Flow Patterns at Stented Coronary Bifurcations

Coronary bifurcations remain one of the most challenging lesion subsets, even in the era of drug-eluting stents. Single stent implantation in the main vessel with provisional stenting to the side branch vessel has been found superior to double stenting and is considered the default approach in most coronary bifurcation lesions. However, in true bifurcation lesions, this provisional approach may leave significant residual stenosis of the side branch vessel after percutaneous coronary intervention (PCI), and in a recent randomized study, double stenting reduced target vessel revascularization without affecting major adverse coronary events compared with provisional side branch stenting. Thus, operators may opt for double stenting in the presence of a large side branch. Still, the ideal stenting technique is not established in this respect. Several methods for deployment of 2 stents at bifurcations have been proposed, but their impact on clinical outcomes such as restenosis and, especially, stent thrombosis and iatrogenic myocardial infarction, still a reason for concern with drug-eluting stents, is not known. Stenting at the site of bifurcation inevitably affects coronary flow patterns that have been associated with restenosis rates and stent thrombosis. Indeed, altered geometry and associated blood flow disturbances induced by stenting can influence restenosis. Disturbed flow may also facilitate the accumulation of platelets and other blood thrombogenic factors close to the wall. Flow patterns in bifurcations are inherently complex, including vortex formation and creation of zones of low and oscillating wall shear stress that coincide with early intimal thickening. Luminal dimensions and flow patterns are theoretically restored after PCI, but bifurcation stenting is associated with geometric deformation of both the main and side branch and, most importantly, introduction of stents struts into the coronary artery with frequent protrusion into the lumen, which alter the original flow environment. Stent struts alter flow conditions both close to the vessel wall and inside the vessel lumen. Thus, each stenting technique has a distinct and possibly significant effect on the flow patterns at the bifurcation region. The disturbances that the various bifurcation Flow Patterns at Stented Coronary Bifurcations Computational Fluid Dynamics Analysis