Comparison of prevalence and severity of coronary calcium determined by electron beam tomography among various ethnic groups

Beyond the Basics: Unraveling the Complexity of Coronary Artery Calcification

Coronary artery calcification (CAC) is mainly associated with coronary atherosclerosis, which is an indicator of coronary artery disease (CAD). CAC refers to the accumulation of calcium phosphate deposits, classified as micro- or macrocalcifications, that lead to the hardening and narrowing of the coronary arteries. CAC is a strong predictor of future cardiovascular events, such as myocardial infarction and sudden death. Our narrative review focuses on the pathophysiology of CAC, exploring its link to plaque vulnerability, genetic factors, and how race and sex can affect the condition. We also examined the connection between the gut microbiome and CAC, and the impact of genetic variants on the cellular processes involved in vascular calcification and atherogenesis. We aimed to thoroughly analyze the existing literature to improve our understanding of CAC and its potential clinical and therapeutic implications.

Association of diabetes with coronary artery calcium in South Asian adults and other race/ethnic groups: The multi-ethnic study of atherosclerosis and the mediators of atherosclerosis in South Asians living in America study

PURPOSE

South Asian (SA) persons have increased risks for diabetes mellitus (DM) and atherosclerotic cardiovascular disease (ASCVD). We examined whether the association of DM with subclinical atherosclerosis assessed by coronary artery calcium (CAC) differs in SA versus other ethnic groups.

METHODS

We studied adults from the Multi-Ethnic Study of Atherosclerosis and the Mediators of Atherosclerosis in South Asians Living in America studies without ASCVD. CAC was examined among those normoglycemic, pre-DM and DM. Logistic regression examined pre-DM and DM with the odds of any CAC > 0 and CAC ≥ 100.

RESULTS

Among 7562 participants, CAC > 0 and CAC ≥ 100 in those with DM was highest in non-Hispanic White (NHW) (80% and 48%) and SA (72% and 41%) persons. Adjusted Ln (CAC + 1) was highest in NHW (3.68 ± 0.21) and SA (3.60 ± 0.23) (p < .01) DM patients. SA and NHW adults with DM (vs normoglycemic) had highest odds of CAC > 0 (2.13 and 2.27, respectively, p < .01). For CAC ≥ 100, SA and Chinese adults had the highest odds (2.28 and 2.27, respectively, p < .01). Fasting glucose and glycated hemoglobin were most strongly associated with CAC among SA.

CONCLUSIONS

Diabetes mellitus most strongly relates to any CAC in SA and NHW adults and CAC ≥ 100 in SA and Chinese adults, helping to explain the relation of DM with ASCVD in these populations.

Leveling the playing field: The utility of coronary artery calcium scoring in cardiovascular risk stratification in South Asians

South Asian (SA) individuals, particularly those that reside in the United States and other Westernized countries, are at an elevated risk for ASCVD and mortality related to ASCVD. The 2018 ACC/AHA/Multi-society Cholesterol guideline listed SA as a high-risk ethnicity, underscoring the importance of treating modifiable risk factors to reduce ASCVD burden. Coronary artery calcium (CAC), a highly specific marker of subclinical atherosclerosis, may be a useful test to improve risk stratification among SA individuals. CAC testing is a cost-effective, highly reproducible, and specific marker of subclinical atherosclerosis, shown to improve ASCVD risk assessment across all racial/ethnic groups, thereby serving as a guide for initiating or deferring preventive therapies. In this White Paper we will discuss the use of CAC scoring to optimize risk stratification and delivery of preventive therapies to individuals of SA ethnicity.

Identification and Management of Atherosclerotic Cardiovascular Disease Risk in South Asian Populations in the U.S

South Asians (SAs, individuals with ancestry from Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka) are among the fastest growing ethnic subgroups in the United States. SAs typically experience a high prevalence of diabetes, abdominal obesity, and hypertension, among other cardiovascular disease risk factors, which are often under recognized and undermanaged. The excess coronary heart disease risk in this growing population must be critically assessed and managed with culturally appropriate preventive services. Accordingly, this scientific document prepared by a multidisciplinary group of clinicians and investigators in cardiology, internal medicine, pharmacy, and SA-centric researchers describes key characteristics of traditional and nontraditional cardiovascular disease risk factors, compares and contrasts available risk assessment tools, discusses the role of blood-based biomarkers and coronary artery calcium to enhance risk assessment and prevention strategies, and provides evidenced-based approaches and interventions that may reduce coronary heart disease disparities in this higher-risk population.

