Beyond Cholesterol

TEK IMAGE/PHOTO RESEARCHERS
STEP ONE: You still have to get your blood drawn

Ask any heart doctor the best way to avoid a heart attack, and he will probably tell you to lower your cholesterol and exercise more. What he's not likely to tell you is that despite cholesterol's well-earned reputation as the heart's primary nemesis, half of all heart attacks occur in people with normal cholesterol levels. That's because though scientists have identified some 250 other risk factors, from obesity to gum disease, they have never found a better indicator of the health of one's cardiovascular system than the levels of good and bad cholesterol in the blood.

Until now. In a groundbreaking study published in the New England Journal of Medicine last week, doctors from Boston's Brigham and Women's Hospital showed that a simple blood test, called CRP, that measures the presence and intensity of inflammation in the walls of the blood vessels is as good as and in some cases better than cholesterol levels at predicting which patients are most likely to suffer a heart attack or stroke.

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The study, led by Dr. Paul Ridker, director of the hospital's center for cardiovascular-disease prevention, is likely to be the talk of the annual meeting of the American Heart Association this week in Chicago. Not only does it provide the strongest evidence to date that inflammation plays a key role in heart disease, but it also supports the growing suspicion among medical researchers that inflammation is a major culprit behind a wide range of disorders, including cancer.

Inflammation is the body's basic emergency-response system. When anything threatens the body's health from disease-causing germs to the buildup of fatty plaque in the walls of a heart vessel the immune system sends in wave after wave of cells to swarm and destroy the invader. In the blood vessels, layers of these immune cells pile up, creating lesions that become increasingly unstable and may eventually rupture, triggering a heart attack. How sensitive this alarm system is depends on such things as diet, stress and one's genetic predisposition.

CRP, for C-reactive protein, is a substance manufactured by the liver in response to the immune system's alarms. It can easily be picked up in the blood and provides a convenient measure of how inflamed the heart arteries may be. Ridker's team, which pioneered the study of CRP's role in heart disease, tracked the levels of both CRP and ldl ("bad" cholesterol) in nearly 28,000 women for eight years. They found that women with high levels of CRP were twice as likely to have heart disease as those with high ldl, and that many women who later suffered heart attacks would have been given a clean bill of health on the basis of their low ldls. For that reason, he and others would like to see CRP join cholesterol as part of the battery of tests in a standard blood workup. "These data," says Ridker, "tell us that continued reliance on ldl alone is really not serving our purpose very well."

But CRP can be tricky; it can jump as much as 10-fold when a person is fighting a cold or the flu. And it shouldn't be used in place of a cholesterol test. The latter measures how much fat is lodged in the vessels of the heart; the CRP test shows how likely it is that those plaques will burst.

If your CRP levels are high, don't despair. They can be lowered. In fact, the lifestyle changes and medications that doctors recommend to lower cholesterol do double duty and also reduce CRP. Avoiding fatty red meat, eating more fruits and vegetables and exercising should be the first response if making those changes is not enough, statin drugs may help.

The broader implications of the new study will require further research. People who suffer from chronic inflammatory responses like arthritis may be at higher risk of heart disease. There may also be a cancer link, for among the substances released during the inflammatory response are free radicals that can trigger tumor growth. Maybe that's why doctors' advice to eat more nutrient-rich vegetables and less fat works equally well for a patient who is at risk for cancer or for heart disease. They've been treating the same underlying cause all along.