Use Of Electron Beam Tomography Research Articles

The mainstream hypothesis that LDL cholesterol drives atherosclerosis may have been falsified by non-invasive imaging of coronary artery plaque burden and progression

That LDL cholesterol drives atherosclerosis is a widely if not almost universally held belief, and this belief strongly influences the mainstream approach to coronary heart disease. However heart disease has a number of stages, and in terms of primary prevention, the initiation and progression of silent or sub-clinical atherosclerosis is clearly fundamental. However, studies that address the efficacy of interventions and practices aimed at the primary prevention of heart disease almost always use event-based endpoints such as fatal or non-fatal myocardial infarction or unstable angina. These endpoints do not directly relate to the primary prevention of silent atherosclerosis and to apply these results to asymptomatic individuals in this context involves an extrapolation. The advent of non-invasive imaging techniques which allow the determination of coronary artery plaque burden and progression of plaque has provided a unique opportunity to examine the relationship between both traditional and emerging risk factors and the extent of sub-clinical coronary artery disease and in particular allow the testing of the hypothesis that LDL cholesterol drives coronary atherosclerosis. Consistent with earlier autopsy studies, the use of electron beam tomography and contrast enhanced CT angiography techniques have created a large body of evidence which appears to falsify this hypothesis. The large number of null results for the association between serum LDL cholesterol levels and the prevalence or progression of both calcified and non-calcified plaque in the appropriate vascular bed and involving large numbers of men and women over a wide range of age, ethnic background, plaque burden and cholesterol levels cannot be easily dismissed. If the hypothesis is false, this has a significant impact on currently held views regarding risk factors and therapeutic interventions in the case of individuals who are asymptomatic, that is, issues associated with primary prevention. Also, if the hypothesis is false, then the use of changes in LDL as a surrogate marker for judging the importance of various risk factors for silent atherosclerosis and thus coronary artery disease can be called into question.

Letter to the Editor

Calcifications are part of the development of atherosclerosis; they occur exclusively in atherosclerotic arteries and are absent in the normal vessel wall.1 Studies have demonstrated calcification in both coronaries and aortic arteries to be a specific marker of underlying atherosclerosis in the respective vascular beds.1 Extensive evidence exist that men are more likely to have calcification in the coronary arteries2,3; however, whether similar difference exists in other vascular beds is not well established. The purpose of this study is to evaluate whether the lower risk of atherosclerosis observed in coronary circulation in women compared with men is also observed in thoracic aorta. This is a cross-sectional study on a consecutive sample of 8549 asymptomatic individuals (69% men, mean age: 52±9 years) patients who presented to a single EBT scanning facility for CHD risk stratification.4 A history of cigarette smoking was considered present if a subject was a current or former smoker. Dyslipidemia was coded as present for any individual self-reporting a history of high total cholesterol, high LDL, low HDL, and/or high triglycerides, or current use of lipid-lowering therapy. Patients were considered to have diabetes if they reported using oral hypoglycemic agents, insulin sensitizers, or subcutaneous insulin and hypertension if they reported a history of high blood pressure or used antihypertensive medications. A family history of CHD was considered premature if the immediate family (parents or siblings) experienced a fatal or nonfatal myocardial infarction before age of 55 years. Individuals …

New Cholesterol Guidelines for Children?

For children and adolescents, comprehensive guidelines for the diagnosis and management of elevated cholesterol have been published once, by the National Cholesterol Education Program in 1992.1 Since then, substantial research on early atherosclerosis and in related clinical areas has been conducted; simultaneously, the obesity epidemic has added the metabolic syndrome and its related high-triglyceride/low–high-density lipoprotein (HDL) phenotype to the agenda of those interested in establishing a consensus approach to early cardiovascular disease prevention.2 Article p 1056 Before assuming that new knowledge and secular trends in risk factors demand substantial revision of cardiovascular health guidelines for children, we must first consider several valuable, often prescient aspects of the 1992 report. First is an emphasis on the importance of nutritional management over pharmacological management of elevated low-density lipoprotein (LDL) cholesterol, unless levels clearly associated with premature cardiovascular disease exist and children are sufficiently old that advanced atherosclerotic lesions may be presumed to be present. Two randomized trials of dietary intervention, the DISC (Dietary Intervention Study in Children) and STRIP (Special Turku coronary Risk factor Intervention Project for babies) studies, have shown that the diet recommended by the 1992 report is safe and mildly effective in lowering LDL cholesterol and thus can be implemented in population-based strategies of cardiovascular disease risk lowering.3,4 Furthermore, the PDAY (Pathobiological Determinants of Atherosclerosis in Youth) study has shown that advanced, irreversible atherosclerotic lesions (American Heart Association grades IV and V) are rarely present before 19 years of age and that the relationship of risk to atherosclerosis in late adolescence is with regard to reversible early lesion grades (American Heart Association grades I through III).5 A second and woefully underrecognized virtue of the 1992 report is the definition of risk strata for LDL cholesterol, with borderline values being 110 to 129 mg/dL and high …

