller thicknesses also influence the variability of calcium scoring, for thinner slices the variability is reduced. When assessing the outcome of a calcium score one has to take in to account what parameters were used during the CT scan for calcium scoring.

Smoking cessation and subclinical atherosclerosis—Results from the Heinz Nixdorf Recall Study

BackgroundSmoking accounts for more than 5 million years of potential life lost per year in the US alone. Leading causes of smoking attributable mortality are acute atherothrombotic complications of coronary heart disease (CHD). Smoking cessation is a key issue in preventive medicine, but quantitative data on its benefit for the coronary arteries are sparse. MethodsThe Heinz Nixdorf Recall Study is an ongoing population-based, prospective cohort study, with 4814 participants aged 45–74 years (49.8% men). Baseline data of 4078 participants without history of established coronary heart disease or stroke are included in this report. Electron beam-computed tomography allows for non-invasive quantification of coronary artery calcium (CAC). We estimate the risk-related ageing of coronary arteries from multivariable regression of CAC on smoking behavior, sex, age and risk factors. ResultsSmoking 20 cigarettes per day since the age of 16 is associated with a CAC burden which is found in a person 10 years older who has never smoked (both sexes). Smoking cessation at 45, 55 or 65 leads to CAC at the age of 75 that would have been reached 9, 6 or 3 years earlier, respectively, had smoking been continued. ConclusionsIn individuals without overt CHD, present smokers are about 10 years older in ‘coronary artery age’ than never smokers. The accumulation of CAC is accelerated by smoking and slows down after smoking cessation, but advanced CAC is persistent for a long period. These quantitative findings strongly support smoking cessation measures as early as possible, to prevent accelerated arterial ageing.

Computed tomography scan for atherosclerosis and emphysema: A great hope or a great hype?

Computed tomography scan for atherosclerosis and emphysema: A great hope or a great hype?

Usefulness of 3D Reconstructed Computed Tomography Imaging for Double Outlet Right Ventricle

To evaluate the value of 3D reconstructed computed tomography (CT) imaging for patients with double outlet right ventricle (DORV). CT images were obtained preoperatively from 17 patients who ranged in age from 5 days to 5 years. Reconstructed 3D images were created using gradient-shading surface rendering, which allowed partial subtraction of the anterior sections of the virtual heart to view the interior. Interpretations of CT, echocardiography and cine-cardioangiography were compared and verified from surgical findings, autopsy, and consensus upon review of all imaging and diagnostic tests. Three subaortic, seven subpulmonary, six non-committed, and one double-committed subtypes of ventricular septal defect (VSD) were observed. The 3D electron beam CT images provided good delineation of the spatial relationship inside the heart. The range of diagnostic accuracy for all VSD types in DORV was 88-100% for 3D CT, 71-94% for echocardiography, and 60-100% for cine-cardioangiography. In comparison, 3D CT offered better diagnostic accuracy for all variants of DORV. 3D constructed CT imaging is a good modality for differentiating VSD type in DORV. It allowed us to directly evaluate the inside of cardiac chambers for the right ventricular outlet, great arterial root, and determine the VSD relationships.

Role of Noninvasive Imaging Using Computed Tomography for Detection and Quantification of Coronary Atherosclerosis

Clinical cardiac computed tomography (CT) began with electron-beam CT in the early 1980s and continues now with multidetector CT in the 21st Century. The major applications of noncontrast cardiac CT are currently for the quantification of coronary artery calcium - a reliable and repeatable means to estimate atherosclerotic plaque burden. The major applications of contrast-enhanced CT (CT angiography) is for a more detailed estimation of total plaque burden by qualitatively defining noncalcified and complex plaque as well as ruling out obstructive coronary artery disease. Both of these applications are discussed and comments are made from the author regarding clinical applications based upon reviewing the published literature and through personal experience.

