Coronary Artery Calcium Density Research Articles

70. Epicardial fat quality effect on subclinical atherosclerosis

Epicardial fat quality measured as Hounsfield Unit (HU) by computed tomography has significant impact on atherosclerosis. Excessive epicardial adipose tissue (EAT) is considered a risk factor for coronary artery disease (CAD). There are limited data, however, about the quality of epicardial fat as a CAD risk factor. We investigated the relation between EAT volume and quality and subclinical CAD defined by positive coronary artery calcification (CAC) using computed tomography (CT). We reviewed 609 CT scans to assess the EAT volume, which was measured by manually tracing the parietal pericardial sac on axial images. Fat density was recorded in mean Hounsfield units (HU). Coronary calcium scores were measured using the Agatston method. The patients’ mean age was 50 ± 11 years, and 398 (65.4%) were men. The mean EAT volume was 65 ± 27 cm 3 , and it had a density of 87.0 ± 3.4 HU. Calcium was present in 135 (22%) of the patients: 97 (16% of the total) were men and 38 (6%) were women. There was no difference between the sexes in regard to EAT volume (66 ± 27 vs. 63 ± 26, p = 0.34) or density (87.4 ± 3.2 vs. 87.0 ± 3.6, p = 0.28). Obese patients (body mass index ⩾30 kg/m 2 had significantly higher EAT volumes than nonobese patients (73 ± 30 vs. 61 ± 29, p = 0.011), but no difference was seen in CAC (33 ± 97 vs. 27 ± 103, p = 0.34) or fat density (87.7 ± 4.0 vs. 88.0 ± 2.7, p = 0.48). Univariate regression analyses showed that higher fat attenuation (HU) was associated with a lower coronary atherosclerosis hazard ratio (HR) (0.871, 95% confidence interval [CI] 0.790–0.948, p p = 0.0001). The quality of EAT, measured as HU on CT, is a strong predictor of subclinical CAD as defined by coronary artery calcifications, with a higher HU associated with a lower incidence of atherosclerosis.

Coronary artery calcium density for the prediction of mortality in CKD patients: One size does not fit all

Coronary artery calcium density for the prediction of mortality in CKD patients: One size does not fit all

Abstract P237: Cardiovascular Disease Risk Factor Associations with Volume and Density Components of Coronary Artery Calcium: The Multi-Ethnic Study of Atherosclerosis (MESA)

Introduction: Coronary artery calcium (CAC) strongly predicts incident cardiovascular disease (CVD) beyond traditional risk factors. CAC volume and density can be determined separately. CAC volume is positively associated with CVD risk, whereas CAC density is inversely associated with CVD risk. Hypothesis: We assessed the hypothesis that traditional CVD risk factors would associate differently with CAC volume than with CAC density. Methods: Baseline measurements from 6814 community-dwelling participants free of known CVD were collected for the Multiethnic Study of Atherosclerosis between 2000 and 2002. The 3398 CAC-positive participants were included in these analyses. Multivariable linear regression models were used to evaluate independent risk factors for CAC volume and CAC density separately. Results and Conclusions: Standardized beta coefficients for risk factors significantly associated with increased CAC volume in the multivariable linear regression model included age (β=0.34), male gender (β=0.48), diabetes (β=0.38), current smoking (β=0.27), hypertension medication use (β=0.18), family history of MI (β=0.21), body mass index (β=0.17), total cholesterol (β=0.06), and reduced walking pace (β=0.12). Compared to the non-Hispanic white (NHW) reference group, Chinese (β=-0.62), African-American (β=-0.48), and Hispanic (β=-0.47) race/ethnicities had decreased CAC volume. Risk factors positively associated with increased CAC density in the multivariable linear regression model included HDL (β=0.03), and Chinese (β=0.39), African-American (β=0.16), and Hispanic (β=0.18) race/ethnicities in comparison with NHW. Diabetes (β=-0.10) and body mass index (β=-0.08) were both inversely associated with CAC density. In conclusion, CVD risk factors predicted both increased CAC volume and decreased CAC density, suggesting they could increase atherosclerotic risk both by increasing CAC volume and decreasing CAC density. Ethnic groups other than NHW had lower risk CAC plaques, with lower volume and greater density.

