Impact of visceral fat on coronary artery disease as defined by quantitative computed tomography angiography

OBJECTIVE

Obesity is associated with all-cause mortality and cardiovascular disease (CVD). Visceral fat (VF) is an important CVD risk metric given its independent correlation with myocardial infarction and stroke. This study aims to clarify the relationship between the presence and severity of VF with the presence and severity of coronary artery plaque.

METHODS

In 145 consecutive asymptomatic patients, atherosclerosis imaging-quantitative computed tomography was performed for total plaque volume (TPV) and percentage atheroma volume, as well as the volume of noncalcified plaque (NCP), calcified plaque, and low-density NCP (LD-NCP), diameter stenosis, and vascular remodeling. This study also included VF analysis and subcutaneous fat analysis, recording of outer waist circumference, and percentage body fat analysis.

RESULTS

The mean age of the patients was 56.1 [SD 8.5] years, and 84.0% were male. Measures of visceral adiposity (mean [SD, Q1-Q3 thresholds]) included estimated body fat, 28.7% (9.0%, 24.1%-33.0%); VF, 169.8 cm2 (92.3, 102.0-219.0 cm2 ); and subcutaneous fat, 223.6 mm2 (114.2, 142.5-288.0 mm2 ). The Spearman correlation coefficients of VF and plaque volume included TPV 0.22 (p = 0.0074), calcified plaque 0.12 (p = 0.62), NCP 0.25 (p = 0.0023), and LD-NCP 0.37 (p < 0.0001). There was a progression of the median coronary plaque volume for each quartile of VF including TPV (Q1: 19.8, Q2: 48.1, Q3: 86.4, and Q4: 136.6 mm3 [p = 0.0098]), NCP (Q1: 15.7, Q2: 35.4, Q3: 86.4, and Q4: 136.6 mm3 [p = 0.0032]), and LD-NCP (Q1: 0.6, Q2: 0.81, Q3: 2.0, and Q4: 5.0 mm3 [p < 0.0001]).

CONCLUSIONS

These findings demonstrate progression with regard to VF and TPV, NCP volume, and LD-NCP volume. Notably, there was a progression of VF and amount of LD-NCP, which is known to be high risk for future cardiovascular events. A consistent progression may indicate the future utility of VF in CVD risk stratification.

Mortality impact of low CAC density predominantly occurs in early atherosclerosis: explainable ML in the CAC consortium

BACKGROUND

Machine learning (ML) models of risk prediction with coronary artery calcium (CAC) and CAC characteristics exhibit high performance, but are not inherently interpretable.

OBJECTIVES

To determine the direction and magnitude of impact of CAC characteristics on 10-year all-cause mortality (ACM) with explainable ML.

METHODS

We analyzed asymptomatic subjects in the CAC consortium. We trained ML models on 80% and tested on 20% of the data with XGBoost, using clinical characteristics ​+ ​CAC (ML 1) and additional CAC characteristics of CAC density and number of calcified vessels (ML 2). We applied SHAP, an explainable ML tool, to explore the relationship of CAC and CAC characteristics with 10-year all-cause and CV mortality.

RESULTS

2376 deaths occurred among 63,215 patients [68% male, median age 54 (IQR 47-61), CAC 3 (IQR 0-94.3)]. ML2 was similar to ML1 to predict all-cause mortality (Area Under the Curve (AUC) 0.819 vs 0.821, p ​= ​0.23), but superior for CV mortality (0.847 vs 0.845, p ​= ​0.03). Low CAC density increased mortality impact, particularly ≤0.75. Very low CAC density ≤0.75 was present in only 4.3% of the patients with measurable density, and 75% occurred in CAC1-100. The number of diseased vessels did not increase mortality overall when simultaneously accounting for CAC and CAC density.

CONCLUSION

CAC density contributes to mortality risk primarily when it is very low ≤0.75, which is primarily observed in CAC 1-100. CAC and CAC density are more important for mortality prediction than the number of diseased vessels, and improve prediction of CV but not all-cause mortality. Explainable ML techniques are useful to describe granular relationships in otherwise opaque prediction models.

Distribution of Coronary Artery Calcium by Age, Sex, and Race Among Patients 30-45 Years Old

BACKGROUND

Coronary artery calcium (CAC) is a measure of atherosclerotic burden and is well-validated for risk stratification in middle- to older-aged adults. Few studies have investigated CAC in younger adults, and there is no calculator for determining age-, sex-, and race-based percentiles among individuals aged <45 years.

OBJECTIVES

The purpose of this study was to determine the probability of CAC >0 and develop age-sex-race percentiles for U.S. adults aged 30-45 years.

METHODS

We harmonized 3 datasets-CARDIA (Coronary Artery Risk Development in Young Adults), the CAC Consortium, and the Walter Reed Cohort-to study CAC in 19,725 asymptomatic Black and White individuals aged 30-45 years without known atherosclerotic cardiovascular disease. After weighting each cohort equally, the probability of CAC >0 and age-sex-race percentiles of CAC distributions were estimated using nonparametric techniques.