Visceral Adiposity and Subclinical Coronary Artery Disease in Elderly Adults: Rancho Bernardo Study

Despite growing attention to central obesity as a predictor of clinical coronary heart disease (CHD), there are few reports about the association between directly measured visceral obesity and subclinical coronary atherosclerosis in elderly adults. We examined this association in elderly, community-dwelling adults without clinically recognized CHD. Elderly adults (190 men, BMI 27.2 +/- 3.6 kg/m(2); 220 women, BMI 25.8 +/- 4.6) aged 55-88 years (median 69 years) with no history of CHD or coronary revascularization had an electron beam computed tomography (EBCT) to measure coronary artery calcification score (CACS), an estimate of coronary plaque burden. Visceral and subcutaneous adiposity were assessed by a triple-slice EBCT scan at the lumbar 4-5 disc level and height, weight, and waist and hip circumferences were measured. In sex-specific ordinal logistic regression analyses, no measure of obesity or body fat distribution, including BMI, waist-to-hip ratio, waist girth, and visceral and subcutaneous fat by EBCT, was significantly associated with CACS before or after adjusting for multiple covariates of CACS (age, smoking, alcohol intake, exercise, pulse pressure, low-density lipoprotein (LDL)/high-density lipoprotein (HDL)-cholesterol ratio, and fasting plasma glucose). In elderly adults without clinically recognized CHD, body weight and fat distribution do not predict coronary artery plaque burden. These results raise questions about the value of weight reduction diets for preventing heart disease in elderly survivors without clinical heart disease.

Is there an independent effect of polycystic ovary syndrome (PCOS) and menopause on the prevalence of subclinical atherosclerosis in middle aged women?

Polycystic ovary syndrome (PCOS), a common reproductive endocrine condition manifests at puberty, and is characterized by hyperandrogenism, chronic anovulation, and obesity. PCOS cases exhibit an adverse coronary heart disease (CHD) profile at an early age, including insulin resistance, dyslipidemia and increased central adiposity. It can be hypothesized that the menopausal transition, whether natural or surgical, may provide an additional "insult", resulting in greater cumulative risk to their vasculature. Coronary artery calcification (CAC), a measure of subclinical atherosclerosis (SCA), was measured by electron beam tomography in 149 PCOS cases and 166 controls (mean age 47.3 and 49.4 respectively). Cases had a higher prevalence of CAC (63.1%) compared to controls (41.0%), (p = 0.037) after adjustment for age and BMI. A total of 22 cases and 39 controls had undergone natural menopause, 12 cases and 26 controls underwent surgical menopause (with biochemical confirmation) and 115 cases and 101 controls reported being currently premenopausal. There was a significant difference in CAC values between cases and controls in all three-menopause categories including pre-menopausal, surgically induced and natural menopause (p < 0.001). Duration since menopause (years) and use of hormone replacement therapy were not different between cases and controls for the two menopause groups. Logistic regression was carried out with CAC (< or = 10 vs > 10) as the dependent variable, and independent variables: PCOS status, current age, BMI, and menopausal status, (pre-menopause, surgical and natural menopause) and selected CHD risk factors. The data indicate that women with PCOS exhibit significantly increased CAC compared to controls after adjustment for age and BMI and menopausal status. PCOS status and fasting glucose were significant risk factors for CAC (p < 0.05). Both natural and surgical menopause were independent risk factors for CAC as well (p < 0.01). HDLT was of borderline significance, p < 0.10. Further follow-up of this cohort will be valuable in determining whether PCOS status continues to affect cardiovascular risk as they undergo the menopausal transition.