Coronary artery calcium incidence and changes using direct plaque measurements: The MASALA study

BACKGROUND AND AIMS

We aimed to identify predictors of change in direct measures of coronary artery calcium (CAC) volume and density in South Asian participants.

METHODS

We used data from participants in the Mediators of Atherosclerosis in South Asians Living in America (MASALA) study with prevalent CAC and direct measures of CAC by serial computed tomography (CT) exams (2010-2013, 2016-2018). We examined the distribution of incident CAC volume and peak density, as well as progression and identified risk factors for progression of change in volume and density in multivariable models.

RESULTS

The study cohort consisted of 102 participants with incident CAC and 285 with CAC progression. CAC volume and density were highest, and incident CAC was most common in the left anterior descending artery (LAD). The greatest progression in volume was in the right coronary artery and the greatest change in density was in the left main. In linear regression models for CAC progression adjusted for baseline density, volume, risk factors, smoking (β +190.1, p = 0.02), baseline volume (β +0.24 per mm³, p < 0.01), and scan interval (β +0.15 per day, p = 0.01) were associated with change in total volume whereas Lp(a) (β +0.81 per mg/dL, p = 0.03), exercise (β +0.19 per 10 MET-min/week, p = 0.01), and baseline volume (β +0.15 per mm³, p < 0.01) and density (β -0.55 per unit, p < 0.01) were associated with change in total density.

CONCLUSIONS

In this South Asian cohort, smoking was associated with CAC volume progression, while Lp(a) and exercise were associated with progression of peak CAC density.

The Morphology of Coronary Artery Disease in South Asians versus White Caucasians and its Implications

South Asians (SAs) experience a higher prevalence and earlier onset of coronary artery disease and have worse outcomes relative to White Caucasians (WCs) following invasive revascularization procedures, a mainstay of coronary artery disease (CAD) management. We sought to review the differences in the CAD pattern and risk factors between SA and WC patients and discuss their potential impact on the development of coronary disease, acute coronary syndrome and revascularization outcomes. SAs have a more diffuse pattern with multi-vessel involvement compared to WCs. However, less is known about other morphological characteristics such as calcification of atherosclerotic plaque and coronary diameter in SA populations. Despite a similar coronary calcification burden, higher non-calcified plaque composition, elevated thrombosis and inflammatory markers likely contribute to the disease pattern. While the current evidence on the role of coronary vessel size remains inconsistent, smaller coronary diameters in SAs could play a potential role in the higher disease prevalence. This is especially important given the impact of coronary artery diameter on revascularization outcomes. In conclusion, SAs have a unique CAD risk profile comprised of traditional and novel risk factors. Our findings highlight the need for additional awareness of healthcare professionals of this specific risk profile and potential therapeutic targets, as well as the need for further research in this vulnerable population.

Obesity Pillars Roundtable: Obesity and South Asians

Background

Compared to other races/ethnicities, individuals from South Asia with obesity are strikingly susceptible to the presence of CVD risk factors and onset of CVD events - in part due to adiposopathic anatomic and metabolic responses to positive caloric balance. Pathogenic endocrine and immune effects of adipocyte hypertrophy and visceral fat accumulation both directly and indirectly promote among the most common metabolic diseases encountered in clinical practice - many being major cardiovascular disease (CVD) risk factors. This is especially applicable to those from South Asia - largely due to genetics, epigenetics, unhealthful nutrition, and physical inactivity.

Methods

This roundtable discussion included 4 obesity specialists engaged in the clinical management of obesity among patients of South Asian descent.

Results

Patients with obesity from South Asia have increased adipocyte size, fewer (functional) adipocytes, and increased visceral adiposity accompanied by functional endocrine and immune abnormalities. This helps explain the increased CVD risk factors and increased CVD risk among this unique population. These CVD risk factors include increased prevalence of metabolic syndrome (even at lower body mass index relative to other races), insulin resistance, type 2 diabetes mellitus, increased lipoprotein (a), and adiposopathic dyslipidemia [(i.e., elevated triglyceride levels, reduced high density lipoprotein cholesterol levels, increased low density lipoprotein (LDL) particle number, and increased prevalence of smaller and denser LDL particles].

Conclusion

The four panelists of this roundtable discussion describe their practical diagnostic processes and treatment plans for patients from South Asia, with an emphasis on a patient-centered approach to obesity in this unique population.

