Health care stocks started the week mixed amid a smattering of earnings, trial data and other news.

AstraZeneca ( AZN) said Monday that its heart drug Brilinta worked better than Bristol-Myers Squibb's ( BMY) and Sanofi-Aventis' ( SNY) blockbuster blood-thinner Plavix in a study.

According to U.K.-based AstraZeneca, the drug was more effective at preventing serious cardiac events such as myocardial infarction, stroke and cardiovascular death than clopidogrel, or Plavix, in a stage III trial. The company said it plans to submit the drug to regulatory authorities in the fourth quarter of 2009.

AstraZeneca shares were up 5.6% to $38.15. Bristol shares were down 0.5% to $20.29, and Sanofi-Aventis slipped 1% to $29.86.

Meanwhile, The Wall Street Journal is reporting that the deaths of two patients in Delaware who took Baxter's ( BAX) blood-thinner heparin have spurred concern of a contamination akin to one in 2008. A third patient also had medical problems, according to The Journal.

A representative for Baxter told the paper that the drug involved in the deaths contained bulk material supplied by Pfizer ( PFE). Pfizer couldn't be reached for comment by The Journal. In the approximately 80 deaths that were linked to tainted heparin last year, the bulk material came from China, Baxter said.

"We are not pointing fingers at Baxter," Wallace Hudson of Beebe Medical Center, which confirmed the deaths, told The Journal. "We don't know what's going on, but heparin is the only commonality that we were able to see ourselves." The heparin is being tested, but so far no problems have been found, the report said.

Baxter shares were up 0.2% to $50.36. Pfizer shares were down 1.7% to $14.15.

Elsewhere in the sector:

Novo Nordisk ( NVO) has reportedly agreed to pay a $9 million fine in an Iraqi kickback scheme in which the company admitted it paid Saddam Hussein's government more than $1 million for contracts. Shares of the company closed down 0.2% to $48.86.

King Pharmaceuticals ( KG) shares rose 4.4% to $9.09 after its first-quarter results surpassed analysts' projections.

Johnson & Johnson ( JNJ) was down 1.6% to $54.11.

Eli Lilly ( LLY) fell 1.7% to $35.35.