Independent Association Between Obstructive Sleep Apnea and Subclinical Coronary Artery Disease

Obstructive sleep apnea (OSA) is associated with coronary risk factors, but it is unknown if OSA is associated with development of coronary disease. We evaluated the association between OSA and the presence of subclinical coronary disease assessed by coronary artery calcification (CAC). Consecutive patients with no history of coronary disease who underwent electron-beam CT within 3 years of polysomnography between March 1991 and December 2003 were included. OSA was defined by an apnea-hypopnea index (AHI) > or = 5 events per hour, and patients were grouped by quartiles of AHI severity. Logistic regression modeled the association between OSA severity and presence of CAC. There were 202 patients (70% male; median age, 50 years; mean body mass index, 32 kg/m(2); 8% diabetic; 9% current smokers; 60% hypercholesterolemic; and 47% hypertensive). OSA was present in 76%. CAC was present in 67% of OSA patients and 31% of non-OSA patients (p < 0.001). Median CAC scores (Agatston units) were 9 in OSA patients and 0 in non-OSA patients (p < 0.001). Median CAC score was higher as OSA severity increased (p for trend by AHI quartile < 0.001). With multivariate adjustment, the odds ratio for CAC increased with OSA severity. Using the first AHI quartile as reference, the adjusted odds ratios for the second, third, and fourth quartiles were 2.1 (p = 0.12), 2.4 (p = 0.06), and 3.3 (p = 0.03), respectively. In patients without clinical coronary disease, the presence and severity of OSA is independently associated with the presence and extent of CAC. OSA identifies patients at risk for coronary disease and may represent a highly prevalent modifiable risk factor.

Non-HDL cholesterol is strongly associated with coronary artery calcification in asymptomatic individuals

Background Growing evidence shows that non-high-density lipoprotein cholesterol (Non-HDL-C) is a strong and independent predictor of cardiovascular disease (CVD). Few studies have assessed the association between traditional lipid measures and subclinical end points. In this study we analyzed the association of Non-HDL-C, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG) with coronary artery calcium (CAC), a marker of subclinical atherosclerosis. Methods The study population consisted of 1611 consecutive asymptomatic individuals (67% men, mean age: 53 ± 10 years) referred to a single electron beam tomography (EBT) facility for CAC screening. Multivariate logistic regression was used to test the association between increasing quartiles of lipid levels and presence of CAC score (CACS) > 0 and CACS ≥ 100, with the lowest levels (first quartile) of lipid values as reference. Results Overall CACS of 0, 1–99, 100–399 and ≥400, were observed in 35%, 44%, 12% and 9% of the study subjects, respectively. The prevalence of CAC increased significantly across increasing quartiles of LDL-C, TG and Non-HDL-C (all p < 0.0001), whereas CACS was significantly lower across increasing quartiles of HDL-C ( p < 0.001). In a multivariate model controlling for age, gender, race, cigarette smoking, hypertension, family history of coronary artery disease and obesity, there was a significant increase in the prevalence of CAC with increasing values of each lipid variable. In a multivariate model simultaneously controlling for increasing quartiles of the remaining lipid variables, only the association of Non-HDL-C with CACS > 0 remained statistically significant ( p = 0.002). Similar results were observed with CACS ≥ 100 ( p = 0.038). Conclusion In this study Non-HDL-C was more strongly associated with subclinical atherosclerosis than all other conventional lipid values. These data suggests that Non-HDL-C may be an important treatment target in primary prevention.

How Low-Risk Is a Coronary Calcium Score of Zero?

Coronary artery calcium (CAC) scoring by computed tomography (CT) has been the subject of intense interest and critical scrutiny since it was first reported as a clinical tool in 1990.1 With improvements in study design, greater availability of coronary CT scanners, and increased attention to the posttest prognosis of patient samples and asymptomatic individuals who have undergone coronary CT, CAC measurement is now considered a potentially useful test for improving coronary risk assessment in selected intermediate-risk asymptomatic patients in whom high CAC scores signify increased cardiovascular risk beyond that predicted by conventional cardiovascular risk factors alone.2 Article p 1693 At the other end of the spectrum, does a very low CAC score signify very low risk? An American Heart Association writing group3 stated that a CAC score of zero (CAC=0; ie, no calcified plaque detected) indicated 1) that the presence of atherosclerotic plaque, including unstable or vulnerable plaque, was highly unlikely; 2) that the presence of significant luminal obstructive disease was highly unlikely (negative predictive value on the order of 95% to 99%); and 3) that the risk of a cardiovascular event in the next 2 to 5 years was quite low (0.1 per 100 person-years). In addition, at least 1 early study suggested that CAC=0 might be useful in the emergency room setting as a tool to rule out myocardial ischemia in symptomatic patients.4 A recent review article5 suggested the same conclusions. However, as pointed out by a different …

