The significance of coronary calcification detected by fluoroscopy. A report of 360 patients

Management of Calcified Coronary Lesions

With an aging population, coronary calcification is increasingly encountered in modern day interventional practice. Unfortunately, it is associated with lower procedural success and higher rates of periprocedural complications, such as failure to deliver stents, perforations, dissections, and other major adverse cardiac events. Furthermore, suboptimal stent deployment in the setting of severe calcification is associated with both short-and long-term major adverse cardiac events, including stent thrombosis, MI, in-stent restenosis, and target lesion revascularization. A variety of treatment options for these lesions exist, including specialized balloons, atherectomy, and intravascular lithotripsy. While there is currently no universally accepted algorithm for choosing between these treatment strategies, several different algorithms exist, and the optimization of these treatment regimens will continue to evolve in the coming years. This review aims to provide insights on the different therapeutic modalities and an understanding of the current body of evidence.

Coronary and Extra-coronary Subclinical Atherosclerosis to Guide Lipid-Lowering Therapy

PURPOSE OF REVIEW

To discuss and review the technical considerations, fundamentals, and guideline-based indications for coronary artery calcium scoring, and the use of other non-invasive imaging modalities, such as extra-coronary calcification in cardiovascular risk prediction.

RECENT FINDINGS

The most robust evidence for the use of CAC scoring is in select individuals, 40-75 years of age, at borderline to intermediate 10-year ASCVD risk. Recent US recommendations support the use of CAC scoring in varying clinical scenarios. First, in adults with very high CAC scores (CAC ≥ 1000), the use of high-intensity statin therapy and, if necessary, guideline-based add-on LDL-C lowering therapies (ezetimibe, PCSK9-inhibitors) to achieve a ≥ 50% reduction in LDL-C and optimally an LDL-C < 70 mg/dL is recommended. In patients with a CAC score ≥ 100 at low risk of bleeding, the benefits of aspirin use may outweigh the risk of bleeding. Other applications of CAC scoring include risk estimation on non-contrast CT scans of the chest, risk prediction in younger patients (< 40 years of age), its value as a gatekeeper for the decision to perform nuclear stress testing, and to aid in risk stratification in patients presenting with low-risk chest pain. There is a correlation between extra-coronary calcification (e.g., breast arterial calcification, aortic calcification, and aortic valve calcification) and incident ASCVD events. However, its role in informing lipid management remains unclear. Identification of coronary calcium in selected patients is the single best non-invasive imaging modality to identify future ASCVD risk and inform lipid-lowering therapy decision-making.

Imaging subclinical coronary atherosclerosis to guide lipid management, are we there yet?

Atherosclerotic cardiovascular disease risk (ASCVD) is an ongoing epidemic, and lipid abnormalities are its primordial cause. Most individuals suffering a first ASCVD event are previously asymptomatic and often do not receive preventative therapies. The cornerstone of primary prevention has been the identification of individuals at risk through risk calculators based on clinical and laboratory traditional risk factors plus risk enhancers. However, it is well accepted that a clinical risk calculator misclassifies a significant proportion of individuals leading to the prescription of a lipid-lowering medication with very little yield or a missed opportunity for lipid-lowering agents with a potentially preventable event. The development of coronary artery calcium scoring (CAC) and CT coronary angiography (CCTA) provide complementary tools to directly visualize coronary plaque and other risk-modifying imaging components that can potentially provide individualized lipid management. Understanding patient selection for CAC or potentially CCTA and the risk implications of the different parameters provided, such as CAC score, coronary stenosis, plaque characteristics and burden, epicardial adipose tissue, and pericoronary adipose tissue, have grown more complex as technologies evolve. These parameters directly affect the shared decision with patients to start or withhold lipid-lowering therapies, to adjust statin intensity or LDL cholesterol goals. Emerging lipid lowering studies with non-invasive imaging as a guide to patient selection and treatment efficacy, plus the evolution of lipid lowering therapies from statins to a diverse armament of newer high-cost agents have pushed these two fields forward with a complex interaction. This review will discuss existing risk estimators, and non-invasive imaging techniques for subclinical coronary atherosclerosis, traditionally studied using CAC and more recently CCTA with qualitative and quantitative measurements. We will also explore the current data, gaps of knowledge and future directions on the use of these techniques in the risk-stratification and guidance of lipid management.

Cardiotoxicity of Radiation Therapy: Mechanisms, Management, and Mitigation

OPINION STATEMENT

Radiation therapy is a key component of modern-day cancer therapy and can reduce the rates of recurrence and death from cancer. However, it can increase risk of cardiovascular (CV) events, and our understanding of the timeline associated with that risk is shorter than previously thought. Risk mitigation strategies, such as different positioning techniques, and breath hold acquisitions as well as baseline cardiovascular risk stratification that can be undertaken at the time of radiotherapy planning should be implemented, particularly for patients receiving chest radiation therapy. Primary and secondary prevention of cardiovascular disease (CVD), as appropriate, should be used before, during, and after radiation treatment in order to minimize the risks. Opportunistic screening for subclinical coronary disease provides an attractive possibility for primary/secondary CVD prevention and thus mitigation of long-term CV risk. More data on long-term clinical usefulness of this strategy and development of appropriate management pathways would further strengthen the evidence for the implementation of such screening. Clear guidelines in initial cardiovascular screening and cardiac aftercare following radiotherapy need to be formulated in order to integrate these measures into everyday clinical practice and policy and subsequently improve post-treatment morbidity and mortality for these patients.

