Diabetes and the associated incidence of subclinical atherosclerosis and coronary artery disease: Implications for management

Coronary computed tomography angiography as a screening tool for moderate-high risk asymptomatic type 2 diabetes mellitus patients

Background

There are few data on the clinical significance of coronary computed tomography angiography (CCTA) in asymptomatic type 2 diabetes mellitus (T2DM) patients. We performed a retrospective study to evaluate coronary heart disease (CHD) screening in asymptomatic patients with T2DM using CCTA and CHD risk stratification prediction.

Materials and methods

Data from 141 T2DM patients (58 ± 8 years, 57% males) without known symptoms suggestive of CHD who underwent CCTA were retrospectively analyzed. The patients were classified into three subgroups based on United Kingdom prospective diabetes study (UKPDS) CHD risk stratification prediction. Seventy-four patients without diabetes mellitus and CHD who underwent CCTA successively were chosen as the control group. The segment involvement score (SIS), segment stenosis score (SSS), stenosis coefficient (SC), severe proximal plaque (SPP) positive ratio and CCTA-adapted Leaman score (CT-LeSc) based on CCTA data were evaluated and compared among the groups.

Results

Compared with the patients in the control group, patients in the moderate-high risk DM groups had higher scores on the SIS, SSS, SC, CT-LeSc, and a higher SPP positive ratio (all p-values < 0.001), and no difference was observed between the low-risk group and the control group (p = 0.136, p = 0.088, p = 0.0.067, p = 0.225, p = 1.000, respectively). Compared with patients in the control group, the patients in the moderate-high risk DM groups had increased odds of SIS > 3 [odds ratio (OR) = 6.557, p < 0.001; OR = 4.455, p < 0.001, respectively], SSS > 5 (OR = 5.727, p < 0.001; OR = 5.144, p < 0.001, respectively), CT-LeSc > 8.7 (OR = 3.780, p = 0.001; OR = 2.804, p = 0.007, respectively), and obstructive stenosis (OR = 7.233, p < 0.001; OR = 5.787, p < 0.001, respectively).

Conclusion

The moderate-high CHD risk patients had increased odds of obstructive coronary artery stenosis, and the distribution of coronary artery stenosis was more extensive and more severe in that group compared to the patients without diabetes mellitus and CHD. CHD can be effectively screened in moderate-high risk asymptomatic T2DM patients using CCTA.

Diabetic patients with chronic kidney disease: Non-invasive assessment of cardiovascular risk

The prevalence and burden of diabetes mellitus and chronic kidney disease on global health and socioeconomic development is already heavy and still rising. Diabetes mellitus by itself is linked to adverse cardiovascular events, and the presence of concomitant chronic kidney disease further amplifies cardiovascular risk. The culmination of traditional (male gender, smoking, advanced age, obesity, arterial hypertension and dyslipidemia) and non-traditional risk factors (anemia, inflammation, proteinuria, volume overload, mineral metabolism abnormalities, oxidative stress, etc.) contributes to advanced atherosclerosis and increased cardiovascular risk. To decrease the morbidity and mortality of these patients due to cardiovascular causes, timely and efficient cardiovascular risk assessment is of huge importance. Cardiovascular risk assessment can be based on laboratory parameters, imaging techniques, arterial stiffness parameters, ankle-brachial index and 24 h blood pressure measurements. Newer methods include epigenetic markers, soluble adhesion molecules, cytokines and markers of oxidative stress. In this review, the authors present several non-invasive methods of cardiovascular risk assessment in patients with diabetes mellitus and chronic kidney disease.

Low short-term and long-term cardiovascular and all-cause mortality in absence of coronary artery calcium: A 22-year follow-up observational study from large cohort

OBJECTIVES

We sought to evaluate the gender-specific predictive value of coronary artery calcium (CAC) score on all-cause mortality and cardiovascular disease (CVD) mortality in individuals with and without diabetes mellitus (DM).

BACKGROUND

CAC score is a robust predictor of CVD and all-cause mortality during long-term follow-up in large cohorts in adults with DM. However, less is known about its sex-specific impact on all-cause mortality in DM.

METHODS

We evaluated 25,563 asymptomatic participants with no known history of coronary artery disease (CAD) who underwent clinically indicated CAC. 1999 (7.8%) individuals had diabetes. CAC was characterized as an Agatston score of 0, 1-99, 100-300, and ≫300. We evaluated the association between CAC and all-cause mortality and CVD mortality.

RESULTS

Overall, 1345 individuals died (5.3%) from all causes during a mean follow-up of 14.7 ± 3.8 years. CAC score was 0 in 57.5% females and 34.4% of males without DM, while 36.6% females and 20.3% males with DM had CAC-0. The frequency of CAC ≫ 300 was 18% and 36% in females and males with DM, respectively. CAC score of zero was associated with low all-cause mortality event rate in females and males with diabetes (1.7 and 2.5 events per 1000 person-years, respectively). Cardiovascular mortality per 1000 person years was ≪1 in females and males with CAC score of 0 irrespective of their diabetes. Adjusted multivariable analysis, compared to CAC-0, HR for all-cause mortality associated with CAC 1-99, 100-299 and ≫300 were 1.74(95% CI 0.65, 4.63, P-0.20), 5.54(95% CI 2.16, 14.22, P ≪ 0.001) and 5.75(95% CI 2.30, 14.37, P ≪ 0.001) in females with DM respectively; in males with DM HR associated with CAC 1-99, 100-299 and ≫300 were 1.87(95% CI 0.95, 3.66, P-0.06), 2.15(95% CI 1.05, 4.38, P-0.035) and 2.60(95% CI 1.34, 5.0, P-0.004), respectively.

CONCLUSION

Presence of subclinical atherosclerosis varies among individuals with DM. The absence of CAC was associated with very low cardiovascular as well as all-cause mortality events in all subgroups during long term follow-up.

NLRP3 inflammasome as a treatment target in atherosclerosis: A focus on statin therapy

Activation of NOD-like receptor (NLR) family and pyrin domain containing 3 (NLRP3) inflammasome contributes to inflammation and may lead to atherosclerosis. The NLRP3 inflammasome as a molecular platform regulates the activation of ATP signaling, K⁺ efflux, cathepsin-B activity, lysosomal function and pro-inflammatory cytokines (i.e. IL-1β and IL-18). Statins has been widely prescribed for the treatment of hyperlipidemia and cardiovascular diseases. In addition to lipid-lowering effect, statins have immunomodulatory, anti-inflammatory, antioxidant and antiapoptotic functions. An increasing number of studies indicated NLRP3 inflammasome and their downstream mediators as important targets for statin drugs in inflammatory diseases. In this review, we discussed different aspect of the NLRP3 inflammasome signaling pathways and focused on the effect of statin drugs on NLRP3 inflammasomes in association to atherosclerosis in order to elucidate possible targets for future research and clinical settings.

