10/15/02
EBT powerfully predicts coronary events rates in the South Bay Heart Watch Study. Circulation, the Journal of the American Heart Association, published results of a study of 1,461 subjects followed for 6.4 years. Coronary calcium score was the best predictor of future risk in non-diabetics. The score was more powerful at predicting heart attack or death than age, smoking, blood pressure, weight, total cholesterol, HDL cholesterol or CRP. Click here to view the article (PDF File)

8/27/02
A new study in Circulation, the Journal of the American Heart Association, shows that EBT can be used to track patients being treated with cholesterol lowering medications. The article reports that those patients receiving treatment had a significant reduction in plaque progression. Click here to view the article (PDF File)

 1/16/01
High Coronary Artery Calcium Scores Pose an Extremely Elevated Risk for Hard Coronary Events
Journal of the American College of Cardiology. 1/16/02; Vol. 39, No.2.

 This article from the Tulane University School of Medicine examines the clinical outcome of 98 patients with coronary calcium scores over 1,000. The patients were followed for an average of 17 months. At the time of their scan, all patients were asymptomatic. During the follow up period, 35 patients (36%) experienced a hard coronary event, defined as either a heart attack or death. None of the patients had a stress test or cardiac catheterization after their scan. The annualized event rate for the subjects was therefore 25%. The authors compared these results to follow-up studies of patients with severe perfusion abnormalities on functional stress imaging. Generally, such patients showed an annual event rate of 7%, significantly less than the high calcium score patients. The authors surmise that the very high event rate is due to a very high coronary plaque burden. Extensive diffuse atherosclerosis of the coronary arteries as measured by coronary calcium appears to be more predictive than extensive existing ischemia for an adverse outcome over the ensuing 2-3 year period.

10/23/01-
Physical Activity, Hormone Replacement Therapy and Atherosclerosis in Midlife Women
Circulation, Vol. 104, No.17

Coronary artery disease (CAD) remains the leading cause of death in women. There is now some controversy on the potential beneficial effects of estrogen in primary prevention. Methods: We conducted a preliminary study of 234 perimenopausal and post menopausal women, aged 50 to 74 years. All women were asymptomatic, apparently healthy, and referred for Coronary Calcium (CC) scanning to measure CV risk. Women were interviewed by a research nurse prior to their cardiac scan on estrogen use, menopausal status and exercise. Women underwent CC measure using an Electron Beam Scanner. Measure of other known cardiovascular risk factors were performed. Multivariate regression analysis was utilized to evaluate the relationship between CC, hormone replacement therapy (HRT) and physical activity. Results: Fifty-two percent of the population studied (n=122) reported HRT use. HRT users had a significant lower prevalence of CC (37%) than non-users (50%, p=0.04), and mean calcium scores of HRT users were significantly lower than non-users (p=0.02), after controlling for all cardiovascular risk factors. Logistic regression demonstrated a significant difference in the presence of CC in HRT users as compared to non-users with an odds ratio of 0.58 (p=0.04). A strong positive relationship was found between age and the presence of coronary calcium as shown by logistic regression (p=0.01), with an odds ratio of 1.79 for every 10 years of age. Body mass index was not significantly related to the presence of CC (p=0.52, OR=1.02). In regards to physical exercise, logistic regression women's CC scores improved with increasing levels of physical activity, and logistic regression indicated a significant interaction between physical activity and HRT (p=0.03, OR=4.05). Conclusions: The coronary calcium score, and prevalence of calcification were found to be significantly lower in postmenopausal women receiving HRT than for postmenopausal women not receiving HRT. Also, physical activity is significantly and inversely associated with CC on EBT. These findings suggest that long-term use of HRT (and physical exercise), in a primary prevention population, might have a protective effect upon a woman’s cardiovascular profile.

