C-Reactive Protein and Your Heart

Can C-Reactive Protein Be Counted As a Risk Factor For Heart Disease?

(LifeWire) - C-reactive protein (CRP) is a relatively recent addition to the list of risk factors for heart disease. And women are particularly vulnerable to elevated CRP. The good news: Elevated CRP levels can be addressed with existing medications of proven safety.

CRP joined the established risk factors -- which include smoking, high total and LDL cholesterol ("bad cholesterol"), obesity, diabetes, family history of heart disease, age and so on -- as a result of advances in medical technology and a growing interest in the role of inflammation in heart disease.

Inflammation is the body's response to tissue injury, infection or irritation, and is generally characterized by redness, swelling and a feeling of heat at the site of an injury.

CRP is produced by the liver and released into the bloodstream as part of the body's inflammatory response. CRP levels are measured via a blood test, enabling the standard CRP test to detect levels as low as 3 milligrams per liter (mg/L). Very high levels (greater than 10 mg/L) are a strong indicator of active inflammation or infection somewhere in the body.

However, it turns out that much lower levels of elevated CRP -- often under 3 mg/L -- can still signal inflammation, specifically inflammation that  involves the cardiovascular system (the heart and blood vessels). Such low levels would typically be missed by the standard CRP test, but during the 1990s, a new, high-sensitivity CRP (hsCRP) test became available. This test can detect blood concentrations of CRP as low as 0.3 mg/L.

Recently, the Centers for Disease Control and Prevention and the American Heart Association have established guidelines for CRP: Levels less than 1 mg/L indicate a low cardiovascular risk; levels between 1 mg/L and 3 mg/L correspond to moderate cardiovascular risk; and those greater than 3 mg/L correspond to high risk.

Women are at particularly high risk for elevated CRP. Large studies have shown that women, in both the general population and among individuals with heart disease, have higher CRP levels than men. A 2002 study of 28,000 American women showed that elevated CRP levels were a stronger predictor of future heart disease than elevated LDL cholesterol levels.

Of particular importance, elevated CRP levels can predict first heart attacks in individuals with no known coronary artery disease -- as well as outcomes for patients who already have heart disease. In one study, men with high CRP levels had up to 5.3 times the risk of suffering a future heart attack when compared to individuals in the general population. Those with the highest risk of had a higher ratio of total cholesterol to HDL cholesterol, indicating higher levels of LDL cholesterol ("bad cholesterol").

Currently, CRP levels are used to help determine the risk of developing heart disease in individuals who already have other risk factors. Because CRP levels can fluctuate, hsCRP levels should be checked twice, two weeks apart, with the average value taken as a reference. The hsCRP test can not only help identify who is particularly at risk for heart disease, but may also lead to more intensive treatment of those individuals, including identifying measures to reduce their other risk factors.

Yet the hsCRP test is not a cure-all. Because high CRP levels nearly always correlate with at least one other established risk factor for cardiovascular disease, experts are not yet recommending across-the-board CRP testing.

CRP and LDL cholesterol are both indicators of potential cardiovascular trouble. Cholesterol is far better understood, but CRP is useful for its ability to predict risk for heart disease and future heart attack. Research suggests that CRP and cholesterol levels are, in effect, warning signs for different sets of people, so a low CRP level does not in and of itself represent a clean bill of health for your heart. Nor are CRP levels a strong predictor of heart disease among people with diabetes, as diabetes itself serves to elevate CRP levels.

The most effective way to lower elevated CRP levels that are associated with heart risk is by taking the cholesterol lowering drugs known as statins. Statins -- including, for example, Lipitor (atorvastatin), Zocor (simvastatin), Lescol (fluvastatin), Crestor (rosuvastatin), Mevacor (lovastatin) and Pravachol (pravastatin) -- not only reduce LDL cholesterol, but also CRP levels. In fact, statins appear to reduce CRP levels even more effectively than they do cholesterol levels. This suggests that statins may have anti-inflammatory benefits independent of their cholesterol-lowering effects.

On the other hand, it is important to remember that medications alone, while helpful, are just one piece of the puzzle. The best way to reduce your overall risk for heart attack, stroke or other cardiovascular problems, is by following a heart-healthy lifestyle: Focus on a healthy low-fat diet, regular exercise, maintain a healthy weight, take medications as prescribed by your doctor or nurse practitioner and do not smoke.

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