Age and gender distribution of coronary artery calcium measured by four-slice computed tomography in 2,030 persons with no symptoms of coronary artery disease

Predictive Value of Coronary Artery Calcium in Patients Receiving Computed Tomography Pulmonary Angiography for Suspected Pulmonary Embolism in the Emergency Department

PURPOSE

Coronary artery calcium (CAC) is a frequent incidental finding on computed tomography pulmonary angiogram (CTPA) in the evaluation of pulmonary embolism (PE) in the emergency department (ED); however, its prognostic value is unclear. In this study, we interrogate the prognostic value of CAC identified on CTPA in predicting adverse outcomes in the evaluation of PE in the ED.

MATERIALS AND METHODS

In this retrospective cohort study, we identified 610 patients presenting to the ED in 2013 and evaluated with CTPA for suspected PE. Ordinal CAC scores were evaluated as absent (0), mild (1), moderate (2), or severe (3) in each of the 4 main coronary arteries. Composite CAC scores were subsequently compared against adverse clinical outcomes, defined as intensive care unit admission, hospital stay longer than 72 hours, or death during hospital course or at 6-month follow-up, using univariate and multivariate logistic regression analyses. Relevant exclusion criteria included a history of cardiovascular disease.

RESULTS

In all, 365 patients met the inclusion criteria (231 women, mean age 56±16 y) with 132 patients (36%) having some degree of CAC and 16 (4%) having severe CAC. Known malignancy was present in 151 (41%) patients and composite adverse clinical outcomes were observed in 98 patients (32%). Age, presence of acute PE, malignancy, and presence of CAC were significant predictors of adverse outcomes on both univariate and multivariate analyses. CAC was not an independent predictor of short-term adverse outcomes on multivariate analysis ( P =0.06) when all patients were considered. However, when patients with known malignancy were excluded, CAC was an independent predictor of short-term adverse outcomes (odds ratio=2.5, confidence interval=1.1-5.5, P =0.03) independent of age and presence of PE.

CONCLUSION

The presence of CAC on CT PA was predictive of adverse outcomes in patients without known cardiac disease presenting to the ED with suspected PE.

Distributions and burden of coronary calcium in asymptomatic Saudi patients referred to computed tomography

Background

Unlike Western and Asian populations, the prevalence and severity of coronary artery calcification (CAC) have not been adequately examined in Saudi Arabia and other nearby Arab Gulf countries.

Objectives

To estimate the age and gender specific percentiles of coronary calcium score (CCS) and to study the severity of CAC in relation to patient risk in a large sample of asymptomatic Saudi patients.

Methods

Retrospective cross-sectional study was conducted between July 2007 and December 2017 at a large Cardiac Centre in Riyadh, Saudi Arabia. The target was adult patients without pre-existing CAD referred to (64 multidetector spiral) computed tomography for standard indications.

Results

A total 2863 patients were included in the current analysis. The 90th percentile of CCS was 95.0 in males compared with 53.2 in females and was 823.95 in patients aged ≥ 75 years compared with zero in patients < 40 years. Extensive CAC (CCS > 400) were 3.1% in males compared with 1.6% in females and 14.0% in patients aged ≥ 75 years compared with 0.0% in patients < 40 years. CCS was steadily higher with increasing European systematic coronary risk evaluation; 3.1 ± 22.5 in mild risk, 37.1 ± 201.9 in moderate risk, 116.1 ± 256.1 in high risk, and 131.0 ± 222.0 in very high risk.

Conclusions

As expected, the findings confirm the higher burden of CAC in males, older age, and higher CAD risk. The burden of CAC in current patients is much lower than reported in US and other Western patients. Local cardiologist should consider using local rather than US percentiles of CCS.

Bariatric surgery and the coronary artery calcium score

OBJECTIVE

to investigate the impact of bariatric surgery on the coronary artery calcium score (CACS), and to establish predictors of progression of this score in patients with obesity.

METHODS

prospective study that evaluated 18 obese patients before and after bariatric surgery. All patients were submitted to computed tomography scans and blood tests (total cholesterol, LDL, HDL, triglycerides, fasting plasma glucose, A1C, insulin, serum calcium, C-peptide and C-Reactive Protein) in order to determine CACS and Framingham risk score (FRS).

RESULTS

the FRS decreased 50% between the pre and postoperative evaluations. The mean CACS increased significantly at the late postoperative period, going from 8.5 to 33.1. HDL levels had also increased between the pre and postoperative periods. All of the other quantitative variables reduced significantly at the postoperative evaluation. When dividing CACS into four degrees, it was observed that 22.2% presented CACS=0 at the postoperative evaluation. The prevalence of mild CACS decreased from 77.8% to 50%, while moderate CACS remained the same (11.1%). Severe CACS increased from 11.1% to 16.7%. Older ages were linked to CACS progression, and this was the only variable that presented statistical association with progression.

CONCLUSION

bariatric surgery leads to positive cardiovascular outcomes, apparently regardless of CACS.

Predictive value of coronary calcifications for future cardiac events in asymptomatic patients: underestimation of risk in asymptomatic smokers

Coronary calcification (CAC) is an established marker for coronary atherosclerosis and has a highly specific predictive value for cardiovascular events. This study aimed to determine the predictive value in the specific group of asymptomatic smokers in comparison to non-smokers. We included 1432 asymptomatic individuals (575 women, 857 men, age 59.2 ± 7.7 years.) in this study. Coronary calcification was calculated by multi-slice computed tomography following a standardized protocol including calcium score (CS). Coronary risk factors were determined at inclusion. After mean observation time of 76.3 ± 8.5 months the patients were contacted and evaluated for cardiovascular events (myocardial infarction, cardiac death and revascularisation). Mean CS was 231 ± 175 in smokers and 239 ± 188 in non-smokers. Cardiovascular events were found in 14.9% of our patients and there were significantly more events in smokers (119 events, 8.3%) than in non-smokers (94 events, 6.6%, p = 0.001). CS > 400 showed a hazard ratio for future cardiac events of 5.1 (95% CI 4.3-7.6) in smokers and 4.4 (95% CI 3.4-6.2) in non-smokers, p = 0.01. Also in smokers determination of CAC is a valuable predictor of future cardiovascular events. In our study smokers showed throughout all score groups a significantly higher risk compared to non-smokers with equal CS. Therefore, CS may underestimate the risk for future cardiac events in smokers compared to non-smokers.

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

Purpose

Obesity is a well-known of risk factor for atherosclerosis. However, recently an “obesity paradox” has been discussed, which is considered as a protective effect of obesity on the development coronary artery disease (CAD). An aim of the study was to investigate the risk of CAD in morbidly obese patients using coronary artery calcium measurement.

Material and methods

Fifty-one patients with morbid obesity (BMI ≥ 40 kg/m²) and thirty controls were scanned to determine the amount of coronary artery calcification (CAC), which was expressed as calcium score (CS) and coronary age (CA). The control group consisted of patients scanned for the clinical suspicion of CAD, who did not fulfil the criteria of obesity.

Results

Mean BMI of obese patients and controls was 47.3 and 26.5, respectively (p < 0.0001). Arterial hypertension, dyslipidaemia, and smoking were more frequent in the control group than in the obesity group (p < 0.02). The prevalence of CAC was higher in the obesity group (53% vs. 23%, p < 0.01). The groups did not differ regarding CS and CA. However, the difference between coronary age and metrical age was higher in obese patients than in controls (+5.6 vs. –4.8 years, respectively, p < 0.005).

Conclusions

Patients with morbid obesity present an increased risk of CAD that is reflected by the difference between their coronary age and metrical age.

