One of the studies shows that prasugrel reduced the risk of recurrent heart attacks in cardiac patients by 23 percent or more compared with Plavix, the reigning blood thinner now on the market.
The other study, which used prasugrel as a maintenance treatment for heart patients, showed platelet aggregation was reduced by nearly 13 percent.
The studies are based on further analysis of data from a massive clinical trial that compared prasugrel against Plavix in 13,600 patients.
Indianapolis-based Lilly first released results of that trial in November, saying that prasugrel reduced heart attacks, strokes and deaths compared with Plavix. But prasugrel also caused more severe bleeding, some of it fatal, in some patients.
Some analysts worry that the bleeding risk will delay prasugrel's approval by the FDA or limit its sales potential.