August 22, 2003
Risk Factor Almost Always Present in Most Heart Attacks
CHICAGO— Results of a large-scale study from the Feinberg School of Medicine dispute claims that, at least half the time, fatal and nonfatal heart attacks occur in individuals who had shown no previous evidence of at least one coronary heart disease (CHD) risk factor, such as high cholesterol, high blood pressure, cigarette smoking, diabetes, and bad eating habits.
Rather, the study found, 87 to 90 percent of people who had had a fatal heart attack had at least one major risk factor, including a cholesterol level of over 240, blood pressure over 140/90, smoking, or diabetes. Of those aged 40 to 59 who had had a fatal heart attack, 87 to 94 percent had at least one major risk factor. At least 92 percent of men and 87 percent of women between the ages of 40 and 59 who had had a non-fatal heart attack had at least one CHD risk factor.
As reported in the August 20 issue of the Journal of the American Medical Association, Philip Greenland, MD, Harry W. Dingman Professor of Cardiology and chair of preventive medicine, and colleagues at the Feinberg School, University of Minnesota, and Boston University examined data from three large prospective studies: the Chicago Heart Association Detection Project in Industry, which included almost 36,000 participants; Multiple Risk Factor Interventions Trial, with nearly 348,000 men and women; and Framingham Heart Study, which had almost 3,300 participants. Follow-up lasted 21 to 30 years across the studies.
“To our knowledge, there are no prior reports of this magnitude of exposures to clinically elevated levels of all major CHD risk factors in [study participants] followed up over a long term,” said Dr. Greenland.
Elevated levels of cholesterol and blood pressure, cigarette smoking, overweight/obesity, and diabetes are well established as the major causes of CHD.
A critically important feature of these risks, Greenland noted, is that each risk factor has a continuous, dose-dependent impact on CHD risk.
“In particular, for cholesterol, blood pressure, smoking, and overweight, higher levels of the risk factors translate into greater CHD risk,” Dr. Greenland said.
Based on the results of the study, the researchers suggested that preventing development of these risk factors, including overweight (as a herald of high blood pressure and cholesterol, as well as diabetes), should be given even more priority.
“Although cholesterol levels are important and major CHD risk factors, a one-sided focus on cholesterol as the major risk factor cannot be justified,” Dr. Greenland said.
Data from the study provide an important reminder that attention must be given to all major risk factor exposures to address the continuing CHD epidemic, he said.
Collaborating on this study were medical school researchers Maria Deloria Knoll; Jeremiah Stamler, MD, emeritus professor of preventive medicine; Alan R. Dyer, PhD, associate chair and professor of preventive medicine; and Daniel B. Garside, BS. Other researchers included James D. Neaton, PhD, University of Minnesota, Minneapolis, and Peter W. Wilson, MD, Boston University School of Medicine.