A Noninvasive, Economical, and Instant-Result Method to Diagnose and Monitor Type 2 Diabetes Using Pulse Wave: Case-Control Study

Background

We should pay more attention to the long-term monitoring and early warning of type 2 diabetes and its complications. The traditional blood glucose tests are traumatic and cannot effectively monitor the development of diabetic complications. The development of mobile health is changing rapidly. Therefore, we are interested in developing a new noninvasive, economical, and instant-result method to accurately diagnose and monitor type 2 diabetes and its complications.

Objective

We aimed to determine whether type 2 diabetes and its complications, including hypertension and hyperlipidemia, could be diagnosed and monitored by using pulse wave.

Methods

We collected the pulse wave parameters from 50 healthy people, 139 diabetic patients without hypertension and hyperlipidemia, 133 diabetic patients with hypertension, 70 diabetic patients with hyperlipidemia, and 75 diabetic patients with hypertension and hyperlipidemia. The pulse wave parameters showing significant differences among these groups were identified. Various machine learning models such as linear discriminant analysis, support vector machines (SVMs), and random forests were applied to classify the control group, diabetic patients, and diabetic patients with complications.

Results

There were significant differences in several pulse wave parameters among the 5 groups. The parameters height of tidal wave (h₃), time distance between the start point of pulse wave and dominant wave (t₁), and width of percussion wave in its one-third height position (W) increase and the height of dicrotic wave (h₅) decreases when people develop diabetes. The parameters height of dominant wave (h₁), h₃, and height of dicrotic notch (h₄) are found to be higher in diabetic patients with hypertension, whereas h₅ is lower in diabetic patients with hyperlipidemia. For detecting diabetes, the method with the highest out-of-sample prediction accuracy is SVM with polynomial kernel. The algorithm can detect diabetes with 96.35% accuracy. However, all the algorithms have a low accuracy when predicting diabetic patients with hypertension and hyperlipidemia (below 70%).

Conclusions

The results demonstrated that the noninvasive and convenient pulse-taking diagnosis described in this paper has the potential to become a low-cost and accurate method to monitor the development of diabetes. We are collecting more data to improve the accuracy for detecting hypertension and hyperlipidemia among diabetic patients. Mobile devices such as sport bands, smart watches, and other diagnostic tools are being developed based on the pulse wave method to improve the diagnosis and monitoring of diabetes, hypertension, and hyperlipidemia.

Oxidative Stress and NLRP3-Inflammasome Activity as Significant Drivers of Diabetic Cardiovascular Complications: Therapeutic Implications

It is now increasingly appreciated that inflammation is not limited to the control of pathogens by the host, but rather that sterile inflammation which occurs in the absence of viral or bacterial pathogens, accompanies numerous disease states, none more so than the complications that arise as a result of hyperglycaemia. Individuals with type 1 or type 2 diabetes mellitus (T1D, T2D) are at increased risk of developing cardiac and vascular complications. Glucose and blood pressure lowering therapies have not stopped the advance of these morbidities that often lead to fatal heart attacks and/or stroke. A unifying mechanism of hyperglycemia-induced cellular damage was initially proposed to link elevated blood glucose levels with oxidative stress and the dysregulation of metabolic pathways. Pre-clinical evidence has, in most cases, supported this notion. However, therapeutic strategies to lessen oxidative stress in clinical trials has not proved efficacious, most likely due to indiscriminate targeting by antioxidants such as vitamins. Recent evidence now suggests that oxidative stress is a major driver of inflammation and vice versa, with the latest findings suggesting not only a key role for inflammatory pathways underpinning metabolic and haemodynamic dysfunction in diabetes, but furthermore that these perturbations are driven by activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome. This review will address these latest findings with an aim of highlighting the interconnectivity between oxidative stress, NLRP3 activation and inflammation as it pertains to cardiac and vascular injury sustained by diabetes. Current therapeutic strategies to lessen both oxidative stress and inflammation will be emphasized. This will be placed in the context of improving the burden of these diabetic complications.

Effect of Long-Term Metformin and Lifestyle in the Diabetes Prevention Program and Its Outcome Study on Coronary Artery Calcium

BACKGROUND

Despite the reduced incidence of coronary heart disease with intensive risk factor management, people with diabetes mellitus and prediabetes remain at increased coronary heart disease risk. Diabetes prevention interventions may be needed to reduce coronary heart disease risk. This approach was examined in the DPP (Diabetes Prevention Program) and the DPPOS (Diabetes Prevention Program Outcome Study), a long-term intervention study in 3234 subjects with prediabetes (mean±SD age, 64±10 years) that showed reduced diabetes risk with lifestyle and metformin compared with placebo over 3.2 years.

METHODS

The DPPOS offered periodic group lifestyle sessions to all participants and continued metformin in the originally randomized metformin group. Subclinical atherosclerosis was assessed in 2029 participants with coronary artery calcium (CAC) measurements after an average of 14 years of follow-up. The CAC scores were analyzed continuously as CAC severity and categorically as CAC presence (CAC score >0) and reported separately in men and women.

RESULTS

There were no CAC differences between lifestyle and placebo intervention groups in either sex. CAC severity and presence were significantly lower among men in the metformin versus the placebo group (age-adjusted mean CAC severity, 39.5 versus 66.9 Agatston units, P=0.04; CAC presence, 75% versus 84%, P=0.02), but no metformin effect was seen in women. In multivariate analysis, the metformin effect in men was not influenced by demographic, anthropometric, or metabolic factors; by the development of diabetes mellitus; or by use/nonuse of statin therapy.

CONCLUSIONS

Metformin may protect against coronary atherosclerosis in prediabetes and early diabetes mellitus among men.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00038727.

Cardiovascular risk assessment in patients with diabetes

Although patients with diabetes have 2 to 4 times increased risk of cardiovascular morbidity and mortality than individuals without diabetes, recent studies indicate that a significant part of patients are in a lower cardiovascular risk category. Men younger than 35 years, women younger than 45 years, patients with diabetes duration of less than 10 years without other risk factors have a much lower risk than patients who have traditional cardiovascular risk factors, and subclinical or established coronary artery disease (CAD). These patients are not risk equivalent as stated in previous studies. On the contrary, when in the presence of traditional risk factors or evidence of subclinical coronary disease (e.g. high coronary calcium score), the coronary risk is much increased and patients may be classified at a higher-risk category. Recent guidelines do not anymore consider diabetes as a CAD risk equivalent and recommend cardiovascular risk stratification for primary prevention. Stratification of diabetic patients improves accuracy in prediction of subclinical CAD, silent ischemia and future cardiovascular events. Stratification also discriminates higher from lower risk patients who may need intensive statin or aspirin prevention, while avoiding overtreatment in lower risk cases. It may also allow the clinician to decide whether to intensify risk reduction actions through specific newer drugs for glucose control such as SGLT-2 inhibitors or GLP-1 agonists, which recently have shown additional cardiovascular protector effect. This review addresses the assessment of cardiovascular disease risk using traditional and non-traditional cardiovascular risk factors. It also reviews the use of risk calculators and new reclassification tools, focusing on the detection of subclinical atherosclerosis as well as silent ischemia in the asymptomatic patients with diabetes.

