One of the pillars in the world of cardiology crumbled today, doctors say, and many sheepish heart specialists have some explaining to do.
For years, many doctors have blindly accepted as fact the notion that half of all heart disease patients lack the four classic factors known to raise a person's risk: smoking, diabetes, high cholesterol and high blood pressure.
Yet, nowhere can they find any evidence to back up the assertion. Philip Greenland of Northwestern University in Chicago knows, because he has looked.
''When we started looking up the evidence,'' he says, ''people kept referring back to articles that didn't prove it at all. It's folklore that grew up and got quoted over and over, apparently erroneously.''
The misconception is more than a minor embarrassment for those who treat ailing hearts, experts say. It is one of the guiding principles of heart disease, governing medical practice, public health and research priorities.
Now two landmark studies, done differently and focusing on entirely different populations, indicate that up to 90% of heart disease patients have one or more of these risks.
The studies are published in today's Journal of the American Medical Association.
Greenland's team examined nearly 400,000 people who started three major lifestyle studies with healthy hearts and were then followed for up to 30 years. The researchers found that 87% to 100% of those who died of heart disease had one or more of the risk factors for heart disease.
The second, led by Umesh Khot of the Indiana Heart Physicians in Indianapolis, offered a cross-sectional snapshot of roughly 120,000 heart patients taking part in 14 clinical trials of heart disease drugs. That study found that 85% of heart patients had one of the classic risk factors, and only 10% to 15% of younger patients -- men younger than 55 and women younger than 65 -- lacked any risk factors.
''If we could get people to stop smoking alone, that would push back the timing of heart disease by a whole decade,'' says Khot, who conducted the study with a team at the Cleveland Clinic during a fellowship.
The studies will reinforce efforts by the World Health Organization, the American Heart Association and the government's National Cholesterol Education Program to get doctors to focus on their patients' ''global risk'' of heart disease: the classic risk factors plus obesity and exercise level.
Sidney Smith of the University of North Carolina-Chapel Hill, a spokesman for the American Heart Association, says patients with healthy hearts who are at high risk should be treated just as aggressively as those who have had heart attacks.
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