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SEATTLE (Reuters Health) – The combination of simvastatin (Zocor) and niacin can reduce the risk factors associated with myocardial infarction (MI) by 60% to 90% in patients at high risk for a major cardiac event, according to the results of a study by researchers at the University of Washington in Seattle. Furthermore, this same patient population should be advised to stop taking antioxidant vitamins.

"Physicians should question their patients and have them stop using [antioxidant vitamins]. It is the opposite of what I used to say," according to lead author Dr. B. Greg Brown.

The study, which is published in the November 29th issue of The New England Journal of Medicine, found that a combination of antioxidant vitamins (vitamin E, vitamin C and beta carotene) blunted the rise in HDL cholesterol seen with the simvastatin and niacin combination. However, Dr. Brown said he is not sure why the antioxidant vitamins had this effect.

The 3-year, double-blind trial included 160 patients with low HDL levels (35 mg/dL or less), normal LDL levels and clinical coronary artery disease. Patients were randomized to receive simvastatin plus niacin; antioxidants; simvastatin, niacin and antioxidants; or placebo. All patients received exercise training, as well as smoking and diet counseling.

Dr. Brown reported that the patients receiving the statin plus niacin had an increase in HDL from 31 mg/dL to 39 mg/dL (+26%), while the average LDL dropped from 125 mg/dL to 76 mg/dL (-42%) compared with those on placebo.

At the start of the study and again after 3 years of treatment, angiograms were performed. The results revealed that most patients who received the niacin and statin combination had a decrease in plaque buildup.

"What is expected with statins is a slowing of the disease progression, but not a reversal," Dr. Brown said. "But when niacin is combined with a statin, the artery blockage actually improves a bit, on average."

Niacin combined with any of the approved statin drugs could prevent many fatal and non-fatal heart attacks, Dr. Brown continued. He estimates that 5 million Americans could benefit from this combination therapy.

"I think we will see more use of niacin," Dr. Brown added. "It has been underused as a pharmaceutical."

For patients receiving antioxidants, the progressive narrowing of the arteries and frequency of major cardiovascular events did not differ from the control patients. Those receiving simvastatin/niacin and antioxidants had less favorable outcomes than the group receiving simvastatin/niacin alone.

"This study is very important. It points out how much of an impact we can have on the natural history of coronary artery disease when using intensive lipid-lowering therapy, and by addressing not only elevated LDL levels but also low HDL levels," Dr. Vera Bittner, a professor of medicine at the University of Alabama-Birmingham, said in an interview with Reuters Health.

"We should be more willing to consider combination therapy for lipid lowering…especially the statin/niacin combination in people with low HDL. We should also caution our patients that there is a potential adverse effect of the over-the-counter antioxidants," she said.

Dr. Peter Counihan, an interventional cardiologist at the University of Pittsburgh, said the study was very exciting, and that he will now change his management of patients with high LDL levels.

"Probably about 20% to 25% of my patients will now be considered for statin therapy along with niacin. Most are now on statin only," Dr. Counihan told Reuters Health. However, he cautioned that this study is relatively small and more research is needed.

"Niacin is not as easily tolerated as statin therapy. It causes flushing and can have adverse effects on blood sugar [and] uric acid," Dr. Bittner added. "Dr. Brown's study suggests, however, that this drug can be used effectively and safely with appropriate patient education and regular follow-up, and that the benefit may be very large."