Calcium Density of Coronary Artery Plaque and Risk of Incident Cardiovascular Events

Coronary artery calcium (CAC), measured by computed tomography (CT), has strong predictive value for incident cardiovascular disease (CVD) events. The standard CAC score is the Agatston, which is weighted upward for greater calcium density. However, some data suggest increased plaque calcium density may be protective for CVD. To determine the independent associations of CAC volume and CAC density with incident CVD events. Multicenter, prospective observational MESA study (Multi-Ethnic Study of Atherosclerosis), conducted at 6 US field centers of 3398 men and women from 4 race/ethnicity groups; non-Hispanic white, African American, Hispanic, and Chinese. Participants were aged 45-84 years, free of known CVD at baseline, had CAC greater than 0 on their baseline CT, and were followed up through October 2010. Incident coronary heart disease (CHD) and all CVD events During a median of 7.6 years of follow-up, there were 175 CHD events and an additional 90 other CVD events for a total of 265 CVD events. With both lnCAC volume and CAC density scores in the same multivariable model, the lnCAC volume score showed an independent association with incident CHD, with a hazard ratio (HR) of 1.81 (95% CI, 1.47-2.23) per standard deviation (SD = 1.6) increase, absolute risk increase 6.1 per 1000 person-years, and for CVD an HR of 1.68 (95% CI, 1.42-1.98) per SD increase, absolute risk increase 7.9 per 1000 person-years. Conversely, the CAC density score showed an independent inverse association, with an HR of 0.73 (95% CI, 0.58-0.91) per SD (SD = 0.7) increase for CHD, absolute risk decrease 5.5 per 1000 person-years, and an HR of 0.71 (95% CI, 0.60-0.85) per SD increase for CVD, absolute risk decrease 8.2 per 1000 person years. Area under the receiver operating characteristic curve analyses showed significantly improved risk prediction with the addition of the density score to a model containing the volume score for both CHD and CVD. In the intermediate CVD risk group, the area under the curve for CVD increased from 0.53 (95% CI, 0.48-0.59) to 0.59 (95% CI, 0.54-0.64), P = .02. CAC volume was positively and independently associated with CHD and CVD risk. At any level of CAC volume, CAC density was inversely and significantly associated with CHD and CVD risk. The role of CAC density should be considered when evaluating current CAC scoring systems.

Relation of Serum Uric Acid to Severity and Progression of Coronary Artery Calcium in Postmenopausal White and Filipino Women (from the Rancho Bernardo Study)

Elevated serum uric acid (UA) is associated with cardiovascular disease (CVD) but its association with coronary artery calcium (CAC) is inconsistent. This study examined ethnic differences in the association of UA levels with CAC severity and progression. Participants included 202 white and 166 Filipino postmenopausal women without known CVD. White women originated from the Rancho Bernardo cohort study, whereas Filipino women were convenience sampled from comparable localities. Baseline UA levels and CVD risk factors were measured in 1995 to 1999. CAC was assessed by electron beam computed tomography (EBCT) in 2000 to 2002 (EBCT1) and repeated in 2005 to 2007 (EBCT2). EBCT1 CAC density scores were categorized by severity: minimal 0 to 10, mild 11 to 100, moderate 101 to 399, and severe ≥400. Progression was defined as CAC volume score increases of ≥2.5 mm3 between scans. White women were older at baseline than Filipinas (64.6 vs 59.3 years, p<0.001). Filipinas had increased UA levels (235.8 vs 294.2 μmol/L, p<0.001), diabetes (35.5% vs 5.2%, p<0.001), hypertension (69.6% vs 45.2%, p<0.001), and statin use (32.8% vs 18.7%, p=0.002). CAC severity did not vary by ethnicity (p=0.502), but Filipinas experienced more CAC progression than whites (53.0% vs 39.1%, p=0.016). Adjustment for CVD risk factors identified a positive association between UA levels and increasing CAC severity at EBCT1 in Filipinas (odds ratio [OR] 1.34, 95% confidence interval [CI] 1.05 to 1.71) but not whites (OR 0.94, 95% CI 0.71 to 1.25). Higher UA levels predicted CAC progression in both cohorts (OR 1.26, 95% CI 1.02 to 1.56). In conclusion, these results support use of UA as an ethnicity-specific marker of CAC severity and as a marker of CAC progression among postmenopausal women.