10/23/01-
Lipid-lowering therapy by cerivastatin significantly reduces the progression of coronary calcifications in hyperlipidemic patients: a prospective study
Circulation, Vol. 104, No. 17

Coronary calcification measured by electron beam tomography (EBT) is a surrogate marker of coronary atherosclerotic plaque burden. In a prospective study, we investigated whether lipid-lowering therapy with the cholesterol synthesis enzyme (CSE) inhibitor cerivastatin reduces the progression of coronary calcification in previously untreated hyperlipidemic patients. METHODS: 50 patients (45 male, 5 female, mean age: 60 years, range: 36-79 years) with hyperlipidemia (LDL-cholesterol > 130 mg/dl on two occasions) and coronary calcifications in EBT were investigated. None of the patients were treated with lipid-lowering drugs. 12 months after the first scan, EBT was repeated and treatment with cerivastatin was initiated (fixed dose of 0.3 mg per day). After 12 months of treatment, a third EBT scan was performed. All EBT scans were performed with identical parameters and coronary calcifications were quantified using a volumetric score. Analysis was performed on an intention-to-treat basis. RESULTS: Cerivastatin therapy lowered the total cholesterol and LDL-cholesterol levels from 245±37 mg/dl and 161±34 mg/dl, respectively, during the untreated period to 183±36 mg/dl and 105±28 mg/dl, respectively, during the treatment period (25% mean reduction in total cholesterol, 35% mean reduction in LDL-cholesterol). HDL-cholesterol increased from 51±11 mg/dl to 55±12 mg/dl (8% increase). The mean volumetric score for calcium was 281±336 at baseline, 355±414 after 12 months without treatment, and 387±439 after 12 months of cerivastatin treatment. The mean absolute increase in coronary calcium therefore was 74±92 score units during the untreated versus 32±64 score units during the treatment period (p = 0.02, t-test for paired samples). The mean annual relative increase in coronary calcium was 30.1% during the untreated and 12.0% during the treatment period (p < 0.001). In 26 patients, the LDL-cholesterol level under treatment was below 100 mg/dl. In these patients, the mean relative increase was 30.7% during the untreated and 2.3% during the treatment period (p < 0.001). CONCLUSION: In hyperlipidemic patients, treatment with the CSE inhibitor cerivastatin significantly reduces the progression of coronary calcification.

7/30/01
Long-Term Prognostic Value of Coronary Calcification Detected by Electron-Beam Computed Tomography in Patients Undergoing Coronary Angiography (Circulation. 2001;104:412.)

Background— Electron-beam CT (EBCT) quantification of coronary artery calcification (CAC) allows noninvasive assessment of coronary atherosclerosis. We undertook a follow-up study to determine whether CAC extent, measured at the time of angiography by EBCT, predicted future hard cardiac events, comprising cardiac death and nonfatal myocardial infarction (MI). We also assessed the potential of selected coronary artery disease (CAD) risk factors, prior CAD event history (MI or revascularization), and angiographic findings (number of diseased vessels and overall disease burden) to predict subsequent hard events.

Methods and Results— Two hundred eighty-eight patients who underwent contemporaneous coronary angiography and EBCT scanning were contacted after a mean of 6.9 years. Vital status and history of MI during follow-up were determined. Cox proportional hazards models were used to compare the predictive ability of CAC extent with selected CAD risk factors, CAD event history, and angiographic findings. Median CAC score was 160 (range 0 to 7633). The 22 patients who experienced hard events during follow-up were older and had more extensive CAC and angiographic disease (P<0.05). Only 1 of 87 patients with CAC score <20 experienced a subsequent hard event during follow-up. Event-free survival was significantly higher for patients with CAC scores <100 than for those with scores >100 (relative risk 3.20; 95% CI 1.17 to 8.71). When a stepwise multivariable model was used, only age and CAC extent predicted hard events (risk ratios 1.72 and 1.88, respectively; P<0.05).

Conclusions— In patients undergoing angiography, CAC extent on EBCT is highly predictive of future hard cardiac events and adds valuable prognostic information.

7/01/01

Screening patients with chest pain in the emergency department using electron beam tomography: a follow-up study (JACC Volume 38, Issue 1, Pages 105-110)

OBJECTIVES -The 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.

BACKGROUND-Three 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.

METHODS-We 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.

RESULTS-Fifty-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).

CONCLUSIONS-These 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%).

6/25/01
The Effect of Type I Diabetes (Juvenile form) on Gender Difference in Coronary Artery Calcium

The December 2000 issue of the Journal of the American College of Cardiology contained an article from the University College London Medical School examining whether early onset diabetes makes women equally susceptible to coronary plaque as men.  It is well known that Type I diabetes raises risk for heart disease in women to a greater degree than in men.  199 diabetic and 201 non-diabetic subjects ages 30-55 had coronary calcification measured with EBT.  Only 1 subject had a prior history of heart disease.  In the non-diabetic subjects, 54% of the men and only 21% of the women had coronary calcification.  In the diabetic group, 47% of the women and 52% of the men had coronary calcification.  Even after adjusting for other risk factors, such as cholesterol and blood pressure, diabetic women had a 300% increase in coronary plaque compared to diabetic men.  The study also discussed the fact that coronary calcification is even better than coronary angiography for measuring the extent of plaque (plaque burden).

