Cover Story | South Asians and Cardiovascular Disease: The Hidden Threat

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February 20, 2019 was shaping up to be just like any other day in the life of Aditya Suresh, a software engineer at Google's campus in Seattle. As he was getting ready to go to work he received the call that would forever change his life.

He remembers vividly speaking with his mom who struggled to communicate that she had just learned that his father, a young Indian man in his late 50s, had been found dead in a hotel bathroom while on a business trip. The cause of death was deemed to be cardiac arrest as a result of aggressive atherosclerotic cardiovascular disease (ASCVD).

It was a shock to all.

By all accounts, Aditya's father was a healthy man. He saw his primary care doctor regularly and was recently taken off his diabetes medications as his HbA1c had fallen below 6.0 percent, indicating his lifestyle and dietary changes were working. He had lost weight and his BMI was only 24 kg/m2, down from 29 kg/m2. He exercised regularly and was the poster child of cardiac health in his South Asian community in South Carolina.

Aditya Suresh is a close friend of mine. As his friend, an interventional cardiologist and a fellow South Asian, when he shared the tragic news I was at a loss for what to say. As a cardiologist, shouldn't I have seen this coming? Unfortunately, his story is not an isolated one.

People of South Asian descent, including those from India, Pakistan, Bangladesh, Nepal, Sri Lanka, Bhutan and the Maldives, have a higher risk of ASCVD – fourfold higher than the general population. Moreover, they develop heart disease up to a decade earlier (often before the fifth decade of life).

Sizing Up a Public Health Crisis

South Asians represent approximately 25 percent of the world's population – yet they account for 60 percent of the world's heart disease patients. Thus, the high incidence of ASCVD in this ethnic group presents a major public health crisis. Although mortality secondary to ASCVD has been declining in the Western world, ischemic heart disease remains the number one cause of death in adults from both low- and middle-income countries.1,2

At the turn of the millennium, it was reported that coronary heart disease mortality was expected to increase approximately 29 percent in women and 48 percent in men in developed countries between 1990 and 2020; the corresponding estimated increases in developing countries were 120 percent in women and 137 percent in men.3

Sandeep's Tips to Help Your South Asian Patients

  1. Screen all young patients of South Asian origin for diabetes. Don't ignore HbA1c levels within normal range. Young South Asian adults often have HbA1c levels just north of 5 percent but these are not flagged as abnormal and usually their diets are suboptimal. Have a low threshold to inform your patients of their high risk for developing insulin resistance and diabetes.
  2. Encourage them to move! South Asians are not very physically active. Inform them of the science behind a mixture of aerobic and anaerobic (i.e., weightlifting) exercise as a means of preventing insulin resistance.
  3. Be aware – diabetes and insulin resistance are silent killers in the Indian subcontinent. Just as rampant is the denial of this scourge among elders in our communities. Ask your South Asian patients about their diet. Counsel them about reducing their carbohydrate intake and increasing their intake of vegetables and lean, non-red meats. Learn more about their typical diet by visiting your local Indian restaurant.
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A Hidden Threat

South Asians living in the U.S. are more likely to die from heart disease than the general population.

This risk though has been largely shrouded by a paucity of data. There were around 3.4 million people of South Asian descent living in the U.S. as of 2010, based on U.S. Census Bureau data. Despite the size of their population, the threats to South Asians' cardiovascular health have been obscured because, until recently, researchers have looked at Asian-Americans as a monolithic group.

However, when examined individually, South Asians have a higher risk of heart disease than other Asian groups, especially East Asians from China, Japan and Korea.4 In the U.S., major federal surveys have only recently started classifying Asian Americans into subgroups, including Asian Indians (South Asians).5

The MASALA study (Mediators of Atherosclerosis in South Asians Living in America) is being conducted in a population-based sample of 1,164 South Asian women and men aged 40-84 years at two university clinical field centers (University of California, San Francisco and Northwestern University). The study is funded by the National Heart, Lung, and Blood Institute.