Assessment of the effective dose for routine protocols in conventional CT, electron beam CT and coronary angiography

To compare the effective dose applied by sequential CT (SEQ), spiral CT (SCT), electron beam CT (EBT) and coronary angiography for investigations of the chest, abdomen and the heart. The Alderson Phantom was used to compare the effective dose for all modalities. In addition, the effective dose for conventional CT (SEQ and SCT) was estimated with a mathematical phantom. For CT investigation of the chest and abdomen the dose was highest for the EBT (11 mSv and 25 mSv, respectively) and slightly lower for the SEQ (7.8 mSv and 21.5 mSv, respectively), whereas spiral CT required the least dose (5.3 mSv and 8.8 mSv, respectively). For coronary calcium screening (0.8 mSv) and EBT coronary angiography (1.7 mSv) the dose was lower than for coronary catheter angiography (3.3 mSv). For conventional CT the difference between the effective dose derived by the mathematical phantom and by the Alderson phantom was 2% to 20%. For investigations of the chest and abdomen the effective dose applied by SCT is significantly lower than that with EBT and SEQ. For investigation of the coronary arteries the effective dose applied by EBT is lower than that for coronary catheter angiography.

Reproductive History and Hormonal Birth Control Use Are Associated with Coronary Calcium Progression in Women with Type 1 Diabetes Mellitus

Coronary artery disease is increased in women with type 1 diabetes (T1D), compared with nondiabetic (Non-DM) women. Women with T1D have more menstrual dysfunction and are less likely to use hormonal birth control (BC) than Non-DM women. The purpose of this study was to determine whether coronary artery calcium (CAC) is associated with menstrual dysfunction and BC use in women with T1D. This was a prospective cohort study, and participants were followed up for an average of 2.4 yr. Patients included 612 women (293 T1D, 319 Non-DM) between the ages of 19 and 55 yr who had CAC measured twice by electron beam tomography. Irregular menses and amenorrhea were more common in T1D than Non-DM women (22.1 vs. 14.9%, P < 0.05 and 16.6 vs. 7.0%, P < 0.001). T1D women reported less BC use than Non-DM women (79.8 vs. 89.9%, P < 0.001) and reached menarche at an older age (13.1 +/- 1.8 vs. 12.8 +/- 1.5 yr, P < 0.05). Use of BC was associated with less CAC progression in all women, but this association was stronger in T1D women (P value for interaction = 0.02). Irregular menses were associated with greater CAC progression only among T1D women. A prior history of BC use is associated with reduced CAC progression among all women, with a stronger association in T1D than in Non-DM women. Women with T1D who report irregular menses have increased CAC progression, compared with those with regular menses.

All High-Risk Patients Should Not Be Screened With Computed Tomographic Angiography