RESULTS

The prevalence of CAC >0 was 26% among White males, 16% among Black males, 10% among White females, and 7% among Black females. CAC >0 automatically placed all females at >90th percentile. CAC >0 placed White males at the 90th percentile at age 34 years compared with Black males at age 37 years. An interactive webpage allows one to enter an age, sex, race, and CAC score to obtain the corresponding estimated percentile.

CONCLUSIONS

In a large cohort of U.S. adults aged 30-45 years without symptomatic atherosclerotic cardiovascular disease, the probability of CAC >0 varied by age, sex, and race. Estimated percentiles may help interpretation of CAC scores among young adults relative to their age-sex-race matched peers and can henceforth be included in CAC score reporting.

Impact of COVID-19 Pandemic on Cardiovascular Testing in Asia

Background

The coronavirus disease-2019 (COVID-19) pandemic significantly affected management of cardiovascular disease around the world. The effect of the pandemic on volume of cardiovascular diagnostic procedures is not known.

Objectives

This study sought to evaluate the effects of the early phase of the COVID-19 pandemic on cardiovascular diagnostic procedures and safety practices in Asia.

Methods

The International Atomic Energy Agency conducted a worldwide survey to assess changes in cardiovascular procedure volume and safety practices caused by COVID-19. Testing volumes were reported for March 2020 and April 2020 and were compared to those from March 2019. Data from 180 centers across 33 Asian countries were grouped into 4 subregions for comparison.

Results

Procedure volumes decreased by 47% from March 2019 to March 2020, showing recovery from March 2020 to April 2020 in Eastern Asia, particularly in China. The majority of centers cancelled outpatient activities and increased time per study. Practice changes included implementing physical distancing and restricting visitors. Although COVID testing was not commonly performed, it was conducted in one-third of facilities in Eastern Asia. The most severe reductions in procedure volumes were observed in lower-income countries, where volumes decreased 81% from March 2019 to April 2020.

Conclusions

The COVID-19 pandemic in Asia caused significant reductions in cardiovascular diagnostic procedures, particularly in low-income countries. Further studies on effects of COVID-19 on cardiovascular outcomes and changes in care delivery are warranted.

Thoracic Aortic Calcium for the Prediction of Stroke Mortality (from the Coronary Artery Calcium Consortium)

Thoracic aortic calcium(TAC) is an important marker of extracoronary atherosclerosis with established predictive value for all-cause mortality. We sought to explore the predictive value of TAC for stroke mortality, independent of the more established coronary artery calcium (CAC) score. The CAC Consortium is a retrospectively assembled database of 66,636 patients aged ≥18 years with no previous history of cardiovascular disease, baseline CAC scans for risk stratification, and follow-up for 12 ± 4 years. CAC scans capture the adjacent thoracic aorta, enabling assessment of TAC from the same images. TAC was available in 41,066 (62%), and was primarily analyzed as present or not present. To account for competing risks for nonstroke death, we utilized multivariable-adjusted Fine and Gray competing risk regression models adjusted for traditional cardiovascular risk factors and CAC score. The mean age of participants was 53.8 ± 10.3 years, with 34.4% female. There were 110 stroke deaths during follow-up. The unadjusted subdistribution hazard ratio (SHR) for stroke mortality in those who had TAC present compared with those who did not was 8.80 (95% confidence interval [CI]: 5.97, 12.98). After adjusting for traditional risk factors and CAC score, the SHR was 2.21 (95% CI:1.39,3.49). In sex-stratified analyses, the fully adjusted SHR for females was 3.42 (95% CI: 1.74, 6.73) while for males it was 1.55 (95% CI: 0.83, 2.90). TAC was associated with stroke mortality independent of CAC and traditional risk factors, more so in women. The presence of TAC appears to be an independent risk marker for stroke mortality.

Sex Differences in Coronary Artery Calcium and Mortality From Coronary Heart Disease, Cardiovascular Disease, and All Causes in Adults With Diabetes: The Coronary Calcium Consortium

OBJECTIVE

While diabetes has been previously noted to be a stronger risk factor for cardiovascular disease (CVD) in women compared with men, whether this is still the case is not clear. Coronary artery calcium (CAC) predicts coronary heart disease (CHD) and CVD in people with diabetes; however, its sex-specific impact is less defined. We compared the relation of CAC in women versus men with diabetes for total, CVD, and CHD mortality.

RESEARCH DESIGN AND METHODS

We studied adults with diabetes from a large registry of patients with CAC scanning with mortality follow-up over 11.5 years. Cox regression examined the relation of CAC with mortality end points.

