A substudy of the BIOFLOW-II trial, presented as a late-breaking trial at EuroPCR (21–24 May, Paris, France), showed that Biotronik’s drug-eluting stent with a biodegradable polymer (Orsiro) was non-inferior to a drug-eluting stent with a durable polymer (Xience Prime, Abbott Vascular) in terms of in-stent late lumen loss at nine months.
The BIOFLOW-II substudy used intravascular ultrasound (IVUS) and optical coherence tomography (OCT) to quantitatively assess neointimal hyperplasia and stent apposition at nine months in patients who (after randomisation) had undergone percutaneous coronary intervention (PCI) with the Orsiro stent or PCI with the Xience Prime stent. Images from baseline and the nine-month follow-up were analysed by independent and blinded core laboratories.
According to the results of the substudy, there was no difference in the angiographic endpoint of in-stent late lumen loss between the two stents at nine months (0.10+0.32mm with the Orsiro stent vs. 0.11+0.29mm with the Xience Prime stent, (on inferiority p=<0.0001). Rates of target lesion failure were also similar at this time point (4.8% vs. 5.3%, p=0.47).
The intravascular ultrasound showed less neointimal hyperplasia over nine months with the Orsiro stent (0.16) compared with the Xience stent (0.43) with 100% stent apposition, but this difference was not significant (p=0.043). Additionally, at nine months, OCT showed less neointimal area with the biodegradable polymer stent than with the durable polymer stent but again this difference was not significant (0.74+0.38mm2 vs. 1.00+0.44mm2, respectively p=0.024). The proportion of well-apposed struts was similar with the two stents and the proportion of covered struts was slightly higher with the Orsiro stent (98.3% vs. 97.5%, p=0.042).
Study presenter Stephan Windecker, professor and chief of Cardiology, Swiss Cardiovascular Center and Clinical Trials Unit Bern, Bern University Hospital, Switzerland, said: “We need to be careful in interpreting the results of a trial set up for an angiographic endpoint, but we can speculate that neointimal hyperplasia may be somewhat less with the Orsiro stent platform. And an important additional finding is that this potentially improved efficacy is not compromised by a lower proportion of uncovered struts. In addition, clinical event rates were low and comparable with both stents.” He concluded: “These results will need to be extended to larger randomised trials including more complex patients and powered for clinical endpoints.”