There were probably some champagne corks popping over at AstraZeneca this weekend as the company unveiled results showing its new drug for thinning blood performs better than one of the world’s current best sellers.

Zeneca’s ticagrelor (marketed as Brilinta) was better at reducing cardiovascular events such as death and stroke than clopidogrel (Plavix). To put this in context: Plavix places as the world’s second or third best selling drug, with annual sales of $6 billion.

Results from a trial of over 18,000 patients were presented at the European Society of Cardiology meeting and also published in the New England Journal of Medicine. Death from vascular causes, myocardial infarction, or stroke occurred in 9.8% of patients on ticagrelor versus 11.7% of those on clopidogrel.

Zeneca says it will be submitting Brilinta for regulatory approval in the fourth quarter of this year, news that seems to be going down well with the stock market.

“It’s clearly better than we anticipated,” Michael Leacock, a Royal Bank of Scotland analyst, told Bloomberg. “It certainly seems to be a more competitive product than we would have expected.”

It may not all be plain sailing though. Clyde Yancy, president of the American Heart Association, told Reuters there were questions raised over the drug when you drilled down into the data.

“One of the things in the trial that jumped off the page was that in the subgroup analysis … the North American cohort did not show a favourable response,” says Yancy. “Is that a statistical fluke? Or is that a circumstance where because of contemporary treatment patterns in the US whatever benefit you might have expected to get from this drug is masked within the morass of everything else we do?”

That question will become vital once / if approval for the huge drug market in the US is gained. For the moment though it’s looking good for AZ.