Cardiovascular Screening for the Asymptomatic Patient with Diabetes: More Cons Than Pros

Diabetes mellitus is associated with an increased risk of coronary heart disease (CHD) morbidity and mortality. Although it frequently coexists with other cardiovascular disease (CVD) risk factors, it confers an increased risk for CVD events on its own. Coronary atherosclerosis is generally more aggressive and widespread in people with diabetes (PWD) and is frequently asymptomatic. Screening for silent myocardial ischaemia can be applied in a wide variety of ways. In nearly all asymptomatic PWD, however, the results of screening will generally not change medical therapy, since aggressive preventive measures, such as control of blood pressure and lipids, would have been already indicated, and above all, invasive revascularization procedures (either with percutaneous coronary intervention or coronary artery bypass grafting) have not been shown in randomized clinical trials to confer any benefit on morbidity and mortality. Still, unresolved issues remain regarding the extent of the underlying ischaemia that might affect the risk and the benefit of revascularization (on top of optimal medical therapy) in ameliorating this risk in patients with moderate to severe ischaemia. The issues related to the detection of coronary atherosclerosis and ischaemia, as well as the studies related to management of CHD in asymptomatic PWD, will be reviewed here.

Noninvasive Cardiovascular Risk Assessment of the Asymptomatic Diabetic Patient: The Imaging Council of the American College of Cardiology

Increased cardiovascular morbidity and mortality in patients with type 2 diabetes is well established; diabetes is associated with at least a 2-fold increased risk of coronary heart disease. Approximately two-thirds of deaths among persons with diabetes are related to cardiovascular disease. Previously, diabetes was regarded as a "coronary risk equivalent," implying a high 10-year cardiovascular risk for every diabetes patient. Following the original study by Haffner et al., multiple studies from different cohorts provided varying conclusions on the validity of the concept of coronary risk equivalency in patients with diabetes. New guidelines have started to acknowledge the heterogeneity in risk and include different treatment recommendations for diabetic patients without other risk factors who are considered to be at lower risk. Furthermore, guidelines have suggested that further risk stratification in patients with diabetes is warranted before universal treatment. The Imaging Council of the American College of Cardiology systematically reviewed all modalities commonly used for risk stratification in persons with diabetes mellitus and summarized the data and recommendations. This document reviews the evidence regarding the use of noninvasive testing to stratify asymptomatic patients with diabetes with regard to coronary heart disease risk and develops an algorithm for screening based on available data.

Coronary artery calcium score and N-terminal pro-B-type natriuretic peptide as potential gatekeepers for myocardial perfusion imaging

Myocardial perfusion imaging (MPI) holds an important place as non-invasive risk assessment in patients with intermediate risk of coronary heart disease (CHD). However, as much as 60-70% of MPI scans are normal. This study evaluates the role of coronary artery calcium scoring (CAC score) and NT-proBNP as potential gatekeepers for MPI. Patients with intermediate risk of CHD referred for standard MPI were included. CAC score and NT-proBNP were both assessed at the day of the stress study. Sensitivity, specificity and NPV for prediction of abnormal MPI scans were calculated for CAC, NT-proBNP and the combination hereof. A total of 190 patients were included (mean age 61 ± 12 years, 55% female) of whom 24% had known CHD. In all 30% of the scans were abnormal. CAC score achieved the highest AUC regardless of whether patients with known CHD were included or not [AUC 0·75 95% CI (0·66-0·84) and AUC 0·79 (0·68-0·91)]. As a singular variable, CAC score was the most potent predictor with a sensitivity of 85%, specificity of 39% and NPV 88%. The combination of CAC score<10 and NT-proBNP>26 reached a sensitivity of 98% and NPV 94%, where 8% of scans tentatively could be avoided. In patients referred for MPI with intermediate risk for CHD, a combination of CAC score and NT-proBNP could be used to identify a group of patients where MPI could be averted with a high degree of diagnostic safety.

Prognostic value of coronary computed tomography angiography in diabetic patients without chest pain syndrome

AIMS

Diabetic patients with coronary artery disease (CAD) are often free of chest pain syndrome. A useful modality for non-invasive assessment of CAD is coronary computed tomography angiography (CTA). However, the prognostic value of CAD on coronary CTA in diabetic patients without chest pain syndrome is relatively unknown. Therefore, the aim was to investigate the long-term prognostic value of coronary CTA in a large population diabetic patients without chest pain syndrome.

METHODS

Between 2005 and 2013, 525 diabetic patients without chest pain syndrome were prospectively included to undergo coronary artery calcium (CAC)-scoring followed by coronary CTA. During follow-up, the composite endpoint of all-cause mortality, non-fatal myocardial infarction (MI), and late revascularization (>90 days) was registered.

RESULTS

In total, CAC-scoring was performed in 410 patients and coronary CTA in 444 patients (431 interpretable). After median follow-up of 5.0 (IQR 2.7-6.5) years, the composite endpoint occurred in 65 (14%) patients. Coronary CTA demonstrated a high prevalence of CAD (85%), mostly non-obstructive CAD (51%). Furthermore, patients with a normal CTA had an excellent prognosis (event-rate 3%). An incremental increase in event-rate was observed with increasing CAC-risk category or coronary stenosis severity. Finally, obstructive (50-70%) or severe CAD (>70%) was independently predictive of events (HR 11.10 [2.52;48.79] (P = .001), HR 15.16 [3.01;76.36] (P = .001)). Obstructive (50-70%) or severe CAD (>70%) provided increased value over baseline risk factors.

CONCLUSION

Coronary CTA provided prognostic value in diabetic patients without chest pain syndrome. Most importantly, the prognosis of patients with a normal CTA was excellent.

Coronary Atherosclerotic Plaque Detected by Computed Tomographic Angiography in Subjects with Diabetes Compared to Those without Diabetes

OBJECTIVES

Little data are available regarding coronary plaque composition and semi-quantitative scores in individuals with diabetes; the extent to which diabetes may affect the presence and extent of Coronary Artery Calcium (CAC) needs more evaluation. Considering that this information may be of great value in formulating preventive interventions in this population, we compared these findings in individuals with diabetes to those without.

