Effect of patient visualization of coronary calcium by electron beam computed tomography on changes in beneficial lifestyle behaviors.

Despite convincing data demonstrating the benefits of aspirin (ASA), exercise, and dietary changes for both primary and secondary prevention of coronary heart disease, they remain underused. In this study, we assess whether higher coronary artery calcium (CAC) scores determined by electron beam computed tomography (EBCT) are associated with beneficial lifestyle behaviors in asymptomatic individuals. A total of 980 asymptomatic patients referred for EBCT risk assessment by their primary physician were sent a survey questioning them about health behaviors. We evaluated long-term ASA utilization, exercise, and dietary changes based on CAC using multivariable analysis. The study population consisted of 980 individuals (78% men, mean age 60 +/- 8 years) who were followed for a mean of 3 +/- 2 years after an initial EBCT scan. Overall, ASA initiation was lowest (29%) among those with CAC = 0, and gradually increased with higher CAC scores (1 to 99, 55%; 100 to 399, 61%; > or =400, 63%; p <0.001 for trend). Similarly, dietary changes and exercise were lowest (33% and 44%, respectively) among those with CAC = 0 and gradually increased with higher CAC scores (1 to 99, 40%; 100 to 399, 58%; > or =400, 56%; p <0.001 for trend for dietary changes; and 1 to 99, 62%; 100 to 399, 63%; > or =400, 67%; p <0.001 for trend for exercise). In multivariable analysis, greater baseline CAC was strongly associated with initiation of ASA therapy, dietary changes, and increased exercise. In conclusion, in addition to risk stratification of asymptomatic individuals, determination of CAC may also improve utilization of ASA therapy and behavioral modification.

Relationship between white blood cell count and Framingham Risk Score in asymptomatic men.

BACKGROUND: There is an independent association between white blood cell (WBC) and coronary heart disease (CHD) risk. However, the relationship between WBC and Framingham Risk Score (FRS) remains unclear. METHODS: This is a cross-sectional study on a consecutive sample of 520 white asymptomatic men (mean age 46 +/- 7 years) without CHD. The study population was divided into WBC quartiles (x10(9) cells/L): 1(st) quartile: 3.1-5.3 (n = 139), 2(nd) quartile: 5.4-6.1 (n = 129), 3(rd) quartile: 6.2-7.1 (n = 131), 4(th) quartile: >/=7.2 (n = 121), and into tertiles according to the 10-year FRS: 1(st) tertile (low risk <5%, n = 180, 35%), 2(nd) tertile (intermediate risk 5-12%, n = 210, 40%), 3(rd) tertile (high risk: >/=13%, n = 130, 25%). RESULTS: WBC correlated only weakly with FRS (r = 0.18, p = 0.001). Among individual components of FRS, WBC correlated minimally with smoking (r = 0.12, p = 0.003), systolic blood pressure (r = 0.07, p = 0.1), and high-density lipoprotein cholesterol (r = -0.06, p = 0.1). However, no correlation was observed with age (p = 0.3) and total cholesterol (p = 0.5). Nearly one third (31%) of men in the low-risk (FRS <5%) had WBC count in the 1(st) quartile compared to 20% of those classified as high risk (FRS >/=13%). The prevalence of WBC in the 4(th) quartile increased across FRS tertiles (18, 22, 32%) (p = 0.09). CONCLUSIONS: WBC correlates weakly with FRS or its individual components. Since WBC count is strongly related to CHD, WBC may reflect different components of cardiovascular risk, which might not be captured by traditional cardiovascular risk factors used in calculating FRS. Inflammatory biomarkers afford adjunctive value to FRS and may be used to improve CHD risk stratification.

Subclinical coronary atherosclerosis: racial profiling is necessary!

OBJECTIVES: We aim to review the studies comparing coronary calcification across different ethnic groups. BACKGROUND: There is still uncertainty regarding ethnic differences in the prevalence, progression, and risk of coronary artery disease. Clues to possible racial differences in rates of coronary heart disease (CHD) may be found by identifying subclinical disease. Coronary artery calcification (CAC) can be used to predict risk of CHD in both symptomatic and asymptomatic subjects. METHODS: Online databases were searched for studies assessing racial differences in CAC. RESULTS: Most of the published studies have shown that racial differences exist in the prevalence and severity of CAC. Whites have a higher prevalence of CAC as compared to African Americans and other ethnic groups even after adjustment for risk factors. These differences in CAC are even more pronounced in men and in the elderly. Data regarding the distribution of CAC in ethnic groups outside the United States are limited. Emerging evidence indicates that while several ethnic groups outside the United States tend to have a greater prevalence of CHD risk factors, their prevalence of CAC is lower, as compared with Americans. Thus, the data obtained in the United States may not be able to be fully extrapolated to populations outside the United States for assessment of CHD risk. CONCLUSIONS: The presence and extent of CAC varies among different racial groups within and outside the United States. The relationship between calcification and the incidence of CHD in these ethnic groups needs further exploration. Thus, it is important to develop ethnic specific CAC nomograms to more accurately determine the underlying CHD risk associated with CAC in these individuals. It will also be imperative to obtain outcome data and relate it to baseline levels of CAC to help us put in perspective the significance of racial differences in CAC and how they impact on cardiac risk prediction.