RESULTS

Among 4,503 adults with diabetes (32.5% women) aged 21-93 years, 61.2% of women and 80.4% of men had CAC >0. Total, CVD, and CHD mortality rates were directly related to CAC; women had higher total and CVD death rates than men when CAC >100. Age- and risk factor-adjusted hazard ratios (HRs) per log unit CAC were higher among women versus men for total mortality (1.28 vs. 1.18) (interaction P = 0.01) and CVD mortality (1.47 vs. 1.27) (interaction P = 0.04) but were similar for CHD mortality (1.48 and 1.48). For CVD mortality, HRs with CAC scores of 101-400 and >400 were 3.67 and 6.27, respectively, for women and 1.63 and 3.48, respectively, for men (interaction P = 0.04). For total mortality, HRs were 2.56 and 4.05 for women, respectively, and 1.88 and 2.66 for men, respectively (interaction P = 0.01).

CONCLUSIONS

CAC predicts CHD, CVD, and all-cause mortality in patients with diabetes; however, greater CAC predicts CVD and total mortality more strongly in women.

Association of Body Mass Index With Coronary Artery Calcium and Subsequent Cardiovascular Mortality: The Coronary Artery Calcium Consortium

BACKGROUND

Obesity is associated with higher risk for coronary artery calcium (CAC), but the relationship between body mass index (BMI) and mortality is complex and frequently paradoxical.

METHODS

We analyzed BMI, CAC, and subsequent mortality using data from the CAC Consortium, a multi-centered cohort of individuals free of established cardiovascular disease (CVD) who underwent CAC testing. Mortality was assessed through linkage to the Social Security Death Index and cause of death from the National Death Index. Multivariable logistic regression was used to determine odds ratios for the association of clinically relevant BMI categories and prevalent CAC. Cox proportional hazards regression modeling was used to determine hazard ratios for coronary heart disease, CVD, and all-cause mortality according to categories of BMI and CAC.

RESULTS

Our sample included 36 509 individuals, mean age 54.1 (10.3) years, 34.4% female, median BMI 26.6 (interquartile range, 24.1-30.1), 46.6% had zero CAC, and 10.5% had CAC ≥400. Compared with individuals with normal BMI, the multivariable adjusted odds of CAC >0 were increased in those overweight (odds ratio, 1.13 [95% CI, 1.1-1.2]) and obese (odds ratio, 1.5 [95% CI, 1.4-1.6]). Over a median follow-up of 11.4 years, there were 1550 deaths (4.3%). Compared with normal BMI, obese individuals had a higher risk of coronary heart disease, CVD, and all-cause mortality while overweight individuals, despite a higher odds of CAC, showed no significant increase in mortality. In a sex-stratified analysis, the increase in coronary heart disease, CVD, and all-cause mortality in obese individuals appeared largely limited to men, and there was a lower risk of all-cause mortality in overweight women (hazard ratio, 0.79 [95% CI, 0.63-0.98]).

CONCLUSIONS

In a large sample undergoing CAC scoring, obesity was associated with a higher risk of CAC and subsequent coronary heart disease, CVD, and all-cause mortality. However, overweight individuals did not have a higher risk of mortality despite a higher risk for CAC.

Association of Coronary Artery Calcium With Long-term, Cause-Specific Mortality Among Young Adults

IMPORTANCE

The level of coronary artery calcium (CAC) can effectively stratify cardiovascular risk in middle-aged and older adults, but its utility for young adults is unclear.

OBJECTIVES

To determine the prevalence of CAC in adults aged 30 to 49 years and the subsequent association of CAC with coronary heart disease (CHD), cardiovascular disease (CVD), and all-cause mortality.

DESIGN, SETTING, AND PARTICIPANTS

A multicenter retrospective cohort study was conducted among 22 346 individuals from the CAC Consortium who underwent CAC testing (baseline examination, 1991-2010, with follow-up through June 30, 2014; CAC quantified using nonconrast, cardiac-gated computed tomography scans) for clinical indications and were followed up for cause-specific mortality. Participants were free of clinical CVD at baseline. Statistical analysis was performed from June 1, 2017, to May 31, 2018.

MAIN OUTCOMES AND MEASURES

The prevalence of CAC and the subsequent rates of CHD, CVD, and all-cause mortality. Competing risks regression modeling was used to calculate multivariable-adjusted subdistribution hazard ratios for CHD and CVD mortality.

RESULTS

The sample of 22 346 participants (25.0% women and 75.0% men; mean [SD] age, 43.5 [4.5] years) had a high prevalence of hyperlipidemia (49.6%) and family history of CHD (49.3%) but a low prevalence of current smoking (11.0%) and diabetes (3.9%). The prevalence of any CAC was 34.4%, with 7.2% having a CAC score of more than 100. During follow-up (mean [SD], 12.7 [4.0] years), there were 40 deaths related to CHD, 84 deaths related to CVD, and 298 total deaths. A total of 27 deaths related to CHD (67.5%) occurred among individuals with CAC at baseline. The CHD mortality rate per 1000 person-years was 10-fold higher among those with a CAC score of more than 100 (0.69; 95% CI, 0.41-1.16) compared with those with a CAC score of 0 (0.07; 95% CI, 0.04-0.12). After multivariable adjustment, those with a CAC score of more than 100 had a significantly increased risk of CHD (subdistribution hazard ratio, 5.6; 95% CI, 2.5-12.7), CVD (subdistribution hazard ratio, 3.3; 95% CI, 1.8-6.2), and all-cause mortality (hazard ratio, 2.6; 95% CI, 1.9-3.6) compared with those with a CAC score of 0.