Prevention of atherosclerotic cardiovascular disease in South Asians in the US: A clinical perspective from the National Lipid Association

It is now well recognized that South Asians living in the US (SAUS) have a higher prevalence of atherosclerotic cardiovascular disease (ASCVD) that begins earlier and is more aggressive than age-matched people of other ethnicities. SA ancestry is now recognized as a risk enhancer in the US cholesterol treatment guidelines. The pathophysiology of this is not fully understood but may relate to insulin resistance, genetic and dietary factors, lack of physical exercise, visceral adiposity and other, yet undiscovered biologic mechanisms. In this expert consensus document, we review the epidemiology of ASCVD in this population, enumerate the challenges faced in tackling this problem, provide strategies for early screening and education of the community and their healthcare providers, and offer practical prevention strategies and culturally-tailored dietary advice to lower the rates of ASCVD in this cohort.

Type 2 Diabetes and Atherosclerotic Cardiovascular Disease in South Asians: a Unique Population with a Growing Challenge

PURPOSE OF REVIEW

The purpose of this review is to summarize our current knowledge of factors that influence clinical decision making and management of type 2 diabetes mellitus (T2DM) and atherosclerotic cardiovascular disease (ASCVD) among South Asians (SA).

RECENT FINDINGS

ASCVD and T2DM in SAs have been examined in recent times. Pathophysiologic and genetic factors including the role of adiponectin, visceral adiposity, lower beta cell function, and psycho-social factors like sedentary lifestyle, poor adherence to medications, and carbohydrate dense meals play a role in early development and the high-risk presentation of both ASCVD and T2DM in SA. Recently, large population-based cohort studies have attempted to compare outcomes and interventions that can be translated to timely detection and targeted interventions in this high-risk group. SAs in the USA are more likely to be diagnosed with T2DM and ASCVD when compared to non-Hispanic whites, non-Hispanic Blacks, and Hispanic populations. The development of personalized ethnic risk assessment tools and better representation of SAs in prospective studies are essential to increasing our understanding and management of cardio-metabolic disease in SA living in the USA.

Incidence and Progression of Coronary Artery Calcium in South Asians Compared With 4 Race/Ethnic Groups

Background

South Asians have a relatively high prevalence of coronary artery calcium (CAC) compared with other race/ethnic groups. We determined CAC incidence and progression among South Asians, and compared them with 4 race/ethnic groups.

Methods and Results

Data from the MASALA (Mediators of Atherosclerosis in South Asians Living in America) study were used to calculate CAC incidence and progression rates and any CAC change. Data from the MESA (Multi‐Ethnic Study of Atherosclerosis) were used to compare the CAC incidence and progression rates. A total of 698 South Asians had repeat CAC measurements after 4.8±0.8 years. Among those with no CAC at baseline, the age‐adjusted CAC incidence was 8.8% (95% CI, 6.8–10.8%) in men and 3.6% (2.5–4.8%) in women. The median annual CAC progression was 26 (interquartile range, 11–62) for men and 13 (interquartile range, 4–34) for women. Compared with MESA, age‐adjusted CAC incidence was similar in South Asian men compared with white, black, and Latino men, but significantly higher than Chinese men (11.1% versus 5.7%, P=0.008). After adjusting for age, diabetes mellitus, hypertension, and statin medication use, Chinese, black, and Latino men had significantly less CAC change compared with South Asian men, but there were no differences between South Asian and white men. There was no difference in CAC incidence or progression between South Asian women and women in MESA.

Conclusions

South Asian men had greater CAC change than Chinese, black, and Latino men but similar change to that of whites after adjusting for traditional risk factors.

Racial Disparities in the Cardiac Computed Tomography Assessment of Coronary Artery Disease: Does Gender Matter

Coronary heart disease (CHD) represents a significant healthcare burden in terms of hospital resources, morbidity, and mortality. Primary prevention and early detection of risk factors for the development of CHD are pivotal to successful intervention programs and prognostication. Yet, there remains a paucity of evidence regarding differences in the assessment of these risk factors and the tools of assessment among different ethnicities. We conducted a narrative review to assess the utility of cardiac computed tomography, particularly coronary artery calcification (CAC), in different ethnicities. We also looked to see whether age, sex, comorbidities, and genetic background have peculiar influences on CAC. In this review, we highlight some of the pivotal studies regarding the question of CAC in relation to the development of CHD among different ethnicities. We identify several key trends in the literature showing that although African Americans have high rates of CHD, their risk of CAC may be relatively lower compared with other ethnicities. Similarly, South Asian patients may be at a high risk for adverse cardiac events due to elevated CAC. We also note that several studies are limited by small sample size and were based on 1 large cohort study. Future studies should include a large international prospective cohort to truly evaluate the effects of ethnicity on CAC and CHD risk. To appropriately apply CAC in the clinical practice, the variations in its scoring based on a subject's age, sex, comorbidity, and ethnicity should be addressed and interpreted beforehand.