Abstract 021: Greater Calcium Density of Coronary Artery Plaque is Protective for Cardiovascular Events. The Multi-Ethnic Study of Atherosclerosis

Background— Coronary artery calcium (CAC) measured by computed tomography (CT) has strong predictive value for incident cardiovascular disease (CVD) events. The standard CAC score is the Agatston, which is the product of the within slice CAC plaque area and a plaque specific density factor of 1, 2, 3, or 4, summed for all CT slices. Thus, the Agatston score is weighted upward for greater CAC density. However, data from both observational studies and randomized trials suggest increased CAC density per se may be protective for CVD. Methods— In a multi-ethnic population of 3398 men and women with Agatston scores &gt; 0 at baseline, we derived a formula using the individual Agatston scores and the volume scores to create a per participant CAC density score. We then analyzed the independent associations of CAC volume and CAC density with incident hard CVD, defined as MI, resuscitated cardiac arrest, cardiac death, stroke, or stroke death, Results— During a median of 7.6 years of follow-up, there were 265 hard CVD events, 175 of which were coronary heart disease (CHD) events. In a proportional hazards model including the General Framingham Risk Score (GFRS) and both the CAC volume and CAC density score, the CAC volume score showed a strong independent association with incident CVD, with a hazard ratio per natural log standard deviation increase of 1.62, p&lt;.0001. Conversely, the CAC density score showed an independent association that was strongly protective for CVD, with a hazard ratio per standard deviation increase of 0.72, p&lt;.0003. Multivariate quartile analyses showed that at any given volume score, a density score in the 4 th quartile (range 3.2 to 4.0) decreased the risk of a CVD event by 51%, p=.002. The density score showed no significant interactions with either sex or ethnicity. The addition of the volume score to the model containing the GFRS increased the area under the ROC curve (AUC) from 0.664 to 0.6869, p=.015, and further addition of the density score increased the AUC to .6994, p=.023. Separate analyses limited to CHD events showed similar results. Conclusions— At any given volume of CAC, increased density in calcified coronary plaques is protective for incident CVD, consistent with the concept that calcium deposition may increase the stability of atherosclerotic plaques. CAC scoring systems should be modified to weight downward for density rather than upward, and thus improve CVD risk prediction.

The association between coronary artery calcification progression and loss of bone density in non-dialyzed CKD patients

Coronary artery calcification (CAC) and low bone density are coexisting deleterious conditions commonly shared by chronic kidney disease (CKD) patients. In the present study, we aimed to investigate whether the progression of CAC was associated with overtime reduction in bone density in non-dialyzed CKD patients. This is a prospective study of 24 months including 72 non-dialyzed CKD patients Stages 2 - 4 (age 57.6 ± 10.3 years, 62% male, 22% diabetics). CAC and vertebral bone density (VBD) were measured by computed tomography. At baseline, 46% of the patients had CAC (calcified group) and calcification was not identified in 54% of the patients (non-calcified group). The calcified group was older, predominantly male, and had lower VBD in comparison to non-calcified group. CAC progression was observed only in the calcified group (91% of the patients increased calcium score). The multiple regression analysis revealed loss of VBD as the independent determinant of CAC progression in these patients. CAC progression was associated with loss of VBD in non-dialyzed CKD patients.