CONCLUSIONS AND RELEVANCE

In a large sample of young adults undergoing CAC testing for clinical indications, 34.4% had CAC, and those with elevated CAC scores had significantly higher rates of CHD and CVD mortality. Coronary artery calcium may have potential utility for clinical decision-making among select young adults at elevated risk of cardiovascular disease.

The association between left main coronary artery calcium and cardiovascular-specific and total mortality: The Coronary Artery Calcium Consortium

BACKGROUND AND AIMS

Left main (LM) coronary artery disease is associated with greater myocardial infarction-related mortality, however, coronary artery calcium (CAC) scoring does not account for disease location. We explored whether LM CAC predicts excess mortality in asymptomatic adults.

METHODS

Cause-specific cardiovascular and all-cause mortality was studied in 28,147 asymptomatic patients with non-zero CAC scores in the CAC Consortium. Multivariate regression was performed to evaluate if the presence and burden of LM CAC predict mortality after adjustment for clinical risk factors and the Agatston CAC score. We further analyzed the per-unit hazard associated with LM CAC in comparison to CAC in other arteries.

RESULTS

The study population had mean age of 58.3 ± 10 years and CAC score of 301 ± 631. LM CAC was present in 21.7% of the cases. During 312,398 patient-years of follow-up, 1,907 deaths were observed. LM CAC was associated with an increased burden of clinical risk factors and total CAC, and was independently predictive of increased hazard for all-cause (HR 1.2 [1.1, 1.3]) and cardiovascular disease death (HR 1.3 [1.1, 1.5]). The hazard for death increased proportionate to the percentage of CAC localized to the LM. On a per-100 Agatston unit basis, LM CAC was associated with a 6-9% incremental hazard for death beyond knowledge of CAC in other arteries.

CONCLUSIONS

The presence and high burden of left main CAC are independently associated with a 20-30% greater hazard for cardiovascular and total mortality in asymptomatic adults, arguing that LM CAC should be routinely noted in CAC score reports when present.

Long-Term All-Cause and Cause-Specific Mortality in Asymptomatic Patients With CAC ≥1,000: Results From the CAC Consortium

OBJECTIVES

This study thoroughly explored the demographic and imaging characteristics, as well as the all-cause and cause-specific mortality risks of patients with a coronary artery calcium (CAC) score ≥1,000 in the largest dataset of this population to date.

BACKGROUND

CAC is commonly used to quantify cardiovascular risk. Current guidelines classify a CAC score of >300 or 400 as the highest risk group, yet little is known about the potentially unique imaging characteristics and mortality risk in individuals with a CAC score ≥1,000.

METHODS

A total of 66,636 asymptomatic adults were included from the CAC consortium, a large retrospective multicenter clinical cohort. Mean patient follow-up was 12.3 ± 3.9 years for patients with cardiovascular disease (CVD), coronary heart disease (CHD), cancer, and all-cause mortality. Multivariate Cox proportional hazards regression models adjusted for age, sex, and conventional risk factors were used to assess the relative mortality hazard of individuals with CAC ≥1,000 compared with, first, a CAC reference of 0, and second, with patients with a CAC score of 400 to 999.

RESULTS

There were 2,869 patients with CAC ≥1,000 (86.3% male, mean 66.3 ± 9.7 years of age). Most patients with CAC ≥1,000 had 4-vessel CAC (mean: 3.5 ± 0.6 vessels) and had greater total CAC area, higher mean CAC density, and more extracoronary calcium (79% with thoracic artery calcium, 46% with aortic valve calcium, and 21% with mitral valve calcium) than those with CAC scores of 400 to 999. After full adjustment, those with CAC ≥1,000 had a 5.04- (95% confidence interval [CI]: 3.92 to 6.48), 6.79- (95% CI: 4.74 to 9.73), 1.55- (95% CI:1.23 to 1.95), and 2.89-fold (95% CI: 2.53 to 3.31) risk of CVD, CHD, cancer, and all-cause mortality, respectively, compared to those with CAC score of 0. The CAC ≥1,000 group had a 1.71- (95% CI: 1.41 to 2.08), 1.84- (95% CI: 1.43 to 2.36), 1.36- (95% CI:1.07 to 1.73), and 1.51-fold (95% CI: 1.33 to 1.70) increased risk of CVD, CHD, cancer, and all-cause mortality compared to those with CAC scores 400 to 999. Graphic analysis of CAC ≥1,000 patients revealed continued logarithmic increase in risk, with no clear evidence of a risk plateau.

