Improving Life with Stents

Extended post-stent treatment reduces risk of coronary thrombosis

Patients who took two anti-clotting medications beyond the standard 12 months after stent placement were significantly less likely to develop blood clots within their stents or to have a heart attack than those whose treatment followed the standard 12-month protocol. This was the result found in a research study presented at the American Heart Association’s Scientific Sessions 2014.

"We know that dual antiplatelet therapy is essential for all patients receiving coronary stents to prevent blood clots within the stents. This study showed that the preventive benefit continues when the medications can be taken for more than one year," said the study’s principal investigator and lead author, Laura Mauri, M.D., M.Sc. She is an interventional cardiologist at Brigham and Women’s Hospital, associate professor of medicine at Harvard Medical School and chief scientific adviser at the Harvard Clinical Research Institute in Boston, Massachusetts.

Investigators found that study participants who took aspirin plus another type of anti-clotting medication (clopidogrel or prasugrel) — for 30 rather than 12 months after stent placement:

  • were .5 times less likely to develop in-stent thrombosis than patients who received dual therapy for 12 months, followed by aspirin plus placebo for 18 months (placebo group)
  • had about half the risk of having new heart attacks compared to the placebo group

A stent is a thin, wire-mesh tube inserted into a blocked coronary artery to hold it open and restore blood flow. Although infrequent, one of the most serious risks after stent placement is the formation of a blood clot, either within the stent or in another blood vessel.

To prevent blood clots, standard post-stent treatment involves dual treatment with aspirin and another anti-clotting medication. European guidelines call for six to 12 months of this treatment; U.S. guidelines recommend it for 12 months after the procedure. What was unclear until now was whether extending this combined treatment for longer than 12 months could reduce the risk of in-stent clots or whether it would prevent heart attack or stroke. The safety of longerterm treatment was also assessed in this trial.

The study has limitations. One is that it only included patients who were known to have tolerated anti-clotting medication for a year. Another is that follow-up ended after 33 months, even though the study data suggest that a longer course of treatment may provide added benefit.

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