Role of coronary artery calcium score in the primary prevention of cardiovascular disease

First developed in 1990, the Agatston coronary artery calcium (CAC) score is an international guideline-endorsed decision aid for further risk assessment and personalized management in the primary prevention of atherosclerotic cardiovascular disease. This review discusses key international studies that have informed this 30 year journey, from an initial coronary plaque screening paradigm to its current role informing personalized shared decision making. Special attention is paid to the prognostic value of a CAC score of zero (the so called "power of zero"), which, in a context of low estimated risk thresholds for the consideration of preventive therapy with statins in current guidelines, may be used to de-risk individuals and thereby inform the safe delay or avoidance of certain preventive therapies. We also evaluate current recommendations for CAC scoring in clinical practice guidelines around the world, and past and prevailing barriers for its use in routine patient care. Finally, we discuss emerging approaches in this field, with a focus on the potential role of CAC informing not only the personalized allocation of statins and aspirin in the general population, but also of other risk-reduction therapies in special populations, such as individuals with diabetes and people with severe hypercholesterolemia.

Electron Beam CT: A Historical Review

OBJECTIVE. At its advent, CT was too slow to image the heart. Temporal resolution improved with electron beam CT (EBCT); subsequently, the heart could be imaged, eventually leading to the discovery of prognostic information obtained from the coronary calcium score. In the early 2000s, EBCT was replaced by MDCT. In this review, we discuss the rise and fall of EBCT and explore its legacy in cardiac imaging. CONCLUSION. Although MDCT rendered EBCT obsolete, EBCT leaves a legacy in cardiac imaging regarding both diagnosis and prognosis. The creators of MDCT emulated the strengths of EBCT and learned from its weaknesses. Moreover, EBCT showed that imaging surrogates can predict outcomes, and the origins of substrate-guided treatment can be traced to EBCT.

Coronary Calcium Score and Cardiovascular Risk

Coronary artery calcium (CAC) is a highly specific feature of coronary atherosclerosis. On the basis of single-center and multicenter clinical and population-based studies with short-term and long-term outcomes data (up to 15-year follow-up), CAC scoring has emerged as a widely available, consistent, and reproducible means of assessing risk for major cardiovascular outcomes, especially useful in asymptomatic people for planning primary prevention interventions such as statins and aspirin. CAC testing in asymptomatic populations is cost effective across a broad range of baseline risk. This review summarizes evidence concerning CAC, including its pathobiology, modalities for detection, predictive role, use in prediction scoring algorithms, CAC progression, evidence that CAC changes the clinical approach to the patient and patient behavior, novel applications of CAC, future directions in scoring CAC scans, and new CAC guidelines.

Current and future applications of CT coronary calcium assessment

INTRODUCTION

Computed tomographic (CT) coronary artery calcium scoring (CAC) has been validated as a well-established screening method for cardiovascular risk stratification and treatment management that is used in addition to traditional risk factors. The purpose of this review is to present an update on current and future applications of CAC. Areas covered: The topic of CAC is summarized from its introduction to current application with focus on the validation and clinical integration including cardiovascular risk prediction and outcome, cost-effectiveness, impact on downstream medical testing, and the technical advances in scanner and software technology that are shaping the future of CAC. Furthermore, this review aims to provide guidance for the appropriate clinical use of CAC. Expert commentary: CAC is a well-established screening test in preventive care that is underused in daily clinical practice. The widespread clinical implementation of CAC will be decided by future technical advances in CT image acquisition, cost-effectiveness, and reimbursement status.

Coronary Artery Calcium Scoring: Is It Time for a Change in Methodology?

Quantification of coronary artery calcium (CAC) has been shown to be reliable, reproducible, and predictive of cardiovascular risk. Formal CAC scoring was introduced in 1990, with early scoring algorithms notable for their simplicity and elegance. Yet, with little evidence available on how to best build a score, and without a conceptual model guiding score development, these scores were, to a large degree, arbitrary. In this review, we describe the traditional approaches for clinical CAC scoring, noting their strengths, weaknesses, and limitations. We then discuss a conceptual model for developing an improved CAC score, reviewing the evidence supporting approaches most likely to lead to meaningful score improvement (for example, accounting for CAC density and regional distribution). After discussing the potential implementation of an improved score in clinical practice, we follow with a discussion of the future of CAC scoring, asking the central question: do we really need a new CAC score?

Coronary Artery Calcium Distribution Is an Independent Predictor of Incident Major Coronary Heart Disease Events: Results From the Framingham Heart Study

BACKGROUND

The presence and extent of coronary artery calcium (CAC) are associated with increased risk for cardiovascular events. We determined whether information on the distribution of CAC and coronary dominance as detected by cardiac computed tomography were incremental to traditional Agatston score (AS) in predicting incident major coronary heart disease (CHD).

METHODS AND RESULTS

We assessed total AS and the presence of CAC per coronary artery, per segment, and coronary dominance by computed tomography in participants from the offspring and third-generation cohorts of the Framingham Heart Study. The primary outcome was major CHD (myocardial infarction or CHD death). We performed multivariable Cox proportional hazards analysis and calculated relative integrated discrimination improvement. In 1268 subjects (mean age, 56.2±10.3 years, 63.2% men) with AS >0 and no history of major CHD, a total of 42 major CHD events occurred during median follow-up of 7.4 years. The number of coronary arteries with CAC (hazard ratio, 1.68 per artery; 95% confidence interval, 1.10-2.57; P=0.02) and the presence of CAC in the proximal dominant coronary artery (hazard ratio, 2.59; 95% confidence interval, 1.15-5.83; P=0.02) were associated with major CHD events after multivariable adjustment for Framingham risk score and categories of AS. In addition, measures of CAC distribution improved discriminatory capacity for major CHD events (relative integrated discrimination improvement, 0.14).