Gender-Based Differences in the Prognostic Value of Coronary Calcification

To investigate the use of electron beam tomography (EBT) screening to predict all-cause mortality in a large cohort of asymptomatic women and men. We obtained mortality information from the National Death Index in 10377 asymptomatic individuals (40% women) referred by primary care physicians for coronary calcification screening. The average follow-up period was 5 +/- 3.5 years. Univariable and multivariable Cox proportional hazard models were developed to predict all-cause mortality. Women had a lower prevalence of coronary calcification and smaller calcification scores than men (p < 0.0001). Death rates were higher among older, diabetic, hypertensive, and currently smoking individuals both in women and in men. In unadjusted (chi-square = 82, p < 0.0001) as well as risk-adjusted (chi-square = 7, p = 0.007) Cox survival models, women had a greater probability of death than men in each strata of calcification. Relative risk (RR) ratios were increased 3.0-fold, 5.5-fold, and 5.5-fold, respectively, for women compared with men with coronary calcification scores of 101-399, 400-1000, and >1000 (p < 0.0001). Using receiver operating characteristics (ROC) curve analyses to assess coronary calcification added incremental prognostic value to Framingham risk scores (p < 0.0001). In this cohort of asymptomatic women, coronary calcification screening provided incremental prognostic information after adjustment for traditional risk factors. EBT may be a useful tool for risk stratification in women, where the early diagnosis of coronary heart disease (CHD) remains a strong challenge.

Impact of electron beam tomography with or without case management, on motivation, behavioral change, and cardiovascular risk profile. A randomized controlled trial

ContextAlthough the use of electron beam tomography (EBT) as a motivational tool to change behavior is practiced, its efficacy has not been studied.ObjectiveTo assess the effects of incorporating EBT as a motivational factor into a cardiovascular screening program in the context of either intensive case management (ICM) or usual care by assessing its impact over 1 year on a composite measure of projected risk.DesignRandomized controlled trial with a 2 × 2 factorial design and 1 year of follow-up.Setting and ParticipantsA consecutive sample of 450 asymptomatic active-duty US Army personnel aged 39 to 45 years stationed within the Washington, DC, area and scheduled to undergo a periodic Army-mandated physical examination were enrolled between January 1999 and March 2001 (mean age, 42 years; 79% male; 66 [15%] had coronary calcification; mean [SD] predicted 10-year coronary risk, 5.85% [3.85%]).InterventionsPatients were randomly assigned to 1 of 4 intervention arms: EBT results provided in the setting of either ICM (n = 111) or usual care (n = 119) or EBT results withheld in the setting of either ICM (n = 124) or usual care (n = 96).Main Outcome MeasureThe primary outcome measure was change in a composite measure of risk, the 10-year Framingham Risk Score (FRS).ResultsComparing the groups who received EBT results with those who did not, the mean absolute risk change in 10-year FRS was +0.30 vs +0.36 (P = .81). Comparing the groups who received ICM with those who received usual care, the mean absolute risk change in 10-year FRS was −0.06 vs +0.74 (P = .003). Improvement or stabilization of cardiovascular risk was noted in 157 patients (40.2%). In multivariable analyses predicting change in FRS, after controlling for knowledge of coronary calcification, motivation for change, and multiple psychological variables, only the number of risk factors (odds ratio, 1.42; 95% confidence interval, 1.16-1.75 for each additional risk factor) and receipt of ICM (odds ratio, 1.62; 95% confidence interval, 1.04-2.52) were associated with improved or stabilized projected risk.ConclusionsUsing coronary calcification screening to motivate patients to make evidence-based changes in risk factors was not associated with improvement in modifiable cardiovascular risk at 1 year. Case management was superior to usual care in the management of risk factors.