Single-centre cohort study of gender influence in coronary CT angiography in patients with a low to intermediate pretest probability of coronary heart disease

Background

In ‘real-world’ patient populations undergoing coronary CT angiography (CCTA), it is unclear whether a correlation exists between gender, coronary artery calcium (CAC) score and subsequent referral for invasive coronary angiography and coronary revascularisation. We therefore investigated the relationship between gender, CAC and use of subsequent invasive coronary angiography and coronary revascularisation in a cohort of patients with chest discomfort and low to intermediate pretest probability of coronary artery disease who underwent a CCTA at our diagnostic centre.

Methods

This is a cohort study that included patients examined between 2010 and 2013. Data were obtained from the Western Denmark Heart Registry. The follow-up ended 11 March 2014.

Results

A total of 3541 people (1621 men and 1920 women) were examined by CCTA. The rate of invasive coronary angiography during follow-up was 28.5% in men versus 18.3% in women (p<0.001). The rate of coronary revascularisation during follow-up was 11.4% in men versus 5.1% in women (p<0.001). The CAC-adjusted HR in women versus men was 0.98 (95% CI 0.85 to 1.13) for invasive coronary angiography and 0.73 (95% CI 0.57 to 0.93) for coronary revascularisation. Further adjustment for age and other risk factors did not change these estimates.

Conclusions

Women had a lower CAC score than men and a corresponding lower rate of invasive coronary angiography. The risk of coronary revascularisation was modestly reduced in women, irrespective of CAC. This may reflect a gender-specific difference in coping with chest discomfort, gender-specific referral bias for CCTA, and/or a gender-specific difference in the balance between coronary calcification and obstructive coronary heart disease.

Long-Term Prognosis After Coronary Artery Calcification Testing in Asymptomatic Patients: A Cohort Study

BACKGROUND

The extent of coronary artery calcification (CAC) and near-term adverse clinical outcomes are strongly related through 5 years of follow-up.

OBJECTIVE

To describe the ability of CAC scores to predict long-term mortality in persons without symptoms of coronary artery disease.

DESIGN

Observational cohort.

SETTING

Single-center, outpatient cardiology laboratory.

PATIENTS

9715 asymptomatic patients.

MEASUREMENTS

Coronary artery calcification scoring and binary risk factor data were collected. The primary end point was time to all-cause mortality (median follow-up, 14.6 years). Univariable and multivariable Cox proportional hazards models were used to compare survival distributions. The net reclassification improvement statistic was calculated.

RESULTS

In Cox models adjusted for risk factors for coronary artery disease, the CAC score was highly predictive of all-cause mortality (P < 0.001). Overall 15-year mortality rates ranged from 3% to 28% for CAC scores from 0 to 1000 or greater (P < 0.001). The relative hazard for all-cause mortality ranged from 1.68 for a CAC score of 1 to 10 (P < 0.001) to 6.26 for a score of 1000 or greater (P < 0.001). The categorical net reclassification improvement using cut points of less than 7.5% to 22.5% or greater was 0.21 (95% CI, 0.16 to 0.32).

LIMITATIONS

Data collection was limited to a single center with generalizability limitations. Only binary risk factor data were available, and CAC was only measured once.

CONCLUSION

The extent of CAC accurately predicts 15-year mortality in a large cohort of asymptomatic patients. Long-term estimates of mortality provide a unique opportunity to examine the value of novel biomarkers, such as CAC, in estimating important patient outcomes.

PRIMARY FUNDING SOURCE

None.

Prevention and endothelial therapy of coronary artery disease

Functional integrity of endothelial cells is an indicator and a prerequisite for vascular health and counteracts the development of atherosclerosis. This concept of 'endothelial therapy' was developed in the late 1990s as an approach to preserve or restore endothelial cell health given that 'the knowledge of the mechanisms involved in 'endothelial dysfunction' allows us to interfere specifically with pathogenic pathways at very early time points and to slow down the progression of disease'. In the present review, the principles underlying endothelial cell health will be discussed as well as the role of endothelial therapy as a preventive measure to reduce the prevalence of coronary artery disease or to delay disease progression in patients with chronic coronary artery disease. This article also highlights the importance of active participation, the need to reduce the number of future patients in view of the rising prevalence of childhood obesity, and the potential of endothelial therapy to improve survival, reduce disability and health costs, and to improve overall quality of life in patients at risk for or already diagnosed with coronary artery disease. The preventive and therapeutic approaches and considerations described herein can be applied by physicians, patients, parents, educators, health agencies, and political decision makers to help reducing the global cardiovascular disease burden in the decades to come.

Cholesterol and atherosclerosis: modulation by oestrogen

PURPOSE OF REVIEW

Oestrogens are important modulators of lipid metabolism, inflammation and vascular homeostasis. Endogenous oestrogens contribute to the low prevalence of atherosclerotic vascular disease in premenopausal women with intact ovarian function, and cessation of oestrogen production following menopause increases cardiovascular risk. Orally administered oestrogens such as postmenopausal hormone therapy increase HDL and reduce LDL cholesterol levels, and they increase triglyceride levels. Current guidelines do not recommend postmenopausal hormone therapy for cardiovascular prevention.

RECENT FINDINGS

Recent clinical studies have suggested potential benefits of natural oestrogen or selective oestrogen receptor modulators on cardiovascular outcomes, effects that are associated with lipid profile improvements. In contrast to earlier studies such as the Women's Health Initiative, the Heart and Estrogen/Progestin Replacement Study or the Estrogen Replacement and Atherosclerosis trial, in which investigators used hormone mixtures derived from horse urine (misleadingly named 'conjugated oestrogens' with unknown activity on oestrogen receptors), triphasic oestrogen therapy started early after menopause as primary prevention study protocol improved outcome. New studies suggest therapeutic potential of natural oestrogens and certain selective oestrogen receptor modulators to reduce coronary artery disease risk in postmenopausal women.

SUMMARY

Endogenous oestrogens are important regulators of lipid metabolism and inhibit inflammation, vascular cell growth and plaque progression in premenopausal women. The recent trials warrant further studies, which should also determine how much of the potential benefits are due to improvements of lipid metabolism.

Comparison of calcium scoring with 4-multidetector computed tomography (4-MDCT) and 64-MDCT: a phantom study

OBJECTIVE

To determine differences in coronary artery calcium (CAC) measurement performed with the use of 2 generations of multidetector computed tomography (CT) scanners of the same manufacturer.

METHODS

Agatston Score (AS) and calcium mass (CM) were measured with a 4-row scanner (AS4 and CM4) and a 64-row scanner (AS64 and CM64) using a cardiac phantom with calcium inserts.

RESULTS

The results of the AS measurements (mean ± SD) varied significantly between the equipment: 880.6 ± 30.1 (AS4) vs 586.5 ± 24.0 (AS64; P < 0.0001). The AS interscanner variability was 31.6% for the phantom and from 25.5% to 110.1% for particular inserts. Mean ± SD CM values were different as well: 192.8 ± 5.0 mg (CM4) vs 152.4 ± 2.6 mg (CM64; P < 0.0001). Determination of CM with 64-row CT was more accurate than that with an older scanner; the mean relative error was -9.1% and 15.0%, respectively (P < 0.0001). The CM interscanner variability was 23.3% for the phantom and from 19.0% to 122.8% for particular inserts. The interexamination variability ranged from 1.7% (CM64) to 5.6% (AS4).

CONCLUSIONS

Coronary artery calcium scoring with the 64-row CT scanner is more accurate than with the 4-row device The difference between the results of AS and CM measurements carried out with both scanners is statistically significant.

