UPDATE 2-CV angina drug not effective in ACS study

(Adds analyst comment)

NEW YORK, March 6 (Reuters) - CV Therapeutics Inc. CVTX.O said on Tuesday its angina drug Ranexa was not effective in a study of acute and long-term treatment of patients with a type of heart disease known as acute coronary syndrome (ACS).

The disappointing results sent CV Therapeutics' shares down more than 25 percent in after-hours trading.

While ineffective for ACS, there was no adverse trend in death or arrhythmias in patients taking the drug, also known by the chemical name ranolazine, the company said.

Based on an agreement with U.S. health regulators, CV Therapeutics said it believes the safety data from the 6,500-patient study could support expansion of Ranexa's approved uses to include the drug as a first choice treatment for angina.

It is currently approved to treat chronic angina in patients who have not achieved an adequate response with other drugs.

Citigroup analyst Yaron Werber was skeptical of CV's assertion that a Ranexa label expansion to include first-line angina was likely to come out of the study.

"We lack the same conviction that this safety data will significantly expand the market," Werber wrote in a research note. "Instead, we believe that it will only modestly drive further market share gains in chronic angina due to the removal of safety warnings from the label."

CV plans to present full data from the study at the American College of Cardiology Scientific Session in New Orleans on March 27.

About 9 million people in the United States suffer from chronic angina, a serious heart condition usually associated with coronary artery disease and marked by attacks of chest pain, according to the American Heart Association.

CV Therapeutics shares fell to $9 in extended electronic trading from their Nasdaq close at $12.30.