Coronary bifurcations: still the touchstone of drug-eluting stents and bioresorbable vascular scaffolds?

Coronary bifurcation lesions that involve significant side branches represent a particularly challenging subset of target lesions for percutaneous coronary interventions. Besides the necessity for the interventional cardiologist to often perform technically demanding interventions with more procedural steps, clinical outcome following percutaneous coronary intervention has usually been somewhat inferior. For more than two decades, coronary bifurcation lesions represent a serious touchstone for both interventional cardiologists and various types of stents and vascular scaffolds. The use of first-generation drug-eluting stents (DES) has reduced the incidence of restenosis following percutaneous coronary intervention of bifurcation lesions as compared to bare metal stents. In a first, small-sized study by Colombo et al, a numerically lower rate of angiographic restenosis was seen in bifurcated lesions treated with a single DES in the main vessel. In the meantime, pooled data of the Nordic Bifurcation and the British Bifurcation Coronary studies, both using first-generation Cypher DES (Cordis; Waaren, New Jersey, United States), have clearly demonstrated at 9-month follow-up that clinical outcome is superior following a simple approach with provisional Tstenting of the side branch vs a complex approach. In addition, the Nordic Bifurcation study has shown that long-term outcome (up to 5 years) following bifurcation stenting with a simple approach was at least as good as the outcome of a complex approach. The aforementioned studies were performed with the first-generation Cypher stent that had a closed-cell design. The results of several in vitro studies and bench tests suggest that DES with different stent materials and designs may act differently in the setting of bifurcation stenting. Moreover, the coatings of various DES types show significant dissimilarities in mechanical properties, which may be relevant during kissing balloon inflations that apply a significant shear stress to the coatings of DES. Consequently, the assessment of clinical outcome