Atherosclerotic Cardiovascular Disease in South Asians in the United States: Epidemiology, Risk Factors, and Treatments: A Scientific Statement From the American Heart Association

South Asians (from Bangladesh, Bhutan, India, the Maldives, Nepal, Pakistan, and Sri Lanka) make up one quarter of the world's population and are one of the fastest-growing ethnic groups in the United States. Although native South Asians share genetic and cultural risk factors with South Asians abroad, South Asians in the United States can differ in socioeconomic status, education, healthcare behaviors, attitudes, and health insurance, which can affect their risk and the treatment and outcomes of atherosclerotic cardiovascular disease (ASCVD). South Asians have higher proportional mortality rates from ASCVD compared with other Asian groups and non-Hispanic whites, in contrast to the finding that Asian Americans (Asian Indian, Chinese, Filipino, Japanese, Korean, and Vietnamese) aggregated as a group are at lower risk of ASCVD, largely because of the lower risk observed in East Asian populations. Literature relevant to South Asian populations regarding demographics and risk factors, health behaviors, and interventions, including physical activity, diet, medications, and community strategies, is summarized. The evidence to date is that the biology of ASCVD is complex but is no different in South Asians than in any other racial/ethnic group. A majority of the risk in South Asians can be explained by the increased prevalence of known risk factors, especially those related to insulin resistance, and no unique risk factors in this population have been found. This scientific statement focuses on how ASCVD risk factors affect the South Asian population in order to make recommendations for clinical strategies to reduce disease and for directions for future research to reduce ASCVD in this population.

Prevalence by Computed Tomographic Angiography of Coronary Plaques in South Asian and White Patients With Type 2 Diabetes Mellitus at Low and High Risk Using Four Cardiovascular Risk Scores (UKPDS, FRS, ASCVD, and JBS3)

The aim of this study was to explore the association between various cardiovascular (CV) risk scores and coronary atherosclerotic burden on coronary computed tomography angiography (CTA) in South Asians with type 2 diabetes mellitus and matched whites. Asymptomatic type 2 diabetic South Asians and whites were matched for age, gender, body mass index, hypertension, and hypercholesterolemia. Ten-year CV risk was estimated using different risk scores (United Kingdom Prospective Diabetes Study [UKPDS], Framingham Risk Score [FRS], AtheroSclerotic CardioVascular Disease [ASCVD], and Joint British Societies for the prevention of CVD [JBS3]) and categorized into low- and high-risk groups. The presence of coronary artery calcium (CAC) and obstructive coronary artery disease (CAD; ≥50% stenosis) was assessed using coronary CTA. Finally, the relation between coronary atherosclerosis on CTA and the low- and high-risk groups was compared. UKPDS, FRS, and ASCVD showed no differences in estimated CV risk between 159 South Asians and 159 matched whites. JBS3 showed a significant greater absolute CV risk in South Asians (18.4% vs 14.2%, p <0.01). Higher presence of CAC score >0 (69% vs 55%, p <0.05) and obstructive CAD (39% vs 27%, p <0.05) was observed in South Asians. South Asians categorized as high risk, using UKPDS, FRS, and ASCVD, showed more CAC and CAD compared than whites. JBS3 showed no differences. In conclusion, asymptomatic South Asians with type 2 diabetes mellitus more frequently showed CAC and obstructive CAD than matched whites in the population categorized as high-risk patients using UKPDS, FRS, and ASCVD as risk estimators. However, JBS3 seems to correlate best to CAC and CAD in both ethnicity groups compared with the other risk scores.

Subclinical atherosclerosis detected by coronary computed tomographic angiography in Qatar: a comparison between Qataris and south Asian migrants

PURPOSE

There are limited data regarding subclinical atherosclerosis in Middle Eastern countries. We aimed to describe and compare coronary computed tomographic angiography (CCTA) findings in Qatari native and South Asian migrants at increased risk of coronary artery disease (CAD).

METHODS

We performed CCTA in 251 consecutive volunteers (126 South Asian, 125 Qatari, mean age 50.0 ± 7.3 years, 27.1% female) at increased risk of cardiovascular disease. Given differences in baseline risk factors, we employed propensity score matching to create a cohort of 162 subjects for comparative analyses. We compared CAD severity, extent, plaque morphology, adverse plaque characteristics, and quantitative measures of atherosclerotic burden in both subgroups.