Cardiovascular risk assessment based on the quantification of coronary calcium in contrast-enhanced coronary computed tomography angiography

AIMS

The extent of coronary artery calcification (CAC) has been shown to be a strong and independent predictor for cardiovascular events. Usually, CAC scoring is performed in non-contrast-enhanced computed tomography (CT) examinations. The ability and accuracy of cardiovascular risk classification according to the degree of CAC determined in contrast-enhanced coronary CT angiography (CCTA) has not been investigated so far. The aim of this analysis was to develop and validate a method for CAC risk classification in CCTA.

METHODS AND RESULTS

In a test series of 100 patients who underwent both non-enhanced CAC scoring and CCTA, we developed a method to assess the extent of coronary calcification and the associated cardiovascular risk category in CCTA. The accuracy of the developed approach of CAC assessment in CCTA was determined in 500 consecutive patients in comparison to CAC scoring in the non-enhanced scan. CAC scoring results in the non-enhanced scan and CCTA scan showed a high correlation (r = 0.954; P < 0.001). CAC quantification in CCTA correctly identified 98% of patients without CAC as shown in the non-enhanced scan (184 of 188 patients). When compared with non-enhanced CAC scoring, CAC scoring in CCTA grouped more than 95% of high-risk patients correctly into the same risk category according to the 75th age- and gender-specific percentiles or the absolute calcium scores.

CONCLUSION

Assessing cardiovascular risk associated with CAC is feasible and accurate in contrast-enhanced CCTA. This new technique may allow for reducing the radiation exposure of coronary CT studies while maintaining an accurate cardiovascular risk assessment, because the addition of non-enhanced scans to CCTA becomes unnecessary for comprehensive coronary CT studies.

Screening Hodgkin lymphoma survivors for radiotherapy induced cardiovascular disease

Long term prognosis of Hodgkin lymphoma (HL) survivors is affected by late toxicity of radiotherapy and chemotherapy. Cardiovascular complications of radiotherapy have been shown to have a great impact on the long term survival. The aim of this review is to summarize the available data on different screening modalities for cardiovascular disease and to suggest a screening program. Patients older than 45 years at HL diagnosis should be screened for coronary artery disease (CAD) starting 5 years after mediastinal radiotherapy; they are at increased risk of pre-existent atherosclerosis which can be accelerated by radiotherapy. Screening for CAD should start 10 years after radiotherapy in younger patients. The best screening modality for CAD is subject of discussion, based on the latest studies we suggest screening by Coronary artery calcium score measurements or CT-angiography. Valvular disorders should be looked for by echocardiography starting 10 years after radiotherapy. Electrocardiograms should be performed at each cardiovascular screening moment in order to detect arrhythmia's or conduction abnormalities. We suggest repeating these screening tests every 5 years or at onset of cardiovascular complaints; patients should be extensively instructed about signs and symptoms of cardiovascular disease. Furthermore traditional risk factors for cardiovascular disease should be carefully monitored and treated. We suggest determining a cardiovascular risk profile at diagnosis of HL in patients older than 45 years. In case of a high risk, treating HL without RT should be considered.

Ordinal scoring of coronary artery calcifications on low-dose CT scans of the chest is predictive of death from cardiovascular disease

PURPOSE

To assess the usefulness of ordinal scoring of the visual assessment of coronary artery calcification (CAC) on low-dose computed tomographic (CT) scans of the chest in the prediction of cardiovascular death.

MATERIALS AND METHODS

All participants consented to low-dose CT screening according to an institutional review board-approved protocol. The amount of CAC was assessed on ungated low-dose CT scans of the chest obtained between June 2000 and December 2005 in a cohort of 8782 smokers aged 40-85 years. The four main coronary arteries were visually scored, and each participant received a CAC score of 0-12. The date and cause of death was obtained by using the National Death Index. Follow-up time (median, 72.3 months; range, 0.3-91.9 months) was calculated as the time between CT and death, loss to follow-up, or December 31, 2007, whichever came first. Logistic regression analysis was used to determine the risk of mortality according to CAC category adjusted for age, pack-years of cigarette smoking, and sex. The same analysis to determine the hazard ratio for survival from cardiac death was performed by using Cox regression analysis.

RESULTS

The rate of cardiovascular deaths increased with an increasing CAC score and was 1.2% (43 of 3573 subjects) for a score of 0, 1.8% (66 of 3569 subjects) for a score of 1-3, 5.0% (51 of 1015 subjects) for a score of 4-6, and 5.3% (33 of 625 subjects) for a score of 7-12. With use of subjects with a CAC score of 0 as the reference group, a CAC score of at least 4 was a significant predictor of cardiovascular death (odds ratio [OR], 4.7; 95% confidence interval: 3.3, 6.8; P < .0001); when adjusted for sex, age, and pack-years of smoking, the CAC score remained significant (OR, 2.1; 95% confidence interval: 1.4, 3.1; P = .0002).

CONCLUSION

Visual assessment of CAC on low-dose CT scans provides clinically relevant quantitative information as to cardiovascular death.

Using noncontrast cardiac CT and coronary artery calcification measurements for cardiovascular risk assessment and management in asymptomatic adults

The presence of mural calcification has, for decades, been recognized as a marker for atheromatous plaque in the coronary arteries and the aorta, but only in the past decade has the application of noncontrast computed tomography (CT) been shown to be a reproducible, safe, and convenient test, which now is available worldwide. However, awareness of coronary artery calcium scanning is insufficient and the practitioner must be aware of the available literature as well as understanding clinical recommendations for applications and interpretation. It is best applied in the medium/intermediate risk, asymptomatic adult regardless of ethnicity across broad age ranges for both men and women; additional prognostic information is also afforded from the calcium distribution in the coronary artery system. Additionally, information can also be derived from the same CT scan regarding heart and aorta size and assessment of the epicardial fat pad (an anatomic marker for the metabolic syndrome). Details of how this test can aid in cardiovascular risk assessment and management in adults are provided.

Imaging biomarkers of atherosclerosis

Atherosclerosis imaging plays a significant role in an understanding of the natural history of vascular disease and is increasingly used to assess the efficacy of novel therapeutics. Furthermore, the concepts of 'vulnerable plaque' and, more recently, of 'vulnerable patient' have driven cardiovascular imaging technologies to develop methods for expanded qualitative and quantitative analyses. Indeed, developmental efforts are underway to better demonstrate thin fibrous cap and large necrotic cores, and to determine the correlation between these findings and subsequent cardiovascular events. In this article, we consider a wide variety of cardiovascular imaging techniques that are used as biomarkers of atherosclerosis. These technologies include traditional imaging such as angiography, as well as advanced imaging techniques using both invasive and noninvasive approaches.

Coronary artery calcification scoring in low-dose ungated CT screening for lung cancer: interscan agreement

OBJECTIVE

In previous studies detection of coronary artery calcification (CAC) with low-dose ungated MDCT performed for lung cancer screening has been compared with detection with cardiac CT. We evaluated the interscan agreement of CAC scores from two consecutive low-dose ungated MDCT examinations.

SUBJECTS AND METHODS

The subjects were 584 participants in the screening segment of a lung cancer screening trial who underwent two low-dose ungated MDCT examinations within 4 months (mean, 3.1 +/- 0.6 months) of a baseline CT examination. Agatston score, volume score, and calcium mass score were measured by two observers. Interscan agreement of stratification of participants into four Agatston score risk categories (0, 1-100, 101-400, > 400) was assessed with kappa values. Interscan variability and 95% repeatability limits were calculated for all three calcium measures and compared by repeated measures analysis of variance.

