South Asians have an increased risk for CHD events, diabetes
MIAMI — Lipid abnormalities in South Asians may be related with CAD outcomes, diabetes and insulin resistance and may be associated with factors such as their smaller coronary artery diameter, according to a presentation at the National Lipid Association Scientific Sessions.
Reports of increased risk
South Asians have been defined as people who originate from India, Bangladesh, Pakistan, Nepal, Sri Lanka, Maldives, Bhutan and Afghanistan, Kris Vijay, MD, FACC, FNLA, FHFSA, medical director of the Institute for Congestive Heart Failure at Abrazo Health Network in Phoenix, clinical professor of medicine at University of Arizona in Tucson and executive council chair for the National Lipid Association, said during the presentation. In 2006, there was an estimated 4.4 million South Asians in the United States and an estimated 30 million around the world, according to the presentation.
WHO previously reported that the highest risk for ischemic heart disease was among South Asians compared with the rest of the world. The report also showed that CHD affects South Asians at an earlier age with higher mortality rates compared with other demographic populations, according to the presentation. Half of MIs occur in Indian men younger than 50 years and 25% occur in those younger than 40 years.
“India accounts for approximately 60% of the world’s heart disease burden, but less than 20% of the world’s population is South Asian,” Vijay said during the presentation. “It is also known as the world’s capital for diabetes.”
South Asians aged 13 to 16 years are also more likely to have higher fasting plasma insulin levels, higher fasting glucose levels and higher incidence of impaired fasting glucose compared with Europeans of the same age, according to the presentation.
“Many of this may be related ... to the abdominal depot, the fat depot is increasing,” Vijay said.
Studies have shown that South Asians are more likely to have increased waist-to-hip ratios and abdominal waist circumference compared with white people and black people.
In the MASALA study, researchers found that South Asians have a higher burden of pericardial fat and coronary artery calcium and a higher OR for impaired fasting glucose and type 2 diabetes compared with other populations. Abdominal visceral fat was linked to impaired fasting glucose and other parameters of body composition despite there being no difference in composition to explain the additional risk, according to the presentation.
When data from the MASALA study was compared with the MESA study, researchers found that CAC incidence in South Asian men was similar as that in black, white and Latino men, but it was significantly higher than in Chinese men. This increase was not seen in South Asian women and women from the MESA study.
The MASALA study also found that South Asians who consumed a vegetarian diet had a lower BMI, insulin resistance, fasting glucose and LDL, in addition to lower odds of fatty liver. Men who ate a vegetarian diet had lower odds of having CAC, although this was not observed in women.
The study also found that there were inconsistencies with estimating 10-year CV risk with the 2013 American College of Cardiology/American Heart Association risk estimator and CAC in South Asians compared with other racial/ethnic groups.
Regarding CAC, it was present in 42% of South Asians from the MASALA study across all quartiles, although carotid intima-media thickness was not linked to lipoprotein(a).
In contrast, the INTERHEART study published in Circulation in 2019 found that the highest Lp(a) concentration was found in African patients, and South Asians with higher Lp(a) concentrations had an increased risk for MI.
The INTERHEART study also found that South Asians presented with MI at earlier ages and that daily intake of fruits and vegetables and regular physical activity was lower in South Asians.
In a study published in Circulation in 2018, researchers found that South Asians had a two- to fourfold higher prevalence of type 2 diabetes, higher prevalence of impaired fasting glucose and higher prevalence of new-onset diabetes compared with non-Hispanic whites. In addition, South Asians living in the United States had a higher plasma levels of total cholesterol, triglycerides and LDL and lower levels of HDL compared with those living in India.
Other factors that may contribute to an increased risk in South Asians include smaller coronary artery diameter, a proinflammatory state, higher homocysteine levels, Lp(a), C-reactive protein, plasminogen activator inhibitor-1 and smaller HDL and LDL particles, according to the presentation.
The environment, metabolic syndrome and a concept called the “thrifty genotype” are some hypotheses that may explain this increased risk in South Asians. This genotype allows the body to convert and store simple sugars to abdominal fat and provides a selective advantage in times of famine, according to the presentation.
The PRACTICE registry found that South Asians with lower levels of adiponectin compared with Europeans had a higher prevalence of new-onset diabetes.
There are several ongoing studies in the United States that focus on healthy lifestyle in South Asians, in addition to CV risk management with digital health technology, change of fructose to fat and a continuation of the MASALA study. Additional studies are also being conducted in Europe and Canada, according to the presentation.
“The next steps are early screening and prevention strategies, diet and physical activity with lifestyle modifications and empowerment, increasing awareness through social media and other avenues, and a large interventional study registry utilizing digital and mobile platforms, artificial intelligence and information and communication technology is probably needed urgently,” Vijay said during the presentation. – by Darlene Dobkowski
Vijay K. Session II: South Asians and Risk of ASCVD: Increasing Awareness in Medical and Non-Medical Communities. Presented at: National Lipid Association Scientific Sessions; May 16-19, 2019; Miami.
Disclosure: Vijay reports he is a speaker for Amarin, Amgen, AstraZeneca, Boehringer Ingelheim/Lilly and Novo Nordisk and consultant for Amgen, Aventyn, Boehringer Ingelheim, Legacy Heart Care and Life 365.