An oral anticoagulant drug given to some heart disease patients may actually enhance blood clot formation, according to a new study. The surprising discovery may help explain why some individuals taking the drugs, called oral thrombin inhibitors or OTIs, have a slightly higher risk of heart attack. OTIs are often prescribed to prevent venous blood clots and reduce the risk of stroke resulting from atrial fibrillation. They are sometimes preferred over another class of anticoagulant drugs called vitamin K antagonists because they work more swiftly and require less frequent monitoring. Here, Petzold and colleagues compared the impacts of OTIs and vitamin K antagonists on mouse models of arterial blood clotting and in human arterial plaque, and found that OTIs encouraged blood clotting under flowing conditions. By contrast, the vitamin K antagonists did not cause the same increase in clotting. The increased propensity for clotting with OTI treatment might explain why those taking these drugs have a higher risk of heart attack, and should be considered when designing individual therapies, the researchers say.
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Science Translational Medicine