Used with permission from Guidant Corporation 2005
Contrary to common belief , most heart attacks are caused not by an artery narrowing due to the buildup of hard, large plaques detectable on angiogram, but by a blood clot that forms after the rupture of a lipid-rich, soft, inflamed plaque, often quite small. This explains why lipid-lowering therapy is far more effective in preventing heart attacks than coronary angioplasty, stent or bypass surgery in the vast majority of cases.
The rates are equally high or higher among the 400 million other South Asians living in Pakistan, Bangladesh, and Sri Lanka.4 The worldwide distribution of Asian Indians and south Asians are given in Table 002.
The term “Asian Indians” will be used in this document to denote people originating from India and to distinguish them from American Indians (Native Americans). The term South Asians is used to denote people originating from the Indian subcontinent (also called south Asia). Since more than 75% of South Asians are Asian Indians most of the data are on Asian Indians both the terms will be used interchangeably. Also the term heart disease when used denotes CAD and the two terms are used interchangeably; the term heart disease does not include other forms of cardiovascular diseases (CVD).
Asian Indian Diasporas
Fifty years after the publication of a 7-fold higher rate of heart disease among Indians in Singapore (compared to Chinese) by Danaraj, most cardiologists, doctors and the general public in the US and India remain largely unaware of the heightened risk of heart disease in this population. This is in sharp contrast to those living in the United Kingdom, Canada, and Australia where the medical community is fully aware of the heightened risk of heart disease among Indians. Several thousand publications from around the world over the past fifty years have consistently shown the highest rates of heart disease among Asian Indians regardless of their religion, gender, country of residence, or socioeconomic background.1
The CAD rates among immigrants are usually intermediate between those of the country of origin and the country of immigration.5 In virtually all populations, the CAD rates blend with those of the adopted country in two to three successive generations, depending upon the degree and speed of acculturation, as well as the prevailing rates in the respective countries.2.6
Asian Indian Diasporas have been a singular exception in having higher rates of CAD than the native population of the adopted country and their rates continue to diverge.2, 7-10 Compared with the compatriots of other ethnic origin, heart disease death rates have been 40% to 400% higher among Indians living in countries as diverse as the US, Canada, Singapore, the UK, South Africa, Middle East, Trinidad, Mauritius, Fiji, Kenya, Guyana, and many other countries.11, 12
The excess risk of heart disease is greater among Indian Diaspora women than Indian men compared to their counterparts in other populations, despite a very low rate of smoking. The CAD rates among women in India are almost as high as in men.13
Asian Indians vegetarian and non-vegetarian have similarly high rates of heart disease, unlike in any other population.
Since the environment contributing to the modifiable risk factors are the same in all these countries, and shared equally by people of all ethnic origin, the continued divergence of CAD rates between Indians and other populations suggest a genetic susceptibility to heart disease among Indians.14, 15
The 2 hallmarks of CAD among Asian Indians are extreme prematurity (onset at a very young age) and severity resulting in malignant CAD at a young age.16-18 During the past thirty years, the average age of a first heart attack increased by more than 10 years in the US, but decreased by more than 10 years in India. Asian Indians are generally 5-10 years younger at the time of first heart attack, development of heart failure, have larger heart attacks, and have more severe coronary disease (by angiogram and post-mortem).19, 20 Occurrence of heart attack in patients under age 40 is 5 to 10-fold higher among Indians than other populations.21, 22
Tsunami of Heart Disease in India
A tsunami of heart disease is now sweeping the Indian subcontinent.23 By 2015, India is estimated to have 62 million patients with CAD. Of these, 23 million will be younger than 40 years of age and only 11 million above 60 years of age. Table 001. Of the 2.9 million projected CAD deaths in 2015, an alarming 52% will be younger than 50 years of age, 32% will be younger than 40 years and 14% will be younger than 30 years of age.24 For comparison, only 1% of all CAD deaths among US whites occur in people younger than 45 years of age and 87% of CAD deaths occur in those older than 65 years of age.25
Over the past 4 decades, the prevalence of CAD quadrupled to 9-12% in urban India.26 Currently, the prevalence of CAD in urban India is 4 times higher than the US population and as high or higher than those of the Diasporas.11, 12 Heart disease rate doubled to 3-5% in rural India but remain about half that of urban India.26 The rates of obesity and physical inactivity is less than half in rural India compared to urban India although tobacco use is roughly double.
