Coronary bifurcation lesions with involvement of a significant side branch are a frequent occurrence. The Rapamycin-Eluting Stent Evaluated At Rotterdam Cardiology Hospital (RESEARCH) study showed that systematic use of drug-eluting stents (DES) resulted in an increase from 8% to 16% in the number of bifurcation lesions being stented over a one-year period. This high incidence of coronary bifurcation can be explained by the propensity for atherosclerosis to develop at branch points because of turbulence and high shear stress.

The incidence of bifurcation disease is also frequently under-appreciated for many reasons – bifurcation lesions may be hard to visualise when the ostium is hidden under the main vessel or overlapping branches, often because of an angulated take-off or when the operator focuses on the main branch only, for example during primary myocardial infarction (MI) intervention or when the side branch is considered too small. Moreover, many cases that were not planned as bifurcation angioplasty, because only one branch was initially involved, ultimately turn into a true bifurcation case during the intervention. These ‘unexpected’ bifurcation lesions (also known as ‘false bifurcations’), are located adjacent to a branch point and, in such cases, the side branch almost always becomes involved in the course of the angioplasty due to axial or circumferential plaque redistribution.

Consequently, operators must accurately visualise the configuration of a diseased coronary bifurcation before the procedure in order to be able to delineate an optimal strategy. In daily practice, a strategy of bifurcation lesion treatment is decided upon in instances when treatment of the main branch is likely to compromise a side branch considered significant by the operator.

Before the Era of Stenting

Prior to the introduction of coronary stents, despite gradual equipment improvements and enhancements in technical approaches, such as kissing-balloon inflation, the immediate and mid-term results of balloon angioplasty for bifurcation disease were relatively disappointing and the presence of a bifurcation lesion with a significant branch constituted a frequent indication for coronary artery bypass graft (CABG) surgery. ‘Debulking’ techniques, such as directional or rotational atherectomy, which were in vogue in the early 1990s, did not significantly improve outcomes of bifurcation angioplasty.

The Bare Metal Stent Era

As early as 1992, it became clear that coronary stenting combined with dual anti-platelet agents would soon become the treatment of choice in the majority of coronary lesions. Nevertheless, the results of early experiences with first-generation stents in bifurcation lesions were relatively poor. More recent studies using second- or thirdgeneration stents have shown that coronary bifurcation stenting has gradually become an alternative treatment to coronary surgery and that it was associated with acceptable immediate and mid-term results.

Currently, in experienced centres using bare metal stents (BMS), the angiographic success rate is more than 95% for the main branch and more than 88% for both branches, with a major adverse cardiac event (MACE) rate at six to 12 month follow-up of 18% to 35% including a target vessel revascularisation (TVR) rate of 12% to 28%. Many approaches involving techniques of varying complexity, using two and even three stents, have been proposed (culotte, simultaneous kissing stent and skirt stent). The simplest of these approaches using BMS (provisional side branch T-stenting with final kissing-balloon inflation), rapidly proved to be associated with the best mid-term outcome.

Figure 1: The ‘Good Side’ of Stent Deformation

Lessons from the Bench

The most important lessons stem from the finding that the opening of struts towards the side branch (see Figure 1) results in stent deformation at the main branch level opposite the ostium of the side branch. This contributed to major strategic changes in the approach to bifurcation treatment. Indeed, final kissing inflation, by re-apposing the stent against the vessel wall, may reduce the risk of stent thrombosis as well as the occurrence of restenosis, especially when DES are implanted.