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.