RESULTS

After matching, no CAD was seen in 58.0% of South Asians and 49.4% of Qataris (p = 0.3), while obstructive CAD (≥50% luminal stenosis) was present in 40.7% of South Asians and 49.4% of Qataris (p = 0.3). There was a high prevalence of adverse plaque characteristics in both ethnicities, particularly positive remodeling. South Asians had significantly smaller vessel and lumen volumes, but the percent aggregate plaque volumes were not significantly different (2.9 ± 6.3% vs. 3.8 ± 8.0%, p = 0.4).

CONCLUSIONS

In this first study of CCTA findings performed in a Middle Eastern country, we observed a high prevalence of obstructive CAD in a middle-aged cohort. There were no significant differences in CCTA findings between Qataris and South Asians after adjustment for clinical risk factors. Future studies are needed to identify patterns of coronary atherosclerosis by CCTA in non-European populations where cardiovascular disease is increasingly prevalent.

Reassessing the Usefulness of Coronary Artery Calcium Score among Varying Racial and Ethnic Groups by Geographic Locations: Relevance of the Korea Initiatives on Coronary Artery Calcification Registry

There is some disparity in the morbidity and mortality rates of cardiovascular disease (CVD) according to race, ethnicity, and geographic regions. Although prediction algorithms that evaluate risk of cardiovascular events have been established using traditional risk factors, they have also demonstrated a number of differences along with race and ethnicity. Of various risk assessment modalities, coronary artery calcium (CAC) score is a sensitive marker of calcific atherosclerosis and correlates well with atherosclerotic plaque burden. Although CAC score is now utilized as a useful tool for early detection of coronary artery disease, prior studies have suggested some variability in the presence and severity of coronary calcification according to race, ethnicity, and/or geographic regions. Among Asian populations, it would appear necessary to reappraise the utility of CAC score and whether it remains superior over and above established clinical risk prediction algorithms. To this end, the Korea initiatives on coronary artery calcification (KOICA) registry has been designed to identify the effectiveness of CAC score for primary prevention of CVD in asymptomatic Korean adults. This review discusses the important role of CAC score for prognostication, while also describing the design and rationale of the KOICA registry.

Comparison by computed tomographic angiography-the presence and extent of coronary arterial atherosclerosis in South Asians versus Caucasians with diabetes mellitus

South Asians in the Western world have a high prevalence of diabetes mellitus (DM) and an increased risk of coronary artery disease (CAD) and mortality compared with Caucasians. CAD in asymptomatic South Asian patients with type 2 DM has not been investigated. The aim of this observational cohort study was to investigate CAD in asymptomatic South Asian patients with type 2 DM and to compare with matched Caucasian patients. A total of 120 asymptomatic South Asian patients with type 2 DM and matched Caucasian patients (mean age 52 years, 55% men) were derived from an ongoing registry of cardiovascular risk stratification in asymptomatic patients with DM. Cardiovascular risk assessment included multidetector row coronary computed tomography angiography. CAD was assessed as the coronary artery calcium score and classified into no signs of atherosclerosis or minor wall irregularities <30%, nonsignificant CAD 30% to 50%, or significant CAD ≥50% stenosis. On a patient base, CAD was scored according to the severity and number of vessels and segments with significant CAD. Subsequently, CAD was assessed per coronary artery and per segment. Compared with Caucasian patients, South Asian patients had a significantly higher coronary artery calcium score and higher prevalence of significant CAD (41% vs 28%, respectively, p = 0.008), involving more coronary vessels and segments. Significant CAD was especially more frequent in the left anterior descending coronary artery. In conclusion, asymptomatic South Asian patients with type 2 DM have a higher prevalence and extent of CAD compared with matched Caucasian patients.

Comparing coronary artery calcium among U.S. South Asians with four racial/ethnic groups: the MASALA and MESA studies

OBJECTIVES

South Asians (individuals from India, Pakistan, Bangladesh, Nepal, and Sri Lanka) have high rates of cardiovascular disease which cannot be explained by traditional risk factors. Few studies have examined coronary artery calcium (CAC) in South Asians.

METHODS

We created a community-based cohort of South Asians in the United States and compared the prevalence and distribution of CAC to four racial/ethnic groups in the Multi-Ethnic Study of Atherosclerosis (MESA). We compared 803 asymptomatic South Asians free of cardiovascular disease to the four MESA racial/ethnic groups (2622 Whites, 1893 African Americans, 1496 Latinos and 803 Chinese Americans).

RESULTS

The age-adjusted prevalence of any CAC was similar between White and South Asian men, but was lower in South Asian women compared to White women. After adjusting for all covariates associated with CAC, South Asian men were similar to White men and had higher CAC scores compared to African Americans, Latinos and Chinese Americans. In fully adjusted models, CAC scores were similar for South Asian women compared to all women enrolled in MESA. However, South Asian women ≥70 years had a higher prevalence of any CAC than most other racial/ethnic groups.