CONCLUSIONS

Distribution of coronary atherosclerosis, especially CAC in the proximal dominant coronary artery and an increased number of coronary arteries with CAC, predict major CHD events independently of the traditional AS in community-dwelling men and women.

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.

Scoring of coronary artery calcium scans: history, assumptions, current limitations, and future directions

Coronary artery calcium (CAC) scanning is a reliable, noninvasive technique for estimating overall coronary plaque burden and for identifying risk for future cardiac events. Arthur Agatston and Warren Janowitz published the first technique for scoring CAC scans in 1990. Given the lack of available data correlating CAC with burden of coronary atherosclerosis at that time, their scoring algorithm was remarkable, but somewhat arbitrary. Since then, a few other scoring techniques have been proposed for the measurement of CAC including the Volume score and Mass score. Yet despite new data, little in this field has changed in the last 15 years. The main focus of our paper is to review the implications of the current approach to scoring CAC scans in terms of correlation with the central disease - coronary atherosclerosis. We first discuss the methodology of each available scoring system, describing how each of these scores make important indirect assumptions in the way they account (or do not account) for calcium density, location of calcium, spatial distribution of calcium, and microcalcification/emerging calcium that might limit their predictive power. These assumptions require further study in well-designed, large event-driven studies. In general, all of these scores are adequate and are highly correlated with each other. Despite its age, the Agatston score remains the most extensively studied and widely accepted technique in both the clinical and research settings. After discussing CAC scoring in the era of contrast enhanced coronary CT angiography, we discuss suggested potential modifications to current CAC scanning protocols with respect to tube voltage, tube current, and slice thickness which may further improve the value of CAC scoring. We close with a focused discussion of the most important future directions in the field of CAC scoring.

The coronary calcium treadmill test: a new approach to the initial workup of patients with suspected coronary artery disease

Due to the growth of cardiac testing and increasing cost of cardiovascular healthcare, the development of more cost-effective strategies has now become a dominant issue regarding future utilization of cardiac imaging procedures. To that end, we review the potential of combining two relatively inexpensive tests, the coronary artery calcium (CAC) scan and exercise electrocardiography (ECG), as a first-line test for the workup of patients with suspected coronary artery disease (CAD). The CAC scan was initially introduced as a screening test for CAD, based on data indicating that it is a specific marker for atherosclerosis, predicts clinical risk in accordance with the magnitude of CAC, and provides incremental information for prognostic risk compared to more readily available clinical data. However, CAC scores also predict the likelihood of observing myocardial ischemia among patients undergoing exercise myocardial perfusion SPECT imaging. Exercise ECG predicts clinical events according to the ST-segment response and according to functional exercise capacity, with the latter parameter as a stronger predictor of clinical outcomes. Like CAC scores, exercise functional capacity can also be used to predict the likelihood of ischemia since ischemia diminishes proportionally with increasing exercise capacity. Recent work indicates that when patients are designated by Bayesian analyses into low, intermediate, and high likelihood categories for CAD based on clinical data and the response to exercise ECG, the frequency of inducible myocardial ischemia is very low among both low and intermediate CAD likelihood patients who have a CAC score <400. Future studies are needed to investigate what clinical factors might further modify the CAC-ischemia relationship. On the basis of current data, an initial testing strategy that employs the combined calcium treadmill test has the inherent ability to designate a substantial number of intermediate likelihood patients who would not require further testing due to relatively low CAC scores and reasonable functional capacity.

KLOTHO gene polymorphism is associated with coronary artery stenosis but not with coronary calcification in a Korean population

Experimental studies have demonstrated KLOTHO gene polymorphism might be associated with vascular atherosclerosis and calcification. However, the impact of this genetic variant on human coronary arteries still remains to be elucidated. We investigated the effect of a KLOTHO gene variant on coronary artery stenosis and calcification. Four hundred and thirty-four patients referred for chest pain were enrolled. All the patients underwent coronary angiography and were investigated for polymorphism of the KLOTHO G395A gene. Coronary artery disease (CAD) was defined as > or = 50% diameter stenosis in at least one coronary artery. The other patients were considered to be controls. Homozygotes or heterozygotes for G395A were significantly more common in the CAD patients than in the controls (30.2% versus 21.5%, P = 0.039). In the subgroup aged < 60 years, the G395A mutant was more frequent in CAD than in control (35.3% versus 18.8%, P = 0.016), but in patients > or = 60 years, there was no difference (28.0% versus 24.1%, P = 0.473). Using multivariate analysis, we identified the KLOTHO gene G395A mutant as an independent risk factor of CAD (OR 1.712, 95% CI [1.066-2.749], P = 0.026). The frequency of the KLOTHO gene G395A mutant was not different between the calcified and noncalcified coronary artery groups (25.7%, 26.4%, respectively, P = 0.861) and an A allele carrier state was not an independent risk factor of coronary artery calcification. In conclusion, the KLOTHO gene G395A allele carrier state may be associated with CAD but not with coronary artery calcification in this Korean population.

Vascular compliance and arterial calcification: impact on blood pressure reduction

PURPOSE OF REVIEW

The aim of this article is to review the relationship between vascular calcification and difficult to control hypertension. This does not address antihypertensive treatment of drug resistant hypertension per se.

RECENT FINDINGS

Vascular calcification occurs in a variety of common hypertension scenarios. Basic mechanisms of how and why vessels calcify are reviewed including new genetic insights. The potential for contributing to or improving calcification through drug therapies for nonhypertensive disorders is reviewed.

SUMMARY

Vascular calcification is common and easily recognized. Studies that target its clinical consequences (arterial stiffness) as primary treatment goals are needed.