The 2-fold urban rural gradient and the 2-4 fold increase in CAD over the past 40 years among the people who share the same genetic pool suggests a powerful impact of lifestyle factors in the epidemic of heart disease in India. Asian Indian culture encourages over-consumption of salt, saturated fat, glycemic load, and reduced exercise. To make matters worse there are social, cultural and other major barriers to change.
Obesity, Metabolic Syndrome and Diabetes
Obesity, particularly abdominal obesity is very common but largely underestimated by using the standard criteria developed for the Europids.27 28 The recognition and adoption of ethnic-specific BMI and waist circumference cutoffs represent a major step forward in refining risk stratification in different ethnic groups, including South Asians.29 New approaches to prevention and management that incorporate the specific lower cutpoints in Indians have been published and needs to be disseminated and implemented.30, 31
Metabolic syndrome is common antecedent and strong predictor for both diabetes and heart disease that is found in approximately one in three Asian Indian men and one in two Asian Indian women.32 Most Indians with high triglycerides and low HDL cholesterol would have this syndrome if thief the blood sugar or blood pressure is above normal and/or if the waist girth is 90 cm or more in a man or 80 cm or more in a woman.
Asian Indians develop diabetes at a younger age and at a lower body mass index (BMI) and waist size. 33 The prevalence of diabetes is 4 to 6 times more common among Asian Indians than Europids and three times higher when adjusted for age, BMI, and other risk factors.30, 34, 35 Diabetes is also more ominous in Indian diabetics with a 3-fold higher mortality from heart disease (compared to Europid diabetics) with greater risk at younger ages.36
Genetic Predisposition to Heart Attack at Very Young Age
Lipoprotein(a) is a genetically determined and dangerous cholesterol which is capable of clogging the coronary arteries from age 2 onwards. It is 10 times more dangerous than LDL-C and is found in 40% of Indians. The adverse effects of the modifiable risk factors related to lifestyle are markedly magnified in those with elevated levels of lipoprotein (a) – a genetic risk factor for premature heart disease and stroke in diverse populations.14
Many Asian Indians are in double jeopardy from nature and nurture – nature being the genetically-determined lipoprotin(a) excess, and nurture being a deadly cocktail of unhealthy lifestyle choices associated with affluence, urbanization, and mechanization.37 This synergy between the nature and nurture best explains the excess burden of heart disease among Indians worldwide.31, 37, 38 This also explains why even non-smoking vegetarians under 40 who exercise regularly and have low levels of traditional risk factors such as cholesterol get heart attacks.39
Greater adverse effects of total cholesterol and diabetes on atherosclerosis and no protective effect of HDL-cholesterol amongst Asian Indians have been reported and provide another novel possible explanation for observed excess rates of cardiovascular disease amongst this population.40
Underestimation of Heart Attack Risk
Since conventional approaches to diagnosis, prevention, and treatment are based on clinical trials performed in Europids, both European and American guidelines result in significant underestimation of risk in Asian Indians and result in underdiagnosis and undertreatment.41
At any given level of obesity, cholesterol, blood pressure, and other major risk factors; the risk of dying from heart disease is at least double among Indians compared to whites, even in countries where there is universal access to free, comprehensive, and advanced medical care such as the United Kingdom.41
The British, European, and Australian Guidelines have specific modifications that qualify South Asians for treatment of high cholesterol and high blood pressure, substantially ahead of whites- at an earlier age and at a lower risk threshold.42 This is the ultimate proof of the recognition of underestimation of heart disease risk among Indians in Europe and Australia (where people receive free medications when they reach a certain risk threshold).
