Stent fracture after stent implantation linked to thrombosis

Oct 2 2012

By Piriya Mahendra, medwireNews Reporter

Stent fracture (SF) after everolimus-eluting stent (EES) implantation occurs in 2.9% of lesions and is associated with a significantly increased rate of major adverse cardiac events (MACE), say researchers.

This significantly higher rate of MACE is driven by increased target lesion revascularization and stent thrombosis, report Shoichi Kuramitsu (Kokura Memorial Hospital, Kitakyushu, Japan) and colleagues.

In a cohort of 1035 patients with 1339 lesions, Kuramitsu et al found that SF, defined as complete or partial separation of the EES as assessed by plain fluoroscopy or intravascular ultrasound during follow-up, was observed in 39 (2.9%) lesions and 39 (3.8%) patients.

Ostial stent location; and lesions with hinge motion, tortuosity, or calcification were independent significant predictors for SF, at respective odds ratios of 12.38, 14.57, 5.45, and 4.27.

Myocardial infarction (MI) and target lesion revascularization rates were significantly higher in the SF than non-SF group, at 5.1% versus 0.4%, and 25.6% versus 2.0%, respectively.

Similarly, stent thrombosis was significantly more common in the SF than the non-SF group, at 5.1% versus 0.4%.

As reported in Circulation: Cardiovascular Interventions, MACE at 9 months were also higher in the SF group, at 25.6% versus 2.3% in the non-SF group.

The authors point out that the EES features a thin-strut, flexible, cobalt-chromium platform, which is expected to prevent SF.

"The mechanisms of in-stent restenosis are probably related to the lower drug delivery at the fracture site and higher mechanical irritation by the fractured struts, causing smooth muscle cell proliferation and impaired re-endothelialization," they suggest.

Kuramitsu and team say that the most important finding of their study is not the incidence of SF, but its impact on clinical outcomes including target lesion revascularization and stent thrombosis. "Therefore, further improvements in stent design and materials are needed to prevent the occurrence of stent fracture," they suggest.

"In particular, stent longitudinal integrity may be a key parameter in the development of newer-generation drug-eluting stents," Kuramitsu et al propose.

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