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12-01-2017 | Interventional cardiology | News | Article

Bioresorbable scaffolds linked to late thrombosis risk

medwireNews: Bioresorbable vascular scaffolds (BVS) are associated with a higher risk for very late thrombosis than everolimus-eluting metallic drug-eluting stents (EES), results of a meta-analysis suggest.

“When considering BVS implantation, patients should be informed appropriately about the reported thrombotic risk of BVS until complete scaffold resorption,” write study author Takeshi Kimura, from Kyoto University, Japan, and colleagues.

In an analysis of data from 24 studies reporting 2-year outcomes of 2567 patients who received BVS and 19,806 who received EES, the researchers found that the risk for very late stent/scaffold thrombosis (VLST) between 1 and 2 years after stent implantation was nonsignificantly higher in the BVS group than the EES group, with pooled incidence rates of 0.24% and 0.003%, respectively (odds ratio [OR]=2.03).

However, BVS was associated with a significantly elevated risk for stent thrombosis compared with EES over the full 2 years of follow-up (1.43 vs 0.56%; OR=2.08).

These findings suggest that the thrombotic risk of BVS should in the future be balanced with the “unknown benefits of BVS after complete scaffold resorption,” say the researchers in JACC: Cardiovascular Interventions.

Despite the elevated risk for VLST associated with BVS, the authors found similar rates of target lesion failure in the two groups, both between 1 and 2 years and throughout 2 years of follow-up (OR=1.40 and 1.08, respectively), suggesting that the risk for this outcome “was neutral between BVS and EES”.

In an editorial comment, Fernando Alfonso and Javier Cuesta, both from Hospital Universitario de La Princesa in Madrid, Spain, note that Kimura and colleagues’ study assessed the incidence of VLST “in a very large number of patients,” but caution that “the main evidence was generated by ‘single-arm’ registries that, by definition, are prone to major selection bias.”

Of the 24 studies included in the meta-analysis, 17 were single-arm registries. The seven head-to-head comparisons included three randomized controlled trials and four observational studies. A total of 10 studies had an all-comer design, whereas three studies involved patients with coronary artery disease, and three included those with myocardial ischemia.

The commentators add that the 2-year follow-up “offers only a preliminary glimpse into the problem of VLST after BVS implantation,” and “the final sample size was probably still insufficiently powered for very rare events.”

And the study authors agree that “2 years may be too early to evaluate fully late adverse events related to the resorption process of BVS,” concluding that “large, randomized trials” should be conducted to evaluate “the role of BVS relative to metallic [drug-eluting stents] in percutaneous coronary intervention.”

By Claire Barnard

medwireNews is an independent medical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2017

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