CONCLUSIONS

Patients with extensive CAC (CAC ≥1,000) represent a unique very high-risk phenotype with mortality outcomes commensurate with high-risk secondary prevention patients. Future guidelines should consider CAC ≥1,000 patients to be a distinct risk group who may benefit from the most aggressive preventive therapy.

Sex differences in calcified plaque and long-term cardiovascular mortality: observations from the CAC Consortium

Aims

Pathologic evidence supports unique sex-specific mechanisms as precursors for acute cardiovascular (CV) events. Current evidence on long-term CV risk among women when compared with men based on measures of coronary artery calcium (CAC) remains incomplete.

Methods and results

A total of 63 215 asymptomatic women and men were enrolled in the multicentre, CAC Consortium with median follow-up of 12.6 years. Pooled cohort equation (PCE) risk scores and risk factor data were collected with the Agatston score and other CAC measures (number of lesions and vessels, lesion size, volume, and plaque density). Cox proportional hazard models were employed to estimate CV mortality (n = 919). Sex interactions were calculated. Women and men had average PCE risk scores of 5.8% and 9.1% (P < 0.001). Within CAC subgroups, women had fewer calcified lesions (P < 0.0001) and vessels (P = 0.017), greater lesion size (P < 0.0001), and higher plaque density (P = 0.013) when compared with men. For women and men without CAC, long-term CV mortality was similar (P = 0.67), whereas detectable CAC was associated with 1.3-higher hazard for CV death among women when compared with men (P < 0001). Cardiovascular mortality was higher among women with more extensive, numerous, or larger CAC lesions. The relative hazard for cardiovascular disease (CVD) mortality for women and men was 8.2 vs. 5.1 for multivessel CAC, 8.6 vs. 5.9 for ≥5 CAC lesions, and 8.5 vs. 4.4 for a lesion size ≥15 mm3, respectively. Additional explorations revealed that women with larger sized and more numerous CAC lesions had 2.2-fold higher CVD mortality (P < 0.0001) as compared to men. Moreover, CAC density was not predictive of CV mortality in women (P = 0.51) but was for men (P < 0.001), when controlling for CAC volume and cardiac risk factors.

Conclusion

Our overall findings support that measures beyond the Agatston score provide important clues to sex differences in atherosclerotic plaque and may further refine risk detection and focus preventive strategies of care.

Clinical indications for coronary artery calcium scoring in asymptomatic patients: Expert consensus statement from the Society of Cardiovascular Computed Tomography

This expert consensus statement summarizes the available data regarding the prognostic value of CAC in the asymptomatic population and its ability to refine individual risk prediction, addresses the limitations identified in the current traditional risk factor-based treatment strategies recommended by the 2013 ACC/AHA Prevention guidelines including use of the Pooled Cohort Equations (PCE), and the US Preventive Services Task Force (USPSTF) Recommendation Statement for Statin Use for the Primary Prevention of Cardiovascular Disease in Adults. It provides CAC based treatment recommendations both within the context of the shared decision making model espoused by the 2013 ACC/AHA Prevention guidelines and independent of these guidelines.

Usefulness of regional distribution of coronary artery calcium to improve the prediction of all-cause mortality

Although the traditional Agatston coronary artery calcium (CAC) score is a powerful predictor of mortality, it is unknown if the regional distribution of CAC further improves cardiovascular risk prediction. We retrospectively studied 23,058 patients referred for Agatston CAC scoring, of whom 61% had CAC (n=14,084). CAC distribution was defined as the number of vessels with CAC (0 to 4, including left main). For multivessel CAC, "diffuse" CAC was defined by decreasing percentage of CAC in the single most affected vessel and by ≤75% total Agatston CAC score in the most calcified vessel. All-cause mortality was ascertained through the social security death index. The mean age was 55±11 years, with 69% men. There were 584 deaths (2.5%) over 6.6±1.7 years. Considerable heterogeneity existed between the Agatston CAC score group and the number of vessels with CAC. In each CAC group, increasing number of vessels with CAC was associated with an increased mortality rate. After adjusting for age, gender, Agatston CAC score, and cardiovascular risk factors, increasing number of vessels with CAC was associated with higher mortality risk compared with single-vessel CAC (2-vessel: HR 1.61 [95% CI 1.14 to 2.25], 3-vessel: 1.99 [1.44 to 2.77], and 4-vessel: 2.22 [1.53 to 3.23]). "Diffuse" CAC was associated with a higher mortality rate in the CAC 101 to 400 and >400 groups. Left main CAC was associated with increased mortality risk. In conclusion, increasing number of vessels with CAC and left main CAC predict increased all-cause mortality and improve the prognostic power of the traditional Agatston CAC score.