Now the Good News of All
The good news is that heart disease has become highly predictable, preventable, and treatable. We now have the knowledge, technology, capacity, and solutions to help combat the triple epidemics of heart disease, diabetes, and obesity.31 According to World Health Organization (WHO), eighty percent of premature heart disease and diabetes is preventable.43
The US, Finland, and several countries have reduced the death rates of heart disease by 60 to 80% in the last 30 years – primarily through changes in lifestyle and appropriate use of medications.44 45There is every reason to believe that such a decrease in premature death from heart disease can be achieved in Indians worldwide through concerted action by the government, the medical community, the general public, and the media at large simply by using the existing knowledge and medications that are already available and affordable.39
Regular physical activity, lifetime abstinence of tobacco, healthy diet, and weight management form the foundation of lifestyle changes. A healthy diet is low in calories, salt, saturated fat, and trans fats (fried and/or crispy foods) and high in fruits, vegetables, whole grains, and fiber.46 Early adoption of healthy lifestyle behaviors, and early recognition of risk factors, and appropriate and targeted use of pharmacological therapy are all warranted. Both lifestyle modifications and pharmacological treatment should be initiated at an earlier age and at a lower threshold in the Indian population.
The current evidence of established safety and broad spectrum benefits of statins – the miracle medicine of the millennium, and prescription niacin would make these agents invaluable in the armamentarium against Asian Indian dyslipidemia.47 For those in whom lifestyle interventions are inadequate in achieving the targets, early and aggressive treatment of hypertension, dyslipidemia, and diabetes is mandatory.48 It is worth highlighting that continued adherence to lifestyle can substantially reduce the dose and even the need for medications.
An integral component of any strategy aimed at reducing the incidence and impact of CAD in Asian Indians is empowering both the general public and health care professionals through education. You can find invaluable scientific information supported by data by clicking the appropriate tabs and links.
More detailed and practical information can be found in How to Beat the Heart Disease Epidemic Among South Asians: A Prevention and Management Guide for Asian Indians and their Doctors. The book can be previewed and ordered from this website.
- Enas EA. How to Beat the Heart Disease Epidemic among South Asians: A Prevention and Management Guide for Asian Indians and their Doctors. Downers Grove: Advanced Heart Lipid Clinic USA; 2011.
- Enas EA, Yusuf S, Mehta J. Prevalence of coronary artery disease in Asian Indians. Am J Cardiol. 1992;70:945 – 949.
- Enas EA, Yusuf S, Sharma S. Coronary artery disease in South Asians. Second meeting of the International Working Group. 16 March 1997, Anaheim, California. Indian Heart J. Jan-Feb 1998;50(1):105-113.
- JafarTH, Jafary FH, Jessani S, Chaturvedi N. Heart disease epidemic in Pakistan: women and men at equal risk. Am Heart J. Aug 2005;150(2):221-226.
- Enas EA, Yusuf S, Mehta J. Meeting of International Working Group on coronary artery disease in South Asians. Indian Heart J. 1996;48:727-732.
- Jha P, Enas E, Yusuf S. Coronary Artery Disease in Asian Indians: Prevalence and Risk Factors. Asian Am Pac Isl J Health. Autumn 1993;1(2):163-175.
- Benfante R. Studies of cardiovascular disease and cause-specific mortality trends in Japanese-American men living in Hawaii and risk factor comparisons with other Japanese populations in the Pacific region: a review. Hum Biol. 1992;64(6):791-805.
- Jha P, Enas E, Yusuf S. Coronary artery disease in Asian Indians: Prevalence and risk factors. Asian Am Pac Isl J Health. 1993;1(2):163-175.
- Enas EA, Garg A, Davidson MA, Nair VM, Huet BA, Yusuf S. Coronary heart disease and its risk factors in first-generation immigrant Asian Indians to the United States of America. Indian Heart J. 1996;48(4):343-353.
- Enas EA. Prevention and treatment of coronary artery disease. JAPI. 1997;45:309-315.