Subclinical disease detection: advanced imaging applications

Coronary events are the leading cause of death in the United States, and sudden coronary death is often the first presenting symptom. Because there is such a large population at risk for coronary events and because many of these patients go undetected before presenting with a significant cardiovascular event or sudden death, there is great interest in better detection and characterization of subclinical disease before it causes morbidity and mortality. This chapter will focus on promising imaging-based methods for the evaluation of subclinical cardiovascular disease. Several imaging methods that are most likely to be useful for future screening and intervention studies for characterizing risk among asymptomatic persons will be presented.

Osteoprotegerin is not associated with angiographic coronary calcification

Coronary artery calcification may play a significant role in the pathophysiology of plaque progression and healing. We hypothesized that osteoprotegerin, an inhibitor of osteoclastogenesis, may participate in the calcification of coronary plaques or the response to injury after coronary stenting. A prospective registry was performed in 2004. Blood samples from 100 patients undergoing percutaneous coronary intervention (PCI) were obtained before PCI and 24 h after PCI. The concentrations of osteoprotegerin (OPG), C-reactive protein, interleukin-6, and soluble CD40 ligand (sCD40L) were determined by ELISA. Quantitative coronary angiography was performed to define the presence of culprit lesion calcification (CLC). Comparisons among markers of inflammation and tertiles of OPG were stratified with respect to CLC. Patients with CLC (n = 28) compared with no CLC (n = 71) were older (P < 0.01), had lower creatinine clearance (P < 0.01), lower hemoglobin (P = 0.02), and were less likely to smoke (P = 0.04). Patients without CLC were over twice as likely to present with a marker-positive acute coronary syndrome. CLC was associated with less pre-PCI platelet-mediated inflammation as measured by sCD40L (4.65 vs. 7.15 pg/ml, P = 0.05), but not with lower levels of OPG. Inflammatory cytokines increased significantly after PCI for patients with and without CLC. For patients in the highest tertile of OPG at baseline, there was a reduction in OPG after PCI. Systemic osteoprotegerin levels are not associated with angiographic calcification of culprit plaques. For patients with elevated levels of OPG prior to PCI, there is a significant reduction after PCI consistent with a counterregulatory role for OPG.

CONDENSED ABSTRACT

Both calcified and non-calcified culprit plaques exhibited a similar inflammatory response to stent-mediated injury. After PCI, osteoprotegerin decreased while proinflammatory cytokines increased, which may be consistent with a counterregulatory role for osteoprotegerin.

Calcifications of the heart

Cardiac calcification usually represents the result of a pathologic process. Some forms of calcification represent chronic change in an ageing population, and must be differentiated from pathologic calcification. Still other forms of calcification are associated with ageing and chronic degeneration, but also reflect ongoing pathologic processes. Recognition of cardiac calcification may be an early sign or only sign of a pathologic process. Characterization of the calcification in terms of its distribution and appearance is a helpful means for determining which structures are calcified, differentiating pathologic from nonpathologic processes. This article provides an overview of the types of calcifications of the heart, pathogenesis, and utility of the various imaging modalities for their detection.

Coronary calcium detected by digital cinefluoroscopy and coronary artery disease in patients undergoing coronary arteriography: effects of age and sex

BACKGROUND

Coronary artery calcium, detected non-invasively, correlates well with angiographically documented coronary artery disease (CAD). This study was conducted to evaluate the diagnostic efficacy of coronary artery calcium detected by digital cinefluoroscopy for CAD and assess the effects of age and sex on it.

METHODS

In 242 patients who underwent coronary angiography, coronary calcium status was determined and related to angiographic findings.

RESULTS

Calcium detection had a sensitivity 85%, specificity 52%, positive predictive value 92%, negative predictive value 33% and diagnostic accuracy 81% for significant CAD. There was a better positive predictive value in men (95% vs. 80%) and negative predictive value in women (65% vs. 16%), while a higher sensitivity and diagnostic accuracy was found in older than in younger (90% and 86% vs. 78% and 74%). The sensitivity of the method increased with the number of the diseased vessels.

CONCLUSIONS

Coronary calcium can be quite accurately detected by digital cinefluoroscopy. This, however, should be made in the context of sex and age.

Secondary hyperparathyroidism and its therapy as a cardiovascular risk factor among end-stage renal disease patients

Secondary hyperparathyroidism (HPTH) was initially viewed as a disorder of the skeletal system; however, recent population-based data have associated markers of HPTH with an increased cardiovascular mortality among patients with end-stage renal disease (ESRD). This has stimulated much interest in further evaluating secondary HPTH as a cardiovascular disease risk factor, as well as the putative role of its therapy. This article explores the current state of scientific evidence concerning the pathophysiology of cardiovascular disease among the ESRD population and potential risk factors for its development, including markers of HPTH, and its therapies.

Coronary arteriographic findings in symptomatic and asymptomatic subjects with coronary artery calcification

The relation of coronary artery calcification with the presence of symptoms of coronary artery disease and its angiographic severity is not clear. We studied 37 apparently healthy, asymptomatic subjects that were found by digital cinefluoroscopy to have coronary calcium and compared to age- and sex-matched group of patients with coronary calcium and symptomatic coronary artery disease. Normal coronary arteries and non-obstructive lesions only were found in 12/37 (32.4%) and 11/37 (29.7%) asymptomatic subjects vs. 1/37 (2.7%) and 2/37 (5.4%) patients; P<0.001 and P<0.012, respectively. Obstructive lesions were more rare in asymptomatic subjects than in patients, 14/37 (37.8%) vs. 34/37 (91.9%) (P<0.0001), as well as total occlusions, 2/37 (5.4%) vs. 10/37 (27%) (P<0.024). Median worst lesion stenosis was 30% in asymptomatic subjects and 95% in patients (P<0.0001). In asymptomatic usual cardiovascular risk subjects, coronary calcium detection by digital cinefluoroscopy is accompanied by a relatively high probability of obstructive disease, although less severe angiographically than in age- and sex-matched catheterized patients with symptomatic coronary artery disease.

