Introduction of coronary stent， together with advances in periprocedural and postprocedural adjunctive pharmacotherapies， have improved outcomes of percutaneous coronary interventions (PCI) for complex coronary lesions， such as bifurcation lesions. In particular， compared with bare-metal stent， drug-eluting stent (DES) reduced the incidence of angiographic restenosis and subsequently the need of repeat revascularization. However， in spite of the great benefit of DES， PCI for bifurcation coronary lesions remains an ongoing challenge. Besides technical complexity of stenting， bifurcation location has been reported an important predictor for late restenosis or stent thrombosis compared with non-bifurcation location. For instance， two-stent strategy， in which stents are implanted in both the main branch (MB) and the side branch (SB) for bifurcations with side branch stenosis， is likely to result in high incidence of restenosis and repeat revascularization compared with single-stent strategy， implanting stent in the MB alone for bifurcations without side branch stenosis. Therefore， according to the initial plan of bifurcation treatment， a ‘provisional stenting’， as opposed to a ‘routine SB stenting’ with two-stent treatment， is often used as based on single-sent treatment for the MB alone. With the provisional approach， stenting for the SB is reserved for suboptimal result or significant dissection in the SB after MB stenting. However， due to a lack of randomized study comparing single- vs. two-stent strategies， a selection of bifurcation stenting technique is generally made by the individual lesion morphology. 

    In general， the most important initial consideration is whether the SB is large enough to have sufficient ischemic territory justifying a stenting irrespective of bifurcation pattern. Although a consensus about the significant SB size has not been reached， the SB diameter > 2.0 mm is often worth being protected during the procedure. Therefore， if SB has the diameter of > 2.0 mm and significant stenosis of > 50%， the SB stenting is considered during PCI for bifurcation lesion. With regard to plaque distribution， the MEDINA classification is now most widely applied. In that classification， lesions with plaque location in the MB alone， such as MEDINA class 1.1.0.， 1.0.0.， or 0.1.0. are usually treated by provisional stenting technique. By contrast， lesions with plaque involving the MB and SB， which are ‘true’ bifurcation lesions， are more likely to result in SB deterioration following the MB stenting， with the provisional stenting approach. However， a patient with bifurcation disease involving the SB ostium， such as MEDINA class 1.1.1.， 1.0.1.， 0.1.1. are often treated with elective double stenting techniques comprising ‘T-stenting’， ‘Culotte stenting’， ‘Crush technique’， ‘V-stenting’， or ‘Kissing stenting’. When the coronary bifurcations are classified according to the angle between the MB and SB， a Y-angulation less than 70 degrees allows easier wire access to the SB than a wider angle. However， precise stent placement at the ostial SB in Y-angulation is difficult due to a narrow angle between the MB and SB. In contrast， T-angulation， in which the angle between the MB and SB is greater than 70 degrees， provides more difficult SB access but， technically easier complete SB coverage with a stent. 

    Provisional treatment of the SB with either balloon angioplasty or stenting is reserved for use in cases with suboptimal results or complications. Despite the controversy， we do not routinely perform balloon angioplasty or final kissing balloon inflation after MB stenting. Therefore， to avoid unnecessary barotraumas at the ostial SB， kissing balloon inflation is selectively performed in lesions having true narrowing after MB stenting. Regarding the type of guidewire， a standard wire is mostly successful in recrossing to the SB. However， when a standard wire fails to advance due to wide angle or severe stenosis， hydrophilic coated wire or intermediate type of stiffer wire is useful to facilitate recross. In case of no success， small sized over-the-wire balloon， fixed-wire balloon， or double lumen catheter can improve support of wire in crossing the stent strut. As a bail-out procedure in provisional stenting， ‘provisional T-stenting’ and ‘reverse Crush technique’ are used. From several clinical researches， the current consensus is that the two-stent strategy does not have long-term advantages compared with single-stent strategy. 

    For both proper evaluation of bifurcation lesions and optimal stenting， physiologic flow assessment with FFR and cross-sectional morphologic assessment with intravascular ultrasound is novel methods to reliably assess the functional flow and anatomical distribution of plaques in the bifurcations. In addition， a careful administration of antiplatelet agents is a very important treatment to prevent the occurrence of stent thrombosis. In fact， premature discontinuation of clopidogrel was strongly associated with stent thrombosis in several studies.  Therefore， as generally recommended， dual antiplatelet therapy including aspirin and clopidogrel (or ticlopidine) should be maintained to 1 year. If the patients seem to be at high risk， a high loading dose (600 mg) or lifelong administration of clopidogrel needs to be considered. 

    In conclusion， a careful selection of stenting strategy and optimal stenting procedure with DES may further improve the outcomes of bifurcation PCI. Moreover， new dedicated stents should be available in the near future. These new devices will undoubtedly simplify the technical approach.