METHODS

Multi-Detector Computed Tomographic (MDCT) images of 861 consecutive patients with diabetes who were referred to Los Angeles Biomedical Research Institute from January 2000 to September 2012, were evaluated using a 15-coronary segment model. All 861 patients underwent calcium scoring and from these; 389 had coronary CT angiography (CTA). CAC score was compared to 861 age, sex and ethnicity matched controls without diabetes after adjustment for Body Mass Index (BMI), family history of coronary artery disease, hyperlipidemia, hypertension and smoking. Segment Involvement Score (SIS; the total number of segments with any plaque), Segment Stenosis Score (SSS; the sum of maximal stenosis score per segment), Total Plaque Score (TPS; the sum of the plaque amount per segment) and plaque compositionwere compared to 389 age, sex and ethnicity matched controls without diabetes after adjustment for BMI, family history of coronary artery disease, hyperlipidemia, hypertension and smoking.

RESULTS

Diabetes was positively correlated to the presence and extent of CAC (P<0.0001 for both). SIS, SSS and TPS were significantly higher in those with diabetes (P<0.0001). Number of mixed and calcified plaques were significantly higher in those with diabetes (P = 0.018 and P<0.001 respectively) but there was no significant difference in the number of non-calcified plaques between the two groups (P = 0.398).

CONCLUSIONS

Patients with diabetes have higher CAC and semi-quantitative coronary plaque scores compared to the age, gender and ethnicity matched controls without diabetes after adjustment for cardiovascular risk factors. Since mixed plaque is associated with worse long-term clinical outcomes, these findings support more aggressive preventive measures in this population.

Prevalence and severity of coronary artery calcium in young persons with diabetes

BACKGROUND

Currently, American Diabetes Association guidelines suggest statin use among persons with diabetes mellitus aged >40 years. The presence of calcified plaque in coronary arteries is a sensitive surrogate of coronary artery disease and has been shown to be an independent predictor of mortality and cardiac events.

OBJECTIVE

We aimed to assess the prevalence and severity of calcified plaque in coronary arteries in patients aged <40 years with and without diabetes.

METHODS

We included 3723 asymptomatic patients aged <40 years who had undergone coronary calcium scanning. Clinical and demographic data were collected. Agatston score was categorized into Agatston score 0 as normal, 1 to 99 as low, 100 to 399 as intermediate, and ≥400 as severe; and statistical analysis was performed.

RESULTS

The study population consisted of 4% persons with diabetes (n = 142) and 56% men with a mean age of 35 ± 5 years. Young persons with diabetes had greater prevalence of Agatston score > 0 than persons without diabetes (43% vs 24%; P < .0001). In addition, 12% of persons with diabetes vs 2.5% of persons without diabetes had an Agatston score ≥ 100 (P < .0001). The prevalence of calcified plaque in coronary arteries was >50% in persons with diabetes aged >35 years. After taking into account risk factors, the presence of diabetes was associated with a 4-fold higher odds of an Agatston score ≥ 100 (odds ratio, 4.19; 95% CI, 2.29-7.65; P < .0001).

CONCLUSION

Our study found that 43% of young patients with diabetes have detectable coronary atherosclerosis. Given the known clinical implications of calcified plaque in coronary arteries, future studies are needed to evaluate interventions in persons aged <40 years who exhibit subclinical atherosclerosis to reduce future cardiovascular disease events in this vulnerable population.

Should diabetes still be considered a coronary artery disease equivalent?

Diabetes is well established as a cardiovascular risk factor and is currently regarded as a coronary artery disease equivalent. However, some recent data have contradicted the concept. We review the currently available data and usefulness or otherwise of this concept. While the concept of coronary artery disease equivalence has served to highlight the importance of diabetes as a risk factor, it has a number of problems. We propose that it would be more useful to consider diabetes as a myocardial infarction risk equivalent. This is not only more precise and in line with the literature but also conveys better the message that patients with diabetes and one or more previous myocardial infarction(s) are at even higher risk.

Comparison of atherosclerotic plaque by computed tomography angiography in patients with and without diabetes mellitus and with known or suspected coronary artery disease

The aim of this study was to compare coronary artery plaque burden, composition, distribution, and the degree of coronary artery stenosis in diabetic and nondiabetic patients with known or suspected coronary artery disease (CAD). The study group consisted of 594 patients with known or suspected CAD, including 122 diabetics, who underwent multidetector computed tomographic coronary angiography and traditional invasive coronary artery angiography. Coronary artery calcium scores were compared in different age subgroups. Noncalcified plaque, calcified plaque, and mixed plaque were analyzed by coronary segment on computed tomographic coronary angiography, as well as the degree of coronary stenosis on coronary artery angiography. Obstructive vessels were compared between the 2 groups. Total coronary artery calcium score was higher in patients with diabetes compared to those without (378.4 ± 613.0 vs 226.0 ± 408.4, p = 0.003). The percentage of patients with coronary artery calcium scores >400 among diabetics (22.1%) was higher than among nondiabetics (14.2%) (p = 0.032). Diabetics had a higher percentage of coronary segments with noncalcified plaque, calcified plaque, and mixed plaque than nondiabetics (35.3% vs 26.2%, p <0.001; 17.5% vs 11.6%, p = 0.017; and 9.8% vs 7.9%, p = 0.008). More diabetics had multivessel obstructive disease compared to nondiabetics (p <0.05). With longer duration of diabetes mellitus, the stenosed segments of coronary arteries increased accordingly. In conclusion, diabetics have more atherosclerotic plaque burden and more severe coronary atherosclerosis than nondiabetics. Most obstructive lesions were caused by mixed plaques in diabetics and nondiabetics.

Importance of the ankle-brachial pressure index in the diagnosis of coronary artery disease in women with diabetes without anginal pain

BACKGROUND

Clinical symptoms of coronary artery disease (CAD) are often atypical in women, particularly in those with diabetes mellitus. Therefore, a simple diagnostic test to identify a high-risk subset of women with diabetes who are likely to have CAD is important.

METHODS AND RESULTS

A total of 407 consecutive patients (319 men and 88 women, age range 68 ± 11 years) with suspected CAD, who were not complaining of anginal pain, were evaluated. Among these patients, 170 had diabetes. Stress myocardial perfusion imaging and simultaneous brachial and ankle blood pressure measurements were performed to obtain the ischemic total perfusion deficit (TPD) and ankle-brachial pressure index (ABI), respectively. Ischemic TPD was not significantly different between men and women, whereas ischemic TPD was significantly greater in diabetic patients than in non-diabetic patients (6.9 ± 7.7% vs. 4.9 ± 6.1%; P = 0.005). In diabetic patients, ischemic TPD was not significantly different between men and women. However, women with ABI<0.9 showed significantly greater ischemic TPD than those with ABI≥0.9 (12.1 ± 10.8% vs. 5.1 ± 5.9%; P=0.04), whereas no difference in ABI was observed in men.

CONCLUSIONS

ABI was useful in evaluating CAD in asymptomatic women with diabetes to detect a high-risk subset showing the ischemic TPD of >10%, which is regarded as a scintigraphic indicator for coronary revascularization.