Coronary calcium: the good, the bad, and the uncertain

BACKGROUND

Coronary calcium deposits have been widely regarded to result from a passive process of encrustation or adsorption of mineral onto advanced, complex atherosclerotic lesions. Increasing interest has focused on noninvasive radiologic detection of these calcium deposits as a diagnostic and prognostic adjunct to clinical evaluation of coronary artery disease, particularly with the use of newer, high-resolution imaging techniques such as electron beam computed tomography.

METHODS AND RESULTS

We reviewed the literature on coronary calcium and its relation to pathologic atherosclerosis, angiographic stenoses,and clinical events. Clinical calcium detection studies have demonstrated an association between coronary calcium and both extent of coronary artery disease and risk of adverse events. These studies have in the past tended to reinforce the perception that calcific deposits result from a passive mineralization process, signify advanced coronary artery disease, and foreshadow future coronary events.

CONCLUSIONS

Recent pathologic, genetic, clinical, and biochemical evidence reviewed in this article suggests that coronary calcium deposits are a manifestation of a complex, organized, and regulated process similar in many respects to new bone formation and may not be a reliable indicator of either the extent of coronary disease or the risk of a future event. These studies also suggest that atherosclerosis and calcific deposits may be distinct pathologic entities that frequently occur together and are related to each other in ways that are poorly understood.

Imaging of coronary artery calcification. Its importance in assessing atherosclerotic disease

Coronary artery calcification is a marker for atherosclerotic disease. The calcifications frequently occur early in the disease process and often before the development of luminal narrowing or cardiac events. Electron beam CT has a high accuracy in detecting calcifications, and thus has prognostic value in predicting luminal narrowing and future cardiac events.

Coronary calcification and coronary atherosclerosis: site by site comparative morphologic study of electron beam computed tomography and coronary angiography

OBJECTIVES

We compared, on a site by site basis, the morphologic features of coronary calcifications determined by electron beam computed tomography (EBCT) and angiographically defined coronary atherosclerosis.

BACKGROUND

Quantification of coronary calcification using EBCT is clinically useful for the prediction of coronary stenosis. However, the relation between calcification and angiographic findings has not been evaluated by site.

METHODS

We studied 251 consecutive patients who underwent elective coronary angiography for suspected coronary artery disease by EBCT and analyzed findings by site. Coronary calcifications were classified according to their length and width versus the diameter of the coronary artery in which the calcification was observed as: none, spotty, long, wide and diffuse.

RESULTS

Coronary calcifications were found in 666 (27%) of 2,470 segments. The positive predictive value (PPV) of coronary calcification for significant stenosis (> or = 75% densitometric narrowing) and for all angiographically detectable atherosclerotic lesions in a segment was 0.36 and 0.80, respectively. The PPV for significant stenosis and all atherosclerotic lesions was 0.04 and 0.17 in none, 0.18 and 0.59 in spotty, 0.32 and 0.87 in long, 0.40 and 0.84 in wide and 0.56 and 0.96 in diffuse calcifications, respectively. The PPV for both significant stenosis and all lesions differed significantly (p = 0.001) among the morphologic groups. Of the 105 eccentric significant stenoses, 54 (53%) were classified as long or diffuse calcifications. Of the 95 significant stenoses with multiple irregularities, 61 (64%) showed diffuse calcification.

CONCLUSIONS

Morphologic evaluation of coronary calcifications using EBCT improved the prediction of coronary stenosis on a site by site basis and provided information related to angiographic morphology.

Coronary artery calcium detected by digital fluoroscopy and risk factors in healthy subjects

Coronary artery calcium detected by digital fluoroscopy is closely associated with known risk factors of coronary artery disease in asymptomatic low-risk populations. Even in the absence of significant luminal narrowing, this may not be an innocent finding, and subjects with coronary calcium may be at greater risk for developing obstruction and clinical disease.

Noninvasive prediction of coronary atherosclerosis by quantification of coronary artery calcification using electron beam computed tomography: comparison with electrocardiographic and thallium exercise stress test results

OBJECTIVES

This study was designed to compare the usefulness of electron beam computed tomography for prediction of coronary stenosis with that of electrocardiographic (ECG) and thallium exercise tests.

BACKGROUND

Electron beam computed tomography can quantify coronary calcifications; however, its clinical value has yet to be established.

METHODS

Using the volume mode of electron beam computed tomography, we studied 251 consecutive patients who underwent elective coronary angiography because of suspected coronary artery disease and compared the results with those of ECG and thallium exercise tests. The total coronary calcification score was calculated by multiplying the area ( > or = 2 pixels) of calcification (peak density > or = 130 Hounsfield units) by an arbitrarily weighted density score (0 to 4) based on its peak density. The mean of two scans was log transformed.

RESULTS

Calcification was first noted in women in the 4th decade of life, approximately 10 years later than its occurrence in men. Among patients with advanced atherosclerosis (two- and three-vessel disease), calcification scores were uniformly high in women but ranged widely in men. Nine percent of patients with significant stenoses ( > or = 75% by densitometry) had no calcification. The calcification scores of patients with significant stenosis in at least one vessel were significantly higher than those of patients without significant stenosis in the study group as a whole and in most patient subgroups classified according to age and gender. A cutoff calcification score for prediction of significant stenosis, determined by receiver operating characteristic curve analysis, showed high sensitivity (0.77) and specificity (0.86) in all study patients; sensitivity was similarly high even in older patients ( > or = 70 years) and was enhanced in middle-aged patients (40 to < or = 60 years). The difference in specificity between calcification scores and ECG exercise test results had borderline significance (p = 0.058) and that between calcification scores and thallium test results was significant (p = 0.001). The latter difference became small but remained significant (p = 0.01) even after the reevaluation of thallium test results in light of each subject's clinical data.

