'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.

Objectives: 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).

Background: 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.

Methods: 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.

Results: 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).

Conclusion: 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.