Prevalence of subclinical atherosclerosis in asymptomatic diabetic patients by 64-slice computed tomography

OBJECTIVES

Patients with diabetes have a 2-fold to 4-fold higher risk of a cardiovascular event than nondiabetic patients. Thus there is a need to identify patients with diabetes who are at risk of cardiovascular events before the onset of symptoms. We studied the prevalence of coronary artery disease in asymptomatic diabetic patients compared with asymptomatic nondiabetic patients by 64-slice computed tomography (CT).

METHODS

From 425 asymptomatic patients with coronary risk factors but without known coronary artery disease who underwent 64-slice CT, we identified 93 asymptomatic diabetic patients (diabetic group) and 93 age-matched and sex-matched asymptomatic nondiabetic patients.

RESULTS

Clinical characteristics were not significantly different between the two groups. Total coronary calcium score was significantly higher in diabetic group than that in nondiabetic group (median 117 vs. 53.5, P<0.0001). No coronary calcium was detected in 30.0% of nondiabetic group compared with 15.1% of diabetic group (P=0.0022). Coronary calcium score more than 400 was detected in 9.7% of nondiabetic group compared with 36.6% of diabetic group (P<0.0001). Coronary plaques were found in 67.7% of nondiabetic group compared with 91.4% of diabetic group (P<0.0001). Multiple plaques were detected in 57.0 and 77.4% of patients in nondiabetic and diabetic group, respectively (P=0.0030). Significant coronary stenosis was found in 16.1% of nondiabetic group compared with 33.3% of diabetic group (P=0.0065).

CONCLUSION

Our results show that the prevalence of coronary plaques detectable by 64-slice CT in asymptomatic diabetic patients is very high.

Coronary artery calcium screening: current status and recommendations from the European Society of Cardiac Radiology and North American Society for Cardiovascular Imaging

Current guidelines and literature on screening for coronary artery calcium for cardiac risk assessment are reviewed for both general and special populations. It is shown that for both general and special populations a zero score excludes most clinically relevant coronary artery disease. The importance of standardization of coronary artery calcium measurements by multi-detector CT is discussed.

Prognostic significance of asymptomatic coronary artery disease in patients with diabetes and need for early revascularization therapy

AIMS

Information on the clinical outcome of patients with diabetes with silent myocardial ischaemia is limited. We compared the clinical and angiographic characteristics, and the clinical outcomes of diabetic patients with asymptomatic or symptomatic coronary artery disease (CAD).

METHODS

Three hundred and ten consecutive diabetic patients with CAD were divided into two groups according to the presence of angina and followed for a mean of 5 years. Fifty-six asymptomatic patients with a positive stress test and CAD on coronary angiography were compared with 254 symptomatic patients, 167 with unstable angina and 87 with chronic stable angina.

RESULTS

Although the severity of coronary atherosclerosis was similar in asymptomatic and symptomatic patients, revascularization therapy was performed less frequently in the asymptomatic than the symptomatic patients (26.8 vs. 62.0%; P < 0.001). Asymptomatic patients experienced a similar number of major adverse cardiac events (MACEs; death, non-fatal myocardial infarction, and revascularization; 32 vs. 28%; P = 0.57), but had higher cardiac mortality than symptomatic patients (26 vs. 9%; P < 0.001). However, patients who underwent revascularization therapy at the time of CAD diagnosis in these two groups showed similar MACE and cardiac mortality (20.0 vs. 22.5%, 6.7 vs. 5.3%, respectively; all P > 0.05).

CONCLUSIONS

This study suggests that diabetic patients with asymptomatic CAD have a higher cardiac mortality risk than those with symptomatic CAD, and that lack of revascularization therapy may be responsible for the poorer survival.

Noninvasive assessment of plaque characteristics with multislice computed tomography coronary angiography in symptomatic diabetic patients

OBJECTIVE

Cardiovascular events are high in patients with type 2 diabetes, whereas their risk stratification is more difficult. The higher risk may be related to differences in coronary plaque burden and composition. The purpose of this study was to evaluate whether differences in the extent and composition of coronary plaques in patients with and without diabetes can be observed using multislice computed tomography (MSCT).

RESEARCH DESIGN AND METHODS

MSCT was performed in 215 patients (86 [40%] with type 2 diabetes). The number of diseased coronary segments was determined per patient; each diseased segment was classified as showing obstructive (> or = 50% luminal narrowing) disease or not. In addition, plaque type (noncalcified, mixed, and calcified) was determined. Plaque characteristics were compared in patients with and without diabetes. Regression analysis was performed to assess the correlation between plaque characteristics and diabetes.

RESULTS

Patients with diabetes showed significantly more diseased coronary segments than nondiabetic patients (4.9 +/- 3.5 vs. 3.9 +/- 3.2, P = 0.03) with more nonobstructive (3.7 +/- 3.0 vs. 2.7 +/- 2.4, P = 0.008) plaques. Relatively more noncalcified (28 vs. 19%) and calcified (49 vs. 43%) and less mixed (23 vs. 38%) plaques were observed in patients with diabetes (P < 0.0001). Diabetes correlated with the number of diseased segments and nonobstructive, noncalcified, and calcified plaques.

CONCLUSIONS

Differences in coronary plaque characteristics on MSCT were observed between patients with and without diabetes. Diabetes was associated with higher coronary plaque burden. More noncalcified and calcified plaques and less mixed plaques were observed in diabetic patients. Thus, MSCT may be used to identify differences in coronary plaque burden, which may be useful for risk stratification.

Noninvasive Screening for Coronary Atherosclerosis and Silent Ischemia in Asymptomatic Type 2 Diabetic Patients

Coronary artery disease (CAD) accounts for 65% to 80% of deaths in diabetic patients. The merits of screening asymptomatic type 2 diabetic patients for either (A) the presence of coronary atherosclerosis by imaging of coronary calcification using cardiac computed tomography or (B) silent ischemia by stress myocardial perfusion imaging (MPI) remain controversial. Some observers have advocated for such noninvasive screening in at least the subset of the diabetic population who have significant clinical CAD risk factors, so that the highest risk patients for future cardiac events can be identified and offered more aggressive intensive medical therapy or coronary revascularization and optimum medical therapy. Computed tomography coronary calcium scanning could be the first noninvasive screening test in these clinically high-risk diabetic patients, followed by stress MPI to detect silent ischemia in those who exhibit high coronary calcium scores.

Perfusion Impairment in Patients with Normal-appearing Coronary Arteries: Identification with Contrast-enhanced MR Imaging

PURPOSE

To prospectively determine the feasibility of using first-pass magnetic resonance (MR) imaging to distinguish between myocardial segments in patients with coronary artery disease (CAD) of different degrees of obstruction and those in patients with normal-appearing coronary arteries.

