Cholesterol Levels May Not Measure Cardiac Risk
Normal readings showed up in many who had heart attacks, study shows
FRIDAY, Jan. 16 (HealthDay News) -- Nearly three-quarters of patients hospitalized for heart attacks had cholesterol levels indicating they were not at high risk for cardiovascular trouble, a new, nationwide study shows.
The finding points to the possibility that current guidelines on cholesterol levels should be changed, said study author Dr. Gregg C. Fonarow, a professor of cardiovascular medicine and science at the University of California, Los Angeles. His report appears in the current issue of the American Heart Journal.
"The LDL cholesterol range at which people have heart attacks shouldn't be regarded as normal," Fonarow said.
LDL cholesterol, the "bad" kind, collects to form plaques that can eventually block arteries. Guidelines compiled by the U.S. National Heart, Lung and Blood Institute set an LDL cholesterol blood level target of 130 milligrams per deciliter for people with no cardiovascular disease or diabetes and 70 for those at high risk because of factors such as obesity, smoking and high blood pressure.
But the study of nearly 137,000 Americans hospitalized for heart attacks between 2000 and 2006 found that about 72 percent had LDL levels below 130 on admission, while 17.6 percent had LDL levels below 70.
"People with LDL cholesterol levels in the 100 to 130 range may feel they are at low risk," Fonarow said. "In this study, there was nothing normal about having an LDL reading of 100."
The study also looked at levels of HDL cholesterol, the "good" kind that helps prevent artery blockage. Current guidelines recommend an HDL level of 60 or higher, but the study found levels below 40 in 54.6 percent of the heart attack patients.
Only 1.4 percent of patients met the recommendation for both an LDL level of 70 or lower and an HDL reading of 60 or higher, Fonarow noted.
The current National Cholesterol Education Program guidelines were first set in 2001, and were updated in 2004. The NHLBI is expected to review those guidelines in the near future, Fonarow said.
"My opinion, based on the totality of the evidence that has come out, is that it is likely that there will be important revisions to the guidelines, but that should be determined by the individual advisory groups that will be writing them," he said.
In its update of the guidelines, the NHLBI called for more use of measures such as physical activity and weight loss to reduce the risk of heart attack and other cardiovascular problems.
Cholesterol is only one part of the heart risk picture, Fonarow said. Risk climbs higher with age, especially for men and for those with close relatives who have had cardiovascular conditions.
"The good news is that as much as 80 percent of the risk factors are under individual control and are modifiable," Fonarow said. "You can't control your family history, age or sex, but you can keep your blood pressure low, exercise and modify your lifestyle in other ways to reduce risk."
While calling the study "excellent," Dr. Manesh Patel, an assistant professor of medicine at Duke University, added, "The problem is that this is a snapshot, but we're not sure we know all the risk factors and how they interplay."
The researchers did not measure blood levels of other molecules involved in cardiovascular disease, such as the inflammation biomarker C-reactive protein and lipoprotein(a), he said.
But it's quite possible that the cholesterol guidelines will be changed, Patel said. "Ongoing studies have led to getting the LDL level to 100 and then to 70," he said. "As more randomized trials come out, there may be further changes."
For the full cholesterol story, go to the U.S. National Library of Medicine.