Training, competency, and certification in cardiac CT: a summary statement from the Society of Cardiovascular Computed Tomography

Training and competency criteria in cardiac CT were developed to guide practitioners in the process of achieving and maintaining skills in performing and interpreting cardiac CT studies. Appropriate training and eventual certification in cardiac CT angiography may be obtained by adhering to the recommendations for competency as set forth by either the American College of Cardiology Foundation (ACCF) or the American College of Radiology (ACR). Competency under either pathway requires both knowledge and experience-based components, with benchmarks set for level of experience on the basis of the extent of training experience. Although these recommended parameters are substantial, meeting these training criteria does not guarantee competence or expertise, which is the responsibility of the individual practitioner and may require further training and experience. Separate from satisfying initial training for the achievement of competency, certification in cardiac CT may be achieved through formal certification under the Certification Board of Cardiovascular Computed Tomography. Eligibility for certification generally follows the ACCF/American Heart Association Level 2 or ACR competency pathways. The ACR also conducts a certificate program related to advanced proficiency in cardiac CT. This official document of the Society of Cardiovascular Computed Tomography summarizes the present criteria for competency and certification in the field of cardiac CT.

From vulnerable plaque to vulnerable patient--Part III: Executive summary of the Screening for Heart Attack Prevention and Education (SHAPE) Task Force report

Screening for early-stage asymptomatic cancers (eg, cancers of breast and colon) to prevent late-stage malignancies has been widely accepted. However, although atherosclerotic cardiovascular disease (eg, heart attack and stroke) accounts for more death and disability than all cancers combined, there are no national screening guidelines for asymptomatic (subclinical) atherosclerosis, and there is no government- or healthcare-sponsored reimbursement for atherosclerosis screening. Part I and Part II of this consensus statement elaborated on new discoveries in the field of atherosclerosis that led to the concept of the "vulnerable patient." These landmark discoveries, along with new diagnostic and therapeutic options, have set the stage for the next step: translation of this knowledge into a new practice of preventive cardiology. The identification and treatment of the vulnerable patient are the focuses of this consensus statement. In this report, the Screening for Heart Attack Prevention and Education (SHAPE) Task Force presents a new practice guideline for cardiovascular screening in the asymptomatic at-risk population. In summary, the SHAPE Guideline calls for noninvasive screening of all asymptomatic men 45-75 years of age and asymptomatic women 55-75 years of age (except those defined as very low risk) to detect and treat those with subclinical atherosclerosis. A variety of screening tests are available, and the cost-effectiveness of their use in a comprehensive strategy must be validated. Some of these screening tests, such as measurement of coronary artery calcification by computed tomography scanning and carotid artery intima-media thickness and plaque by ultrasonography, have been available longer than others and are capable of providing direct evidence for the presence and extent of atherosclerosis. Both of these imaging methods provide prognostic information of proven value regarding the future risk of heart attack and stroke. Careful and responsible implementation of these tests as part of a comprehensive risk assessment and reduction approach is warranted and outlined by this report. Other tests for the detection of atherosclerosis and abnormal arterial structure and function, such as magnetic resonance imaging of the great arteries, studies of small and large artery stiffness, and assessment of systemic endothelial dysfunction, are emerging and must be further validated. The screening results (severity of subclinical arterial disease) combined with risk factor assessment are used for risk stratification to identify the vulnerable patient and initiate appropriate therapy. The higher the risk, the more vulnerable an individual is to a near-term adverse event. Because <10% of the population who test positive for atherosclerosis will experience a near-term event, additional risk stratification based on reliable markers of disease activity is needed and is expected to further focus the search for the vulnerable patient in the future. All individuals with asymptomatic atherosclerosis should be counseled and treated to prevent progression to overt clinical disease. The aggressiveness of the treatment should be proportional to the level of risk. Individuals with no evidence of subclinical disease may be reassured of the low risk of a future near-term event, yet encouraged to adhere to a healthy lifestyle and maintain appropriate risk factor levels. Early heart attack care education is urged for all individuals with a positive test for atherosclerosis. The SHAPE Task Force reinforces existing guidelines for the screening and treatment of risk factors in younger populations. Cardiovascular healthcare professionals and policymakers are urged to adopt the SHAPE proposal and its attendant cost-effectiveness as a new strategy to contain the epidemic of atherosclerotic cardiovascular disease and the rising cost of therapies associated with this epidemic.

Tomographic Plaque Imaging with CT

X-ray computed tomography (CT) is widely available in the world and has the ability to provide high definition, thin section imaging of any body part. In particular, CT over the past decade has been shown in numerous publications to allow for quantitation of coronary calcification, a proven surrogate for coronary artery atheromatous plaque. Electron beam tomography (EBT) and multi-detector CT (MDCT) have been studied for these purposes; although the majority of the data has been derived from EBT studies.This chapter details the patho-biology of atherosclerotic disease, the basis of using EBT (and/or CT in general) to define atherosclerotic plaque including the technical and engineering pitfalls and promises, and details issues of clinical application.