MATERIALS AND METHODS

The study was approved by the institutional ethics committee, and all patients provided informed consent. First-pass contrast material-enhanced MR imaging was performed at rest and after the infusion of dipyridamole in 37 patients (29 men, eight women; mean age, 57.2 years +/- 10.5 [standard deviation]) who had positive exercise test results or a clinical history of CAD. Myocardial segments were divided into five groups according to the degree of obstruction in the supplying artery. Signal intensity upslope, peak signal intensity, and time to peak signal intensity, as well as hyperemia-to-rest (HR) ratios for each of these three variables, were analyzed for each segment by using a generalized linear model.

RESULTS

Signal intensity upslope in patients with normal coronary arteries at angiography was significantly higher than that in patients with CAD (P < .001). Signal intensity upslope for segments in patients without CAD was significantly different from that for normal-appearing segments in patients with CAD (P < .001). Signal intensity upslope (P < .05) and peak signal intensity (P < .01) enabled the differentiation of segments with more than 70% reduction in luminal diameter from those in all other groups. HR ratios demonstrated findings that were similar to those obtained by using each signal intensity variable alone.

CONCLUSION

First-pass MR imaging can be used to distinguish segments with different degrees of obstructive CAD. Importantly, MR imaging can help identify segments with impaired perfusion and normal-appearing coronary arteries in patients with CAD and can demonstrate obstructive lesions in other territories.

Ischemia imaging and plaque imaging in diabetes: complementary tools to improve cardiovascular risk management

Cardiovascular disease is the most frequent cause of death and disability in diabetes, and the morbidity and mortality for coronary artery disease (CAD) in this population is two to four times higher than in nondiabetic subjects. Traditional risk factors do not fully explain the level of cardiovascular risk, and coronary disease events are often silent in diabetic patients. Thus, research has recently focused on improving the risk assessment of an individual patient with new tools in an effort to better identify subjects at highest risk and in need of aggressive management. Cardiovascular imaging has proven very helpful in this regard. Traditional methods to assess CAD are based on detection of obstructive luminal disease responsible for myocardial ischemia. However, acute coronary syndromes often occur in the absence of luminal stenoses. Hence, the utilization of imaging methodologies to visualize atherosclerosis in its presymptomatic stages has received mounting attention in recent years. In this article, we review the current literature on the utility of traditional imaging modalities for obstructive CAD (nuclear and echocardiographic stress testing) as well as atherosclerosis plaque imaging with carotid intima-media thickness and coronary artery calcium for risk stratification of diabetic patients.

Progression of coronary artery calcium and occurrence of myocardial infarction in patients with and without diabetes mellitus

Progression of coronary artery calcium, a marker of atherosclerosis, can be slowed with statins, and continued progression of calcium is associated with an increased risk of myocardial infarction. However, it is not known whether statins are effective in slowing calcium progression in diabetes mellitus. In a retrospective study, we examined 1153 nondiabetic and 157 diabetic subjects who underwent sequential electron beam tomography scans at a minimum 1-year interval to assess progression of coronary calcium. A yearly score increase >15% was considered evidence of true progression. The use of statins and occurrence of myocardial infarction were recorded. There was no difference in baseline calcium score between diabetic and nondiabetic patients. Diabetic patients with no coronary calcium on the baseline scans developed it more often than nondiabetic subjects (42% versus 25%; P=0.046) during follow-up. Calcium progression was 33% greater in diabetic patients than nondiabetic subjects (P<0.001) if no statin therapy was provided and 17.7% greater when statins were used (P<0.001). Among the 49 subjects who experienced a myocardial infarction, the calcium score increased on average 20% more in diabetic than nondiabetic patients (P<0.001). In logistic models, diabetes mellitus and systemic hypertension were the best predictors of calcium progression (odds ratio, 3.1 and 1.9, respectively), whereas baseline calcium score percentile and statin therapy were the best predictors of infarction. These findings support the notion that diabetes mellitus causes accelerated atherosclerosis, even in the presence of statin therapy, and provide evidence that coronary calcium monitoring is an effective method to assess treatment efficacy.

Determinants of coronary artery calcification in diabetics with and without nephropathy

BACKGROUND

In the general population, including those with diabetes mellitus, coronary artery calcification (CAC) correlates with atherosclerotic plaque burden. On the other hand, accumulating evidence suggests that disordered mineral metabolism significantly contributes to the vascular calcification in individuals with end-stage renal disease (ESRD).

METHODS

In order to determine the relative contribution of accelerated atherosclerosis and disordered mineral metabolism to CAC in chronic kidney disease, a pilot study of 90 patients with type 2 diabetes mellitus was done [age, 40-65 years; normoalbuminuria, N= 30; diabetic nephropathy (DN), N= 60].

RESULTS

CAC was more prevalent and severe among individuals with DN compared to diabetic controls (odds ratio for prevalence 8.1, 95% CI 2.3-28.5; median scores, 66 vs. 4, P < 0.001). None of the 4 measures of disordered mineral metabolism evaluated in this study (serum calcium, phosphorus, parathyroid hormone, and 1,25 di-hydroxy vitamin D levels) correlated with the prevalence or severity of CAC, or accounted for the differences seen between DN and diabetic controls. On the other hand, the difference in the severity of hypertension (number of antihypertensive medications) appeared to account for the differences in CAC burden seen between DN and diabetic controls.

CONCLUSION

This first such study of nondialyzed individuals with DN suggests that, unlike ESRD patients, the high CAC burden seen at earlier stages of diabetic chronic kidney disease is probably unrelated to disordered mineral metabolism. The relationship between the severity of hypertension and CAC burden provides a probable target for intervention in the predialysis phase of DN.

Diabetes and progression of coronary calcium under the influence of statin therapy

BACKGROUND

Coronary artery calcium (CAC) is a sensitive marker for the detection of coronary heart disease (CHD). Coronary artery calcification can be accurately quantified using electron beam tomography (EBT). We sought to evaluate the progression of atherosclerosis in asymptomatic persons with type 2 diabetes and measure the influence of statin therapy on CAC progression.

METHODS

We evaluated 163 asymptomatic patients with type 2 diabetes (120 men, 43 women). Patients were physician referred and underwent 2 consecutive EBT scans at least 1 year apart. Demographic data, risk factors for CHD, and medication use were collected. Patients with symptoms or known CHD were excluded.

RESULTS

The mean age was 65 +/- 10 years. The mean CAC score at baseline was 651 +/- 414. Only 9 (6%) of 163 of participants had scores of 0 at baseline. The time between scans averaged 27 +/- 15 months. Patients not treated with statins demonstrated a median annual increase in CAC progression of 20% (4%-44%), whereas statin-treated patients demonstrated increase of 10% (4%-25%) (P = .0001). Hemoglobin A 1c was weakly associated with CAC progression.

CONCLUSIONS

Asymptomatic diabetic patients show a high prevalence of atherosclerosis based on high frequency of coronary calcification. Statin therapy induced a 50% reduction in the rate of CAC progression. As rapid CAC progression has been associated with coronary events, EBT may serve as a noninvasive method for following atherosclerosis and response to therapy.

