INTERVENTION FOR BIFURCATION LESIONS
Bifurcation lesions have been reported to constitute 15% to 20% of all percutaneous coronary interventions (PCI).1 Since they are associated with an increased risk of procedure-related complication, especially side branch (SB) occlusion after stent implantation, treating these distinct lesion subsets has been a significant challenge for interventional cardiologists. Rapid advancements in novel techniques, devices, and adjunctive pharmacotherapies have considerably reduced the risk of acute complications, restenosis, and stent thrombosis (ST), and ultimately have led to the extension of PCI’s clinical application for various complex bifurcation lesions. Moreover, interventional cardiologists have learned lessons from extensive clinical experiences in that many important anatomic features, including relative plaque distribution to the bifurcation, degree of SB angulation, and severity or length of SB lesion, should be taken into account for technical success and favorable clinical outcome.2 Considering that currently there are no clear guidelines to address the use of particular interventional techniques with regard to the specific anatomy of a given bifurcation lesion, every effort should be made to obtain understanding of the technical, clinical, and fundamental aspects of the management of bifurcation disease.
Definition and Classification of Bifurcation Lesions
According to the consensus of the European Bifurcation Club, bifurcation coronary lesion can be defined as “a coronary artery narrowing occurring at, or adjacent to, a significant division of a major epicardial coronary artery.” A “significant SB” is a branch that the operator does not want to lose in a global context of a particular patient (eg, symptoms, comorbidity, diameter and length of SB, size of the myocardial mass supplied by the SB, location of ischemia, viability of the supplied myocardium, collateralizing vessel, left ventricular function, results of functional tests).3
Although several classification systems of bifurcation lesions have been proposed to facilitate PCI, planning the treatment approach according to the angulation of the bifurcation and the degree of plaque burden seems to be most practical (Fig. 38-1). The Y-shaped lesion is defined when the SB and the main vessel (MV) angulation is less than 70%, while that of the T-shaped lesion is greater than 70%. In general, the risk of atheromatous plaque shifting (snow-plow effect) and deterioration of SB flow during stent implantation is higher in Y-shaped lesions. Furthermore, it is technically difficult to achieve the whole coverage of the SB ostium using popular T-stenting in these lesions. Although the risk of SB occlusion is relatively low in T-shaped lesions, wire access can be problematic when large plaque burden is present at a significant SB ostium. The location of stenosis in each of the 3 segments that constitute the bifurcation is also crucial for the treatment strategy, and 7 lesion types, with each type assumed to be associated with a specific treatment technique, have been described in the Medina classification, the simplest and most widely used classification system4 (Fig. 38-2).