CONCLUSIONS

South Asian men have similarly high CAC burden as White men, but higher CAC than other racial/ethnic groups. South Asian women appear to have similar CAC burden compared to other women, but have somewhat higher CAC burden in older age. The high burden of subclinical coronary atherosclerosis in South Asians may partly explain higher rates of cardiovascular disease in South Asians.

Aggressive and diffuse coronary calcification in South Asian angina patients compared to Caucasians with similar risk factors

BACKGROUND

Ethnic differences in prevalence and severity of coronary artery disease are well established and are usually attributed to risk factors variation. This study investigates the differences in coronary artery narrowing and coronary calcification between two age- and gender-matched cohorts of South Asian and Caucasian symptomatic angina patients.

METHODS

We identified 101 symptomatic angina patients of South Asian origin who had undergone CT angiography and calcium scoring, and compared them with 101 age and gender matched Caucasian patients.

RESULTS

South Asians had a greater mean number of arterial segments with both obstructive and non-obstructive plaque than Caucasians (p=0.006 and p=0.0003, respectively) and higher prevalence of triple-vessel disease (p=0.0004). Similarly, South Asians had a higher mean CAC score (p<0.0001) and the percentage of South Asians with CAC>0 and in all categories of CAC score 100-1000 were also higher, as was the number of arterial segments with calcified and non-calcified plaque. These results were more marked in patients aged >50 but in those ≤ 50, Caucasians showed a higher mean number of diseased segments (p=0.019), with non-obstructive plaque (p=0.02), possibly suggesting that Caucasians are likely to have more diffuse atherosclerosis at an earlier age. CAC prevalence and severity in this age-group were not significantly different between South Asians and Caucasians.

CONCLUSION

Despite similar conventional risk factors for CAD, symptomatic South Asians seem to have more aggressive and diffuse arterial calcification compared to Caucasians. These differences are more profound above the age of 50, suggesting potential genetic or other risk factors yet to be determined.

Prevalence of coronary artery calcium scores and silent myocardial ischaemia was similar in Indian Asians and European whites in a cross-sectional study of asymptomatic subjects from a U.K. population (LOLIPOP-IPC)

BACKGROUND

Coronary heart disease (CHD) mortality is 70% higher among Indian Asians (IA) than European whites (EW), the reasons for this excess remain unexplained. Coronary artery calcification (CAC) is highly correlated with coronary plaque burden and silent myocardial ischaemia in EW; but fails to identify excess risk in IA. We hypothesised that IA have a higher prevalence of silent myocardial ischaemia compared to EW, despite similar CAC, and this may explain their excess CHD mortality.

METHODS

CAC was measured for 2,369 asymptomatic men and women, aged 35 to 75 years, as part of the London Life Sciences Population (LOLIPOP) study. 518 subjects had CAC scores >100 Agatston units and of these 256 (49%) patients underwent myocardial perfusion scintigraphy (MPS).

RESULTS

CAC scores were similar among IA and EW, after adjustment for conventional risk factors. MPS abnormalities were seen in 56 (22%) subjects. Presence of diabetes (P = .03) and increasing CAC (P < .001) were independent predictors for severity of silent myocardial ischaemia. Ethnicity did not influence the prevalence or the extent of silent myocardial ischaemia.

CONCLUSION

MPS did not identify greater ischaemia among IA compared with EW. This appears incongruent with almost 2-fold higher risk of CHD mortality observed in IA.

Type 2 diabetes does not attenuate racial differences in coronary calcification

AIMS

Coronary artery calcification (CAC) is a strong predictor of atherosclerotic cardiovascular disease (CVD). Whites appear to have a higher prevalence of CAC than African-Americans (AAs), but it is unknown if type 2 diabetes, a major cardiovascular risk factor, attenuates this difference. We investigated the relationship of race and CAC in a sample of patients with type 2 diabetes without clinical CVD.

METHODS

multivariable analyses of self-reported ethnicity and CAC scores, stratified by gender, in 861 subjects [32% AA, 66.9% male] with type 2 diabetes.

RESULTS

AA race was associated with lower CAC scores in age-adjusted models in males [Tobit ratio for AAs vs. Whites 0.14 (95% CI 0.08-0.24, p<0.001)] and females [Tobit ratio 0.26 (95% CI 0.09-0.77, p=0.015)]. This persisted in men after adjustment for traditional, metabolic and inflammatory risk factors, but adjustment for plasma triglycerides [0.48 (95% CI 0.15-1.49, p=0.201)] and HOMA-IR [0.28 (95% CI 0.08-1.03, p=0.055)] partially attenuated the association in women.

