Blood levels of CRP may predict sudden cardiac death
C-reactive protein (CRP) is a protein produced by the liver that increases 1000-fold in response to inflammation caused by infection, injury, burns, and ischemia (reduced blood flow through the arteries). Ischemia is the result of atherosclerosis—fatty deposits also known as plaques—in the arteries. Research suggests that elevated blood levels of CRP predict increased risk of heart attack and stroke. Research recently published in Circulation: Journal of the American Heart Association suggests that elevated blood levels of CRP are associated with increased risk of sudden death due to severe heart disease.
About the study
Researchers from several U.S. medical centers studied the hearts of 302 men and women who had died suddenly. The average age at death was 50. As part of an autopsy, researchers measured the CRP levels in the blood of each person’s heart and evaluated the plaques in their coronary arteries. The control group comprised the 158 people who did not have atherosclerosis or any other inflammatory conditions that would raise their CRP levels. The cases comprised the 144 people who had atherosclerosis—71 with stable plaques and 73 with heart attacks due to ruptured or eroded plaques (unstable plaques). Other than atherosclerosis, cases did not have any inflammatory conditions that would raise their CRP levels.
In addition to measuring CRP levels and evaluating plaques, the researchers counted vulnerable plaques—those most likely to rupture. Finally, they compared the CRP levels and various plaques among cases and controls.
People with atherosclerosis (stable or unstable) had higher CRP levels in their blood and in their plaques than their counterparts without atherosclerosis. Specifically, average blood CRP levels were 3.2 mcg/mL in people who died of acute plaque rupture, 2.9 mcg/mL in plaque erosion, 2.5 mcg/mL in stable plaques, and 1.4 mcg/mL in the control group. In addition, the average number of vulnerable plaques in people with the lowest CRP levels was .95 compared with 3.0 among people with the highest CRP levels.
These findings suggest that blood levels of CRP may be a good predictor of your risk of sudden cardiac death. In calculating these statistics, the researchers controlled for age, sex, body mass index, and smoking.
Although these results are interesting, there are limitations to this study. Because this study was done postmortem, the researchers had little or no information regarding participants’ lifestyle factors or medications that may have influenced their risk of cardiac death.
How does this affect you?
If you’re an adult at high risk for atherosclerosis, your health care provider will likely test your CRP levels to determine if you have dangerous atherosclerotic plaques. “In the future, all patients should have their CRP levels checked,” says Dr. Renu Virmani, lead author of the study.
Although plaques in your arteries are not good news, knowing about them up front does allow you to take steps to correct the problem. Your health care provider can prescribe the appropriate dietary changes, physical activity, and medications (such as aspirin and cholesterol-lowering drugs) to lower your risk of rupturing a plaque, which can be life threatening.
Burke AP, et al. Elevated C-reactive protein values and atherosclerosis in sudden coronary death. Circulation . April 15, 2002; 105. Note: Published online. Print version to be published at a later date.
Last reviewed Apr 18, 2002
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