On the basis of the most recent American Heart Association/American College of Cardiology guidelines for assessment of cardiac risk,1 high-risk patients are defined as those with a 10-year coronary heart disease risk of >20% based on Framingham risk criteria or the presence of diabetes mellitus. The major independent risk factors for coronary heart disease comprising the Framingham Risk Score are cigarette smoking, hypertension, elevated total cholesterol and low-density lipoprotein cholesterol, low serum high-density lipoprotein cholesterol, diabetes mellitus, advanced age, and male gender.1 Derived from National Health and Nutrition Examination Survey statistics from 1999 to 2000,2 the prevalence of risk factors in patients aged 20 to 74 years is 17% for total cholesterol ≥240 mg/dL, 14.9% for hypertension, 26.4% for smoking, and 8% for diabetes (including undiagnosed). Data from the 2003 Behavioral Risk Factor Surveillance System survey of 103 191 adults aged >18 years3 show that >37% of the population surveyed had ≥2 risk factors for coronary heart disease and thus are considered to be at high risk. These figures together suggest that the number of high-risk patients who are potential candidates for screening programs is quite high. Response by Gottlieb p 1339 Multiple studies over the last 2 decades have confirmed the prognostic utility of coronary artery calcium (CAC) measurements primarily with electron-beam computed tomography (EBCT) and more recently with multidetector CT (MDCT) technology (Figures 1 and 2⇓). The 2 techniques are fairly equivalent as long as the latter is performed with at least a 4-detector scanner.4,5 The reproducibility of MDCT, however, may not be as good as EBCT at lower calcium scores.4 Figure 1. Noncontrast ECG-gated CT for CAC scoring in a single axial plane demonstrating dense calcification of the left anterior descending artery. Figure 2. Noncontrast ECG-gated CT for CAC scoring …

Incident coronary artery calcium among postmenopausal women

Recent studies have shown that individuals with 0 coronary artery calcium (CAC) scores have very low risk of coronary heart disease. In the Healthy Women Study, we evaluated development of new CAC among postmenopausal women ( n = 272) over a 6-year period, age 62 at the 1st and 68 at the 3rd electron beam tomography (EBT) examination. At the 1st EBT, 155 of 272 (57%) women had 0 CAC. By the 3rd, 56 (36%) of these women had developed new CAC, including 38 with ≥5 Agatston units. There was practically no regression from having CAC at the 1st EBT to no CAC at the 3rd EBT. The risk of developing new CAC over 6 years among women with 0 CAC on their 1st EBT was strongly and significantly related to presence of both aortic calcium and carotid plaque at the time of 1st EBT. Baseline premenopausal risk factors, age 47, apolipoprotein B, body mass index (BMI) and triglycerides, were significant predictors of incident CAC as were the changes in BMI and low density lipoprotein cholesterol between premenopause and the 1st post exam, age 53. Risk factors measured premenopause and change in risk factors from premenopause to the 1st post exam and the extent of subclinical disease in other vascular beds are primary determinants of the risk of developing incident CAC in women over a 6-year period.

Imaging of the heart with computed tomography

Imaging of the heart with computed tomography (CT) was already introduced in the 1980Is and has meanwhile entered clinical routine as a consequence of the rapid evolution of CT technology during the last decade. In this review article, we give an overview on the technology and clinical performance of different CT-scanner generations used for cardiac imaging, such as Electron Beam CT (EBCT), single-slice CT und multi-detector row CT (MDCT) with 4, 16 and 64 simultaneously acquired slices. We identify the limitations of current CT-scanners, indicate potential of improvement and discuss alternative system concepts such as CT with area detectors and dual source CT (DSCT).

A synergistic relationship of elevated low-density lipoprotein cholesterol levels and systolic blood pressure with coronary artery calcification

We sought to evaluate this “response-to-injury” hypothesis of atherosclerosis by studying the interaction between systolic blood pressure (SBP) and LDL- cholesterol (LDL-C) in predicting the presence of coronary artery calcification (CAC) in asymptomatic men. We studied 526 men (46 ± 7 years of age) referred for electron-beam tomography (EBT) exam. The prevalence of CAC was determined across LDL-C tertiles (low: <115 mg/dl; middle: 115–139 mg/dl; high: ≥140 mg/dl) within tertiles of SBP (low: <121 mmHg; middle: 121–130 mmHg; high: ≥131 mmHg). CAC was found in 220 (42%) men. There was no linear trend in the presence of CAC across LDL-C tertiles in the low ( p = 0.6 for trend) and middle ( p = 0.3 for trend) SBP tertile groups, respectively. In contrast, there was a significant trend for increasing CAC with increasing LDL-C (1st: 44%; 2nd: 49%; 3rd: 83%; p < 0.0001 for trend) in the high SBP tertile group. In multivariate logistic analyses (adjusting for age, smoking, triglyceride levels, HDL-cholesterol levels, body mass index, and fasting glucose levels), the odds ratio for any CAC associated with increasing LDL-C was significantly higher in those with highest SBP levels, whereas no such relationship was observed among men with SBP in the lower two tertiles. An interaction term (LDL-C × SBP) incorporated in the multivariate analyses was statistically significant ( p = 0.038). The finding of an interaction between SBP and LDL-C relation to CAC in asymptomatic men support the response-to-injury model of atherogenesis.