One of the first clues to explain these health disparities unearthed by the MASALA study is that South Asians have a lot of visceral fat in the abdominal area, the liver and around the heart. Namratha R. Kandula, MD, MPH, and Alka Kanaya, MD, co-principal investigators for MASALA, stated that even though South Asians typically have low body mass indices, this accumulation of visceral fat causes different types of inflammation and activates certain biological pathways that contribute to atherosclerosis.

The Tip of the Iceberg

These ethnic health disparities extend far below the surface of the skin. South Asians undergoing coronary angiography in the U.S. have been noted to have smaller luminal diameters, higher-grade stenoses and a higher prevalence of multivessel disease.6

Additionally, South Asians are more likely to require a CABG. Studies evaluating cardiovascular events and mortality after isolated CABG have shown consistently poorer outcomes for South Asians compared with Caucasians.7,8

To explain these macrovascular differences, one needs to delve further into the risk factors that seem to be embedded in the genes of many South Asians.

Excess Risk For Diabetes

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The greatest risk factor disparity in South Asians is their predilection for impaired glucose tolerance resulting in twofold higher rates of type 2 diabetes (T2D) when compared with their Caucasian counterparts.9

The MASALA study found a higher prevalence of T2D in South Asians (23 percent) compared with other ethnicities even after adjustment for age and adiposity (18 percent in blacks, 17 percent in Latinos, 13 percent in Chinese Americans and 6 percent in Caucasians).10

Furthermore, the investigators noted that 9.7 percent of participants reported gestational DM, and women with gestational DM were 3.2-times more likely to develop T2D than those without gestational DM.11 These observations highlight the need for early intervention in this young, high-risk population,12 which oftentimes is never done until it is too late.

Along these lines, the American Diabetes Association and the World Health Organization (WHO) have recommended lowering the BMI cut points for defining overweight and obesity in South Asians to increase the identification of cardiometabolic risk in this population.13,14

The WHO recommends using 23 kg/m2 and 27.5 kg/m2 for overweight and obesity, respectively.15

Although South Asians in the MASALA study had lower BMI, body weight and waist circumference compared with their peers in MESA, South Asians had higher levels of visceral and hepatic fat, but less total lean abdominal muscle mass compared with all other racial/ethnic minority groups.16

Diet: Cataclysmic Integration of East and West

Dietary habits have a large impact on the incidence of ASCVD. The integration of the typical South Asian diet with the Western diet has been cataclysmic. The South Asian diet focuses on carbohydrates (rice, lentils, chapatis, naan) and saturated fats (ghee, butter) with a conspicuous absence of focus on lean meats. This merged with a Western diet of dairy products, fried snacks, pizzas and potatoes has proven disastrous and has only added to the inherent predisposition to insulin resistance many South Asians are facing.

Aditya's father was a true mensch and his passing is a big loss for not only his family but for the world. Let's help prevent other tragic stories together.

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Sandeep's Story

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Despite my strong family history of diabetes and cardiovascular disease, I was totally unaware (all through medical school and even my internal medicine residency) of the genetic battle I've been fighting since I was born. I had no idea I was prone to insulin resistance. Consequently, I spent much of my teenage years eating a typical South Asian diet centered around bread and rice dipped in lentil curries.

When I left home for college and medical school, I enjoyed the stereotypically most unhealthy parts of the Western diet – pizza, sugar-laden cereals, pasta and fatty meats. I enjoyed meals alongside my non-South Asian friends without giving my pancreas or rising insulin resistance a second thought. In fact, I was working out every day, so I felt healthy!

It wasn't until my penultimate year of residency that I had my labs checked. Over the ensuing years of training I noticed a concerning trend – my fasting glucose levels were rising as was my HbA1c. Were it not for a chance referral to a South Asian endocrinologist who was aware of my genetic predisposition to diabetes and ultimately cardiovascular disease, I would have been diagnosed with T2D by now.

Since then, I've made significant changes to my diet and exercise regimen. I've noticed a steady decline in my blood sugar levels and my HbA1c is no longer in the prediabetic range. I am intensely grateful for the early intervention and prevention. And I'm passing this on to my family.

