More than 8 of every 10 patients with a nonfatal or fatal coronary event have at least one of the 4 major risk factors for coronary heart disease, smoking, hypercholesterolemia, hypertension, or diabetes, according to an article in the August 20th issue of the Journal of the American Medical Association.

According to background information in the article, the concept that major risk factors are absent in many patients with coronary heart disease has been frequently mentioned in print. However, prior studies had not systematically evaluated the extent to which patients presenting with a fatal or nonfatal coronary event have documented previous exposure to at least one major risk factor.

Philip Greenland, M.D., and his American colleagues assembled data from 3 large studies with follow-ups of 21 to 30 years and assessed the prevalence and consistency of major risk factor exposures for fatal as well as nonfatal events due to coronary heart disease. The studies were the Chicago Heart Association Detection Project in Industry (35,642 employed men and women aged 18 to 59 years), adults screened for entry into the Multiple Risk Factor Intervention Trial (347,978 men aged 35 to 57 years), and a sample from the Framingham Heart Study (population-based group of 3,295 men and women aged 34 to 59 years).

The major coronary heart disease risk factors were defined as a total cholesterol level of at least 240 mg/dL, systolic blood pressure of at least 140 mm Hg, diastolic blood pressure of at least 90 mm Hg, cigarette smoking, and diabetes mellitus.

A total of 20,995 people from the three studies died from a coronary event: Frequency for at least 1 clinically elevated major risk factor ranged from 87 percent to 100 percent. "Among those aged 40 to 59 years at baseline who developed fatal coronary heart disease (19,263 people), exposure to at least 1 major risk factor ranged from 87 percent to 94 percent. For nonfatal myocardial infarction, prior exposure was documented in 92 percent of men aged 40 to 59 years at baseline (167 subjects) and in 87 percent of women in this age group (94 subjects)."

"These results challenge claims in the medical literature that coronary heart disease events commonly occur (as often as 50 percent of the time) in persons who have not been exposed to at least 1 major risk factor," wrote the authors. "These data underscore the importance of considering all major risk factors in [coronary heart disease] risk estimation and in attempting to prevent clinical coronary heart disease. Based on these and related findings concerning the major risk factors, we suggest that preventing development of unfavorable levels of blood cholesterol and blood pressure, cigarette smoking, diabetes, and unfavorable body weight (as a precursor of unfavorable blood lipid and blood pressure levels and diabetes) should be given even greater priority than is presently the case."

In the same issue is a related article on the prevalence of major risk factors among people diagnosed with coronary heart disease (by Umesh N. Khot, M.D., and his American colleagues), which evaluated 122,458 participants in 14 international randomized clinical trials and had very similar findings: the presence of at least 1 of the 4 major risk factors among 84.6 percent of women and 80.6 percent of men.

In an accompanying editorial, John G. Canto, M.D., M.S.P.H., and Ami E. Iskandrian, M.D., wrote that the reports "may have enormous public health implications for targeting a large segment of the population at risk of developing coronary heart disease."

They added that the articles "provide evidence that convincingly challenges the frequent claim that 'only 50 percent' of coronary heart disease is attributable to the conventional risk factors of smoking, diabetes, hypertension, and hyperlipidemia, and clearly point out that additional research is needed to establish the role of other novel risk markers. Perhaps more important, these studies emphasize that to reduce the burden of cardiovascular disease, physicians should have even greater vigilance in identifying conventional coronary heart disease risk factors and must redouble efforts to control them effectively."