Introduction
South Asians in the United States (SAUS) include a heterogeneous group of individuals who trace their ancestry to the Indian subcontinent (India, Pakistan, Bangladesh, Sri Lanka, Maldives, Bhutan, and Nepal). Despite the common origin from the Indian subcontinent, there are considerable difference lifestyle patterns and dietary habits.¹

When compared to other ethnic subgroups, SAUS have a disproportionately greater burden of atherosclerotic cardiovascular disease (ASCVD) which often occurs earlier in life (<50 years) and is more aggressive. In this setting, the recent scientific statement from the National Lipid Association provides further guidance on the prevention of ASCVD among SAUS.²

Limitations of Available ASCVD Risk Assessment Specific to SAUS
While risk assessment is a fundamental aid for ASCVD risk reduction counseling, risk prediction, discrimination and calibration in SAUS remains challenging because 1) available risk algorithms have not been derived from or prospectively validated in SA adults living in North America; 2) limited considerations have been given for native versus migrant populations; and 3) there is a limited availability of disaggregated data, masking meaningful ASCVD health differences in SA subgroups.^3,4 As such, population-specific risk assessment tools unreliably estimate risk in this group.

For example, when accounting for ethnicity in the United Kingdom (UK), the National Institute for Health & Care Excellence (NICE) guidelines recommended an adjustment factor to the Framingham Risk Score (FRS) for SA (FRS multiplied by 1.4 for SA men; no recommendation for women).⁵ Of note, the FRS and UK Prospective Diabetes Study underestimates risk in SA when compared to a white European population.⁶ QRISK2 underestimates risk in SA women.⁷ The 3rd Joint British Societies' cardiovascular disease (CVD) risk calculator (incorporates QRISK and QRISK2 databases) accounts for SA ethnicity, but also underestimates risk when considering the very small proportion (2% and 0.7%, respectively) of SA adults included in the cohort.^8,9 The World Health Organization (WHO) risk charts have been shown to misclassify high-risk SA to low-risk categories.¹⁰

The INTERHEART Modifiable Risk-Score has been internally and externally validated for the prediction of future ASCVD risk in SA, however, its application is limited considering case-control data used to develop the risk calculator.¹¹ SA ethnicity is defaulted to "white" race when using the American Heart Association (AHA)/American College of Cardiology (ACC) Pooled Cohort Equations (PCE), resulting in risk underestimation. The 2016 European prevention guidelines and 2018 AHA/ACC multi-society cholesterol guidelines now include SA ethnicity as a risk-enhancer when considering the initiation of statin therapy.^12,13

Highly Prevalent Risk Factors
Cardiovascular risk among SAUS includes a constellation of traditional risk factors (hypertension, diabetes mellitus, and smoking) superimposed on a milieu of unhealthy modifiable behaviors (e.g. limited physical activity and unhealthy dietary patterns).

The age-adjusted prevalence of hypertension was estimated around 27% in the New York City Community Health Survey and 43% in men and 35% in women in the Mediators of Atherosclerosis in South Asians Living in America (MASALA) study.^14,15 SA adults with a history of hypertension have an increased risk of acute myocardial infarction (odds ratio 2.69, p = 0.001).^16,17

Diabetes is a highly prevalent cardiovascular risk factor among SAUS patients. Findings from the MASALA study demonstrate a prevalence of 25% of diabetes and 33% of prediabetes.¹⁸ In conjunction with the high prevalence of diabetes, SAUS have a disproportionately elevated burden of metabolic syndrome, which is defined as increased body mass index (BMI) and/or waist circumference, low HDL-C, elevated triglycerides, and insulin resistance.

The predilection to these risk factors is sometimes compounded by less-than-ideal modifiable lifestyle patterns including smoking, sedentary activity, and unhealthy dietary patterns such as increased intake of animal protein, fried foods, snacks that are rick in refined carbohydrates, sweets (i.e. mithai, jalebi, and gulab jamun), and other foods that are high in saturated fats (i.e. ghee, coconut oil, and paneer).² With respect to biomarkers, SAUS, on average, tend to have higher levels of lipoprotein(a) [Lp(a)], which is independently associated with an increased risk of major adverse cardiovascular events including coronary heart disease (CHD) and stroke.²

Management of Modifiable Cardiovascular Risk Factors
Despite the high burden of disease in these individuals, there is robust potential for intervention to reduce ASCVD risk. First, lifestyle modifications such as increased physical activity and healthy eating should be emphasized. Regular and culturally tailored physical activity (e.g. Bollywood dancing, bhangra, yoga, or brisk walking) at a minimum of 150 minutes per week at moderate intensity is recommended.¹⁹ Increasing intake of fresh fruit, vegetables, whole grains, low fat, and lean proteins should be emphasized in conjunction with reducing the intake of tropical oils, fried, salty, sugary or processed foods, and refined carbohydrates.¹ Healthy cooking lessons and referrals to culturally tailored dietary therapy may assist in making these changes.