Point: Diabetic Patients and Coronary Calcium: Risk stratification, compliance, and plaque progression.

The use of electron beam tomography (EBT) is becoming increasingly accepted for risk stratification in the asymptomatic patient (1). Coronary artery calcium (CAC), as measured by EBT, has been shown to be a marker of increased risk in every prognostic study published to date, in both symptomatic and asymptomatic cohorts (2). The relationship of CAC to angiographic disease holds the same tight correlation in persons with diabetes as in nondiabetic patients (3), suggesting that the risk stratification with EBT will be as robust in individuals with diabetes as in others. The only prognostic study of EBT and diabetes published to date demonstrates that diabetic subjects with CAC were four times more likely to suffer a cardiac event than nondiabetic subjects with low calcium scores ( P < 0.001) (4). The new National Cholesterol Education Panel (NCEP) guidelines (5) support the conclusions of the Prevention Conference V and the American College of Cardiology (ACC)/American Heart Association (AHA) report that high coronary calcium scores signify and confirm increased risk for future cardiac events. “Therefore, measurement of coronary calcium is an option for advanced risk assessment in appropriately selected persons. In persons with multiple risk factors, high …

Usefulness of electron beam tomography in the prone position for detecting atrial thrombi in chronic atrial fibrillation.

We compared the usefulness of electron beam tomography (EBT) in the prone position relative to that in the supine position for detecting atrial thrombi. We studied 96 patients with chronic atrial fibrillation, of whom 71 were scanned in the supine position and 25 were scanned in the prone position. Electron beam tomography was performed twice after contrast medium injection to obtain early- and late-phase images. Filling defects were detected in 13 patients in the supine position by EBT. Transesophageal echocardiography (TEE) revealed a thrombus in the region of the filling defect in 9 patients. In 4 patients, filling defects in the left atrial appendage were not confirmed as thrombi by TEE. Filling defects were detected in 4 patients in the prone position, all of which were confirmed as thrombi by TEE. Electron beam tomography in the prone position is an effective technique for reducing false-positive results in the detection of atrial thrombi.

Electron beam tomography and angiography: Sex differences

Background We sought to study a large cohort of symptomatic women to determine the clinical use of electron beam tomography (EBT), with evaluation of the sensitivity and specificity of obstructive coronary disease and the differences between premenopausal and postmenopausal cohorts. Methods Patients who underwent angiography for evaluation of coronary artery disease (CAD) and EBT within 3 months were enrolled. Receiver operating characteristic curves were used to establish relationships between EBT calcium scores and angiographic disease. Results We studied 1120 symptomatic patients, 387 women and 733 men. We found no significant differences with respect to sensitivity for obstructive disease (96% in men and women). However, women had a significantly higher specificity (46% in men versus 57% in women; P =.01). The area under the curves for coronary calcium score predicting angiographic disease was 0.85 for all patients and 0.84 in women. Evaluation of scores on the basis of age revealed a 14.4-year lag between men and women. One hundred thirty-five women had negative EBT study results (score, zero; no calcium present), with 6 with single-vessel disease and 129 with normal coronaries or nonobstructive disease only (negative predictive value, 96%). Conclusion EBT may have a great value in evaluation of women with possible CAD. The high sensitivity and high negative predictive value may serve as the basis for a new diagnostic approach to filter symptomatic women with suspected CAD before coronary angiography. (Am Heart J 2002;143:877-82.)