From vulnerable plaque to vulnerable patient: a call for new definitions and risk assessment strategies: Part II

Atherosclerotic cardiovascular disease results in >19 million deaths annually, and coronary heart disease accounts for the majority of this toll. Despite major advances in treatment of coronary heart disease patients, a large number of victims of the disease who are apparently healthy die suddenly without prior symptoms. Available screening and diagnostic methods are insufficient to identify the victims before the event occurs. The recognition of the role of the vulnerable plaque has opened new avenues of opportunity in the field of cardiovascular medicine. This consensus document concludes the following. (1) Rupture-prone plaques are not the only vulnerable plaques. All types of atherosclerotic plaques with high likelihood of thrombotic complications and rapid progression should be considered as vulnerable plaques. We propose a classification for clinical as well as pathological evaluation of vulnerable plaques. (2) Vulnerable plaques are not the only culprit factors for the development of acute coronary syndromes, myocardial infarction, and sudden cardiac death. Vulnerable blood (prone to thrombosis) and vulnerable myocardium (prone to fatal arrhythmia) play an important role in the outcome. Therefore, the term "vulnerable patient" may be more appropriate and is proposed now for the identification of subjects with high likelihood of developing cardiac events in the near future. (3) A quantitative method for cumulative risk assessment of vulnerable patients needs to be developed that may include variables based on plaque, blood, and myocardial vulnerability. In Part I of this consensus document, we cover the new definition of vulnerable plaque and its relationship with vulnerable patients. Part II of this consensus document will focus on vulnerable blood and vulnerable myocardium and provide an outline of overall risk assessment of vulnerable patients. Parts I and II are meant to provide a general consensus and overviews the new field of vulnerable patient. Recently developed assays (eg, C-reactive protein), imaging techniques (eg, CT and MRI), noninvasive electrophysiological tests (for vulnerable myocardium), and emerging catheters (to localize and characterize vulnerable plaque) in combination with future genomic and proteomic techniques will guide us in the search for vulnerable patients. It will also lead to the development and deployment of new therapies and ultimately to reduce the incidence of acute coronary syndromes and sudden cardiac death. We encourage healthcare policy makers to promote translational research for screening and treatment of vulnerable patients.

From vulnerable plaque to vulnerable patient: a call for new definitions and risk assessment strategies: Part I

Atherosclerotic cardiovascular disease results in >19 million deaths annually, and coronary heart disease accounts for the majority of this toll. Despite major advances in treatment of coronary heart disease patients, a large number of victims of the disease who are apparently healthy die suddenly without prior symptoms. Available screening and diagnostic methods are insufficient to identify the victims before the event occurs. The recognition of the role of the vulnerable plaque has opened new avenues of opportunity in the field of cardiovascular medicine. This consensus document concludes the following. (1) Rupture-prone plaques are not the only vulnerable plaques. All types of atherosclerotic plaques with high likelihood of thrombotic complications and rapid progression should be considered as vulnerable plaques. We propose a classification for clinical as well as pathological evaluation of vulnerable plaques. (2) Vulnerable plaques are not the only culprit factors for the development of acute coronary syndromes, myocardial infarction, and sudden cardiac death. Vulnerable blood (prone to thrombosis) and vulnerable myocardium (prone to fatal arrhythmia) play an important role in the outcome. Therefore, the term "vulnerable patient" may be more appropriate and is proposed now for the identification of subjects with high likelihood of developing cardiac events in the near future. (3) A quantitative method for cumulative risk assessment of vulnerable patients needs to be developed that may include variables based on plaque, blood, and myocardial vulnerability. In Part I of this consensus document, we cover the new definition of vulnerable plaque and its relationship with vulnerable patients. Part II of this consensus document focuses on vulnerable blood and vulnerable myocardium and provide an outline of overall risk assessment of vulnerable patients. Parts I and II are meant to provide a general consensus and overviews the new field of vulnerable patient. Recently developed assays (eg, C-reactive protein), imaging techniques (eg, CT and MRI), noninvasive electrophysiological tests (for vulnerable myocardium), and emerging catheters (to localize and characterize vulnerable plaque) in combination with future genomic and proteomic techniques will guide us in the search for vulnerable patients. It will also lead to the development and deployment of new therapies and ultimately to reduce the incidence of acute coronary syndromes and sudden cardiac death. We encourage healthcare policy makers to promote translational research for screening and treatment of vulnerable patients.