RESULTS

An Agatston score > 0 was detected in 443 baseline CT examinations (75.8%). Interscan agreement of the four risk categories was good (kappa = 0.67). The Agatston scores were in the same risk category in both examinations in 440 cases (75.3%); 578 participants (99.0%) had scores differing a maximum of one category. Furthermore, mean interscan variability ranged from 61% for calcium volume score to 71% for Agatston score (p < 0.01). A limitation of this study was that no comparison of CAC scores between low-dose ungated CT and the reference standard ECG-gated CT was performed.

CONCLUSION

Cardiovascular disease risk stratification with low-dose ungated MDCT is feasible and has good interscan agreement of stratification of participants into Agatston score risk categories. High mean interscan variability precludes the use of this technique for monitoring CAC scores for individual patients.

Progression of coronary atherosclerosis after heart transplantation on electron-beam computed tomography

RATIONALE AND OBJECTIVES

Cardiac transplant vasculopathy is the most important long-term complication of heart transplantation, with overlapping features with conventional, atherosclerotic coronary artery disease. The aim of this study was to determine the progression of coronary artery disease after heart transplantation by measuring total coronary calcium load.

MATERIALS AND METHODS

After heart transplantation, 185 patients were serially examined using electron-beam computed tomography for coronary calcium load for clinical reasons. The mean time between the initial examination and the follow-up scan was 566 days (range, 126-1,436). Coronary calcium load was measured by the Agatston method, and the total calcium scores at both examinations were compared between patients taking and those not taking lipid-lowering medications (statins).

RESULTS

Patients not taking statins (n = 94) displayed a median annualized percentage increase in total calcium score of 0 Agatston units, whereas patients taking at least the lowest recommended daily dose of a statin (n = 84) displayed an annualized percentage decrease of 11 Agatston units. The difference was not statistically significant (Wilcoxon's rank-sum test, P = .35). Only 17 patients had increases of > 24 Agatston units, and eight of them were taking statins (chi(2) test, P = .99).

CONCLUSION

The annual rate of progression of coronary calcium load after heart transplantation is low. In this investigation, no beneficial effects of statins could be detected.

Age-dependent changes in oxygen tension, radiation dose and sensitivity within normal and diseased coronary arteries-Part A: dose from radon and thoron

PURPOSE

There is mounting evidence that a significant fraction of radiation-induced mortality and years-life lost are non-cancerous in nature. This study quantifies the radon dose to the coronary artery walls, especially the intimal layer, vulnerable to the development of atherosclerosis, and associated cardiovascular disease (CVD). Two accompanying papers determine the oxygen levels (Part B) in coronary arteries and the oxygen effect for radon and other exposures (Part C).

MATERIALS AND METHODS

The alpha-radiation dose to coronary artery walls was calculated from the proportion of inhaled radon ((222)Rn), thoron ((220)Rn) and their short-lived progeny, which was not deposited in the lung and passed into blood. Age- and gender-dependent morphology and composition for the wall layers of coronary arteries were developed from published data for a normal population and also for individuals with cardiovascular disease. The alpha particle dose to the coronary artery walls was evaluated taking account the diffusion of radon from blood and the solubility of radon-gas in tissues.

RESULTS

Diseased arteries exhibited a moderate increase in the solubility of lipophylic radon (190%) in arteries with 88% luminal narrowing, as the high Rn solubility in fat was partially offset by the lower solubility in calcium deposits. The average worldwide dose rate to the diseased intimal layer from (222)Rn and its short-lived progeny was estimated to be as high as 68 muSv y(-1) per 40 Bq m(-3) in air, whereas the corresponding dose rate from (220)Rn per 0.3 Bq m(-3) in air was <or=0.1% in comparison. Gender had little influence on the dose.

CONCLUSION

The Rn dose to the coronary arteries is significant, but has a large uncertainty due to poor knowledge of Rn and its progeny concentrations in the body.

Diagnosis of atherosclerosis by imaging

New and experimental imaging techniques are being developed that will permit better visualization and compositional characterization of atheromatous plaques. This review provides discussion of techniques that are currently used in clinical practice, as well as techniques that are investigational only, including coronary angiography, intravascular ultrasound, computed tomography, magnetic resonance imaging, positron emission tomography, and single-photon emission computed tomography. Types of atheromatous plaque are reviewed, and the value of examining vascular calcification in risk assessment is discussed. Experimental use of these imaging techniques in animal models and in clinical studies will enhance our understanding of the development of plaque and will determine whether these techniques would be useful and practical for predicting disease course. Early detection and identification of the type of plaque that is present may generate novel opportunities for primary prevention through changes in lifestyle or even through drug therapy, especially in patients at high cardiovascular risk.

Predictive value of coronary calcifications for future cardiac events in asymptomatic patients with diabetes mellitus: a prospective study in 716 patients over 8 years

Background

To establish an efficient prophylaxis of coronary artery disease reliable risk stratification is crucial, especially in the high risk population of patients suffering from diabetes mellitus. This prospective study determined the predictive value of coronary calcifications for future cardiovascular events in asymptomatic patients with diabetes mellitus.

Methods

We included 716 patients suffering from diabetes mellitus (430 men, 286 women, age 55.2 ± 15.2 years) in this study. On study entry all patients were asymptomatic and had no history of coronary artery disease. In addition, all patients showed no signs of coronary artery disease in ECG, stress ECG or echocardiography. Coronary calcifications were determined with the Imatron C 150 XP electron beam computed tomograph. For quantification of coronary calcifications we calculated the Agatston score. After a mean observation period of 8.1 ± 1.1 years patients were contacted and the event rate of cardiac death (CD) and myocardial infarction (MI) was determined.

Results

During the observation period 40 patients suffered from MI, 36 patients died from acute CD. The initial Agatston score in patients that suffered from MI or died from CD (475 ± 208) was significantly higher compared to those without cardiac events (236 ± 199, p < 0.01). An Agatston score above 400 was associated with a significantly higher annualised event rate for cardiovascular events (5.6% versus 0.7%, p < 0.01). No cardiac events were observed in patients with exclusion of coronary calcifications. Compared to the Framingham risk score and the UKPDS score the Agatston score showed a significantly higher diagnostic accuracy in the prediction of MI with an area under the ROC curve of 0.77 versus 0.68, and 0.71, respectively, p < 0.01.

Conclusion

By determination of coronary calcifications patients at risk for future MI and CD could be identified within an asymptomatic high risk group of patients suffering from diabetes mellitus. On the other hand future events could be excluded in patients without coronary calcifications.

Need for research on estrogen receptor function: importance for postmenopausal hormone therapy and atherosclerosis

BACKGROUND

Cardiovascular disease is the leading cause of morbidity and mortality in men and women worldwide. Although rare in premenopausal women, its incidence rises sharply after menopause, indicating atheroprotective effects of endogenous estrogens.

OBJECTIVE

This review discusses the differential effects of estrogen receptor function on atherosclerosis progression in pre- and postmenopausal women, including aspects of gender differences in vascular physiology of estrogens and androgens.

METHODS

Recent advances in the understanding of the pathogenesis of atherosclerosis, estrogen receptor function, and hormone therapy are reviewed, with particular emphasis on clinical and molecular issues.

RESULTS

Whether hormone therapy can improve cardiovascular health in postmenopausal women remains controversial. Current evidence suggests that the vascular effects of estrogen are affected by the stage of reproductive life, the time since menopause, and the extent of subclinical atherosclerosis. The mechanisms of vascular responsiveness to sex steroids during different stages of atherosclerosis development remain poorly understood in women and men.

CONCLUSION

In view of the expected increase in the prevalence of atherosclerotic vascular disease worldwide due to population aging, research is needed to determine the vascular mechanism of endogenous and exogenous sex steroids in patients with atherosclerosis. Such research may help to define new strategies to improve cardiovascular health in women and possibly also in men.

