Clot Formation in Stents Higher than Estimated

The incidence of clot formation inside stents, which can be potentially life threatening, is almost three times higher than previously reported, according to an analysis conducted by cardiologists at Duke University Medical Center (DUMC, Durham, NC, USA). Stent thrombosis is infrequent but catastrophic, usually occurring within the first two weeks of placement and usually involving a large infarction or death.

The cardiologists combined data from two clinical trials involving anti-platelet therapies designed expressly for patients with acute coronary syndromes, patients with more severe disease who were typically excluded from earlier trials. Among a group of patients with acute coronary syndromes who underwent angioplasty followed by stent placement, the overall rate of stent thrombosis was 3.5%. This is in contrast to the rate of about 1% found in earlier clinical trials of a highly selective group of patients, whom the researchers say were not representative of the patient mix they commonly see in their practice. In addition, the data from the two trials showed that those who are at greatest risk for stent thrombosis are patients with diabetes, patients who are elderly, patients who are female, or patients who have had a prior heart attack or angioplasty procedure.

"Will these findings change practice? Not immediately,” said Dr. Kristin Newby, a DUMC cardiologist and senior author of the study, "but it should stimulate further studies on new treatments—both before and after stent placement—to lower these rates.”




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