(In U.S. dollars. Adds company and analyst comments)

By Scott Anderson

TORONTO, July 14 (Reuters) - Cardiome Pharma Corp (COM.TO: Quote, Profile, Research) (CRME.O: Quote, Profile, Research) said on Monday an oral version of its vernakalant heart drug reduced the rate at which patients in a study relapsed into irregular heart rhythm, and its shares jumped 28 percent after it announced the results.

After disclosing the findings of the mid-term trial, the Canadian drug company said it plans to begin key, phase 3 clinical trials of the treatment late this year or early in 2009. It is aiming for U.S. market approval for the drug, designed to prevent an abnormal heart rhythm known as atrial fibrillation from recurring, by late 2012.

The Vancouver-based company estimates the global market value for the oral version of the product at between $1.5 billion and $3 billion annually, President Doug Janzen told Reuters. He sees a market of $300 million to $400 million for an intravenous version.

"That has always been the story behind the story," said John Maletic, an analyst at Scotia Capital. "The IV has been the original drug, but the real value has always been in the oral product, which would be a reasonable attraction for anyone looking to buy the company."

Cardiome has been waiting since January for U.S. Food and Drug Administration approval of the intravenous version, which it is marketing in partnership with Astellas Pharma (4503.T: Quote, Profile, Research).

The phase 2b study results, announced Monday, showed the oral version of the treatment reduced the rate at which atrial fibrillation recurred in patients, compared with those receiving a placebo. The study involved almost 1,000 patients over a 90-day period.

Atrial fibrillation is an irregular heart rhythm originating in the atrium, or upper region of the heart.