Features October 2013 Issue

Understanding Niacin’s Role In Your Cardiovascular Care

New studies question niacin’s role in reducing the risk of cardiovascular disease, yet it may still be effective for some, says a Cleveland Clinic expert.

Niacin, also known as vitamin B3, became popular more than 30 years ago when the Coronary Drug Project trial, which looked at 8,341 patients after heart attack, suggested the possibility that the drug might reduce the risk of recurrent heart disease. From that point forward, niacin has been the hope for elevating the good (HDL) while assisting the decrease in the bad (LDL) cholesterol levels.

Niacin pills are available in fast-acting and extended-release formats. They are usually taken once daily.

Yet, two recent studies are questioning the validity of niacin’s impact on cardiovascular disease prevention, in addition to raising concerns about an increase in side effects. Although these studies support caution against the widespread use of niacin, especially in light of the expected side effect profile, there may still be a role for the drug for some patients, according to Michael Rocco, MD, Medical Director of Cardiac Rehabilitation and Stress Testing and staff cardiologist at Cleveland Clinic.

“Some patients are not able to achieve recommended LDL goal or non-HDL goal levels on standard therapies for various reasons, including statin intolerance and extent of lipid abnormalities,” says Dr. Rocco. “These new studies tested specific populations, and we have to interpret the results within the context of the population studied. In both sets of research, participants were very well treated with statins and in some cases, additional medications. This is not the subgroup of patients we would typically introduce niacin for added cholesterol-lowering benefit.”

What They Found
To determine niacin’s actual effectiveness on cardiovascular disease in well-treated patients on statin therapy, two recent studies took a deeper look. The first, known as the AIM-HIGH study (Atherothrombosis Intervention in Metabolic Syndrome with Low HDL Cholesterol/High Triglyceride and Impact on Global Health Outcomes), reviewed the use of high-dose extended-release niacin (Niaspan) in patients with a history of cardiovascular disease and low levels of HDL cholesterol. After an interim review of almost 3,500 patients, the study was stopped because the researchers found no additional benefit to the participants. There was also a small but non-statistically significant increase in ischemic stroke in the niacin group, according to the National Heart Lung and Blood Institute (NHLBI), which sponsored the trial.

The overall frequency of stroke among AIM-HIGH participants was a difference of less than one percent, according to Dr. Rocco. “This slight increase was not of statistical significance and has not been supported in other niacin trials, and it’s important to understand that the study was stopped prematurely due to niacin’s lack of efficacy and not due to serious adverse events,” he says.

“Additionally, there was a relatively small increase in HDL levels, but this may have not been sufficient enough to demonstrate a difference in a group with a well-controlled LDL cholesterol levels of less than 70 mg/dL,” says Dr. Rocco.

Adding to niacin’s lack of efficacy, a separate study looked at the specifically formulated combination of niacin and laropiprant (a drug used to reduce skin flushing) compared to placebo in reducing the risk of cardiovascular disease. Results from this large study—known as HPS2-THRIVE (Heart Protection Study 2-Treatment of HDL to Reduce the Incidence of Vascular Events), which looked at 25,673 high-risk patients— also showed no significant difference in reducing cardiac events, but an increase in expected side effects, including skin flushing, poorer diabetes control and upset stomach, as well as an unexpected increase in infections and bleeding.

“Whether the excess in some of these side effects in the treatment group was due to the niacin alone or the laropiprant in combination remains unknown,” says Dr. Rocco.
What this means for you

“The really important question in the era of statin use is does adding HDL-modulating therapies such as niacin add incremental benefit. In these two studies, subjects were very well treated and the participants were not the types of patients in which we most often consider niacin use,” Dr. Rocco says. “While we need to be a more cautious in the widespread use of niacin, there still may be a use for medications in certain patients.”
Patients who may still benefit from adding niacin to statin therapy include those who have high triglyceride levels, and whose LDL and non-HDL cholesterol levels are resistant to statin therapy. “The first line of therapy should always be statins and titration to maximally tolerated doses to achieve treatment objectives, but in patients who are not responding to treatment the addition of niacin remains an option to consider,” he says.

 

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