The Heart Disease Conundrum
November 28, 2015
By Sandeep Jauhar
SOUTH ASIANS today account for more than half of the world's cardiac patients. Heart disease is the leading cause of death in India, Pakistan and Bangladesh, and rates have risen over the past several decades. South Asian immigrants to the United States, like me, develop earlier and more malignant heart disease and have higher death rates than any other major ethnic group in this country.
The reasons for this have not been determined. Traditional cardiac risk models, developed by studying mostly white Americans, don't fully apply to ethnic communities. This is a knowledge gap that must be filled in the coming years. Fortunately, there is a model for doing so: research performed in a small town in Massachusetts over the past seven decades. Known as the Framingham Heart Study, it is perhaps the most influential investigation in the history of modern medicine.
The Framingham Heart Study is a big reason we have achieved a relatively mature understanding of heart disease in the United States, at least for a large segment of our population. It established the traditional risk factors, such as high blood pressure, diabetes and cigarette smoking, for coronary heart disease. Framingham also spearheaded the study of chronic noninfectious diseases in this country, and indeed introduced many doctors to the very idea of preventive medicine.
The impetus for Framingham was clear. In the 1940s, cardiovascular disease was the main cause of mortality in the United States, accounting for nearly half of all deaths. Knowledge of coronary risk factors was spare. As Dr. Thomas Wang and colleagues wrote in the journal Lancet last year, "Prevention and treatment were so poorly understood that most Americans accepted early death from heart disease as unavoidable."
One victim of this ignorance was President Franklin Delano Roosevelt. When Roosevelt began his second term in 1937, his blood pressure was already high: 170/100. When the Japanese bombed Pearl Harbor in 1941, records show it was 190/105. By the time American soldiers landed in Normandy, in June 1944, his blood pressure was 226/118, life-threateningly high. But Roosevelt's personal physician insisted that the president's problems were "no more than normal for a man of his age." Unfortunately, Roosevelt's blood pressure remained mortally high until he died on April 12, 1945, at the age of 63, from a stroke and brain hemorrhage.
Roosevelt's death spurred passage of the National Heart Act, in 1948, which promoted research into the prevention and treatment of cardiovascular disease. One of the first grants was for an epidemiological study of heart disease in Framingham. A solidly middle-class industrial town with a predominantly white population of Western European descent, it was believed to be representative of the United States at that time. A key goal of the Framingham study was to establish risk factors for coronary heart disease. The initial outlay was modest: about $94,000, mostly to cover office supplies (including ashtrays for the study researchers who smoked). At the time, factors hypothesized to increase coronary risk included "nervous and mental states," occupation and use of stimulants like Benzedrine.
After about 10 years of close monitoring of approximately 5,000 patients, the Framingham researchers in 1957 published a key paper (out of the nearly 1,200 produced by the study) showing a nearly fourfold increase in the incidence of coronary heart disease in patients with high blood pressure. Later publications found correlations between coronary disease and diabetes, high blood cholesterol levels and cigarette smoking. This information led to lifestyle changes that have undoubtedly saved countless lives.
However, Framingham risk models do not tell the whole story for nonwhite ethnic groups. In 1959, the first study was published showing the increased risk of premature heart disease in Indian immigrant males, who had four times the rate compared with the men in Framingham, despite having lower rates of hypertension, smoking and high cholesterol, and more often following a vegetarian diet.
What is it about South Asian genetics or environments that lead to so much heart disease? We need a Framingham-type study to answer this question.
Fortunately, the National Institutes of Health have started such a study. Named Mediators of Atherosclerosis in South Asians Living in America, or Masala, it has enrolled about 900 South Asian men and women in two large metropolitan areas, the San Francisco Bay Area and Chicago. Researchers are focusing on novel risk factors, including malignant forms of cholesterol (previous research has suggested that South Asians may have smaller and denser cholesterol particles that are more prone to causing hardening of the arteries), as well as other social, cultural and genetic determinants.
Prospective results from Masala will be published in the next couple of years. They cannot come soon enough.
Sandeep Jauhar, a cardiologist and a contributing opinion writer, is the author of "Doctored: The Disillusionment of an American Physician" and "Intern: A Doctor's Initiation."