In response to release of ENHANCE study data, the American Heart Association (AHA) notes that large, longer-term studies are needed to correlate use of combination ezetimibe/simvastatin with clinical outcomes rather than markers such as arterial plaque growth.

The pharmaceutical companies that produce simvastatin and the ezetimibe/simvastatin combination drug recently released the ENHANCE study findings: Researchers found that the combination drug was no more effective in reducing carotid atherosclerotic plaque than simvastatin alone.

The AHA statement noted that the combination drug decreased low-density lipoprotein cholesterol significantly more than simvastatin alone; the unexpected finding was the lack of difference in arterial plaque over time.

As the statement said, the ENHANCE study was not large enough or long enough to determine whether the combination was more or less effective in reducing negative clinical outcomes such as myocardial infarction and death.

"It will be very important for those larger studies, directed at assessing cardiac outcomes, to be completed, so we can fairly assess the potential of ezetimibe," said American Heart President Daniel W. Jones, MD.

Because high cholesterol levels are such an important risk factor for coronary heart disease, the American Heart Association urges patients and physicians to talk before changing or stopping any medication regimen.

"Because Vytorin [combination ezetimibe/simvastatin] does not appear to be unsafe, lipid-lowering therapy with simvastatin is of proven benefit, and some patients have been prescribed Vytorin because a statin alone may not have been sufficiently effective in lowering their LDL or was not appropriate for them because of other medical conditions, we do not believe patients should stop taking the drug on their own," said Jones. "However, patients on this combination drug should check with their doctor to see if they should stay on the drug, be switched to a statin alone, or take another combination of drugs for their cholesterol."