- Enas EA, Yusuf S, Mehta JL. Prevalence of coronary artery disease in Asian Indians. Am J Cardiol. Oct 1 1992;70(9):945-949.
- Yusuf S, Reddy S, Ounpuu S, Anand S. Global burden of cardiovascular diseases: Part II: variations in cardiovascular disease by specific ethnic groups and geographic regions and prevention strategies. Circulation. 2001;104(23):2855-2864.
- Enas EA, Senthilkumar A, Juturu V, Gupta R. Coronary artery disease in women. Indian Heart J. May-Jun 2001;53(3):282-292.
- Enas EA, Dhawan J, Petkar S. Coronary artery disease in Asian Indians: lessons learnt and the role of lipoprotein(a). Indian Heart J. Jan-Feb 1997;49(1):25-34.
- Enas EA. Why Indians are more susceptible to Coronary artery disease: Role of specific risk factors In: Chatterjee SS, ed. Update in Cardiology Hyderabad: Cardiology Society of India; 2007.
- Enas EA, Mehta J. Malignant coronary artery disease in young Asian Indians: thoughts on pathogenesis, prevention, and therapy. Coronary Artery Disease in Asian Indians (CADI) Study. Clin Cardiol. Mar 1995;18(3):131-135.
- Enas EA. Why is there an epidemic of malignant CAD in young Indians? Asian J Clin Cardiol. 1998;1:43-59.
- Bhalodkar NC, EA E. Malignant Coronary Artery Disease and the Asian Indian Paradox Proceedings of the 13th International Congress on Heart Disease Conference, New Trends in Research, Diagnosis, and Treatment 2007:157-164.
- Gupta M, Doobay AV, Singh N, et al. Risk factors, hospital management and outcomes after acute myocardial infarction in South Asian Canadians and matched control subjects. CMAJ. 2002;166(6):717-722.
- Singh N, Gupta M. Clinical characteristics of South Asian patients hospitalized with heart failure. Ethn Dis. Autumn 2005;15(4):615-619.
- Hughes LO, Raval U, Raftery E. First myocardial infarctions in Asian and White men. BMJ. 1989;298:1345-1350.
- Yusuf S, Hawken S, Ounpuu S, et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet. Sep 11 2004;364(9438):937-952.
- Anand SS, Yusuf S. Stemming the global tsunami of cardiovascular disease. Lancet. Feb 12 2011;377(9765):529-532.
- Indrayan A. Forecasting vascular disease cases and associated mortality in India. 2010;http://www.whoindia.org/LinkFiles/Commision_on_Macroeconomic_and_Health_Bg_P2_Forecasting_vascular_disease_cases_and_associated_
mortality_in_India.pdf (197-215):Accessed Sept 25, 2010.
- American Heart Association. Heart and Stroke Statistical Update2010.
- Gupta R, Joshi P, Mohan V, Reddy KS, Yusuf S. Epidemiology and causation of coronary heart disease and stroke in India. Heart. Jan 2008;94(1):16-26.
- Enas EA, Garg A, Davidson MA, Nair VM, Huet BA, Yusuf S. Coronary heart disease and its risk factors in first-generation immigrant Asian Indians to the United States of America. Indian Heart J. Jul-Aug 1996;48(4):343-353.
- McKeigue PM, Shah B, Marmot MG. Relation of central obesity and insulin resistance with high diabetes prevalence and cardiovascular risk in South Asians. Lancet. 1991;337(8738):382-386.
- Alberti KG, Eckel RH, Grundy SM, et al. Harmonizing the metabolic syndrome: a joint interim statement of the International Diabetes Federation Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and international association for the Study of Obesity. Circulation. Oct 20 2009;120(16):1640-1645.
- Barnett AH, Dixon AN, Bellary S, et al. Type 2 diabetes and cardiovascular risk in the UK south Asian community. Diabetologia. Oct 2006;49(10):2234-2246.
- Enas EA. How to Beat the Heart Disease Epidemic among South Asians: A Prevention and Management Guide for Asian Indians and their Doctors. Downers Grove: Advanced Heart Lipid Clinic USA; 2010.
