A new angle on classifying coronary artery bifurcation stenoses. The DINO system.

ver the past 3 decades continued technological innovation has improved the safety and efficacy of percu taneous coronary intervention (PCI). Advances in guidewire, balloon, bare metal stent, and drug-eluting stent technologies have resulted in marked improvement in short term procedural success and in clinical cardiovascular outcomes for PCI patients. Despite the excellent results of PCI in simple lesions, significant challenges remain in the treatment of bifurcation stenoses, which currently account for approximately 20% of coronary interventions.1 Compared to singlevessel procedures, procedural success and clinical outcomes are significantly worse following bifurcation PCI, 2 and interventional cardiologists are challenged by suboptimal treatment strategies for bifurcation disease. Article p 299 Several different PCI techniques have been developed to treat coronary artery bifurcation stenoses. Culote, crush, T-stent, and kissing-stent, are the predominant bifurcation PCI techniques; 3 however, randomized studies have consistently demonstrated that a single-stent provisional strategy of stenting just the main branch (MB) has the best clinical outcomes compared to 2-stent techniques.4–8 Indeed, in studies comparing provisional MB stenting to a planned 2-stent strategy of stenting both branches, the 2-stent approach showed no major benefit in follow up angiographic stenosis or major adverse cardiovascular events, and was associated with significant periprocedural increases in myocardial necrosis bio markers, contrast utilization, and fluoroscopy time. 4 Despite best efforts to utilize a provisional strategy, modern investigations of drug-eluting stent bifurcation stenting demonstrate that bifurcations treated with a provisional strategy will frequently require balloon dilation and bail-out implantation of a second stent in the side branch (SB). 3 Importantly, the rates of bail-out SB stenting following a single-stent MB provisional strategy vary based on trial definitions for when a SB should be treated. In the CACTUS study, SB stenting was recommended following provisional single-stent MB PCI when the SB stenosis was greater than 50%.8 In CACTUS, 31% of the provisional single-stent-treated bifurcations required SB stenting. The Nordic bifurcation study, recommended balloon dilation only if the SB had less than Thrombolysis in Myocardial Infarction (TIMI)-3 flow, and recommended SB stenting only if the SB had TIMI-0 flow following balloon dilation. 4 Because of the higher tolerance for SB stenosis in the Nordic study, 32% of provisional single-stent-treated bifurcations were treated with SB balloon dilation, and only 4.3% were treated with bail-out SB stenting. In order to optimize treatment strategies for bifurcation stenosis, and to facilitate research on the efficacy of various bifurcation PCI techniques, several bifurcation classification strategies have been developed.9–12 These classification strate gies categorize bifurcation stenoses based on anatomic parameters that include stenotic involvement of MB and/or SB, size of the SB, and angulation of the SB. Experientially, these anatomic features strongly influence acute PCI success, mea sured by angiographic patency, residual stenosis of the MB or SB, and periprocedural myocardial infarction. Less is known about the impact of bifurcation stenosis anatomy or angle on clinical outcomes; however, it is certainly possible that the