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.

Cardiovascular risk factors and signs of subclinical atherosclerosis in the Heinz Nixdorf Recall Study

INTRODUCTION

Modern investigation modalities allow markers of atherosclerosis to be detected at a subclinical stage. The aim of the study was to analyze the prevalence of these markers in relation to traditional risk factors.

METHODS

The population based study included 4814 participants, aged 45 to 75 years, with a response rate of 55.8% of those contacted. The patients' history, psychosocial and environmental risk factors were assessed.

RESULTS

The prevalence of obesity was 26.2% in men and 28.1% in women, 26% of men and 21% of women were smokers. Hypertension was found in 46% of men and 31% of women, diabetes in 9.3% of men and 6.3% of women. Markers of subclinical peripheral arterial disease were found in 6.4% of men and 5.1% of women, of subclinical carotid artery disease in 43.2% and 30.7%, and of subclinical coronary artery calcification in 82.3% and 55.2%, respectively. The prevalence of coronary calcification measured using an Agatston Score >100 was in 40% in men and 15% in women, using a score >400, 16.8% and 4.5%, respectively.

DISCUSSION

A high prevalence of subclinical atherosclerosis was found in the older population. The follow-up period will demonstrate whether the detection of markers of subclinical atherosclerosis will improve risk stratification beyond that offered by traditional risk factors.

Predictive value of coronary calcifications for future cardiac events in asymptomatic individuals

BACKGROUND

Reliable risk stratification is crucial for efficient prevention of coronary artery disease. The following prospective study determined the predictive value of coronary calcifications for future cardiovascular events.

METHODS

We included 1726 asymptomatic individuals (1018 men, 708 women, age 57.7 +/- 13.3 years) referred for a cardiological examination. Coronary calcifications were determined with the Imatron C 150 XP electron beam computed tomography scanner. For quantification of coronary calcifications, we calculated the Agatston score. Over a mean observation period of 40.3 +/- 7.3 months we registered the event rate for cardiac death (CD) and myocardial infarction (MI).

RESULTS

The Agatston score in patients who died of CD (n = 65) or had an MI (n = 114) was significantly higher compared with those without cardiac events (458 +/- 228 vs 206 +/- 201, P < .01). An Agatston score above the 75th percentile was associated with a significantly higher annualized event rate for MI (3.6% vs 1.6%, P < .05) and for CD (2.2% vs 0.9%) compared with patients with scores below the 75th percentile. No cardiac events were observed in patients where coronary calcifications could be excluded.

CONCLUSIONS

By determination of coronary calcifications, patients at risk for future MI and CD could be identified within an asymptomatic population independent of concomitant risk factors. At the same time, future cardiovascular events could be excluded in patients without coronary calcifications.

Value of conventional chest radiography for the detection of coronary calcifications: comparison with MSCT

PURPOSE

To evaluate if computed tomography (CT) coronary calcium scoring is needed after detection of coronary calcifications on conventional chest radiographs.

MATERIALS AND METHODS

One hundred and five patients (67 men; 57.2+/-12.8 years) with suspected coronary artery disease underwent conventional chest radiography and non-enhanced, retrospectively ECG-gated multislice spiral CT (MSCT) of the heart (4 mm x 2.5 mm, 120 kV, 133 mAs(eff.)). Chest radiographs were assessed independently by two radiologists. Detection of coronary calcifications was compared between both methods. Sensitivity, specificity, negative and positive predictive values, median, 25% and 75% percentiles for the detection of coronary calcifications were calculated. Receiver operating characteristics (ROC) analyses were computed.

RESULTS

In 90 patients, MSCT revealed coronary calcifications. The mean coronary calcium score was 526.2 (0-4784.5). On chest radiographs, coronary calcifications were correctly detected in 46 (61) patients by observer 1 (observer 2). The corresponding sensitivity was 51.1% in observer 1 and 67.8% in observer 2. Median of detected coronary calcifications was 361.9 (426.4) for observer 1 (observer 2). Corresponding 25% und 75% percentiles were 109.6 (109.6) and 798.5 (898.5). The area under the ROC curve was 0.636 for observer 1 and 0.715 for observer 2. There was no correlation between image quality and the detection of coronary calcifications on plain film radiographs.

CONCLUSION

As coronary calcifications of various extents are inconsistently detected on plain chest radiographs, CT calcium scoring may not be omitted even if coronary artery calcifications were detected on conventional chest radiographs.

Coronary calcification: effect of small variation of scan starting position on Agatston, volume, and mass scores

PURPOSE

To retrospectively evaluate the effect of a small variation of scan starting position on coronary artery calcium scores based on nonoverlapping 3-mm multidetector computed tomographic (CT) data sets.

MATERIALS AND METHODS

Informed consent and institutional review board approval were obtained. A retrospective study was performed by using prospective unenhanced electrocardiographically triggered cardiac multidetector CT scans in 228 women (mean age, 67 years +/- 5 [standard deviation]). From the original 1.5-mm data set, two sets of adjacent images with a section thickness of 3 mm and a variation in starting point of 1.5 mm were obtained. Calcium scoring was performed to acquire Agatston, volume, and mass scores. Subjects were assigned to one of five risk categories (I-V) according to the Agatston score of each 3-mm data set and the average score. Kappa value was calculated to assess agreement in risk category assignment. Differences and relative differences between scores obtained for both 3-mm data sets were calculated overall and according to risk category. The effect of scoring algorithm on the relative differences between scores was analyzed with the Wilcoxon signed rank test.

RESULTS

Categories I-V contained 102, 35, 48, 31, and 12 subjects, respectively. For all scoring algorithms, median relative differences decreased from more than 130% in category II to less than 10% in category V. In the three highest categories, relative differences were significantly smaller for volume and mass scores than for Agatston scores (P < .05). Twenty-one subjects were assigned to different risk categories between the two data sets (kappa = 0.87). Eleven patients were assigned a nonzero score in one and a zero score in the other data set.

CONCLUSION

A small variation in scan starting position can substantially influence calcium measurements and poses an inherent limit to calcium scoring with contiguous 3-mm sections. Mass and volume scores are slightly less affected than are Agatston scores.

Multislice computed tomography for determination of coronary artery disease in a symptomatic patient population

BACKGROUND

Multislice computed tomography (MSCT) has started to replace Electron beam CT for quantitation of coronary artery calcium. However no study has evaluated the diagnostic accuracy of MSCT for prediction of coronary artery disease (CAD) in a symptomatic patient population using the volume score.

METHODS AND RESULTS

1347 symptomatic subjects (male = 803, mean age = 62 years) with suspected CAD underwent MSCT studies 1 +/- 2 days before the coronary angiogram. The Agatston (ACS) and Volumetric calcium score (VCS) were calculated using a proprietary workstation. Statistical analyses included the Pearson's correlation coefficient and the nonparametric Mann-Whitney U-test to compare the calcium score in different age groups and between men and women. Sensitivity, specificity and predictive accuracy were calculated for different calcium thresholds for prediction of CAD. ROC curve analyses were used to establish relations between the coronary calcium score and presence or absence of CAD. In 720 (53%) subjects (male = 419) angiography revealed a minimal lumen diameter stenosis greater than 50%. Patients with significant CAD had significantly higher total calcium score values than patients without CAD (P = 0.001). ACS and VCS demonstrate a close correlation for the whole study group, r = 0.99. The overall sensitivity of any calcium to predict stenosis was 99%, specificity = 32%. Exclusion of calcium was highly accurate for exclusion of CAD in subjects older than 50 years (predictive accuracy = 98%). An absolute cutoff >100 and an age and sex specific threshold (score over 75th percentile) were identified as the cutoff levels with the highest sensitivities (86-89%) and lowest false positive rates (20-22%). ROC analyses revealed MSCT calcium scanning as a good clinical test which can be performed with similar accuracy in all age groups with an area under the curve of 0.84.

