Cholesterol – What’s New?
PART 2: Heart Disease in South Asians
The major news during the past month among the Indian community was the sudden death of a 48-year-old prominent Indian physician practicing in Orlando. Apparently, he died in his sleep, presumably from a heart attack. Reactions in the Indian community varied from “How could this happen to such an educated professional at such a young age?” to “We are not paying attention to our own health amidst this crazy, stressful life.” Well, now is the time to discuss this burning issue – high incidence of coronary artery disease (CAD) that leads to heart attacks and death among South Asians, Indians included, and explore preventive measures.
Let us first define ‘South Asians’ who account for a quarter of the world’s population. They are people whose lineage can be traced to India, Pakistan, Sri Lanka, Bangladesh, Nepal and Bhutan and often collectively referred to as South Asians. Yes, we share similar genetic composition, skin color, looks and other bodily features. So, it would be logical to conclude that we may suffer from similar health problems as well.
In the early 1980s, Dr. Enas A. Enas, a prominent practicing cardiologist in Chicago, observed that many young patients of Indian origin were being admitted to the hospital with massive heart attacks and many of them succumbing to the first heart attack. “Coronary Artery Disease in Indians (CADI): A Cause for Alarm and Call for Action!” wrote Dr. Enas in 1990. Soon, there were similar reports coming from other countries such as Malaysia, Bangladesh, United Kingdom, etc., about CAD in patients of South Asian origin. Since then, there has been a lot of research on this very issue, especially the landmark CADI study by Dr. Enas and colleagues. “Indians around the globe have the highest rate of CAD despite the fact that many do not indulge in red meat, a lot of them are predominantly vegetarians, and generally have low body weight and waist circumference index. The death rate from CAD among overseas Indians has been 50 to 300 percent higher than Americans, Europeans, Chinese and Japanese, irrespective of gender, religion or social class. Conventional risk factors fail to explain this difference completely,” he concluded.
Initially, there was some skepticism about these findings but more research and reports started coming in, confirming his findings. According to the latest study from the U.K. involving nearly 500,000 subjects, South Asians had double the number of heart attacks compared to whites, even after adjusting for various risk factors associated with CAD.
Just to refresh your memory: Coronary atherosclerosis (hardening of the arteries of the heart), the main cause for heart attacks and death, is a condition associated with narrowing of the diameter of the arteries, mostly medium and large-sized arteries, due to buildup of plaques primarily composed of bad cholesterol or LDL. When arteries are sufficiently narrowed such that they reduce the flow of oxygenated blood to heart muscle, it leads to heart attacks. You already know the conventional risk factors like high cholesterol, high blood pressure, diabetes mellitus –Type 2 (T2D), smoking, obesity, family history and a diet high in saturated fats. According to the latest data from the Mediators of Atherosclerosis in South Asians Living in America (MASALA) study, the prevalence of T2D in Asian Indian adults in the U.S. is 23 percent compared to 13 percent for whites and 7-8 percent among Indians in India.
Among the various risk factors, high cholesterol appears to be the most important factor followed by T2D, especially among Indians. Often, they have mild to moderate elevation of total cholesterol, triglycerides and LDL but most have generally low HDL, sometimes called the good cholesterol. Lately, HDL has lost its importance as the protection fraction of cholesterol and hence all emphasis is on how to deal with high LDL. In addition, the level of a sub-fraction of LDL called Lipoprotein(a), or Lp(a), which is at least twice as atherogenic as LDL, is significantly elevated in South Asians. Lp(a) level is genetically determined and 25 percent of South Asians have elevated Lp(a); this makes them genetically predisposed to early heart disease. According to Dr. Enas, Indians do not have small coronary arteries as some Indian studies reported previously but the extensive plaque buildup throughout the coronary arteries may masquerade as smaller-size coronary arteries.
M.P. Ravindra Nathan, M.D., is a cardiologist and Emeritus Editor of AAPI Journal. For further reading, “Second Chance - A Sister’s Act of Love” by Dr. Nathan from Outskirts Press, can be found at www.amazon.com