Published data show bifurcation lesions treated using bare metal stents (BMS) have typical six to 18 month major adverse cardiovascular events (MACE) rates of 20-38% with one-stent strategies and 33-56% with twostent strategies, and target lesion revascularisation (TLR) rates of 16-39% (see Table 1). Despite the advances in available equipment, bifurcation intervention is still associated with increased rates of complication when compared with non-bifurcated lesion intervention. There is a significantly lower probability of procedural success (86% versus 94%, p<0.001), with an increased rate of in-hospital MACE (7% versus 5%, p=0.1). At one year, treatment of bifurcation lesions is associated with significantly more MACE (32% versus 26%, p<0.05). A rise in cardiac enzymes, from loss or even temporary closure of a side branch (SB), has been shown to have a significant adverse effect on long-term outcome. Therefore, the challenges of bifurcation PCI are preservation of both the main branch (MB) and SB, along with a reduction in restenosis and complication rates. The recent advances in interventional cardiology mean that now, for the majority of bifurcation lesions, the question is not whether to perform angioplasty, but to decide which type of stent to use, and which technique to use to maintain SB patency. In this article we will discuss what is known about bifurcation lesions at present, and what issues still need to be addressed.

The numerous different anatomical and angiographic variations of bifurcation lesions have given rise to a number of different classifications, which can be difficult to remember and compare when assessing results. Medina has recently proposed an easily memorable classification, which makes description of the involved anatomy much simpler. He suggested using three components: MB proximal, MB distal and SB, with each component assigned a binary value (1,0) according to whether it is diseased or not (see Figure 1). The emergence of drug-eluting stents (DES) has led to re-evaluation of the treatment of bifurcation lesions given their proven reduced rates of TLR and restenosis in both simple and complex coronary disease. In bifurcation stenting DES have shown reduced rates of restenosis and MACE (see Table 1), but ostial SB restenosis remains a problem. Colombo et al. randomised patients to a one- or two-stent strategy using sirolimus-eluting stents (SES) and showed MB restenosis rates of 6%. The study confirmed that a twostent strategy had a higher rate of SB restenosis (21% versus 14%); however, the results are of limited value because of a high cross-over rate (51%) from the oneto two-stent strategy due to a sub-optimal result. Pan et al. also randomised patients with bifurcation lesions in a similarly designed study using SES, but had a crossover rate of only 2%. Their results also showed higher rates of restenosis in the MB (2% versus 10%) and SB (5% versus 15%) in the two-stent strategy, but this did not affect clinical outcome. The recently presented Nordic Bifurcation Study, which randomised 413 patients to a complex two-stent or single stent with provisional side branch stenting (PSBS) strategy using SES found no significant difference in the rate of MACE or TLR at six months.

Figure 1: The Medina Classification of Bifurcation Lesions


MB = main branch, SB = side branch, 0 = no significant disease, 1 = significant
disease present.

In true bifurcation lesions, where significant plaque is present in both MB and SB, or lesions with thrombus, both branches should always be wired. Two guidewires offer several advantages, most notably maintaining a degree of antegrade flow and patency in the SB particularly if there is SB compromise after MB stenting. There is easier identification of the SB ostium, and also an advantageous change in the angle between the MB and SB, facilitating re-access. There are few associated risks with jailing the wire. Wire fracture is very rare and commonest with hydrophilic wires; proximal vessel trauma can occur when withdrawing the wire, but this can minimised by avoiding large-diameter highpressure deployment of the MB stent on a jailed wire.

Table 1: Summary of Trials Evaluating Percutaneous Coronary Intervention with Stent Implantation for Bifurcation Lesions

Patients with bifurcation lesions involving a small SB are best treated with a single stent to the MB with PSBS if required (see Figure 2). Even in the era of DES, restenosis is inversely related to stent diameter, and this is of particular importance in bifurcation lesions where the SB vessel diameter is often <2.5 mm; it would seem intuitive therefore to avoid stenting such small vessels if possible. However, stenting the main vessel may compromise flow in an SB through plaque shift, thrombus formation, spasm or pinching by stent struts, resulting in the need for SB intervention. The rate of SB occlusion varies from 5% to 26%, and is associated with an adverse outcome. In the NIR Vascular Advanced North American (NIRVANA) study of the NIR stent, SB occlusion was associated with a significantly higher rate of Q-wave (7%) and non-Qwave (20%) myocardial infarction (MI) compared with patients without SB occlusion (p<0.05).