CONCLUSION

Determination of coronary calcium with MSCT is an accurate imaging modality for prediction of significant CAD in a patient population with intermediate likelihood of CAD. Exclusion of any calcium provided strong evidence that patients older than 50 years did not have obstructive CAD. ACS and VCS show an equivalent diagnostic accuracy.

Cardiac CT: coronary arteries and beyond

Multi-detector-row computed tomography (MDCT) has emerged as a rapidly developing method for non-invasive imaging of the heart. An understanding of ECG synchronization, contrast material administration, patient preparation and image post-processing is needed to optimize image quality. The basic technical principles and essentials of these technical basics are described here. Correctly applied cardiac MDCT allows imaging of the coronary arteries including coronary anatomy and stenosis detection. The same is true for evaluation of coronary artery bypass grafts and, to some extent, coronary artery stents. While quantification of total calcified plaque burden has been long established, coronary MDCT allows assessing plaque morphology and constitution. Recent approaches go beyond the coronaries and include evaluation of left ventricular function at rest and myocardial viability. In combination with experimental approaches for assessing aortic valve function and myocardial perfusion imaging, cardiac MDCT offers the potential for a comprehensive examination of the heart using a single breath-hold examination.

Devices for chronic occlusion

Interventional cardiology has advanced into domains once believed to be beyond the reach of percutaneous procedures. As technologic advances continue to push the limits of the interventionalist's capabilities, several areas still exert considerable resistance to this forward momentum. These technically difficult frontiers include bifurcated lesions, small-vessel disease, multivessel disease, diffuse disease, and chronic total occlusions.

Role of computed tomography in risk assessment for coronary heart disease

Coronary heart disease is the most common cause of death in Western countries, with a rising incidence in developing countries. It is part of the spectrum of cardiovascular diseases that have common end points of myocardial infarction, stroke and death. As these end points often occur suddenly and often in those with no known disease, identification of those people at high risk is important. Besides the known traditional risk factors, direct imaging of the calcified plaque as a marker for atherosclerotic disease has been extensively studied with electron beam computed tomography and now with multislice computed tomography. This review discusses the role of computed tomography in assessment of cardiovascular risk in both people with or without symptoms.

Frequency of coronary artery calcification on low-dose computed tomography screening for lung cancer

PURPOSE

The purpose of this study was to determine the frequency of coronary artery calcification (CAC) in high-risk people undergoing computed tomography (CT) screening for lung cancer.

METHODS

Between 1999 and 2004, we performed CT screening for lung cancer on 4250 participants, all without documented prior cardiovascular disease, using multidetector-row (MD) CT. Of the patients, 1102 underwent imaging with a four-detector-row CT at 120 kVp and 40 mA, with pitch 1.5 and collimation of 2.5 mm in a single breath hold of 15-20 seconds, and 3148 did with an eight-detector-row CT at the same kVp, mA, and pitch settings but with collimation of 1.25 mm. Visualized CACs in each coronary artery (main, left anterior descending, circumflex, and right) were scored separately as 0 (absent), 1 (mild), 2 (moderate), or 3 (severe), yielding a possible score of 0-12 for each person. Frequency distributions by gender, age, and pack-years of smoking were determined. Odds ratios (ORs) were calculated using logistic regression analysis of the prevalence of CAC as a joint function of gender, age, pack-years of smoking, and presence of diabetes.

RESULTS

Among the subjects younger than 50 years, positive CAC scores were three times more frequent for men than for women (22% vs. 7%); among those older than 50 years, the frequency increased for both men and women but the increase for women was greater than that for men. The frequency of positive CAC scores increased with increasing pack-years of smoking; it was always higher for men than for women. The ORs were 2.6 for male gender (P<.0001), 3.7 and 9.6 for ages 60-69 years and 70 years or older, respectively, for increasing age (P<.0001 for both), 1.6 and 2.3 for 30-59 pack-years and 60 pack-years or longer, respectively, for increasing pack-years of smoking (P<.0001 for both), and 1.6 for having diabetes (P=.016).

CONCLUSION

The CAC score can be derived from ungated low-dose MDCT images. This information can contribute to risk stratification and management of coronary artery disease.

Coronary artery calcium scanning: Clinical paradigms for cardiac risk assessment and treatment

BACKGROUND

Coronary artery calcium (CAC) scanning is being increasingly used for cardiac risk assessment in asymptomatic patients, particularly in those with a Framingham 10-year risk of 10% to 20%. Physician awareness of this technology and its appropriate uses and limitations is crucial to appropriate use.

METHODS

With the goal of establishing clinical paradigms, this document integrates the results of key published articles, Framingham Risk Score, National Cholesterol Education Program Adult Treatment Plan III guidelines, American College of Cardiology/American Heart Association exercise testing and angiographic guidelines, and the authors' extensive clinical experience.

RESULTS

Coronary artery calcium scanning is best used in the asymptomatic population with a 10% to 20% risk of cardiac events over 10 years, with selected application in higher and lower risk categories. In the 10%-20% risk patient, coronary artery calcium scores >100 or >75th percentile for age and sex transform the moderately high-risk patient to higher risk status with the attendant recommendation for more aggressive therapy; scores from 11 to 100 and <75th percentile are consistent with the 10%-20% 10-year risk status and scores from 0 to 10 and <75th percentile convert the patient to lesser risk categories. If stress testing is planned in the asymptomatic patient, it should be preceded by coronary artery calcium scanning and performed only for scores >400; it should always precede coronary angiography in these patients.

CONCLUSIONS

Coronary artery calcium scanning is an important risk assessment tool with direct clinical applications; it is of particular utility in the Framingham 10%-20% 10-year risk population.

Variability of Aortic Valve Calcification Measurement With Multislice Spiral Computed Tomography

OBJECTIVES

We sought to assess the variability of aortic valve calcifications (AVCs) regarding the reconstruction window at different heart phases using multislice-spiral computed tomography.

MATERIALS AND METHODS

A total of 46 patients (26 men; mean age. 65 years) underwent AVC scoring with multislice-spiral computed tomography (12 x 0.75 mm, 120 kV, 133 mAseff). Image reconstruction was performed every 10% of the RR-interval (0-90%). AVC was quantified using Agatston score, calcium volume, and calcium mass. Images were assessed for least motion artifacts. Coefficients of variation and Wilcoxon test were calculated.

RESULTS

AVC scores are lowest at 60% and highest at 0% of the RR-interval (P < 0.001). Mean coefficients of variation were 36.2% (Agatston score), 38.7% (calcium volume), and 32.9% (calcium mass). At 60% (50-70%). minimal motion artifacts and the lowest variability of the scores were found.

CONCLUSIONS

AVC scores show large variability depending on the point of image reconstruction. Diastolic image reconstruction at 60% of the RR-interval is recommended.

Evidence for lower variability of coronary artery calcium mineral mass measurements by multi-detector computed tomography in a community-based cohort--consequences for progression studies

PURPOSE

To compare the measurement variability for coronary artery calcium (CAC) measurements using mineral mass compared with a modified Agatston score (AS) or volume score (VS) with multi-detector CT (MDCT) scanning, and to estimate the potential impact of these methods on the design of CAC progression studies.