On a recent trip to visit family in Germany, I brought my glucometer and my fifteen-year-old nephew and I checked our blood sugar levels together. We also went on several bike rides and runs over the weekend. I hope that by setting an example of eating healthy and being active, he will not have to fight the same battles with his genes that I've already had to face.

Adi's Story

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My father's death came as a complete shock to our family. Given his history of diabetes, we assumed the cause was blood-sugar related. We were completely surprised to learn he had severe heart disease.

After immigrating to the U.S. in 1986, my father started gaining weight as he ate foods he never had access to in India: doughnuts, pizza, ice cream, etc. In fact, going through his things after his death, we found a photo of the first time my dad ate pizza, with his writing on the back: This is pizza. It tastes good.

Within three years of being in the U.S., my dad was diagnosed with Type 2 diabetes. After being diagnosed, he was more careful of what he ate and regularly took his medications. Within the last two years, my father really took his health more seriously. He started walking every day for an hour, at a pace so brisk that his dog could barely keep up.

Additionally, he made an effort to cut his overall food consumption to lose weight, trading red meats for salads and reducing his rice consumption. With those lifestyle changes, my father lost enough weight to no longer be classified as overweight, and he no longer needed his blood sugar medication. Sadly, two years of improving his lifestyle could not counteract decades of the poor dietary choices.

Seeing my father pass in my mid-20s was a wake-up call for me. I've been overweight the last three years and my diet consisted of mostly starchy and fatty takeout from Grubhub and Uber Eats. My father always had a saying that some people need to learn for themselves and others are wise enough to learn from others.

I am using his passing as a learning experience to improve my health and increase my longevity. I have embraced a healthier diet centered around colorful salads, healthy sources of fat and lean meats. And I'm now learning to cook! I can't bring my father back. I can make healthy decisions to make sure I am around as long as possible for my family.

Until my father died, I was not aware of the plight that many of us in the South Asian community are facing in terms of our genetics and diet. I want all doctors to know that their Indian patients are at higher risk and ought to be monitored closely. I hope that my lesson does not have to come at such a high price for anyone else.

Piriyah's Story

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Diabetes? I'm only 28 years old, surely that's not a concern for me. At least that is what I thought until November 2018 when I was diagnosed with prediabetes. One morning, despite my resistance, my medic friend decided to check my fasting blood sugar levels.

Thankfully he did, as to my great dismay, I was found to be prediabetic with a fasting sugar level of 112 mg/dL. Surely that could not have been right, so we tested it again on a different machine – 115!

I've always had a difficult relationship with food and my diet. I lost around 15 kg (33 pounds) in my late teens and put it back on in my mid-twenties while studying for the British Bar. Upon being diagnosed with prediabetes, I was determined to fight and get better, especially because many of my family members have diabetes including my father.

I adopted a low-carb diet and started exercising four days a week. With this shift in my diet and lifestyle, I was finally able to find a way to lose weight safely.

By making changes to my diet and exercising regularly, my blood sugar levels have normalized in just six months. Raising awareness about diabetes in the South Asian community is important, as often it is denial and the lack of understanding of the disease that can end in tragedy.

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Sandeep Krishnan, MD, RPVI, FACC, is an interventional and structural cardiologist at Ascension St. John Heart and Vascular Center in Tulsa, OK, and a clinical assistant professor at the University of Oklahoma School of Medicine.

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Clinical Topics: Arrhythmias and Clinical EP, Cardiovascular Care Team, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Interventions and Imaging, Angiography, Nuclear Imaging, Diet

Keywords: ACC Publications, Cardiology Magazine, Asian Americans, Asian Continental Ancestry Group, Insulin Resistance, Risk Factors, Insulin, Adiposity, Intra-Abdominal Fat, Glucose Intolerance, Diabetes Mellitus, Type 2, Body Mass Index, Developed Countries, Coronary Angiography, Developing Countries, Reference Values, Universities, Research Personnel, Constriction, Pathologic, Cause of Death, Weight Loss, Obesity, European Continental Ancestry Group, Hispanic Americans, Diet, Coronary Disease, Atherosclerosis, Life Style, Heart Diseases, Western World, Myocardial Ischemia, Inflammation, Heart Arrest, Primary Health Care

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