CONCLUSIONS

relative to African-Americans, White race is a strong predictor of CAC, even in the presence of type 2 diabetes. The relationship in women appears less robust possibly due to gender differences in metabolic risk factors.

Ethnic Differences in the Prognostic Value of Coronary Artery Calcification for All-Cause Mortality

OBJECTIVES

The purpose of this study was to evaluate the prognostic value of coronary artery calcium (CAC), a known marker of subclinical atherosclerosis, in a large, ethnically diverse cohort of 14,812 patients for the prediction of all-cause mortality.

BACKGROUND

Disparities in case fatality rates for heart disease among ethnic groups are well known. In 2001, rates of death from heart disease were 30% higher among African Americans (AA) than non-Hispanic whites (NHW). Some of this variability may be due to differing pathophysiological mechanisms and effects of underlying atherosclerosis.

METHODS

Ten-year death rates from all causes (total deaths = 505) were compared using risk-adjusted Cox proportional hazards models in AA (n = 637), Hispanic (HS, n = 1,334), Asian (AS, n = 1,065), and NHW (n = 11,776) populations.

RESULTS

Ethnic minority patients were generally younger (0.3 to 4 years), more often persons with diabetes (p < 0.0001), hypertensive (p < 0.0001), and female (p < 0.0001). The prevalence of CAC scores > or =100 was highest in NHW (31%) and lowest for HS (18%) (p < 0.0001). Overall survival was 96%, 93%, and 92% for AS, NHW, and HS, respectively, as compared with 83% for AA (p < 0.0001). When comparing prognosis by CAC scores in ethnic minorities as compared with NHW, relative risk ratios were highest for AA with CAC scores > or =400 exceeding 16.1 (p < 0.0001). Hispanics with CAC scores > or =400 had relative risk ratios from 7.9 to 9.0, whereas AS with CAC scores > or =1,000 had relative risk ratios 6.6-fold higher than NHW (p < 0.0001).

CONCLUSIONS

Consistent with population evidence, AA with increasing burden of subclinical coronary artery disease were the highest-risk ethnic minority population. These data support a growing body of evidence noting substantial differences in cardiovascular risk by ethnicity.

Indian Asian men have less peripheral arterial disease than European men for equivalent levels of coronary disease

OBJECTIVES

Indian Asians have high rates of heart disease and stroke, but risks of peripheral arterial disease appear to be low. This paradox, and reasons for it, have not been explored. We compared ethnic differences in peripheral arterial disease for a given level of coronary disease.

METHODS

We studied 83 European and 84 Indian Asian men with a range of coronary disease. Extent of coronary atheroma was quantified by coronary artery calcification score on multislice CT. Femoral intima-media thickness (IMT) was measured by ultrasound.

RESULTS

Femoral IMT was 1.58, 2.06, 2.12, and 2.69 mm in Europeans, and 0.61, 1.41, 1.81 and 2.29 in Indian Asians by increasing categories of coronary atheroma (p=0.003 for ethnic difference, adjusted for age and lumen diameter). Adjustment for smoking and systolic blood pressure, the only risk factors adversely distributed in Europeans, only partly accounted for this ethnic difference (p=0.05). Other risk factors, including lipids, obesity, insulin and glycaemic status, more adversely distributed in Indian Asians, could not account for ethnic differences. Prevalence of abnormal ankle brachial index and lower limb atherosclerotic plaque was also greater in Europeans.

CONCLUSIONS

For a given level of coronary disease, Indian Asians have less lower limb atherosclerosis than Europeans, unexplained by established risk factors. Further study of these populations would help tease out relative contributions of risk factors to atherosclerosis in different vessel beds.

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.

Ethnic differences in coronary calcification: the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

There is substantial evidence that coronary calcification, a marker for the presence and quantity of coronary atherosclerosis, is higher in US whites than blacks; however, there have been no large population-based studies comparing coronary calcification among US ethnic groups.