Screening patients with chest pain in the emergency department using electron beam tomography: a follow-up study

OBJECTIVESThe high sensitivity of electron beam tomography (EBT) in the detection of coronary artery calcium (CAC) and obstructive coronary artery disease prompted us to investigate the association between CAC detection and future cardiac events in patients with acute chest pain syndromes requiring hospitalization.BACKGROUNDThree studies have documented that EBT is a rapid and efficient screening tool for patients admitted to the emergency department (ED) with chest pain, but there is a paucity of long-term follow-up data on these chest pain patients.METHODSWe conducted a prospective observational study of 192 patients admitted to the ED of a large tertiary care hospital for chest pain syndromes. Upon admission, patients underwent EBT scanning in addition to the usual care for chest pain syndromes. During the 17-month enrollment period, 221 patients were scanned (54% men with a mean age of 53 ± 9 years). Average follow-up was 50 ± 10 months using chart review.RESULTSFifty-eight patients had coronary events confirmed by a blinded medical record review. The presence of CAC (a total calcium score >0) and increasing score quartiles were strongly related to the occurrence of hard cardiac events including myocardial infarction and death (p < 0.001) and all cardiovascular events (p < 0.001). Stratification by age- and gender-matching further increased the prognostic ability of EBT (for scores above vs. below the age- and gender-matched CAC scores; odds ratio: 13.1, 95% confidence intervals: 5.62, 35.9).CONCLUSIONSThese data support previous reports demonstrating that the presence of CAC in a symptomatic cohort is a strong predictor of future cardiac events. This study supports the use of EBT in a symptomatic cohort with prompt discharge of those patients with negative scans. Furthermore, the absence of CAC is associated with a very low risk of future cardiac risk events in this population over the subsequent seven years (annual event rate <1%).

Usefulness of electron beam tomography to detect progression of coronary and aortic calcium in middle-aged women

Electron beam tomography (EBT) permits the noninvasive quantification of coronary and aortic calcium as a marker of atherosclerosis. Coronary and aortic calcium are strongly related to premenopausal cardiovascular risk factors in middle-aged women. This report evaluates changes in coronary and aortic calcium over an average of 18 months in 80 women. Measurement variation over time and between readings is also evaluated in these women who were followed through the menopausal transition. Eight years after menopause, 80 women (average age 63 years) underwent serial EBT of the coronary arteries and aorta separated by 18 months. Calcium scores were based on the number and density of calcific deposits. Duplicate readings were obtained to evaluate the effect of reading variation on calcium scores. At baseline, the median calcium score was 0 in the coronary arteries and 58 in the aorta. Average change in coronary (+11) and aortic (+112) calcium were significantly different from zero (p <0.001). Reading variability did not contribute significantly to the variation in calcium scores. Extent of calcium in the coronary arteries was associated with progression of calcium in the aorta (p = 0.013). Both coronary and aortic calcium were significantly associated with premenopausal cardiovascular risk factors. Thus, progression of coronary and aortic calcium using EBT can be observed over a short time in healthy middle-aged women.

Practice guidelines for electron beam tomography: a report of the Society of Atherosclerosis Imaging

Practice guidelines for the use of electron beam tomography to detect and quantitate coronary atherosclerotic plaque burden have been formulated by the Society of Atherosclerosis Imaging using American College of Cardiology/American Heart Association classifications of indications.

Improved Coronary Risk Assessment With Electron Beam Computed Tomography in an Asymptomatic Female With Familial Hypercholesterolemia

Improved Coronary Risk Assessment With Electron Beam Computed Tomography in an Asymptomatic Female With Familial Hypercholesterolemia

Usefulness of electron beam tomography in adolescents and young adults with heterozygous familial hypercholesterolemia.

Because of the success of secondary prevention of coronary events by intense risk factor modification, a more precise measure of atherosclerosis in youth would have great clinical value both in the design of clinical trials for the demonstration of the usefulness of coronary disease prevention early in life and in guiding therapy. Identification of calcium in coronary arteries by electron beam tomography has been associated with severity of atherosclerosis in adults. Twenty-nine youths 11 to 23 years old with familial hypercholesterolemia (average LDL cholesterol, 5.95 mmol/L) underwent electron beam tomography as well as comprehensive risk factor assessment with measurement of total cholesterol, triglycerides, HDL cholesterol, lipoprotein (a), apolipoprotein E phenotype, blood pressure, body mass index, and history of tobacco use. Significant coronary calcium was identified in 7 of 29 subjects. Increased body mass index was significantly associated with the presence of coronary calcium (25.3 versus 20.6 kg/m2, P<0.03). No other risk factors were associated with the presence of coronary calcium. Coronary calcium, uncommonly identified before the fourth decade, was found in a significant percentage of adolescents and young adults with familial hypercholesterolemia. Overweight may increase the likelihood of coronary calcium being present in individuals already at high risk.