The popular blood thinner warfarin is known for its potentially serious interactions with many drugs. And here may be another.

More isn't always better, and that may be especially true when it comes to heart attack medications.

The prescription blood-thinners Pradaxa (dabigatran) and warfarin aim to reduce stroke and other cardiovascular disorders, but like most medications, they do carry some risks.

Stroke risk runs high for individuals with atrial fibrillation. Taking blood thinners, however, may not only lower this risk, it may reduce the likelihood of brain damage if stroke happens anyway.

Blood thinners are commonly given after heart surgery to reduce the risk of blood clots, strokes and other complications. The question is how much they reduce the risk.