MATERIALS AND METHODS

We studied 162 consecutive subjects (83 women, 79 men, mean age 51 +/- 11 years) from a general Caucasian community-based cohort (Framingham Heart Study) with duplicate runs of prospective electrocardiographically-triggered MDCT scanning. Each scan was independently evaluated for the presence of CAC by four experienced observers who determined a "modified" AS, VS and mineral mass.

RESULTS

Of the 162 subjects, CAC was detected in both scans in 69 (42%) and no CAC was detected in either scan in 72 (45%). Calcium scores were low in the 21/162 subjects (12%) for whom CAC was present in one but not the other scan (modified AS < 20 in 20/21 subjects, mean AS 4.6 +/- 1.9). For all three quantification algorithms, the inter- and intraobserver correlation were excellent (r > 0.96). However, the mean interscan variability was significantly different between mineral mass, modified AS, and VS (coefficient of variation 26 +/- 19%, 41 +/- 28% and 34 +/- 25%, respectively; p < 0.04), with significantly smaller mean differences in pair-wise comparisons for mineral mass compared with modified AS (p < 0.002) or with VS (p < 0.03). The amount of CAC but not heart rate was an independent predictor of interscan variability (r = -0.638, -0.614 and -0.577 for AS, VS, and mineral mass, respectively; all p < 0.0001). The decreased interscan variability of mineral mass would allow a sample size reduction of 5.5% compared with modified AS for observational studies of CAC progression and for randomized clinical trials.

CONCLUSION

There is significantly reduced interscan variability of CAC measurements with mineral mass compared with the modified AS or VS. However, the measurement variability of all quantification methods is predicted by the amount of CAC and is inversely correlated to the extent of partial volume artifacts. Moreover, the improvement of measurement reproducibility leads to a modest reduction in sample size for observational epidemiological studies or randomized clinical trials to assess the progression of CAC.

Threshold-dependent variability of coronary artery calcification measurements -- implications for contrast-enhanced multi-detector row-computed tomography

INTRODUCTION

The present study investigated the threshold-dependent variability of coronary artery calcification (CAC) measurements and the potential to quantify CAC in contrast-enhanced multi-detector row-computed tomography (MDCT).

METHODS

We compared the mean CT attenuation of CAC to luminal contrast enhancement of the coronary arteries in 30 patients (n = 30) undergoing standard coronary contrast-enhanced spiral MDCT. The modified Agatston score [AS], calcified plaque volume [CV], and mineral mass [MM]) at four different thresholds (130, 200, 300, and 400 HU) were measured in 50 patients who underwent non-contrast-enhanced MDCT.

RESULTS

Mean CT attenuation of CAC was similar to the attenuation of the contrast-enhanced coronary lumen (CAC 297.1 +/- 68.7 HU versus 295 +/- 65 HU (p < 0.0001), respectively). Above a threshold of 300 HU CAC measurements significantly varied to standard measurements obtained at a threshold of 130 HU (p < 0.0001). The threshold-dependent variation of MM measurements was significantly smaller than for AS and CV (130 HU versus 400 HU: 63, 75, and 81, respectively; p < 0.001). These differences resulted in a change of age and gender based percentile category for AS in 78% of subjects.

DISCUSSION

We demonstrated that CAC measurements are threshold dependent with MM measurements having significantly less variation than AS or CV. Due to the similarity of mean CT attenuation of CAC and the contrast-enhanced coronary lumen accurate quantification of CAC may be difficult in standard coronary contrast-enhanced spiral MDCT.

[Impact of both cardiac-CT and cardiac-MR on the assessment of coronary risk]

Today's definition of coronary artery disease (CAD) comprises two forms: obstructive and non-obstructive CAD. The 31-72% chance of a life-threatening event-like a myocardial infarction-with non-obstructive CAD is well documented in numerous studies. The objective in modern strategies of diagnosis and therapy should therefore be expedient identification of patients at high risk for coronary events, who will benefit from a customized therapy. Before initiating diagnostic procedures of CAD, a well defined strategy should be pursued. There are two possible primary objectives: ASSESSMENT OF THE INDIVIDUAL RISK FOR A CORONARY EVENT: Assessment of the individual "absolute" risk for a coronary event is not possible using single traditional risk factors. The individual risk can be estimated by integrating several of the traditional risk factors into a scoring system. These so-called risk scores (e.g. Framingham score and Procam score), however, have been associated with shortcomings: insufficient discrimination of high-risk from low-risk individuals. The calcium score has therefore become increasingly established; this Agatston score is independent of the traditional risk factors, so there is no correlation between Agatston and Procam scores. Today, the calcium score is considered the superior test for identifying individuals at high risk for a coronary event and its use is recommended by the European Society of Cardiology (ESC) guidelines for prevention of cardiovascular diseases. PROOF OR EXCLUSION OF A HEMODYNAMICALLY SIGNIFICANT CORONARY STENOSIS: Another concept is the definitive proof or exclusion of a hemodynamically "significant" coronary narrowing. The probability of an obstructive CAD is traditionally assessed by the type of chest pain, age, gender and stress-ECG. In patients with a low probability of an obstructive CAD, cardiac catheterization is not indicated, whereas in patients with a high probability of a hemodynamically significant coronary stenosis, an invasive strategy should be performed. Since non-invasive coronary angiography (CTA) with cardiac-CT has been shown to provide a high negative predictive value, CTA (with good imaging quality) is suitable for ruling out a significant obstructive CAD in the group at intermediate risk for an obstructive CAD. Another approach could be a functional test to initially prove a relevant, inducible myocardial ischemia: In a large cohort it was shown that patients will only prognostically benefit from revascularization procedures if the ischemic myocardial area is greater than 10%. Therefore, the assessment of the extent of myocardial ischemia is the domain of modern stress imaging tests. Stress-echocardiography and myocardial scintigraphy have almost the same sensitivity (74-80%, 84-90%, respectively) and specificity (84-89%, 77-86%, respectively), which are considerably higher than for stress-ECG. Cardiac MR is most suitable for the assessment of myocardial perfusion, because it traces the first pass dynamics of gadolinium at rest and during stress in reproducible slices at an acceptable spatial and a high temporal resolution without ionizing radiation. Whether the non-invasive coronary angiography with cardiac-CT and the Adenosin-perfusion imaging with cardiac-MR will completely replace diagnostic cardiac catheterization and stress-echocardiography as well as myocardial scintigraphy remains to be evaluated in further studies.

The StarClose® vascular closure system: Interventional results from the CLIP study

BACKGROUND

The StarClose Vascular Closure System is a femoral access site closure technology that uses a flexible nitinol clip to complete a circumferential, extravascular arteriotomy close. The Clip CLosure In Percutaneous Procedures study was initiated to study the safety and efficacy of the StarClose device in subjects undergoing diagnostic and interventional catheterization procedures.

METHODS

A total of 17 U.S. sites enrolled 596 subjects, with 483 subjects randomized at a 2:1 ratio to receive StarClose or standard compression of the arteriotomy after the percutaneous procedure. The study included roll-in (n = 113), diagnostic (n = 208), and interventional (n = 275) arms with a primary safety endpoint of major vascular complications through 30 days and a primary efficacy endpoint of postprocedure time to hemostasis.

RESULTS

The results of the diagnostic StarClose cohort have been reported separately. Results for the interventional arm revealed major vascular complications occurring in 1.1% of StarClose subjects (2/184) and 1.1% in manual compression subjects (1/91; P = 1.00). No infections were seen in either cohort. Minor complications in the StarClose interventional group occurred at a rate of 4.3% (8/184) and with compression at 9.9% (9/91; P = 0.107). Pseudoaneurysm or arteriovenous fistula was not seen with StarClose. With StarClose, procedural success was 100% (136/136) for the diagnostic group and 98.9% (181/183) in the interventional group. Device success for the treatment group was 86.8%. In the interventional cohort, 87.3% (158/181) of StarClose subjects reported a pain scale of 0-3 compared with 93.3% (84/90) in the compression group, which was not statistically different.

