May 27, 2011 -- The combination of statins and niacin, both cholesterol modifying medications, don't reduce the chances of having a heart attack, according to findings by the AIM-HIGH trial conducted by the National Heart Lung and Blood Institute, an arm of the National Institutes of Health.
The findings prompted the NHLBI to stop their trial a year and a half early.
The AIM-HIGH study looked at patients who had lowered their LDL, or so-called bad cholesterol, with the help of statins and tried to see if raising HDL, or good cholesterol, by adding niacin to their therapy would additionally reduce the risk of having a heart attack. But the combined therapy of extended release niacin taken with statins showed no benefit in the patients tested.
Previous studies showed that low HDL cholesterol increases the risk of cardiovascular events in men and women, regardless of LDL cholesterol.
"We have had great clinical data that low HDL levels are bad for decades, but there is no evidence that raising HDL levels does anything to reduce the risk," said Dr. Cam Patterson, chief of the division of cardiology at the University Carolina at Chapel Hill.
Still, many cardiologists believe raising HDL reduces the chance of having a heart attack. In fact, the Framingham Cardiac Risk Score, a risk assessment tool used by cardiologists, looks mainly at the HDL score to assess a patient's risk of heart disease. It's unclear which HDL-raising treatments can reduce the risk of heart disease.
Niacin, found over-the-counter and frequently recommended to be taken two to three times daily, blocks the breakdown of HDL while preventing fat cells from releasing LDL. But niacin, also known as vitamin B3, has also been shown to increase the risk of stroke in some patients.
While many experts said they were surprised by the AIM-HIGH findings, some said they wouldn't abandon their longstanding belief in targeting HDL just yet.
In fact, some patients in the control group of the randomized trial may have had a longstanding history of niacin use before they started the study. The entire group of patients studied also had well-controlled LDL levels, which could indicate that their risk of heart disease or heart attack already may be lower compared to those with uncontrolled cholesterol.
Still, many doctors may be too focused on raising HDL without clear evidence of its benefits, according to Dr. Dean Ornish, founder and president of the preventative medicine research institute at the University of California San Francisco.
"There should be less emphasis on raising HDL and more on lowering LDL via diet and lifestyle, and focus on lipid lowering drugs in combination with diet and lifestyle changes to lower LDL, not raise HDL," said Ornish.
Many experts say patients should not stop taking cholesterol-lowering drugs like niacin or statins without talking to their doctor.
"Niacin has good lipid effects," said Dr. Christopher Cannon, senior investigator of the TIMI study group at Brigham and Women's Hospital in Boston.
Niacin has been successful in raising HDL and lowering LDL and triglycerides for many patients, said Cannon. But based on the findings, doctors may choose to wean many patients off of niacin and increase their statin dose, he said.
"Sometimes people hear negative lipid drug news and get confused and stop them," said Cannon. "That would be bad."