ATLANTA, Nov. 8 -- Individuals who undergo heart surgery are more likely to survive longer and stay healthy if they have high levels of high-density lipoprotein (HDL) -- the "good" cholesterol, researchers reported at the American Heart Association Scientific Sessions today.
"In this study, individuals with low levels of HDL cholesterol were more likely to die or eventually need additional surgery. This study shows that HDL cholesterol may be more significant than LDL, the "bad" cholesterol, in predicting the long-term outcome of coronary bypass surgery patients," says JoAnne Micale Foody, M.D., cardiology fellow, preventive cardiology section, department of cardiology, Cleveland Clinic Foundation, Cleveland, Ohio.
The researchers found that men undergoing bypass surgery who had low levels of HDL cholesterol were nearly twice as likely to die in the next two decades than men whose HDL levels were higher. "Men with higher HDL cholesterol levels survived longer and had fewer cardiac events during their lifetime," says Foody. "It looks like HDL cholesterol is playing a bigger role than previously thought."
HDL helps clear bad cholesterol from the blood, and high levels are protective against heart disease. However, the role of low HDL cholesterol following bypass surgery had not previously been clearly established. HDL cholesterol is considered low at 35 mg/dl or below in men and 45 mg/dl or below in women. The researchers identified 432 men registered in the Cardiovascular Information Registry at the Cleveland Clinic Foundation who had undergone lipid studies before having coronary bypass surgery. The study lasted 20 years. Patients were contacted at 5-year intervals to recheck their lipid levels. Lipids are fatty substances, such as cholesterol, found in the blood.
"These results point toward the potential benefit of raising HDL cholesterol in patients who undergo coronary bypass surgery, as well as others with heart disease," she says.
Foody says this is the largest study to examine the role of HDL cholesterol in survival rates following heart surgery. The findings add to a growing body of evidence suggesting the significant role of HDL cholesterol in the development of heart disease, she says.
"We need to make greater use of therapies that help raise the levels of HDL cholesterol in patients who have had heart surgery," Foody says. She adds that perhaps the use of certain drugs such as niacin and gemfibrozil, which regulate cholesterol levels, could help raise HDL cholesterol either before or after surgery. Exercise has also been shown to raise HDL levels.
One limitation of this study, according to Foody, is that the men involved all had heart surgery 20 years ago -- before widespread use of beta blockers, ACE inhibitors, antiplatelets and many cholesterol lowering drugs. "This group of patients was probably healthier than the current group undergoing bypass surgery today," she says. "They were less obese and less likely to have diabetes and hypertension. That's because 20 years ago, only the healthiest heart patients were considered good candidates for open heart surgery."
Other researchers included Francis D. Ferdinand, M.D.; Bruce W. Lytle, M.D.; Delos M. Cosgrove, M.D.; Dennis L. Sprecher, M.D.; and Gregory L. Pearce, statistician.
Media advisory: Dr. Foody can be reached by phone at (216) 444-9417. (Please do not publish telephone number.)