A New Technique for Coronary Bifurcations: Good News!
- Volume 15 - Issue 6 - June, 2003
- Posted on: 8/1/08
- 0 Comments
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Bifurcated coronary artery lesions represent one of the challenging areas in interventional cardiology. Coronary stenting resulted in more predictable results and higher angiographic success rate compared to balloon angioplasty. Angiographic restenosis rates nevertheless remain high, irrespectively of the different approaches employed.1–6
A limited number of studies are available in the literature regarding treatment of pseudo-bifurcation lesions.7 Traditionally bifurcated lesions have been classified according to the presence of disease in the main branch (MB), in both or only in the sidebranch (SB). Three major classifications have been reported: the Duke classification,8 the Safian classification,9 and the classification by Lefevre et al.10 The type 4a bifurcated lesion, according to the classification proposed by Lefevre et al., involves the MB right distally to the origin of the SB and it is frequently called pseudo-bifurcation. The same term is also used when the lesion is in the MB proximally to the origin of the SB.7
Treatment of a type 4a pseudo-bifurcation may be challenging. Plaque shift during dilatation of the lesion in the MB can result in involvement of the ostium of the SB and sometimes the proximal part of the MB. Although there are no published data regarding the actual rate of involvement of the SB while treating these cases, it is common experience that plaque shift happens very often. As a result, the recommended strategy for this lesion type is an approach similar to the one used in true bifurcated lesions: stent implantation in the MB, covering the bifurcation site, with provisional stenting of the SB and final kissing balloon inflation.
In this issue of the Journal, Dardas et al.11 present a new technique for treatment of type 4a bifurcation lesions. [See Dardas et al. on pages 180–183] This is a very interesting approach aiming to limit stenting only to the segment diseased at baseline (MB distal to the carina) and concurrently avoiding the snowplough effect toward the SB. In order to prevent plaque shift an undersized balloon is positioned to cover the SB and the MB proximal to the carina. This balloon is inflated at low pressure during stent implantation in the MB. The same maneuver is used in case post-dilatation of the stent is required.
The technique was used in the treatment of 11 coronary bifurcated lesions (10 lesions involving the left anterior descending/diagonal and 1 in the left circumflex/obtuse marginal bifurcation) succeeding to avoid plaque shift in all cases. The angiographic success rate was 100%, without need of additional stenting in the SB. All patients had clinical follow-up and 10 of them had non-invasive evaluation at 6 months with either exercise stress test (3 cases) or thallium scintigraphy (7 cases). There was no evidence of ischemia except in one patient. Coronary angiography was performed in that patient and revealed the absence of restenosis. All patients remained asymptomatic at 16 ± 6 months post-procedure.
An important advantage of the described technique is the fact that it is less demanding, since there is no need to re-wire the SB through the struts of the stent implanted in the MB. Access of the SB may sometimes be troublesome or even impossible, leading to angiographic failure. Dedicated techniques such as the “jailed” wire or dedicated stents with two wire accesses have been employed to overcome this problem.12,13 Avoidance of any additional maneuver leads to a more predictable outcome and reduces the radiation exposure time.
The proposed technique may also be cost-effective, provided that the avoidance of additional stent implantation is confirmed in a larger patient subset. One potential risk of this approach is the occurrence of a dissection necessitating stent implantation in the SB or MB proximal to the bifurcation. The other potential risk is incomplete coverage of the lesion in the MB that will almost always partially occur, due to the fact that the stent is never mounted to fully cover the deploying balloon, even with the most advanced delivery systems. A possible way to minimize this risk is to have the proximal part of the stent delivery balloon slightly proximal to the bifurcation as shown in Figure 2 in the report by Dardas et al.11 The usage of an undersized balloon for the SB has two goals: to minimize overdilatation of the proximal segment of the bifurcation, where two balloons are present, and to avoid any dissection in the SB.
The impact of this technique on restenosis rates for this lesion type needs further evaluation. Although the non-invasive testing should suffice for the subset of lesions treated, more cases are required to provide fully supporting data. Our experience with the use of bare metal stents for true bifurcated lesions has indicated that stent implantation for both branches, using technically demanding techniques, did not pay back.1,2,4 The approach described by Dardas et al.11 looks attractive from that point of view, since it uses one stent and is relatively simple.
The proposed approach may even become more attractive with the introduction of drug-eluting stents, a situation where the need to limit, if possible, the usage of multiple stents may become more important.