Factors predicting thrombus formation after stenting identified
MedWire News: Japanese researchers have identified the factors that most significantly predict risk for long-term thrombus formation after stent implantation.
Although drug-eluting stents (DES) can significantly reduce the risk for restenosis, they have also been associated with more frequent formation of thrombosis compared with bare metal stents.
To investigate further, Yasunori Ueda (Osaka Police Hospital) and associates used angioscopy to look for indications of in-stent thrombosis in 118 consecutive patients implanted with paclitaxel- or sirolimus-eluting stents for approximately 1 year.
As published in the journal Thrombosis Research, the authors found that lesions that were yellow in color, and therefore lipid rich, were 5.5 times more likely to be associated with in-stent thrombosis than were red or white lesions.
Neo-intimal stent coverage also significantly predicted the presence of thrombosis. Specifically, in patients with stents that were fully visible or visible on the surface but covered by a thin layer, thrombus risk was increased 5.5 times relative to patients with stents that were not visible under the neo-intima, or visible through the neo-intima but were below the level of neo-intimal surface.
The authors comment that this increased risk is likely due to the fact that poor neo-intima coverage results in thrombogenic materials being continuously exposed to the blood.
Finally, paclitaxel-eluting stents were associated with a 7.6-fold higher rate of in-stent thrombosis than were sirolimus-eluting stents.
Commenting on their results, the authors say that caution in interpretation is needed because the thrombi they evaluated after identification with angioscopy are not necessarily the thrombi that eventually cause clinical adverse events.
"This might be demonstrated by our prospective follow-up study DESNOTE trial, in which we routinely perform angioscopic 1-year follow-up for all DES-implanted patients and follow them for the clinical event of very late stent thrombosis to clarify what factors among angioscopic findings at 1-year are predictive of the event," they write.
In addition, the authors highlight the need for further study of in-stent thrombus formation and characteristics in patients with second-generation DES, as well as the first-generation stents examined in the current study.
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By Philip Ford