The Relationship Between Coronary Artery Calcification and Bone Mineral Density in Patients According to Their Metabolic Syndrome Status

Background and ObjectivesThe extent of coronary artery calcification (CAC) is closely related to total atherosclerotic plaque burden. However, the pathogenesis of CAC is still unclear. Conditions such as diabetes mellitus, renal failure, smoking, and chronic inflammation have been suggested to link vascular calcification and bone loss. In the present study, we hypothesized that bone loss can contribute to the pathogenesis of CAC in patients with the chronic inflammatory condition that accompanies metabolic syndrome (MetS). The objective of this study was to investigate the relationship between CAC and bone mineral density (BMD) in patients with MetS and in patients without MetS, by using coronary multidetector-row computed tomography (MDCT).Subjects and MethodsData from 395 consecutive patients was analyzed retrospectively. From the MDCT database, only those patients who underwent both coronary MDCT and dual-energy X-ray absorptiometry within an interval of one month, were selected. The presence of MetS was determined by the updated criteria as defined by the Third Adult Treatment Panel Report of the National Cholesterol Education Program.ResultsIn patients with MetS, a significant correlation was found between CAC and age {odds ratio (OR)=1.139, 95% confidence interval (CI) 1.080 to 1.201, p<0.001}, CAC and male sex (OR=3.762, 95% CI 1.339 to 10.569, p=0.012), and CAC and T-score of L-spine (OR=0.740, 95% CI 0.550 to 0.996, p=0.047) using a forward multiple logistic regression analysis model including clinical variables of gender, age, lipid profile, body mass index, diabetes mellitus, hypertension, smoking, and BMD. But in patients without MetS, BMD by itself was not found to contribute to CAC.ConclusionBMD was inversely correlated with CAC only in patients with MetS. This finding suggests that low BMD accompanied by MetS, may have significant clinical implications.

The association of coronary artery calcification and carotid artery intima-media thickness with distinct, traditional coronary artery disease risk factors in asymptomatic adults.

Coronary artery calcification (CAC) and common carotid artery intima-media thickness (CIMT) are measures of subclinical vascular disease. This 2000-2006 study aimed to characterize the associations among coronary artery disease risk factors, CAC quantity, and CIMT and to estimate shared genetic and environmental contributions to both CAC and CIMT among 478 asymptomatic Amish adults in Lancaster County, Pennsylvania. Heritability for CAC quantity and CIMT, adjusted for age and sex, was 0.42 (P = 0.0001) and 0.29 (P = 0.003), respectively. CAC quantity and CIMT were modestly correlated (adjusted r = 0.14, P = 0.003) but showed little evidence of shared genetic or environmental factors. However, significant genetic correlations were found for CAC quantity and total cholesterol (0.44 (standard error, 0.19); P = 0.03), for CAC quantity and low density lipoprotein cholesterol (0.55 (standard error, 0.17); P = 0.005), and for CIMT and waist circumference (0.58 (standard error, 0.25); P = 0.046), suggesting shared genes for these risk factors and measures of subclinical disease. Results suggest that some of the same genes influence variation in CAC and low density lipoprotein cholesterol, whereas a different set of genes influences variation in CIMT and waist circumference.

The Visual Scoring of Sleep in Adults

The 1968 Rechtschaffen and Kales (R & K) sleep scoring manual was published 15 years after REM sleep was discovered. Advances in the ensuing 28 years warranted a re-look at visual scoring of sleep stages. This paper describes the work of the AASM Visual Scoring Task Force, including methodology, a literature review and the rationale behind the new rules. Reliability studies of R & K scoring were reviewed; reliability was low for stage one and moderate for slow wave sleep. Evidence indicated that K complexes and slow waves are expressed maximal frontally, spindles centrally and alpha rhythm over the occipital region. Three derivations of EEG, two of electro-oculography, and one of chin EMG were recommended. Scoring by 30-second epochs was retained. New terminology for sleep stages was proposed. Attenuation of alpha rhythm was determined to be the most valid electrophysiological marker of sleep onset. Alternative measures were proposed for non-alpha generating subjects. K complexes associated with arousals were determined to be insufficient alone to define the new stage N2. No evidence was found to justify dividing slow wave sleep into two stages. No reasons were found to alter the current slow wave amplitude criteria at any age. The phenomena of REM sleep were defined. The rules for defining onset and termination of REM sleep periods were simplified. Movement time was eliminated and major body movements defined. Studies are needed to test the reliability of the new rules. Future advances in technology may require modification of these rules with time.