Should we screen for occult coronary artery disease among asymptomatic patients with diabetes?

Diabetes mellitus predisposes people to premature atherosclerotic coronary artery disease (CAD). The risk of a myocardial infarction in diabetics without overt evidence of obstructive CAD matches that of patients without diabetes who have had a previous myocardial infarction. The available data suggest that occult CAD is a common finding among asymptomatic diabetics, ranging from 20% to >50%. The diagnostic accuracy of myocardial perfusion single-photon emission computed tomography (SPECT) in diabetics appears to be comparable to that observed in nondiabetic individuals. As shown in other patient groups, the ischemic burden assessed by stress SPECT in subjects with diabetes is also linked to their increased risk of adverse cardiovascular events. Among patients with normal stress SPECT, however, those with diabetes are at significantly greater risk than non-diabetics. Testing diabetics with an abnormal resting electrocardiogram or with evidence of peripheral or carotid occlusive arterial disease appears to result in an excellent yield of abnormal SPECT findings, as does testing in the setting of dyspnea. However, recent evidence suggests that achieving an adequate yield in asymptomatic diabetics without overt evidence of CAD is a greater challenge. Further investigation of sequential testing strategies is needed in order to identify an efficient means for screening asymptomatic patients with diabetes.

Identifying high-risk asymptomatic diabetic patients who are candidates for screening stress single-photon emission computed tomography imaging

OBJECTIVES

The purpose of this study was to identify which asymptomatic diabetic patients are candidates for screening single-photon emission computed tomography (SPECT) imaging and to examine angiographic findings and mortality in patients according to SPECT imaging categories.

BACKGROUND

Previously we reported a high percentage of abnormal and high-risk SPECT imaging scans in asymptomatic diabetic patients.

METHODS

We examined the associations between several clinical and laboratory variables and a high-risk stress SPECT imaging scan in 1,427 asymptomatic diabetic patients without known coronary artery disease (CAD). Results of coronary angiography and long-term outcome were also analyzed.

RESULTS

An abnormal stress SPECT imaging scan was present in 826 patients (58%) and a high-risk scan in 261 patients (18%). Multivariate analysis demonstrated that seven variables were independently associated with a high-risk scan (model chi-square=107, p <0.0001). The two most important variables were electrocardiogram (ECG) Q waves (adjusted chi-square=38.3, p <0.001) and peripheral arterial disease (PAD) (adjusted chi-square=13.9, p <0.001). Coronary angiography was performed in 127 (49%) high-risk SPECT imaging patients, 61% of whom had angiographic high-risk CAD. Annual mortality rates for patient subsets categorized by SPECT imaging scans were high-risk 5.9%, intermediate-risk 5.0%, and low-risk 3.6% (p <0.001 for differences between groups).

CONCLUSIONS

High-risk findings on stress SPECT imaging were present in 18% of asymptomatic diabetic patients without known CAD. Patients with high-risk scans had a high prevalence of severe CAD and a high annual mortality rate. ECG Q waves and/or evidence of PAD identified the most suitable candidates for screening.

The association of coronary calcium score and conventional cardiovascular risk factors in Type 2 diabetic subjects asymptomatic for coronary heart disease (The PREDICT Study)

AIM

To determine the association between coronary calcification score (CACS) obtained by electron beam computed tomography (EBCT) and cardiovascular risk factors in Type 2 diabetic subjects entered into a prospective cohort study.

METHODS

Type 2 diabetic subjects attending routine hospital diabetic clinics without known coronary heart disease (CHD) underwent EBCT to measure CACS. Demographic data were obtained and conventional cardiovascular risk factors were measured at baseline.

RESULTS

Four hundred and ninety-five subjects were assessed of whom 67.7% were male. They had a mean (SD) age of 62.9 (7.1) years, with median (inter-quartile range) duration of diabetes of 8 (4-13) years. None had a history of coronary artery disease. Forty-five per cent were receiving lipid-lowering agents (including 36% statins). In a univariate analysis, there were significant associations between increased CACS and age, duration of diabetes, male gender, waist-hip ratio (WHR), systolic blood pressure, and the use of statins. In a multivariate model adjusting for the possible interaction of these and other factors, the significant association between CACS and WHR, systolic blood pressure, male gender and statin use remained.

CONCLUSIONS

The close association between CACS and WHR and the association with systolic blood pressure suggest that coronary calcification may be particularly linked to the metabolic syndrome in Type 2 diabetes.

Prognostic value of coronary artery calcium screening in subjects with and without diabetes

OBJECTIVES

The study was done to determine the interaction of coronary artery calcium and diabetes mellitus for prediction of all-cause death.

BACKGROUND

Diabetes is a strong risk factor for coronary artery disease (CAD) and is associated with an elevated overall mortality. Electron beam tomography (EBT) provides information on the presence of subclinical atherosclerosis and may be useful for risk stratification.

METHODS

We followed 10,377 asymptomatic individuals (903 diabetic patients) referred for EBT imaging. Primary end point was all-cause mortality, and the average follow-up was 5.0 +/- 3.5 years. Cox proportional hazard models, with and without adjustment for other risk factors, were developed to predict all-cause mortality.

RESULTS

Patients with diabetes had a higher prevalence of hypertension and smoking (p < 0.001) and were older. The average coronary calcium score (CCS) for subjects with and for those without diabetes was 281 +/- 567 and 119 +/- 341, respectively (p < 0.0001). Overall, the death rate was 3.5% and 2.0% for subjects with and without diabetes (p < 0.0001). In a risk-factor-adjusted model, there was a significant interaction of CCS with diabetes (p < 0.00001), indicating that, for every increase in CCS, there was a greater increase in mortality for diabetic than for nondiabetic subjects. However, patients suffering from diabetes with no coronary artery calcium demonstrated a survival similar to that of individuals without diabetes and no detectable calcium (98.8% and 99.4%, respectively, p = 0.5).

CONCLUSIONS

Mortality from all causes is increased in asymptomatic patients with diabetes in proportion to the screening CCS. Nonetheless, subjects without coronary artery calcium have a low short-term risk of death even in the presence of diabetes mellitus.

Role of surrogate markers in assessing patients with diabetes mellitus and the metabolic syndrome and in evaluating lipid-lowering therapy

Diabetes mellitus and the metabolic syndrome (MS) are reaching epidemic proportions in the United States, and cardiovascular disease continues to be the leading cause of death among patients with diabetes. A range of noninvasive screening tools may help reduce the morbidity and mortality of patients with diabetes because of early detection of subclinical cardiovascular disease and active monitoring of the effectiveness of therapy. Surrogate markers of subclinical disease include conventional and contrast-enhanced ultrasound imaging of carotid artery intima-media thickness (c-IMT), 2-dimensional echocardiography, coronary artery calcium imaging, cardiac magnetic resonance imaging, ankle-brachial indices, and brachial artery reactivity testing. Because these noninvasive imaging tools are relatively comfortable and entail relatively low risk to the patient, they are ideal for initial screening and for the repeated imaging that is required for monitoring the effectiveness of therapy. Moreover, when used in large numbers of patients with diabetes, prediabetes, and the MS, these imaging tools may be useful in developing and validating thresholds for the use of lipid-lowering therapy as well as clear therapeutic goals for this population. In addition, contrast-enhanced c-IMT scans now produce real-time images of the vasa vasorum and neovascularization of atherosclerotic plaque, potentially causing a paradigm shift in our view of the genesis of atherosclerosis and affecting treatment options for all populations. Thus, surrogate markers may not only help improve individual patient outcomes, they also may help direct scarce medical resources to maximize medical benefits, improve overall medical care, and minimize costs and untoward side effects.

