People who are native to South Asia experience heart attacks at a younger age because of greater levels of heart attack risk factors such as smoking and diabetes at a younger age, according to a study in the January 17 issue of JAMA.
The South Asian countries of India, Pakistan, Bangladesh, Sri Lanka, and Nepal account for about a quarter of the world's population and contribute the highest proportion of cardiovascular diseases compared with any other region globally. Deaths related to cardiovascular disease occur 5 to 10 years earlier in South Asian countries than in Western countries, according to background information in the article. This has raised the possibility that South Asians exhibit a special susceptibility for acute myocardial infarction (AMI; heart attack) that is not explained by traditional risk factors. Despite documenting the higher rates of earlier coronary heart disease (CHD) in South Asians, few studies have been able to shed light on its reasons.
Prashant Joshi, M.D., of the Government Medical College, Nagpur, India, and colleagues attempted to determine the reasons for the higher rates of CHD in native South Asians compared with individuals from other parts of the world. The study included 1,732 heart attack patients and 2,204 controls from 15 medical centers in 5 South Asian countries and 10,728 heart attack cases and 12,431 controls from other countries.
The researchers found that the average age for first heart attack was lower in South Asian countries (53.0 years) than in other countries (58.8 years). The prevalence of protective risk factors (leisure time physical activity, regular alcohol intake, and daily intake of fruits and vegetables) were markedly lower in South Asian study participants compared with those from other countries.
Some harmful factors were more common in native South Asians than in individuals from other countries: history of diabetes, current and former smoking, history of hypertension, psychosocial factors such as depression and stress at work or home, and elevated ApoB/ApoA-I ratio (a protein/lipid). When stratified by age, South Asians had more risk factors at ages younger than 60 years.
"The younger age of first AMI among the South Asian cases in our study appears to be largely explained by the higher prevalence of risk factors in native South Asians," the authors write. "These data suggest that lifestyle changes implemented early in life have the potential to substantially reduce the risk of AMI in South Asians."
(JAMA. 2007;297:286-294. Available pre-embargo to the media at www.jamamedia.org)
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