South Asian people (i.e., from India, Pakistan, Bangladesh, Nepal, Sri Lanka, Maldives, or Bhutan) are the fastest-growing minority group in the United States, with nearly 5.4 million residents.1,2 Family physicians should be aware that people of South Asian ancestry have a disproportionately higher burden of aggressive and premature atherosclerotic cardiovascular disease (ASCVD) compared with other racial and ethnic groups.3 South Asian people also have higher hospitalization and mortality rates from ASCVD than other ethnic groups and at younger ages. The American College of Cardiology (ACC) and American Heart Association (AHA) recognize South Asian ancestry as a risk-increasing factor for cardiac disease.4–6
Unfortunately, the etiologies behind this disparity are not well understood. South Asian people represent a diverse population from multiple countries with complex intergenerational and sociocultural histories that affect health and access to medical care.7 More research on the causes and long-term outcomes of ASCVD in South Asian people is needed. Although research is lagging in studying this population in the United States, it is reasonable to use the country of family origin as a crude measure to prevent potentially catastrophic outcomes.
Risk calculators such as the Framingham Risk Score and AHA/ACC pooled cohort equation underestimate cardiovascular risk in South Asian people because these traditional tools were not validated in that population.8 Although the AHA's newer PREVENT (Predicting Risk of Cardiovascular Disease Events) calculator is more comprehensive because it focuses on younger patients with cardiovascular/kidney/metabolic risk factors, it has the potential for underestimating ASCVD risk in patients of South Asian ethnicity.9 Importantly, race and ethnicity were defined as social factors, not biologic variables. The PREVENT tool has not been evaluated independently in South Asian people, which misses the potential genetic implications of ancestry.10 Therefore, the AHA has called for increasingly diverse samples and more studies in populations at high risk in future iterations of the tool.9
The QRISK3 calculator includes South Asian ethnicity as an additional risk factor to estimate the risk of having a heart attack or stroke in the next 10 years.1,7 This risk assessment tool was derived and validated in 2.3 million people in England and Wales to more accurately estimate cardiovascular risk in ethnic groups and found higher median risk scores for South Asian people than other tools.11,12 QRISK3 asks for the standard deviation of blood pressure, which is not needed to complete the assessment. Although similar tools are lacking in the United States, studies are ongoing.13,14
Cardiovascular health disparities in South Asian people are thought to be driven by an increased prevalence of traditional risk factors, specifically insulin resistance and metabolic syndrome.15–17 South Asian people tend to have increased central obesity at a lower body mass index (BMI).18 The World Health Organization, ACC, and Diabetes.co.uk support ethnicity-specific BMI cutoffs and advocate targeting a lower BMI in South Asian people (less than 23 kg per m2 instead of the traditionally accepted 25 kg per m2).19–23 The International Diabetes Federation has also introduced ethnicity-specific waist circumference cutoffs (less than 90 cm in men instead of 102 cm; less than 80 cm in women instead of 88 cm) for South Asian people to improve early recognition of metabolic syndrome.24 Higher levels of atherogenic inflammatory lipids (i.e., lipoprotein (a), apolipoprotein B, triglycerides, low-density lipoprotein cholesterol, and low-density lipoprotein particles), increased truncal obesity, and increased insulin levels have also been implicated in the development of early, aggressive ASCVD in South Asian people.1,3,25
Early detection of impaired glucose metabolism (fasting blood glucose level greater than 100 mg per dL [5.55 mmol per L]) can help identify patients at high risk instead of relying on A1C alone.3,24 Some experts recommend treating patients to a goal A1C of less than 6%.25 In addition to screening for a family history of premature heart disease (younger than 55 years) or a personal history of hyperlipidemia, a lipoprotein(a) blood test can help identify patients at high risk who may not know their family history.1,25 Obtaining a urine albumin-creatinine ratio when indicated, such as in diabetes mellitus, can detect kidney disease, an established risk factor for ASCVD.9 To further improve cardiac risk stratification of South Asian people in the United States, the QRISK3 score can be adopted from the United Kingdom and used with current AHA/ACC risk calculators.
Primary prevention of cardiac events through lifestyle changes is essential in South Asian people because of cultural practices related to diet and physical activity. Studies investigating cardiovascular risk in this population have demonstrated increased high-carbohydrate consumption (e.g., rice, roti, grains, bread) and low-protein diets, making them susceptible to insulin resistance.1,3,26 Studies in this population have documented lower levels of physical activity and cardio-respiratory fitness and decreased awareness of the importance of regular exercise.1,3,27,28 Many may not be familiar with their generational family history due to differences in medical care in their countries of origin. Recognizing sociocultural risk factors makes culturally informed counseling on diet and exercise especially important in South Asian people.
Family physicians can prevent early deaths in this population by recognizing disparate health outcomes, considering ethnicity-specific cardiovascular risk assessments and counseling, and referring South Asian patients to cardiology when appropriate to treat ASCVD early and aggressively.
