Pfizer (NYSE: PFE) and Bristol-Myers Squibb (NYSE: BMY) are celebrating approval of their blood-thinning drug Eliquis in Europe for atrial fibrillation. In this video, Motley Fool health care analyst David Williamson talks about why the approval was largely expected and therefore didn't drive share prices much, why the drug's U.S. rejection back in June was more of a minor setback than a major blow, and just how big of a drug this is going to be for both companies.

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