CONCLUSIONS

Quantification of coronary artery calcification with electron beam computed tomography noninvasively predicted angiographically confirmed coronary stenosis. Results obtained with this method were at least as useful and potentially better in some patient groups than those obtained with thallium and ECG exercise testing.

Racial differences in coronary calcium prevalence among high-risk adults

A total of 1,461 asymptomatic high-risk adult subjects were studied with digital subtraction fluoroscopy and conventional cinefluoroscopy to detect coronary calcium. Ethnicity and risk factor data were recorded. No subject had a history or electrocardiographic evidence of prior myocardial infarction. The prevalence of coronary calcium by digital subtraction fluoroscopy was high (58%). Substantial ethnic differences in prevalence were noted: 36% of African American subjects, 60% of Caucasian subjects, and 60% of Asian American subjects had definite radiographic evidence of coronary calcium. The difference in prevalence between African American and other subjects was significant (p < 0.0001) by chi-square test for all 3 races. These differences persisted in the unsubtracted cinefluoroscopic images (p < 0.0001) and after controlling for age, gender, and other risk factors (p = 0.003). After 20 +/- 11 months of follow-up, African Americans had more coronary artery disease events (13%) than Caucasians (6%) or Asian Americans (5%) (p = 0.04). Thus, African Americans have a significantly lower prevalence of coronary calcium than do Caucasians or Asian Americans. Based on the follow-up results, these differences in prevalence are not explained by differences in coronary artery disease risk.

Usefulness of cinefluoroscopic detection of coronary artery calcification in the diagnostic work-up of coronary artery disease

AIM

To determine in which patients (cine)fluoroscopic detection of coronary artery calcifications is recommended for the diagnosis of coronary artery disease and the consequence of this finding for referral for cinecoronary arteriography.

MATERIALS AND METHODS

Data were retrospectively obtained from 778 patients who had been referred for cinecoronary arteriography. Excluded were patients with a previous myocardial infarction, a previous abnormal cinecoronary arteriogram and patients with unstable angina. The discriminating value was assessed with the help of the crude likelihood ratio (LR), as well as the LRs stratified for gender, age and symptomatology. The gold standard was the coronary arteriogram. Furthermore, the post-test probability was estimated using logistic regression to take dependence on age, sex and symptomatology into account.

RESULTS

The crude LR of a positive and negative test result, with 95% confidence intervals, was, respectively 5.8 (4.1-8.2) and 0.52 (0.47-0.58), but was dependent on the clinical variables. Estimated probabilities of having coronary artery disease (CAD) varied substantially for a negative as well as a positive test result with the categories of clinical variables.

CONCLUSION

(Cine)fluoroscopy discriminates between patients with and without disease; the test proved to be especially useful in females with atypical angina and patients of both sexes with non-specific chest pain.

Comparison of the diagnostic value of cinefluoroscopy and simple fluoroscopy in the detection of calcification in coronary arteries

AIM

Comparison of the diagnostic value of cinefluoroscopy and simple fluoroscopy in the detection of calcification in coronary arteries.

PATIENTS AND METHODS

Data were prospectively obtained from 143 patients in whom simple fluoroscopy as well as cinecoronary arteriography were performed. Excluded were patients with a previous myocardial infarction, a previous abnormal cinecoronary arteriogram and patients with unstable angina. With the coronary arteriogram as the gold standard, the likelihood ratios (LR) of simple fluoroscopy were determined, mismatches with cinefluoroscopy were analysed and Kappa, as a measure for inter-test agreement, was calculated.

RESULTS

The LRs with 95% confidence intervals for a positive and negative result were 5.3 (2.6-11.0) and 0.43 (0.28-0.69), respectively. There was a mismatch in 12 (8.3%) patients. Kappa with a 95% confidence interval was 0.90 (0.73-1.0).

CONCLUSIONS

Both test modalities are almost identical and conclusions with respect of the diagnostic value of cinefluoroscopy also holds for simple fluoroscopy.

Quantitation of in vitro coronary artery calcium using ultrafast computed tomography

Ultrafast computed tomography (UFCT) has the potential to quantify coronary hydroxyapatite (HAP). However, no definitive studies validating this technique are available. We constructed a human chest phantom model with coronary arteries represented by cylindrical holes containing: (1) calcium chloride solutions, (2) a block of HAP immersed in paraffin (without partial volume effect), and (3) HAP granules embedded in a gelatin matrix (with partial volume effect). We scanned this model to determine the relationship between measured CT number per voxel and density of the calcium per voxel. The relationships between CT number and concentration of calcium chloride was linear (r = 0.992 to 0.999). Using a commercially available standard bone mineral phantom, we were able to estimate the concentration of HAP to an accuracy from 94 to 97% when partial volume effects were absent. However, when partial volume effects were present, two methods of estimating HAP produced significant errors (1 to 384%, and 17 to 52%). We conclude that significant partial voluming errors degrade the accuracy of HAP quantitation and that further evaluation and corrections are needed before such quantitation is clinically applied.

Prognostic significance of cardiac cinefluoroscopy for coronary calcific deposits in asymptomatic high risk subjects

OBJECTIVES

This research investigated the prognostic significance of radiographically detectable coronary calcific deposits.

BACKGROUND

Coronary calcific deposits are almost always associated with coronary atherosclerosis. We investigated the association between fluoroscopically determined coronary calcium and coronary heart disease end points at 1 year of follow-up.