Coronary calcium scoring: modelling, predicting and correcting for the effect of CT scanner spatial resolution on Agatston and volume scores

The purpose of this study was to evaluate the impact of spatial resolution on coronary calcium scoring by x-ray CT, to assess the scoring performance of different CT scanners as they are operated in the field and to correct for the effects of CT scanner spatial resolution on coronary calcium scoring. A phantom consisting of five aluminium wires of known diameter in water was used to measure spatial resolution and to assess scoring performance. Fourteen CT scanners (three helical, two dual, two electron-beam and seven multi-detector) from four manufacturers were evaluated, some under different operating conditions. One scanner was monitored over a 3 month period and again 6 months later. Both spatial resolution and image pixel size significantly affect calcium scoring results. Spatial resolution can be measured with a precision of about 2%. Scanner spatial resolution ranged from 1 to 1.7 mm full-width-half-maximum (FWHM), and pixel size from 0.25 to 0.86 mm. Spatial resolution differences introduce systematic scoring differences that range from 38% to 1100% depending on wire size. Significant temporal variations in spatial resolution were observed in the monitored scanner. By correcting all the scanners to the same target spatial resolution, the standard deviation of individual scanners with respect to a mean value (the spread) can be reduced by 25-70% for different wires. In conclusion, scanner spatial resolution significantly affects calcium scoring and should be controlled for. Scanner performance can change over time. Under ideal conditions, CT scanners should be operated with a standard spatial resolution for calcium scoring. When this is not possible, post-processing correction is a viable alternative.

Prevalence and Correlates of Coronary Calcification in Black and White Young Adults

Abstract —Whereas cardiovascular risk factor levels are substantially different in black and white Americans, the relative rates of cardiovascular disease in the 2 groups are not always consistent with these differences. To compare the prevalence of coronary calcification, an indicator of coronary atherosclerosis, in young adult blacks and whites, we performed electron-beam computed tomography of the heart in 443 men and women aged 28 to 40 years recruited from a population-based cohort. The presence of calcium, defined as at least 1 focus of at least 2.05 mm 2 in area and >130 Hounsfield units in density within the coronary arteries, was identified in 16.1% of black men, 11.8% of black women, 17.1% of white men, and 4.6% of white women ( P =0.04 for comparison across groups). Coronary calcium was associated with age and male sex, and after adjustment for age, race, and sex, coronary calcium was positively associated with body mass index, weight, systolic blood pressure, total cholesterol, low density lipoprotein cholesterol, triglycerides, and fasting insulin and negatively associated with education (all P <0.05). Independent risk factors included male sex, body mass index, and low density lipoprotein cholesterol. Race was not significantly associated with coronary calcium in men or women, before or after adjustment for risk factors. Coronary calcification is associated with increased levels of cardiovascular risk factors in young adults, and its prevalence is not significantly different in blacks and whites.

Coronary artery calcium in acute coronary syndromes: a comparative study of electron-beam computed tomography, coronary angiography, and intracoronary ultrasound in survivors of acute myocardial infarction and unstable angina

BACKGROUND

Quantification of coronary artery calcified plaques by electron-beam CT (EBCT) may predict cardiovascular events. However, whereas advanced coronary atherosclerotic plaques can be identified, mildly stenotic lipid-rich (soft) plaques may be difficult to detect. The value of EBCT in a subgroup of patients has therefore been questioned. To investigate this, we evaluated patients with acute coronary syndromes by EBCT and compared the results with coronary angiography and, in patients with an indeterminate angiogram, intracoronary ultrasound (ICUS).

METHODS AND RESULTS

EBCT was performed in 118 consecutive patients (57+/-11 years of age) with previous myocardial infarction (n=101) or unstable angina (n=17). A standard protocol requiring a CT density >130 Hounsfield units in an area > or =1.03 mm2 was used for the definition of coronary artery calcium. We found that 110 patients had moderate to severe coronary artery disease by coronary angiography, and 8 had either mildly stenotic plaques at a single site (4 patients, confirmed by ICUS) or nonatherosclerotic causes of the unstable coronary syndrome (4 patients). One hundred and five of the 110 patients (96%) with moderate to severe angiographic disease but only 1 of the 8 other patients (13%) had a positive EBCT. Patients with acute coronary syndromes and negative EBCTs were significantly younger than patients with positive EBCTs (46+/-12 versus 58+/-10 years, P<.001), and a higher percentage was actively smoking (100% of the smokers versus 46%, P<.05).

CONCLUSIONS

The vast majority of patients with acute coronary syndromes and at least moderate angiographic disease have identifiable coronary calcium by EBCT. Those patients with negative EBCTs have minimal or no atherosclerotic plaque formation. They are younger and tend to be active cigarette smokers.

Evaluation of coronary bypass graft patency by ultrafast computed tomography

A noninvasive technique for determining bypass graft patency is greatly needed. To determine if bypass graft patency could be accurately assessed with ultrafast computed tomography (CT) following an intravenous contrast injection, ten patients with 21 coronary bypass grafts were studied. All patients had cardiac catheterization and ultrafast computed tomographic studies within one month of each other. The sensitivity of detecting angiographically open grafts with ultrafast CT was 94.1% (16/17), specificity of detecting angiographically closed grafts was 100% (4/4), and accuracy was 95.2% (20/21). These preliminary results in a small clinical series indicate that ultrafast CT may be a useful, minimally invasive technique for evaluating coronary bypass graft patency.