Residual risk for ASCVD conveyed by hypertension, diabetes, and hyperlipidemia should be targeted with guideline-recommended pharmacologic therapy for primary and secondary prevention.² Table 1 depicts desirable metrics to optimize cardiovascular health in SAUS.²

Figure 1: Desirable Levels of Cardiovascular Disease Risk Factors For South Asian Patients

Further Risk Assessment – Coronary Artery Calcium
In addition to frequent and universal screening for traditional risk factors and metrics, the use of coronary artery calcium (CAC), a highly specific marker of subclinical atherosclerosis, may be a useful test to improve risk stratification in SAUS.^20-24 The extent of ASCVD-risk overestimation using the PCE is greater among SA adults considered at low/intermediate risk than among white adults, such that intermediate-risk SA individuals have a 73% higher odds of CAC=0.²⁰ The presence of a family history of CHD is associated with a high burden of CAC (>300).²² With respect to hypertension management, CAC may help identify those SA adults who would best qualify for lifestyle optimization and anti-hypertensive pharmacotherapy.¹⁴ When compared to available non-traditional risk markers, CAC scoring should be the preferred noninvasive modality for further risk refinement in SA.^2,25

Conclusion
It is critical that appropriate and adequate strategies be developed to screen and manage ASCVD in SAUS. It is apparent that in addition to genetic and established coronary risk factors, the higher prevalence of ASCVD and related cardiovascular events are also related to poor diet choices and unhealthy lifestyle patterns. Structured interventions at a societal level for increasing physical activity and implementing dietary are needed. 

In addition to these preventive strategies, earlier recognition, and treatment of cardiovascular risk factors and in selected individuals, appropriate imaging should help identify and mitigate the burden of ASCVD events. Future studies should be geared towards understanding the reason behind the disproportionately higher burden of ASCVD in SAUS and developing appropriate therapeutic strategies in a disaggregated manner. Equally important is the promotion and engagement of existing SA community-level ASCVD programs to further educate, promote health literacy, and provide culturally competent health care (Table 1).

Table 1: South Asian Cardiovascular Health and Prevention Clinics

Program Name and Physicians	State and City
	California
South Asian Heart Center	Fremont, Los Gatos, Mountain View
Stanford Center for Asian Health Research and Education (CARE)/ Stanford South Asian Translational Heart Initiative (SSATHI)	Portola Valley, Santa Clara, Stanford
Mediators of Atherosclerosis in South Asians Living in America (MASALA) (Alka Kanaya MD)	San Francisco
PRevention and AwareNess for South Asians (PRANA) – Sutter Health/Palo Alto Medical Foundation	Los Altos, Los Gatos, Fremont, Palo Alto, San Jose
	Georgia
NCS Cardiology	Cumming, Johns Creek
Emory - Atlanta South Asian Health Alliance (ASHA)	Atlanta
	Illinois
Advocate Health Care - South Asian Cardiovascular Center (SACC)	Park Ridge
South Asian Healthy Lifestyle Initiative (SAHELI) (Namratha Kandula MD)	Chicago, Evanston
	Maryland
Ciccarone Center at Greater Baltimore Medical Center and Greenspring Station (Fall 2021) (Roger Blumenthal MD, Michael Blaha MD, Garima Sharma MBBS & Jaideep Patel MD)	Towson
	Minnesota
SEWA-AIFW (Asian Indian Family Wellness)	Minneapolis
	New York
Memorial Sloan Kettering Cancer Center – South Asian Health Initiative (SAHI)	New York
	New Jersey
Rutgers – Robert Wood Johnson Medical School, South Asian Total Health Initiative (SATHI)	New Brunswick
	Ohio
The Christ Hospital Outpatient Center – Montgomery, South Asian Comprehensive Cardiovascular Clinic	Cincinnati
Cardiovascular Health in Asian Indians (CHAI) (Ankur Kalra MD)	Cleveland
	Texas
Baylor Scott & White Heart Hospital Baylor Plano (Anandita Agarwala MD)	North Dallas/Plano
Baylor College of Medicine Cardiometabolic Initiative (Salim Virani MD)	Houston
	Canada
South Asian Risk Assessment Clinic	Ontario – Brampton, Toronto
Fraser Health – South Asian Health Institute	British Columbia – multiple locations
*List is not comprehensive, however we encourage the reader to seek out South Asian related ASCVD resources near them if available.

References

1. Volgman AS, Palaniappan LS, Aggarwal NT, et al. Atherosclerotic cardiovascular disease in South Asians in the United States: epidemiology, risk factors, and treatments: a scientific statement from the American Heart Association. Circulation 2018;138:e1-e34.
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Clinical Topics: Diabetes and Cardiometabolic Disease, Dyslipidemia, Prevention, Advanced Lipid Testing, Hypertriglyceridemia, Lipid Metabolism, Nonstatins, Novel Agents, Statins, Hypertension

Keywords: Dyslipidemias, Cardiovascular Diseases, Body Mass Index, Antihypertensive Agents, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Lipoprotein(a), Metabolic Syndrome, Ethnic Groups, Waist Circumference, Prediabetic State, Hyperlipidemias, American Heart Association, Public Health, Insulin Resistance, Prospective Studies, Secondary Prevention, Coronary Vessels, Benchmarking, Cost of Illness, Risk Factors, Myocardial Infarction, Atherosclerosis, Coronary Disease, Stroke, Asian Continental Ancestry Group, Risk Assessment, Cardiology, Hypertension, Risk Reduction Behavior, Cholesterol, World Health Organization, Biomarkers, Delivery of Health Care, Triglycerides, Asian Americans, Asia

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