A pre-specified substudy of BIOSCIENCE, published in EuroIntervention, has found that a sirolimus-eluting stent with a biodegradable polymer (Orsiro, Biotronik) is associated with a significantly lower rate of target lesion failure than is an everolimus-eluting stent with a durable polymer (Xience, Abbott Vascular) in patients with ST-segment elevation myocardial infarction (STEMI).
The BIOSCIENCE study, which was presented at the 2014 European Society of Cardiology (ESC) meeting and simultaneously published in The Lancet, found that Orsiro was non-inferior to Xience for the management of patients with at least one coronary lesion ( >50% diameter stenosis or restenosis) in a native coronary artery or bypass graft. However, it also suggested that the biodegradable polymer stent was associated with a significantly lower rate of target vessel failure than was the durable polymer stent in a subgroup of patients with STEMI. Randomisation of the BOIOSCIENCE trial was stratified according to presence or absence of STEMI. Therefore, the aim of this present substudy was to further explore the STEMI findings.
Of 2,119 patients in the BIOSCIENCE study, 407 presented with STEMI. Of these, 211 were randomised to undergo percutaneous coronary intervention (PCI) with Orsiro and 196 were randomised to undergo PCI with Xience. Writing in EuroIntervention, Thomas Pilgrim (Department of Cardiology, Swiss Cardiovascular Center, Bern University Hospital, Bern, Switzerland) and others comment that the one-year rate of study’s primary endpoint—target lesion failure—was 3.4% among patients who received Orsiro and 8.8% among patients who received Xience (p=0.024 for the comparision). They note that this difference was driven “by non-significant, numerical differences in cardiac death and target vessel myocardial infarction” between the two patient groups. For example, the rate of cardiac death was 1.5% for the Orsiro patients vs. 2.1% for the Xience patients (p=0.082). However, the authors state that there were no differences between groups in rate of repeat revascularisation.
According to Pilgrim et al, a previous study found that a biodegradable polymer biolimus-eluting stent (Biolimus A9, Biosensors) was associated with a lower rate of major adverse cardiac events at nine months than was a first-generation permanent polymer drug-eluting stent in a subgroup of STEMI patients—“a finding which was maintained during long-term follow-up throughout five years”. They add: “The present study may extend the potential benefit of biodegradable polymer-based drug-eluting stents among STEMI patients observed with early-generation thick-strut stainless steel drug-eluting stents to newer-generation thin-strut cobalt chromium drug-eluting stents”.
The authors write that biodegradable polymers may provide “favourable results on arterial healing after drug-eluting stent implantation” and the effect of an enhanced healing response “may be augmented in the inflammatory milieu of STEMI”. However, they state, that Orsiro’s biodegradable polymer may not “fully account” for the present study findings because “while the sirolimus is released over a period of 12 to 14 weeks, the PLLA polymer matrix degrades over a period of 12 to 14 months.” “In addition to the biodegradable polymer, the reduced strut thickness of the novel stent platform as well as the passive stent coating may play a role when implanted into lesions of patients with STEMI, by reducing acute arterial injury and the risk for peripheral embolisation as well as affording a more rapid re-endothelisation,” Pilgrim et al write.
They conclude: “Biodegradable-polymer sirolimus-eluting stents may be associated with improved clinical outcomes compared with durable-polymer everolimus-eluting stents among STEMI patients undergoing primary PCI. The findings are hypothesis-generating and have to be reproduced in a dedicated, randomised trial in order to substantiate the potential benefit of biodegradable polymer sirolimus-eluting stents in patients with STEMI.”
Pilgrim told Cardiovascular News that the planned BIOSTEMI randomised controlled trial (NCT02579031) has been designed to compare Orsiro with Xience in patients with STEMI and enrolment for the trial will start early this year.