METHODS AND RESULTS

Using computed tomography, we measured coronary calcification in 6814 white, black, Hispanic, and Chinese men and women aged 45 to 84 years with no clinical cardiovascular disease who participated in the Multi-Ethnic Study of Atherosclerosis (MESA). The prevalence of coronary calcification (Agatston score >0) in these 4 ethnic groups was 70.4%, 52.1%, 56.5%, and 59.2%, respectively, in men (P<0.001) and 44.6%, 36.5%, 34.9%, and 41.9%, respectively, (P<0.001) in women. After adjustment for age, education, lipids, body mass index, smoking, diabetes, hypertension, treatment for hypercholesterolemia, gender, and scanning center, compared with whites, the relative risks for having coronary calcification were 0.78 (95% CI 0.74 to 0.82) in blacks, 0.85 (95% CI 0.79 to 0.91) in Hispanics, and 0.92 (95% CI 0.85 to 0.99) in Chinese. After similar adjustments, the amount of coronary calcification among those with an Agatston score >0 was greatest among whites, followed by Chinese (77% that of whites; 95% CI 62% to 96%), Hispanics (74%; 95% CI 61% to 90%), and blacks (69%; 95% CI 59% to 80%).

CONCLUSIONS

We observed ethnic differences in the presence and quantity of coronary calcification that were not explained by coronary risk factors. Identification of the mechanism underlying these differences would further our understanding of the pathophysiology of coronary calcification and its clinical significance. Data on the predictive value of coronary calcium in different ethnic groups are needed.

Subclinical Coronary Atherosclerosis in Asymptomatic Filipino and White Women

Background— Coronary heart disease (CHD) is the leading cause of morbidity and mortality in persons with type 2 diabetes mellitus (T2DM). Electron-beam computed tomography (EBCT) detects coronary artery calcium (CAC), a marker of atherosclerotic plaque. Few studies have described EBCT-defined CHD among ethnic minorities with elevated T2DM prevalence. The objective of this study was to compare EBCT-defined CAC in Filipino and white women without known cardiovascular disease.

Methods and Results— Subjects were participants aged 55 to 78 years in the Rancho Bernardo Study (n=196) and the University of California at San Diego’s Filipino Women’s Health Study (n=181). Glucose, blood pressure, lipids, anthropometric measurements, and lifestyle factors were measured from 1995 to 1999. EBCT-defined CAC scores, visceral and subcutaneous fat, and statin use were assessed in 2001 to 2002. Compared with whites, Filipinas had a significantly higher prevalence of T2DM (32.6% versus 6.1%, P <0.001) and the metabolic syndrome (32.6% versus 13.8, P <0.001). Filipinas were younger (64.4 versus 66.7 years), had higher triglyceride levels (155 versus 135 mg/dL), had a higher ratio of total cholesterol to HDL cholesterol (4.3 versus 3.5), more frequently used statins (31% versus 19%), and had more visceral fat (69.4 versus 62.1 cm 3 ) and lower HDL cholesterol levels (54 versus 66 mg/dL) than whites. Exercise frequency, body mass index, and waist girth did not differ by ethnicity. Nevertheless, extensive (CAC score ≥400; 9% versus 9%) and moderate (CAC score 150 to 399; 13% versus 11%) atherosclerotic plaque did not differ by ethnicity, even after adjustment for age, T2DM, hypertension, estrogen use, statin use, smoking, lipids, and visceral fat.

Conclusions— Filipinas had no excess of subclinical atherosclerosis despite their significantly higher prevalence of T2DM, the metabolic syndrome, hypertension, and visceral adiposity.

Ethnic differences in atherosclerosis, cardiovascular disease and lipid metabolism

PURPOSE OF REVIEW

Comparison of risk factors and cardiovascular disease among racial and ethnic groups is a powerful approach to study genetics and lifestyle, or environmental interactions.

RECENT FINDINGS

Most, mean or median, cardiovascular risk factor levels are similar among black and white people. There are much greater differences in the distribution of risk factor level within a specific race and ethnic group than between US populations. There are also very large differences in levels of risk factors for coronary heart disease between specific ethnic migrant populations such as comparing black people in Africa with those in the US, or Japanese people in Japan with those in Hawaii and California. Differences in distribution of risk factors and disease between race and ethnic group are a function of the frequency of specific genotypes and interaction with environmental factors. Several of the most important differences between racial groups are higher blood pressure, lower triglycerides and higher HDL cholesterol among blacks, higher prevalence of diabetes and insulin resistance among Mexican Americans and American Indians, and higher triglyceride levels among the Japanese.

SUMMARY

Further studies of racial and ethnic differences should focus on unique phenotypes and genotypic differences, international and migrant studies and large enough sample sizes to provide robust results. The sprinkling of a percentage of minority participants in each study is worthless. The study of racial and ethnic differences in disease and detection of risk factor levels must be based on solid hypotheses that can evaluate the interaction of lifestyle and possible genetic attributes. Many of the reported ethnic differences in risk factors and disease in US populations are primarily a function of differences in education, socioeconomic variations, and utilization of preventive and clinical treatments.