4/10/01
Management Approach to Risk Factors as Influenced by EBCT

Dr. Thomas Knickelbine (Minneapolis Heart Institute) presented this paper at the American College of Cardiology 2001 Annual Meeting.  2022 consecutive patients were scanned and underwent conventional risk factor testing.  The patients were divided into low, intermediate, and high risk groups both based on risk factors and, independently, by EBCT.  In the risk factor intermediate risk group, 73% of the patients fell into either high risk or low risk groups when evaluated with EBCT.  In the risk factor high risk group, 67% fell into low or intermediate risk groups based on their EBCT scans. In the risk factor low risk group, 36% fell into intermediate or high risk groups based on EBCT.  These results suggest that a management approach that includes both risk factor analysis and EBCT will be most effective in identifying candidates for aggressive LDL cholesterol reduction and evaluation for flow-limiting coronary disease.

3/16/01
EBT Shown to Detect Atherosclerosis in Apparently Healthy Subjects

Dr. Jerel Zoltick, from the Walter Reed Army Medical Center in Washington, DC, presented this study at the American Heart Association's 41st Annual Conference on Cardiovascular Disease Epidemiology and Prevention. He studied 436 senior military officers with an average age of 43.5. The officers underwent EBT coronary scanning, and had exercise treadmill tests, resting electrocardiograms, fitness and nutritional histories, blood lipid profiles, and fasting blood sugar measurements. He was able to identify people at high risk for a cardiovascular event who were fit, athletic, healthy, did not smoke, and were free of diabetes, hypertension, and high cholesterol. Dr. Zoltick found that the absolute magnitude of each individual's 'calcium score' was not predicted by the degree of risk factor abnormalities. Almost all of those with the highest scores did have at least one risk factor. But two people with similar risk factor profiles could have calcium scores that differed by hundred of points.

This study indicates the ability for severe cardiovascular disease to be present in people who would have been considered low risk using standard risk factor screening. Dr. Zoltick concludes: " I definitely feel that an EBT scan is an extremely good test to add to a regular physical exam, especially for people with a family history of early heart disease."

3/16/01
The Absence of Coronary Artery Calcium on EBT Identifies a Major Subgroup of Symptomatic Patients with Very Low Probability of Significant Coronary Artery Blockage

The February 2001 issue of the Journal of the American College of Cardiology presents a study involving 1,764 patients with symptoms suggestive of heart disease who underwent EBT scans of their coronary arteries and angiography of the coronary arteries. 56% of the men and 47% of the women had significant narrowing of the coronary arteries. 14% of the subjects had 0 calcium scores, and had <1% likelihood of a narrowing on angiography. For any given age group, the authors were able to identify threshold calcium scores that predicted 90% of those with significant narrowing of at least 1 artery, and 95% of those without significant narrowing.

The authors note that the use of symptoms and conventional noninvasive methods (stress testing) was quite poor at predicting obstructive disease on angiography (only 50% had narrowings). Only 24% of those who had angiography went on to have an intervention, such as angioplasty or bypass surgery.

The authors conclude that EBT has the potential to be an excellent filter in symptomatic patients to reduce the number who undergo unnecessary invasive angiograms.

3/16/01
EBT Predicts Heart Attack and Cardiac Death Better Than Standard Risk Factors

The March 2001 issue of the American Heart Journal contains this article. The authors followed 676 people, mean age 52, for up to 32 months after their EBT coronary scan. The intent of the article was to determine whether EBT could predict events better than standard risk factor analysis, or add incremental value to risk factor analysis. The authors found that by far the most powerful predictor of events was the calcium score percentile (that is, the calcium score compared to scores of others of the same age and sex- 90th percentile would mean 90% with a lower score, 10% with a higher score). Those in the 90th percentile of scores had 15 times the risk of those in the 10th percentile.

EBT calcium score was better than standard risk factor analysis at predicting adverse events, and also improved the diagnostic power of risk factor analysis, when they were combined. The conclusion was that calcium scores may significantly improve our ability to predict coronary events, and to identify high risk patients in need of more aggressive management.