METHODS

This prospective population-based cohort study was conducted in the suburbs of Los Angeles. Fourteen hundred sixty-one asymptomatic adults with an estimated > or = 10% risk of having a coronary heart disease event within 8 years underwent cardiac cinefluoroscopy for assessment of coronary calcium at initiation of the study. Clinical status including angina, documented myocardial infarction, myocardial revascularization and death from coronary heart disease were determined after 1 year.

RESULTS

The prevalence of calcific deposits was high (47%). A follow-up examination at 1 year was successfully completed in 99.9% of subjects. Six subjects (0.4%) had died from coronary heart disease and 9 (0.6%) had had a nonfatal myocardial infarction. Thirty-seven subjects (2.5%) reported angina pectoris, and 13 (0.9%) had undergone myocardial revascularization. Fifty-three subjects had at least one event during the 1-year period. Radiographically detectable calcium was associated with the presence of at least one of these end points, with a risk ratio of 2.7 (confidence limits 1.4, 4.6). The presence of coronary calcium was an independent predictor of at least one end point when controlling for age, gender and risk factors. However, three deaths due to coronary heart disease and two nonfatal myocardial infarctions occurred in subjects without detectable coronary calcium.

CONCLUSIONS

The presence of coronary calcific deposits incurs an increased risk of coronary heart disease events in asymptomatic high risk subjects at 1 year. This increased risk is independent of that incurred by standard risk factors.

Coronary arterial calcification as an active process: a new perspective on an old problem

The mechanism and purpose of coronary atherosclerotic calcification remain unknown. However, evidence reviewed here suggests that calcification is not passive precipitation or adsorption, but instead is organized and regulated. Gla containing proteins and other proteins normally associated with bone metabolism appear to play an important role in this process. A variety of studies are currently in progress in our laboratory which we hope will provide a more comprehensive understanding of processes leading to coronary calcification as well as prognostic data useful in clinical cardiologic practice. A clearer understanding of the nature and significance of coronary calcification may well pave the way toward new interventions to protect myocardium and minimize the morbidity and mortality associated with coronary artery disease.

Coronary calcium and atherosclerosis by ultrafast computed tomography in asymptomatic men and women: relation to age and risk factors

We evaluated 675 men and 190 women who had no symptoms or history of clinical CHD, to determine the prevalence and risk factor correlates of CAC deposits as a marker of atherosclerosis. Measurements were taken noninvasively by ultrafast CT. The presence and extent of CAC deposits as measured by ultrafast CT was determined in all subjects, who also received personal and family medical history and risk factor questionnaire. The prevalence of CAC deposits increased significantly with age, ranging from 15% and 30% in men and women, respectively, < 40 years of age to 93% and 75% in those aged > or = 70 years. Prevalence and total score also increased by the number of risk factors present, although in those aged > 60 years a high prevalence (> 80% in men) of calcium was present regardless of the presence of risk factors. In multiple logistic regression, age, male gender, hypertension, diabetes, hypercholesterolemia, and obesity were independently associated with CAC deposits. These results suggest a high prevalence of atherosclerosis with increasing age and the presence of risk factors in men and women who have no symptoms. Studies to determine the prognostic value of CAC in individuals with no symptoms are needed to determine which populations may benefit most from CAC deposit screening.

Differences in prevalence and extent of coronary artery calcium detected by ultrafast computed tomography in asymptomatic men and women

Coronary artery calcium is a marker of atherosclerosis in asymptomatic subjects. Ultrafast computed tomography (CT) can detect and quantify coronary calcium, simply and noninvasively, with greater sensitivity than can other techniques. The prevalence and extent of coronary calcium in a large population of asymptomatic men and women were measured and compared. Coronary calcium studies were performed in an asymptomatic population of 1,396 male and 502 female subjects (age range 14 to 88 years). The prevalence of calcium, and the distribution of total calcium scores (which reflect the amount of calcium present) were determined and compared for men and women at 5- and 10-year intervals. The prevalence of calcium in women was half that of men, until the age of 60 years when the difference diminished. The mean total calcium score distributions of men between the ages of 40 and 69 years were virtually identical to those of women between the ages of 50 and 79. The quantitative data obtained by Ultrafast CT showed very close agreement with autopsy studies of coronary calcium. Ultrafast CT is a sensitive technique to measure coronary calcium in both men and women. The differences in prevalence and extent of coronary calcium appear to be parallel to those observed in the clinical incidence of coronary artery disease in men and women. Ultrafast CT may have a greater impact on the treatment of women than of men, because it can be used to provide objective evidence of coronary atherosclerosis.

Risk factor correlates of coronary calcium as evaluated by ultrafast computed tomography

Coronary artery calcium is invariably associated with atherosclerosis and has been linked to an increased risk of coronary events. Ultrafast computed tomography (CT) was recently used to document the presence and relative quantity of coronary calcium. The use of the self-reported coronary risk factors to identify persons with coronary calcium as documented by ultrafast CT screening was examined in 458 men and 139 women aged 26 to 81 years (88% asymptomatic). All subjects underwent ultrafast CT scanning, and received a questionnaire and underwent an interview regarding medical and risk factor history. Total calcium score was calculated as the sum of lesion-specific scores, each calculated as the product of density > or = 130 Hounsfield units and area > or = 0.51 mm2. The prevalence of coronary calcium increased significantly (p < 0.01) by age group, and the greater the number of risk factors present, the greater the likelihood of calcium. From multiple logistic regression, age (p < 0.01), male sex (relative risk [RR] 3.03; p < 0.01), and history of smoking (RR 1.85; p < 0.01) and hypertension (RR 1.65; p < 0.05) were independently associated with the probability of detectable calcium. Among asymptomatic subjects, an association with hypercholesterolemia was also seen (RR 1.56; p < 0.05). The results demonstrate that cardiovascular risk factors can help in identifying the likelihood of coronary calcium.

