Introduction on Personal Experience with Bioresorbable Scaffolds in Bifurcation
Since Andreas Gruentzig presented his pioneering work in 1977, 'three revolutions in percutaneous coronary interventions (PCI) have characterised the field of interventional cardiology. Plain old balloon angioplasty (POBA) was refined by the introduction of bare metal stenting (BMS) (second revolution) to address the issue of acute vessel recoil and unacceptably high rates of restenosis. Drug-eluting stents (DES) (third revolution) further decimated the burden of target vessel revascularisation into the low single-digit figures. The bioresorbable scaffold technology such as the Absorb™ Bioresorbable Vascular Scaffold (Absorb BVS, Abbott Vascular, Santa Clara, California, US) may represent the fourth revolution in PCI as the implanted scaffolds provide transient vessel support and drug delivery, which is followed by substantial polymer degradation at two-years post-implantation, with a complete disappearance of the BVS strut footprint in the vessel wall within a four year period.1 This concept precludes permanent caging of the coronary artery, may avoid persistent or acquired device malapposition and delayed hypersensitivity reactions to contemporary stent platforms and/ or drug polymers, which may solve the smouldering yet clinically devastating problem of late stent thrombosis.2
Flow-limiting atherosclerotic disease at bifurcations of coronary arteries, remain a challenging substrate for PCI. POBA in bifurcations was characterised by a relatively low success rate and a high incidence of restenosis.3,4 BMS improved acute procedural success yet was still associated with reserved long-term clinical outcomes irrespective of the applied stenting technique.5-11 Even in the DES era overall long-term clinical results in bifurcations seem suboptimal. The pathophysiology may appear paradoxical with both increased atherogenesis and restenosis at the ostium of the side branch but also delayed vascular healing and incomplete neointimal coverage making the side branch more vulnerable to (very) late stent thrombosis.12-15
Bioresorbable vascular scaffolds (BVS) may be interesting in bifurcation lesions as it precludes permanent side branch jailing after complete scaffold bioresorption. Okamura et al. recently described serially the appearance of a coronary artery side branch ostium after BVS implantation in the main vessel. At six-months the BVS struts were overhanging the side branch ostium but at two-year follow-up the struts proximal to the side branch were fully incorporated into the vessel wall and the struts located distally were replaced by asmooth membranous neocarina.