CONCLUSIONS

The clinical results of this study demonstrate that the StarClose Vascular Closure System is noninferior to manual compression with respect to the primary safety endpoint of major vascular events in subjects who undergo percutaneous interventional procedures. StarClose significantly reduced time to hemostasis, ambulation, and dischargeability when compared with compression.

Distribution of coronary artery calcium by race, gender, and age: results from the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Coronary artery calcium (CAC) has been demonstrated to be associated with the risk of coronary heart disease. The Multi-Ethnic Study of Atherosclerosis (MESA) provides a unique opportunity to examine the distribution of CAC on the basis of age, gender, and race/ethnicity in a cohort free of clinical cardiovascular disease and treated diabetes.

METHODS AND RESULTS

MESA is a prospective cohort study designed to investigate subclinical cardiovascular disease in a multiethnic cohort free of clinical cardiovascular disease. The percentiles of the CAC distribution were estimated with nonparametric techniques. Treated diabetics were excluded from analysis. There were 6110 included in the analysis, with 53% female and an average age of 62 years. Men had greater calcium levels than women, and calcium amount and prevalence were steadily higher with increasing age. There were significant differences in calcium by race, and these associations differed across age and gender. For women, whites had the highest percentiles and Hispanics generally had the lowest; in the oldest age group, however, Chinese women had the lowest values. Overall, Chinese and black women were intermediate, with their order dependent on age. For men, whites consistently had the highest percentiles, and Hispanics had the second highest. Blacks were lowest at the younger ages, and Chinese were lowest at the older ages. At the MESA public website (http://www.mesa-nhlbi.org), an interactive form allows one to enter an age, gender, race/ethnicity, and CAC score to obtain a corresponding estimated percentile.

CONCLUSIONS

The information provided here can be used to examine whether a patient has a high CAC score relative to others with the same age, gender, and race/ethnicity who do not have clinical cardiovascular disease or treated diabetes.

Comprehensive coronary risk determination in primary prevention: an imaging and clinical based definition combining computed tomographic coronary artery calcium score and national cholesterol education program risk score

Cardiovascular disease (CVD) is the leading cause of mortality and a major cause of morbidity. Coronary heart disease (CHD) accounts for nearly half of all CVD deaths. Currently estimation of risk in primary prevention is based on the Framingham risk equations, which inputs traditional risk factors and is helpful in predicting the development of CHD in asymptomatic individuals. However many individuals suffer events in the absence of established risk factors for atherosclerosis and broad based population risk estimations may have little precision when applied to a given individual. To meet the challenge of CHD risk assessment, several tools have been developed to identify atherosclerotic disease in its preclinical stages. This paper aims to incorporate information from coronary artery calcification (CAC) scoring from a computed tomographic "heartscan" (using Electron Beam Tomography (EBT) as the validated prototype) along with current Framingham risk profiling in order to refine risk on an absolute scale by combining imaging and clinical data to affect a more comprehensive calculation of absolute risk in a given individual. For CAC scores above the 75th percentile but <90th percentile, 10 years is added to chronological age, and for CAC scores above the 90th percentile, 20 years is added to current chronological age. Among those in whom a positive CAC score is the norm such as older individuals (men> or =55 years, women> or =65 years) a CAC = 0 will result in an age point score corresponding to the age-group whose median CAC score is zero i.e., 40-44 years for men and 55-59 years for women. The utilization of CAC scores allows the inclusion of sub-clinical disease definition into the context of modifiable risk factors as well as identifies high-risk individuals requiring aggressive treatment.

Atherothrombosis and High-Risk Plaque

This second part of the review on atherothrombosis highlights the diffuse nature of the disease analyzing the feasibility and potential of the noninvasive imaging modalities, including computed tomography (electron-beam computed and multi-detector computed tomography) and magnetic resonance imaging for its detection and monitoring. These imaging modalities are being established as promising tools in high-risk cardiovascular patients for identification and/or management of coronary calcification, stenotic or obstructive disease, high-risk plaques (not necessarily stenotic), and overall burden of the disease. In addition, such technology facilitates the understanding of the processes involved in the development and progression of atherothrombosis responsible for coronary, cerebral, and peripheral ischemic events.

Coronary Artery Calcium Measurement with Multi–Detector Row CT and Low Radiation Dose: Comparison between 55 and 165 mAs

PURPOSE

To prospectively compare the results of coronary artery calcium (CAC) measurements obtained with 55- and 165-mAs electrocardiographically gated multi-detector row computed tomography (CT).

MATERIALS AND METHODS

Institutional clinical study review board approval and written informed consent were obtained. Fifty-one consecutive subjects (mean age, 59 years +/- 10) were scanned consecutively by using 165 and 55 mAs. For each examination, the number of lesions, total calcium score (TCS) calculated with Agatston algorithm (130-HU threshold), and calcium mass (in milligrams) were measured. Noise was measured by averaging 1 standard deviation of the CT attenuation values in five consecutive transverse sections of the ascending aorta. Paired t test and Pearson correlation were used to compare measurements between the examinations.

RESULTS

By using 55 mAs, CAC was detected (TCS > 0) in all 33 subjects in whom CAC was initially detected with 165 mAs. The mean values of CAC measures with 165 and 55 mAs, respectively, were as follows: number of lesions, 6.2 +/- 9.6 and 6.1 +/- 9.4; TCS, 123 +/- 223 and 126 +/- 225; and calcium mass, 23.25 mg +/- 43 and 24.25 mg +/- 44 (P value was not significant for all parameters). Significant high correlation was found between the two methods for all measures (r > 0.90, P < .01). Similar results were obtained with analysis by coronary vessel. Image noise was 9.3 HU +/- 2.1 with 165 mAs and 14.7 HU +/- 3.9 with 55 mAs (P < .001), with a parallel decrease in the volume CT dose index from 12 to 4 mGy.

CONCLUSION

Radiation dose can be reduced (eg, 55 mAs) for CAC detection and measurement at multi-detector row CT and provides results comparable to those obtained with 165 mAs.

Population-based assessment of subclinical coronary atherosclerosis using electron-beam computed tomography

AIMS

Coronary artery calcification (CAC) is determined as a measure of the extent of coronary atherosclerosis and can be used for expanded cardiovascular risk stratification. It was our aim to establish reference CAC scores in a population-based unselected European cohort.

METHODS AND RESULTS

The Heinz Nixdorf Recall study (HNR) recruited a total of 4814 participants aged 45-74 years. Cardiovascular risk factors and medications were recorded, and CAC was measured using electron-beam CT (EBCT). CAC score distribution was compared with previous studies in subjects who were self-referred, volunteered, or were physician-referred. Of the 4472 (92.9%) subjects free of clinical coronary artery disease, the CAC score was available in 4275 (95.3%) (2027 men, 2248 women). CAC scores were lower in particular in the higher age groups (> or = 60 years) in men than in the previous studies. Also, in most age groups (except the highest, 70-74 years), subjects with no cardiovascular medications had significantly lower CAC scores than subjects using cardiovascular medications.

CONCLUSIONS

The current report characterises the distribution of EBCT-derived CAC scores in a European unselected population. Compared with previous reports, CAC scores were lower in our cohort, in particular in subjects not receiving cardiovascular medications. Classification of the CAC score may underestimate true risk if previously published referral cohorts are used as the reference.