Assessment of cardiac function using multidetector row computed tomography.

In patients with suspected or documented heart disease, a precise quantitative and qualitative assessment of cardiac function is critical for clinical diagnosis, risk stratification, management and prognosis. Cardiac CT is increasingly being used in diagnosis of coronary artery disease. Initially multi-detector row computed tomography (MDCT) was used chiefly for detecting coronary artery stenosis and assessment of cardiac morphology. Electron beam computed tomography has been shown to provide a highly accurate ejection fraction (+/-1%), with 50 ms image acquisition per image. Retrospective electrocardiographic gating allows for image reconstruction in any phase of the cardiac cycle. Thus, end systolic and end diastolic images can be produced to assess ventricular volumes and function. Despite lower temporal resolution than electron beam computed tomography, the ability of MDCT to assess ejection fraction is preserved. In the assessment of cardiac function, MDCT has been shown to be in good agreement with echocardiography, cineventriculography, single photon emission computed tomography and magnetic resonance imaging. The fast technical development of scanner hardware along with multisegmental image reconstruction has led to rapid improvement of spatial and temporal resolution and significantly faster cardiac scans. The same data that is acquired for MDCT angiography can also be used for evaluation of cardiac function. Considering contrast media application, radiation exposure, and limited temporal resolution, MDCT solely for analysis of cardiac function parameters seems not reasonable at the present time. However, because the data is already obtained during coronary evaluation, the combination of noninvasive coronary artery imaging and assessment of cardiac function with MDCT is a suitable approach to a conclusive cardiac workup in patients with suspected coronary artery disease. MDCT seems suitable for assessment of cardiac function by MDCT when results are held in comparison to magnetic resonance imaging as the reference standard. Given the radiation dose and contrast requirement, referring a patient to MDCT only for evaluation of function is not warranted, but rather adds important clinical information to the already acquired data during retrospective triggering for MDCT angiography.

Association of increased cardiorespiratory fitness with low risk for clustering of metabolic syndrome components in asymptomatic men.

BACKGROUND: From a preventive aspect, it is especially important to investigate the lifestyle risk factors associated with cardiovascular disease (CVD). The purpose of this study was to determine the relationship of increasing metabolic syndrome (MS) components across increasing levels of estimated cardiorespiratory fitness (CRF) in asymptomatic young to middle-aged men. METHODS: We studied 449 consecutive asymptomatic men (47 +/- 7 years) who underwent a maximal treadmill exercise test according to the Bruce protocol. Cardiorespiratory fitness (CRF) was divided into tertiles based on metabolic equivalents (METs). The following MS components were studied: 1) waist circumference > 102 cm; 2) serum triglycerides > or = 150 mg/dL; 3) HDL cholesterol levels of < 40 mg/dL; 4) fasting blood glucose (FBG) > or = 110 mg/dL or 5) blood pressure > or = 130/85 mmHg or treated hypertension. Multinomial logistic regression was used to investigate the relationship between clustering of MS components and CRF as determined by metabolic equivalents (METs). We used polytomous logistic regression to determine the likelihood of clustering of increasing components of metabolic syndrome with intermediate (2nd tertile) and low (1st tertile) levels of CRF as compared to those with highest levels of CRF (3rd tertile). RESULTS: Overall in the study population, zero, 1, 2 and > or = 3 (i.e., metabolic syndrome) risk factors for MS were observed in 29% (n = 129), 26% (n = 118), 22% (n = 98) and 23% (n = 104) men, respectively. The mean METS achieved in the study population was 10 +/- 2 (range 4-20). Nearly half (49%) of individuals with the highest levels of CRF had no MS risk factors whereas only 18% of those with low CRF (METS < 9) had no MS risk factors. On the other end of the spectrum, the prevalence of MS (> or = 3 MS risk factors) increased significantly across decreasing levels of CRF (6, 22, 33% p < 0.0001 for trend). Multivariable polytomous logistic regression (adjusting for age, smoking, cholesterol-lowering therapy) demonstrated that individuals with low CRF (1st tertile of METS) compared to those with highest CRF had 3.1- (p = 0.001) and 11.8- (p < 0.0001) fold higher risk of having 2 and > or = 3 MS components, respectively. Similar results were observed when the analyses was repeated adjusting for Framingham risk score. CONCLUSIONS: Asymptomatic men with low levels of CRF have a greater likelihood for clustering of MS components and thus are at higher CVD risk. Further studies are needed to define the risk of cardiovascular disease in patients with intermediate levels of CRF and address which treatment strategies are most important given an individual's risk profile.