‘Fused-Gold’ vs. ‘Bare’ stainless steel NIRflex stents of the same geometric design in diseased native coronary arteries. Long-term results from the NIR TOP Study

Abstract

We evaluated the long-term clinical and angiographic results of 'fused-gold' (NIRFlex Royal) and 'bare' (NIRFlex) stainless steel stents in patients undergoing percutaneous coronary intervention (PCI). Recent studies have shown high clinical and angiographic restenosis rates following the intracoronary implantation of 'gold-coated' stainless steel stents. The new 'fused-gold' stent, with improved surface characteristics and flexibility, was developed to improve procedural and long-term results, while maintaining enhanced radiopacity. A total of 305 patients (358 lesions) with symptomatic native coronary artery disease (CAD) undergoing native vessel PCI were randomised to receive a 'fused-gold' (n=147) or 'bare' (n=158) stent. Primary endpoint was minimal luminal diameter (MLD) at 6 months angiographic follow-up. Secondary endpoints included technical and procedural success, major adverse cardiac events (MACE), target vessel failure (TVF), angiographic binary restenosis rates, and additional angiographic comparisons. There were no major differences in the baseline angiographic variables or patient characteristics between the two groups, however there was a trend towards a higher risk in the 'fused-gold' stent group. Clinical and angiographic follow-up was 100% and 87% respectively. MLD at 6 months follow-up was smaller in the 'fused-gold' stent group compared to the 'bare' stent group (1.61+/-0.65 vs. 1.81+/-0.60 mm, respectively); Therefore, the null hypothesis of non-inferiority cannot be rejected (p=0.49); equivalency cannot be claimed for the two stent types. The 'fused-gold' stents were also associated with a higher angiographic binary and clinical restenosis rates (33 vs. 18%; p=0.002 & 26.9 vs. 20.3%; p<0.001, respectively). The 'bare' NIRflex stent was associated with excellent long-term clinical and angiographic results. Taking into account the equivalence margin, the null hypothesis of non-equivalence between the 'fused-gold' NIRflex Royal stent and the 'bare' NIRflex stent cannot be rejected (p=0.49), so equivalence cannot be claimed for the two stent types.