CHAMPAIGN, Ill. -- Cholesterol levels may reflect a person's diet, but they say little about cardiac health, researchers say. In a new study, cholesterol levels were found to be under so-called danger levels for 750 men and women who were diagnosed with serious blockage of coronary arteries and had bypass surgery after complaining of chest pains and undergoing cardiac catheterization.
Researchers also found that elevated levels of four oxysterols -- metabolic products of cholesterol made in the liver -- were present in the patients with seriously blocked arteries. They conclude that plasma cholesterol levels should not be relied on as a measure for potential heart disease. Their findings appear in two studies in the March issue of the journal Atherosclerosis.
"If you have a chest pain, you better have it checked out thoroughly, and don't be satisfied with even a treadmill run or an EKG [electrocardiogram]," said Fred A. Kummerow, a professor emeritus of food chemistry at the University of Illinois. "Have a cardiologist check you out. You cannot depend on your cholesterol level to indicate heart disease. You cannot depend on your HDL-LDL ratio."
Kummerow and colleagues from the UI and Carle Foundation Hospital in Urbana, Ill., studied 1,200 patients who were cardiac-catheterized. Sixty-three percent had at least 70 percent of their arteries blocked -- enough to warrant bypass surgery. Of the 506 men who had a bypass, only 71 (14 percent) had plasma cholesterol levels above 240; 50 percent had levels below 200. Thirty-two percent of the 244 women who had bypass surgery had levels above 240; 34 percent were below 200.
The second study looked at the plasma of 105 of the catheterized patients who had angina (chest pains). All of them had elevated levels of four oxysterols. When these oxysterols were added to blood taken from a control group of angina-free patients, there was a marked influx of calcium infiltration into arterial cells -- similar to that found in the patients with chest pain. Calcium infiltration is the hallmark of heart disease.
"This study has identified why members of families in apparent good health may suddenly develop angina," Kummerow said. "Failure to recognize angina as a warning signal contributes to needless deaths from heart disease. Cardiac catheterization can determine if bypass surgery is needed."
To date, a 3-to-1 ratio of LDL (bad cholesterol) to HDL (good cholesterol) is a low heart-disease risk -- with a total cholesterol of less than 200 being the most desirable. However, in this study, Kummerow noted, 51 percent of the catheterized men had levels below 200 but needed a bypass.
Eating a well-balanced diet remains the best medicine to protect against heart disease, he said. Antioxidants such as vitamins E and C and those in vegetables and fruits can reduce oxysterol production and slow down calcification, but they won't reduce existing problems, he added. The Wallace Research Foundation of Cedar Rapids, Iowa, and the Carle Foundation in Urbana, Ill., supported the research.
Journal
Atherosclerosis