Effect of Patient Visualization of Coronary Calcium by Electron Beam Computed Tomography on Changes in Beneficial Lifestyle Behaviors

Despite convincing data demonstrating the benefits of aspirin (ASA), exercise, and dietary changes for both primary and secondary prevention of coronary heart disease, they remain underused. In this study, we assess whether higher coronary artery calcium (CAC) scores determined by electron beam computed tomography (EBCT) are associated with beneficial lifestyle behaviors in asymptomatic individuals. A total of 980 asymptomatic patients referred for EBCT risk assessment by their primary physician were sent a survey questioning them about health behaviors. We evaluated long-term ASA utilization, exercise, and dietary changes based on CAC using multivariable analysis. The study population consisted of 980 individuals (78% men, mean age 60 +/- 8 years) who were followed for a mean of 3 +/- 2 years after an initial EBCT scan. Overall, ASA initiation was lowest (29%) among those with CAC = 0, and gradually increased with higher CAC scores (1 to 99, 55%; 100 to 399, 61%; > or =400, 63%; p <0.001 for trend). Similarly, dietary changes and exercise were lowest (33% and 44%, respectively) among those with CAC = 0 and gradually increased with higher CAC scores (1 to 99, 40%; 100 to 399, 58%; > or =400, 56%; p <0.001 for trend for dietary changes; and 1 to 99, 62%; 100 to 399, 63%; > or =400, 67%; p <0.001 for trend for exercise). In multivariable analysis, greater baseline CAC was strongly associated with initiation of ASA therapy, dietary changes, and increased exercise. In conclusion, in addition to risk stratification of asymptomatic individuals, determination of CAC may also improve utilization of ASA therapy and behavioral modification.

Intima-media thickness of the carotid artery and the distribution of lipoprotein subclasses in men aged 40 to 49 years between whites in the United States and the Japanese in Japan for the ERA JUMP study

In men in the post–World War II birth cohort, that is, men aged 40 to 49 years, whites in the United States had significantly higher levels of intima-media thickness of the carotid arteries (IMT) than the Japanese in Japan (Electron-Beam Tomography and Risk Assessment Among Japanese and US Men in the Post World War II Birth Cohort [ERA JUMP] study). The difference remained after adjusting for traditional risk factors. Primary genetic effects are unlikely, given the degree to which IMT is increased in the Japanese who migrated to the United States. We investigated whether the differences in the distributions of lipoprotein subclasses explain the difference in IMT between the 2 populations. We examined population-based samples of 466 randomly selected men aged 40 to 49 years (215 whites from Allegheny County, Pennsylvania, and 241 Japanese from Kusatsu, Shiga, Japan). Lipoprotein subclasses were determined by nuclear magnetic resonance (NMR) spectroscopy. The whites had significantly higher levels of large very low-density lipoprotein particles and significantly lower levels of large high-density lipoprotein particles than the Japanese, whereas the 2 populations had similar levels of small low-density lipoprotein particles. The 2 populations had similar associations of IMT with NMR lipoproteins. Adjusting for NMR lipoproteins did not attenuate the significant difference in IMT between the 2 populations (0.671 ± 0.006 mm for the whites and 0.618 ± 0.006 mm for the Japanese, P = .01, mean ± SE). Differences in the distributions of NMR lipoproteins between the 2 populations did not explain the higher IMT in the whites.