The prevalence of coronary artery calcium among diabetic individuals without known coronary artery disease

OBJECTIVES

We sought to examine the age and gender distribution of coronary artery calcium (CAC) by diabetes status in a large cohort of asymptomatic individuals.

BACKGROUND

Among individuals with diabetes, coronary artery disease (CAD) is a major cause of morbidity and mortality. Electron-beam tomography (EBT) quantifies CAC, a marker for atherosclerosis.

METHODS

Screening for CAC by EBT was performed in 30,904 asymptomatic individuals stratified by their self-reported diabetes status, gender, and age. The distribution of CAC across the strata and the association between diabetes and CAC were examined.

RESULTS

Compared with nondiabetic individuals (n = 29,829), those with diabetes (n = 1,075) had higher median CAC scores across all but two age groups (women 40 to 44 years old and men and women > or =70 years old). Overall, the likelihood of having a CAC score in the highest age/gender quartile was 70% greater for diabetic individuals than for their nondiabetic counterparts.

CONCLUSIONS

Younger diabetic individuals appear to have calcified plaque burden comparable to that of older individuals without diabetes. These findings call for future research to determine if EBT-CAC screening has an incremental value over the current CAD risk assessment of individuals with diabetes.

Value of coronary artery calcium scanning by computed tomography for predicting coronary heart disease in diabetic subjects

OBJECTIVE

The South Bay Heart Watch is a cohort study designed to determine the significance of coronary calcium in high-risk asymptomatic patients. This is a report of the relative risk (RR) for outcomes of coronary artery calcium in diabetic and nondiabetic subjects.

RESEARCH DESIGN AND METHODS

A total of 1312 diabetic and nondiabetic subjects underwent risk factor screening and computed tomography testing for coronary calcium at baseline and were followed clinically for 6.3 +/- 1.4 years. End points were either 1). hard events of nonfatal myocardial infarction (MI) or coronary death or 2). any cardiovascular event (nonfatal MI, coronary death, coronary revascularization, or stroke).

RESULTS

The incidence rates of a hard event and any cardiovascular event for diabetic and nondiabetic subjects were 14.5 and 6.1% and 23.8 and 12.2%, respectively (P < 0.001). Cox regression analyses of the combined risk relationship of diabetes status and calcium score demonstrated that relative to nondiabetic subjects with low calcium scores (<2.8), diabetic subjects with calcium scores >or=2.8 exhibited at least a fourfold increase in the risk of either a hard or any cardiovascular event (P < 0.001). Cox regression analyses conducted separately for nondiabetic and diabetic subjects revealed that coronary calcium score risk groups were significantly associated with events in nondiabetic subjects (RR >or= 2.6, P <or= 0.01), but not in diabetic subjects (RR <or= 1.7, P > 0.05).

CONCLUSIONS

The risk of coronary heart disease increases with increasing calcium scores and diabetes status. Calcium scores have less prognostic value in diabetic subjects.

Association of multiple risk factors and insulin resistance with increased prevalence of asymptomatic coronary artery disease by an electron-beam computed tomographic study

The insulin resistance syndrome, consisting of resistance to insulin and several metabolic abnormalities, is associated with an increased risk of symptomatic coronary artery disease. Asymptomatic persons with increased coronary calcification have increased coronary plaque and an increased likelihood of future cardiovascular events. Electron-beam computed tomography-derived coronary artery calcium scores, metabolic and anthropometric parameters, and fasting and stimulated concentrations of glucose and insulin were measured in 1160 asymptomatic men and women. Coronary artery calcium scores were positively correlated with glucose, insulin, and homeostasis model assessment (HOMA) insulin resistance. Calcium scores were positively correlated with intra-abdominal adiposity, age, total cholesterol/high density lipoprotein (HDL) ratio, low density lipoprotein, triglycerides, blood pressure, and HOMA beta cell function and inversely correlated with HDL and peripheral fat. These correlations, except for 2-hour glucose, remained significant for all subjects with fasting serum glucose <126 mg/dL or all subjects with fasting serum glucose 110 mg/dL. In a multivariate analysis, age, sex, family history of premature coronary artery disease, intra-abdominal adiposity, low density lipoprotein, and smoking independently predicted calcium scores. Blood pressure, HDL, triglycerides, glucose, insulin, and HOMA insulin resistance or beta cell function were not independently correlated with coronary artery calcium scores. Asymptomatic individuals with insulin resistance have elevated coronary calcium scores. The association between insulin resistance and coronary calcification persists with impaired glucose tolerance and normal fasting serum glucose. Central/visceral adiposity may be a determinant of insulin resistance and atherosclerosis even in asymptomatic nondiabetic persons.

Pathophysiology of apolipoprotein E deficiency in mice: relevance to apo E-related disorders in humans

Apolipoprotein E (apo E) deficiency (or its abnormalities in humans) is associated with a series of pathological conditions including dyslipidemia, atherosclerosis, Alzheimer's disease, and shorter life span. The purpose of this study was to characterize these conditions in apo E-deficient C57BL/6J mice and relate them to human disorders. Deletion of apo E gene in mice is associated with changes in lipoprotein metabolism [plasma total cholesterol (TC) (>+400%), HDL cholesterol (-80%), HDL/TC, and HDL/LDL ratios (-93% and -96%, respectively), esterification rate in apo B-depleted plasma (+100%), plasma triglyceride (+200%), hepatic HMG-CoA reductase activity (-50%), hepatic cholesterol content (+30%)], decreased plasma homocyst(e)ine and glucose levels, and severe atherosclerosis and cutaneous xanthomatosis. Hepatic and lipoprotein lipase activities, hepatic LDL receptor function, and organ antioxidant capacity remain unchanged. Several histological/immunohistological stainings failed to detect potential markers for neurodegenerative disease in the brain of 37-wk-old male apo E-KO mice. Apo E-KO mice may have normal growth and development, but advanced atherosclerosis and xanthomatosis may indirectly reduce their life span. Apo E plays a crucial role in regulation of lipid metabolism and atherogenesis without affecting lipase activities, endogenous antioxidant capacity, or appearance of neurodegenerative markers in 37-wk-old male mice.