- Enas EA, Mohan V, Deepa M, Farooq S, Pazhoor S, Chennikkara H. The metabolic syndrome and dyslipidemia among Asian Indians: a population with high rates of diabetes and premature coronary artery
disease. J Cardiometab Syndr. Fall 2007;2(4):267-275.
- Enas EA, Singh V, Munjal YP, Bhandari S, Yadave RD, Manchanda SC. Reducing the burden of coronary artery disease in India: challenges and opportunities. Indian Heart J. Mar-Apr 2008;60(2):161-175.
- Kanaya AM, Wassel CL, Mathur D, et al. Prevalence and correlates of diabetes in South asian indians in the United States: findings from the metabolic syndrome and atherosclerosis in South asians living in america study and the multi-ethnic study of atherosclerosis. Metab Syndr Relat Disord. Apr 2010;8(2):157-164.
- Tillin T, Forouhi N, Johnston DG, McKeigue PM, Chaturvedi N, Godsland IF. Metabolic syndrome and coronary heart disease in South Asians, African-Caribbeans and white Europeans: a UK population-based cross-sectional study. Diabetologia. Apr 2005;48(4):649-656.
- Chaturvedi N, Fuller JH. Ethnic differences in mortality from cardiovascular disease in the UK: do they persist in people with diabetes? J Epidemiol Community Health. 1996;50(2):137-139.
- Enas EA, Chacko V, Pazhoor SG, Chennikkara H, Devarapalli HP. Dyslipidemia in South Asian patients. Curr Atheroscler Rep. Nov 2007;9(5):367-374.
- Enas EA. Lipoprotein(a) is an important genetic risk factor for coronary artery disease in Asian Indians. Am J Cardiol. 2001;88:201-202.
- Enas EA. Coronary artery disease epidemic in Indians: a cause for alarm and call for action. J Indian Med Assoc. Nov 2000;98(11):694-695, 697-702.
- Chow CK, McQuillan B, Raju PK, et al. Greater adverse effects of cholesterol and diabetes on carotid intima-media thickness in South Asian Indians: comparison of risk factor-IMT associations in two population-based surveys. Atherosclerosis. Jul 2008;199(1):116-122.
- Forouhi NG, Sattar N, Tillin T, McKeigue PM, Chaturvedi N. Do known risk factors explain the higher coronary heart disease mortality in South Asian compared with European men? Prospective follow-up of the Southall and Brent studies, UK. Diabetologia. Nov 2006;49(11):2580-2588.
- Graham I, Atar D, Borch-Johnsen K, Boysen G, Durrington PN. European guidelines on cardiovascular disease prevention in clinical practice: executive summary: Fourth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (Constituted by representatives of nine societies and by invited experts). Eur Heart J. Oct 2007;28(19):2375-2414.
- World Health Organization. Prevention of cardiovascular disease: A vital investment. World Health Organization, Geneva Switzerland2007.
- Ford ES, Ajani UA, Croft JB, et al. Explaining the decrease in U.S. deaths from coronary disease, 1980-2000. N Engl J Med. Jun 7 2007;356(23):2388-2398.
- Rodriguez T, Malvezzi M, Chatenoud L, et al. Trends in mortality from coronary heart and cerebrovascular diseases in the Americas: 1970-2000. Heart. Apr 2006;92(4):453-460.
- Enas EA, Senthilkumar A, Chennikkara H, Bjurlin MA. Prudent diet and preventive nutrition from pediatrics to geriatrics: current knowledge and practical recommendations. Indian Heart J. Jul-Aug 2003;55(4):310-338.
- Enas E.A., Hancy Chennikkara Pazhoor MD, Arun Kuruvila MBBS, Krishnaswami Vijayaraghavan MD F. Intensive Statin Therapy for Indians:Part I Benefits. Indian Heart J (In press). 2011.
- Enas EA. High rates of CAD in Asian Indians in the United States despite intense modification of lifestyle: What next? Current Science. 1998;74:1081-1086.