The possible link between C-reactive protein (CRP) and heart disease may be the most interesting development in the field of coronary health since heart disease was linked to cholesterol, according to some experts. In fact, this once obscure protein may play an important role in predicting the risk of heart disease. Read on to learn more about CRP and what it means for your health.

Studies suggest that a key component of heart disease is inflammation, and researchers believe chronically inflamed blood vessels set the stage for atherosclerosis (hardening of the arteries). Inflamed patches become "sticky" and start collecting plaque. In an article entitled "The Fire Within," Scientific American reports the new thinking about the way this plaque -- and the accompanying inflammation -- affect the arteries:

"As recently as [10] years ago, most physicians would have confidently described atherosclerosis as a straight plumbing problem: Fat-laden gunk gradually builds up on the surface of passive artery walls. If a deposit (plaque) grows large enough, it eventually closes off an affected 'pipe,' preventing blood from reaching its intended tissue. After a while the blood-starved tissue dies. When a part of the cardiac muscle or the brain succumbs, a heart attack or stroke occurs.

"Few believe that tidy explanation anymore. Investigations begun more than 20 years ago have now demonstrated that arteries bear little resemblance to inanimate pipes. They contain living cells that communicate constantly with one another and their environment. These cells participate in the development and growth of atherosclerotic deposits, which arise in, not on, vessel walls. Further, relatively few of the deposits expand so much that they shrink the bloodstream to a pinpoint. Most heart attacks and many strokes stem instead from less obtrusive plaques that rupture suddenly, triggering the emergence of a blood clot, or thrombus, that blocks blood flow."

When tissues become inflamed, they release several different proteins, including CRP. For this reason, CRP is a "marker" for systemic inflammation. While injuries and infections can cause brief spikes in CRP, a persistently elevated level of C-reactive protein may (in the absence of other reasons) suggest that blood vessels are inflamed. For this reason, it may be a useful predictor of heart disease risk.

CRP may turn out to be as strong a predictor of heart disease as cholesterol levels. This first became evident in a landmark study of nearly 28,000 women without a prior "coronary event" (a heart attack, unstable angina, or sudden cardiac death) published in the Nov. 14, 2002 issue of the New England Journal of Medicine. Surprisingly, the study found that high levels of CRP were a stronger predictor of risk than high levels of LDL (bad) cholesterol. After adjusting for other variables, such as age, smoking status, and diabetes, women with the highest levels of CRP were more than twice as likely as women with low CRP to have a heart attack or stroke. In contrast, women in the group with the highest LDL cholesterol were only about one and a half times as likely than women with low cholesterol to have a heart attack or stroke.

This study helped confirm what many experts had already suspected. Taken together, high cholesterol and high CRP may predict heart disease. But even if a person has low cholesterol levels, a high CRP may be cause for concern.

At this time, there are no firm guidelines for CRP testing. Still, the American Heart Association has some suggestions: If your doctor says you're at low risk for heart disease, there's probably no reason to have the test. But if you're at intermediate risk -- that is you have a 10 to 20 percent chance of having a heart attack, stroke, sudden cardiac death, or unstable angina in 10 years -- the AHA says such a test can help predict such problems and help a doctor determine treatment. The tests for both cholesterol and CRP can be conducted with the same blood sample.

Many well-known risk factors for heart disease also seem to raise the levels of CRP. According to a recent report in the journal Circulation, smoking, high blood pressure, extra weight, and lack of exercise are all associated with high CRP. Genes also seem to play a strong role. If your parents had high levels of CRP, there's a good chance you will too.

The same tried-and-true strategies for reducing the risk of heart disease can also help lower CRP. Eating diet high in fruits, vegetables, and whole grains, exercising regularly, maintaining a healthy weight, controlling blood pressure, and avoiding tobacco are all important steps.

Talk with your doctor about whether medications will help. Patients who were given high doses of a cholesterol-lowering statin drug also experienced a drop in CRP levels and in heart attacks, according to the New England Journal of Medicine study.

The link between CRP and heart disease underscores what researchers have said for years: If a heart attack or stroke is looming in your future, now is the time to act. By maintaining a healthy lifestyle and working with your doctor, you can protect your heart -- and perhaps save your life.

-- Chris Woolston, MS, a health and medical writer with a master's degree in biology, is a contributing editor at Consumer Health Interactive. He is co-author of the 2005 book Generation Extra Large: Rescuing Our Children from the Epidemic of Obesity.

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First published March 2, 2006
Copyright © 2006 Consumer Health Interactive