Hypothesis: etiology of atherosclerosis and osteoporosis: are imbalances in the calciferol endocrine system implicated?

Atherosclerosis and osteoporosis are currently considered unrelated diseases. Osteoporosis involves bone calcium (Ca) loss and predominantly affects females after menopause. Atherosclerosis is an illness predominantly affecting males, and is primarily characterized by abnormal lipid metabolism. However, pathological calcification of the arterial wall is an underlying feature of atherosclerosis. Ca homeostasis is thus important in atherosclerosis as well as in osteoporosis. Men also develop osteoporosis although at a later age than women, and, as osteoporosis progresses in women, there is an accompanying calcification of arteries leading to increased incidence of atherosclerosis in aging women. Thus, during old age, both atherosclerosis and osteoporosis are prevalent in both males and females. The dramatic increase in atherosclerosis among women as they develop osteoporosis suggests that the two illnesses may be more closely related than previously realized. The use of vitamin D as a food supplement coincides with epidemic onsets of atherosclerosis and osteoporosis, and excess vitamin D induces both conditions in humans and laboratory animals. These observations suggest a role for chronic vitamin D excess in the etiology of the two illnesses. Magnesium (Mg) deficiency, nicotine, and high dietary cholesterol are contributing factors that accentuate adverse effects of vitamin D.

Clinical significance of the calcification of coronary arteries in patients with angiographically normal coronary arteries

In order to clarify the clinical significance of coronary calcification in patients with angiographically normal coronary arteries, exercise electrocardiography was used and left ventricular function was examined noninvasively and invasively. The patient groups were as follows: (1) patients with coronary artery calcification on only the left anterior descending artery but no narrowing lesion on any other arteries (calcified group), (2) patients with a significant stenosis on only the left anterior descending artery (stenotic group), and (3) the control group. The left ventricular function in the calcified group, as indicated by systolic time intervals and invasive parameters such as ejection fraction and mean systolic ejection rate, showed a depression similar to that in the stenotic group, compared with the control group. The incidence of electrocardiographically ischemic responses to exercise testing was significantly higher in the calcified group (75%, p less than 0.01) and the stenotic group (68%, p less than 0.01) than in the control group (25%). Exercise tolerance time and the maximum double product were markedly smaller in the calcified and the stenotic groups as compared with the control group. These results indicate that the left ventricular function and coronary reserve in the calcified group were reduced and almost identical with those in the stenotic group. The authors conclude that a calcified coronary artery, even if patent, cannot supply an adequate blood flow for the myocardium, resulting in impaired left ventricular function.

Fluoroscopic coronary artery calcification and associated coronary disease in asymptomatic young men

Little is known about the diagnostic significance of coronary artery calcification detected fluoroscopically in apparently healthy young men. This study compared the presence of fluoroscopically detected coronary artery calcification with angiographic coronary artery disease in asymptomatic male military aircrew undergoing noninvasive cardiac screening tests and coronary arteriography for occupational indications. Of 1,466 men screened with coronary fluoroscopy, 613 underwent coronary arteriography because of one or more abnormal noninvasive test results. The mean age (+/- SD) of all subjects screened was 40.2 +/- 5 years (range 26 to 65). Significant coronary artery disease (greater than or equal to 50% diameter stenosis) was found in 104 of the 613 subjects with arteriograms (16.9% disease prevalence). Overall sensitivity and specificity for coronary artery calcification detection of significant disease, based only on those subjects undergoing arteriography, were 66.3% and 77.6%, respectively. For measurable disease (mild plus significant), sensitivity was 60.6% and specificity 85.9%. Positive and negative predictive values were 37.7% and 91.9%, respectively, for significant disease. For measurable disease, positive and negative predictive values were 68.9% and 80.9%, respectively. In these asymptomatic young men, a fluoroscopic examination negative for coronary artery calcification indicated a low risk of significant coronary artery disease, whereas a positive test result (calcification present) substantially increased the likelihood of angiographically significant coronary artery disease.

Detection of coronary artery calcification by X-ray computed tomography and its significance: a new CT scoring technique

In order to study the utility of X-ray computed tomography (CT) for the evaluation of coronary stenosis, the authors developed a scoring system for calcification seen through CT and compared the results with coronary angiographic (CAG) findings (Friesinger's scoring system). Their study included 143 patients (angina pectoris 53, myocardial infarction 44, control 46) who received both CT and CAG. Judkins method was selected for CAG, and stenosis greater than or equal to 75% was defined as significant. Horizontal slices of CT from ascending aorta to cardiac apex at 1 cm intervals were imaged without contrast enhancement. CT scoring system was as follows: no calcification = 0, the length of calcification less than 1 cm = 1, 1-2 cm = 2, more than 2 cm = 3 points. They then totaled the separate scores of all the slices for each coronary artery. Sensitivity, specificity, and predictive value of CT against coronary stenosis were good (79%, 80%, 69%, respectively). The correlation between CT and CAG scores was significant (r = 0.644, p less than 0.01). For all coronary arteries, no correlation was found between the CAG and CT findings for patients less than forty-five years of age. However, from 45 years of age upward, the results were significant. Until now, to the best of their knowledge, no satisfactory system to define the severity of coronary calcification has existed. Density cannot be used, because values are dependent on the area of the region of interest used. They demonstrated the considerable potential usefulness of CT in predicting the presence of coronary stenosis and analyzing its severity.