NEW YORK (CNN/Money) - Shares of Bristol-Myers Squibb tumbled nearly 15 percent Wednesday to hit a four-year low after the company released trial information on its Vanlev medication designed to treat hypertension and heart failure.

Dr. Milton Packer of Columbia University, lead researcher for the heart failure trial of the Bristol-Myers' (BMY: down $7.33 to $41.32, Research, Estimates) medicine Vanlev, said Vanlev is equivalent to Merck's Vasotec, although analysts had hoped it would be superior.

"This is clearly disappointing," said Mara Goldstein, an analyst at CIBC World Markets Corp. "We would have liked to see stronger data" for Vanlev. Because it has not proved to be superior to Vasotec, Vanlev would have difficulty competing in the marketplace, she said.

Vanlev is crucial to the earnings growth of Bristol-Myers, whose profit has been badly hurt in the past two years by generic competition for several key medicines. The data on Vanlev, which is the most important drug in New York-based Bristol's pipeline, was presented at the annual meeting of the American College of Cardiology in Atlanta.

Some analysts had said Vanlev could garner peak annual sales of up to $2 billion, if it were approved. Heart failure, in which the weakened organ cannot pump enough blood to meet the body's requirements, is a hard-to-treat condition that is a leading cause of death.

One worrisome side effect seen with Vanlev in earlier trials for hypertension was a severe type of allergy called angioedema, also seen in the Vanlev heart failure trial. The incidence of angioedema was 0.8 percent in patients taking Vanlev, versus 0.5 percent in the Vasotec group.

The potentially deadly side effect, which can cause the throat and tongue to swell up, caused concern among U.S. regulators two years ago and forced Bristol-Myers to conduct a large new 25,000-patient trial to test Vanlev for treatment of hypertension. Results of that separate hypertension trial will be presented later Wednesday in Atlanta.

-- from staff and wire reports