UPDATE 2-Vytorin heart study expanded, results being delayed

(Adds details, physician comment, background)

By Julie Steenhuysen

CHICAGO, March 28 (Reuters) - U.S. researchers said on Friday they plan to expand the size of a major study to determine the heart benefits of the controversial cholesterol fighter Vytorin, which they said would delay results until 2012.

Vytorin combines the statin Zocor, known generically as simvastatin with another cholesterol medicine, Zetia or ezetimibe, and is marketed by a joint venture of Merck & Co (MRK.N) and Schering-Plough Corp SGP.N.

The study tests Vytorin against Zocor alone, which is now available in cheaper, generic form. The companies hope to show added benefits from the combination drug.

Academic researchers running the trial said in a statement they would expand the study to 18,000 patients to strengthen the results, which aim to show that the drug prevents heart attacks and other heart problems. The study, originally designed for 10,000 patients, is expected to be completed in 2011.

Trial chairman Dr. Eugene Braunwald of Brigham and Women's Hospital said in a statement that expanding the trial will allow researchers to test definitively whether the additional lowering of low-density lipoprotein -- or LDL, the so-called bad cholesterol -- with Zetia will translate into additional benefits for patients.

Researchers have been awaiting the results of the study, dubbed "IMPROVE-IT," to resolve questions raised by an earlier study released in January that suggested the higher-priced combination drug Vytorin fared no better than an inexpensive statin in patients with an inherited form of heart disease.

In January, Merck and Schering-Plough announced that Vytorin did not stop the accumulation of fatty deposits in arteries any better than Zocor in these high-risk patients.