UPDATE 2-Canada approves AstraZeneca's key new heart drug
* Move has "no bearing" on U.S. decision, due by July 20
* Sales seen $1.3 bln in 2015 - Thomson Reuters Pharma
* Shares give up early gains, off 0.1 percent
(Adds analyst comment, shares, sales forecast)
LONDON, June 1 (Reuters) - Canadian regulators have approved AstraZeneca's (AZN.L) key new heart drug Brilinta, a boost for a product whose future in the all-important U.S. market is still uncertain.
The green light from Health Canada means the medicine is now approved in 33 countries, including in the European Union under the trade name Brilique, the drugmaker said in Wednesday.
Despite the growing tally of approvals, Brilinta's prospects in the United States remain under a cloud because American patients taking it in a pivotal clinical trial appeared to do worse than those on rival Plavix.
Astra stressed the go-ahead from Health Canada was an independent regulatory decision and would have "no bearing" on the ongoing reviews of Brilinta in the United States or other markets.
The new drug is viewed as a potential multibillion-dollar seller that would compete with Sanofi (SASY.PA) and Bristol-Myers Squibb's (BMY.N) Plavix, but only if doctors are convinced it will work better. Plavix, the world's second- biggest selling drug, brings in some $9 billion a year.
There has been speculation that the U.S. Food and Drug Administration (FDA) may ask for more evidence of the drug's effectiveness in U.S. patients before approving it.
The FDA is due to make an approval decision on the drug, considered the company's most important new product, by July 20.
Analysts' forecasts for Brilinta, which is designed to prevent blood clots in patients with serious chest pain or previous heart attacks, have been muted due to uncertainty about U.S. approval.
Current consensus forecasts point to worldwide sales of $1.3 billion in 2015, according to Thomson Reuters Pharma.
Mike Mitchell, an industry analyst at Seymour Pierce, said U.S. approval would probably be given in the end -- despite the delays and requests for additional analysis by the FDA -- but prospects for the drug would be determined by labelling if it is to be positioned as an improvement over Plavix.
"We remain less positive on AstraZeneca's ability to sustain broader pipeline productivity in the longer term," he added, reiterating his "reduce" recommendation on the stock.
Shares in AstraZeneca erased early gains to stand 0.1 percent lower by 0805 GMT, while the European drugs sector .SXDP slipped 0.4 percent
As well as competing with Plavix, which is now off patent in Europe and will lose U.S. patent protection in 2012, Brilinta is also a rival for Eli Lilly's (LLY.N) and Daiichi Sankyo's (4568.T) newer drug Effient. Effient has so far had slow sales, due to concerns about bleeding risks.
Plavix, Brilinta and Effient all work by stopping blood platelets from sticking together and forming clots that can cause heart attacks and strokes. (Reporting by Ben Hirschler; Editing by Erica Billingham and Andrew Callus)