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Title: Common Blood Test May Predict Carotid Artery Disease: Presented at ACS

"Common Blood Test May Predict Carotid Artery Disease: Presented at ACS"

By Mike Fillon NEW ORLEANS, LA -- October 14, 2004 -- A new study by United States Army surgeons shows that increased levels of C-reactive protein (CRP) in serum may be a better predictor of carotid stenosis than are cholesterol levels and other risk factors for cardiovascular disease. Researcher Philip S. Mullenix, MD, a resident in vascular surgery, Madigan Army Medical Center in Tacoma, Wichita, said the research is raising questions about whether CRP might be used to predict neurologic disease due to atherosclerosis. If this theory is proven to be correct, monitoring of CRP levels could lead to a new way of identifying patients who need treatment to prevent stroke. Dr. Mullenix presented these findings here on October 12th during a Forum on Vascular Surgery at the American College of Surgeons 90th Annual Clinical Congress. A systemic marker for inflammation, CRP is known to increase in individuals with conditions such as rheumatoid arthritis, chronic inflammation, infection, and malignancy. Because atherosclerosis is a systemic inflammatory disease, researchers have been testing studying whether CRP could be used as a predictor of future acute atherosclerotic coronary events. Until Dr. Mullenix's study, there has been no study that looked at how carotid disease might contribute to elevations in CRP. In the study, the researchers measured serum levels of CRP and low-density lipoprotein (LDL) and compared how well each of the two tests predicted carotid disease in 58 men who were suspected of having carotid stenosis. All patients also underwent duplex ultrasound of their carotid bifurcations. Results show that CRP was statistically correlated (P <.001) with carotid stenosis, but LDL was not. Patients with stenosis had higher average CRP levels than did those with no carotid disease. The two groups had similar LDL levels. When the researchers adjusted for other carotid stenosis risk factors, such as age, history of smoking, diabetes, hypertension, and coronary artery disease, CRP was independently associated with stenosis, while LDL was not. When the researchers broke down CRP and LDL levels into quartiles, they found that 4th quartile CRP levels independently predicted stenosis compared to the lower three quartiles, a significant difference (OR 63.1, 95% CI, P < 0.01), but LDL levels were not significantly predictive (OR 1.5, 95% CI, P = 0.68). The data also showed that absolute and 4th quartile CRP levels were similarly and significantly associated to the degree of stenosis. This was not observed for LDL levels. Patients with high LDL levels commonly are treated with statin drugs to reduce their risk of atherosclerosis. Dr. Mullenix said that, if other studies confirm that elevated CRP is a danger sign for stroke, it might become common practice to also treat patients who have low LDL levels if their CRP levels are high, given CRP-lowering effect of these agents. Dr. Mullenix and his team are now expanding the study to more than 500 patients, who will be evaluated for the next 3 years to determine whether individuals with elevated CRP levels have a higher incidence of transient ischemic attacks or of full-blown stroke. "We will be following these patients every 3 to 6 months and tracking who has an adverse neurologic event related to carotid disease. It will be interesting to see if patients with an elevated CRP have an increased risk down the road of an adverse neurologic outcome," he said. He added that CRP levels might become a tool to help prioritize patients for carotid surgery, instead of the current standard, carotid artery blood flow velocity. Blood flow velocity, he said, is a surrogate measure of plaque buildup on blood vessel walls. "What we're really interested in is plaque that has a propensity to cause a stroke," he explained. "It's thought that elevated CRP is associated with plaque that has ulcerated or thrombotic components and, therefore, is unstable, breaking off and lodging in blood vessels downstream, blocking blood supply to the brain and causing a stroke." Dr. Mullenix added that CRP might change the frequency of surveillance of patients with carotid disease, so that patients with high CRP levels might be assessed every six months instead of every year. "In an adjunctive way, along with other factors, [CRP level] might tip the balance toward surgery for those patients we're on the fence about, in terms of our clinical impression," Dr. Mullenix said. [Presentation title: "Comparison of C-reactive Protein and Low-Density Lipoprotein Cholesterol Levels in the Prediction of the Presence and Degree of Carotid Stenosis." Session SF-VS01]

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