By Alfredo Galassi
Treatment of bifurcation lesions remains a technical challenge for the interventionalist, as it is still hampered by an increased rate of restenosis as compared with nonbifurcated lesions. Part of this treatment complexity is related to the different anatomic patterns of the stenosis, considering that all anatomical bifurcation characteristics may influence the treatment strategy.
The best treatment for bifurcation lesions has not been established yet. In the absence of proven efficacy of dedicated devices, drug-eluting stents and various techniques – generally divided into two basic strategies, with or without side-branch stenting – are commonly used to treat patients with bifurcation lesions. Because some recent randomised studies of stenting of both branches failed to demonstrate superiority over main-vessel stenting and balloon dilatation with provisional stenting of the side branch1-4, the routine usage of two stents is not generally recommended as a default procedure and is only used in case of long and diffuse side-branch disease.
The Colombo trial utilising sirolimus-eluting stents showed that a simple strategy with a one-stent technique is not inferior to a complex strategy with two stents; however, the study might be difficult to interpret, as the number of patients is limited and there was a very high crossover rate from simple to complex strategies1.
The CORPAL (Drug-eluting stents for complex lesions: randomised rapamycin vs. paclitaxel) trial showed that elective side-branch stenting did not provide an advantage over the simple T-provisional stent; however, the trial was dealing with a limited number of cases and the complex strategy was performed with a technique that did not have much success when it employed T-provisional but not as double-stent intention-to-treat technique2.
The Nordic trial considered a two-stent technique to perform worse than an one-stent technique, in patients with a stenosis diameter, as determined by angiography, of >50% of the main vessel or an occlusion of the side branch. Indeed, in this series, restenosis rate in the side branch was significantly higher in the group using a simple strategy (19.2%) as compared with those using a complex strategy (10.9%)3.
The recent CACTUS (Coronary bifurcations: application of the crushing technique using sirolimus-eluting stents) trial, comparing two different techniques – the crush and the provisional side-branch T-stenting – showed in 350 patients in 12 European centres a similar major adverse cardiac event rate for both treatments (15.8% in the crush group vs. 15% in the provisional stenting group, p=NS). Also in this study, there was a high crossover rate from a one-stent technique to two (31%), determining a difficult interpretation of its findings.
In conclusion, a one-stent technique does not seem to perform worse than two-stent technique, although, as recently stated, it could be impossible to do randomised trials in bifurcation lesions as each patient’s anatomy may favour a particular technique; trial patients will be overall heterogeneous5 and still a remarkable subgroup of patients with bifurcation lesions (with larger side branches and/or large myocardium at risk supplied by the side branch and/or more diseased vessels and/or with suboptimal result of the side branch), and may be treated with double stenting even if the intention is to try to avoid it.
For these reasons, although randomised controlled trials remain a gold standard in clinical investigation, large single-centre series provide important information and help calibrate results from randomised studies evaluating treatments for bifurcation lesions and contribute to our knowledge as we try to select the best therapy for each patient.
In a pilot study, we described a further refinement of the crush technique, which consists of crushing the 1-2mm proximal side branch stent with a balloon (minicrush) instead of crushing the 3-4mm proximal side branch stent with another stent, as in the standard crush6. Following this approach, it seems that there is less risk that the main-vessel stent will be deformed and potentially unopposed to the vessel wall and thus predisposed to restenosis or stent thrombosis of the side branch, as is suggested by Ormiston and colleagues7. This study showed excellent in-hospital outcomes for the minicrush technique with low major advance cardiac events and restenosis rates, especially at the side branch (2%)6.
In our recently published retrospective study8, the largest single-centre experience so far, we looked at 457 consecutive patients who were treated with either two-stent minicrush technique (n=199) or the T-provisional approach (n=258), in which a second stent was used only if deemed necessary at the operator’s discretion (T-provisional one-stent=170 and two-stent n=88). Clinical follow-up was available for all patients at 25±15 months and cumulative major adverse cardiac events were similar between minicrush and both T-provisional patient groups (20.6% vs. 25.9% vs. 26.1%, p=NS across all three groups). However, it is interesting to note that target bifurcation revascularisation (defined as a repeat revascularisation with a stenosis of 50% within 5mm proximal or distal to the carina of bifurcation, both onto the main branch and/or side branch) was significantly lower in minicrush patients as compared with T-provisional two-stent patients (8.5% vs. 17.4%, p=.05).
At nine month angiographic follow-up, after propensity score adjustment for baseline differences, there was significantly less restenosis in both the main and side branch in the minicrush compared with patients in the provisional group who received a single stent (HR .52, 95% CI, .27-.99; p=.047, and HR .41, 95% CI, .20-.85, p=.016, respectively). Comparing minicrush with entire T-provisional group after propensity score adjustment for baseline differences restenosis was significantly reduced in minicrush arm only for the side branch (HR .55, 95% CI, .37-.82, p=.004).
Both techniques of bifurcation treatment met high procedural success with low complication rates and similar major adverse cardiac event long-term outcome. However, the minicrush technique yields a lower restenosis rate at both main and side branches. These results may confirm the advantage of using prescheduled two-stent technique to give a complete coverage of the side branches’ ostium, when the side branch is suitable for stenting and has disease extending beyond the ostium.
Four good reasons why we prefer the minicrush technique as a two-stent strategy
Firstly, as shown by Ormiston7 in a phantom model among two-stent techniques, crush stenting and his modifications (minicrush and two-step crush technique) are performing better than other two-stent techniques. Indeed, these latter have strengths, but many weaknesses as compared to crush: With “T” stenting there are gaps in metal coverage and drug application at the side branch ostium especially in shallow angles1. Culotte stenting9-10 is technically more difficult and is associated with double layering of stent struts. The simultaneous kissing stent (SKS) technique is simple and quick, but produces a metallic septum upstream from the bifurcation that may predispose to stent thrombosis, despite of being more successful in medium-to-large coronary arteries11. Both “V” stenting12 – a variation of simultaneous kissing stent technique – and “Y” stenting13 have the potential to cover the bifurcation, but they are limited in true bifurcation lesions.
Secondly, as previously described the minicrush technique has the advantage, as compared to the standard crush, of avoiding manipulation or positioning of two bulky stent simultaneously, and, as compared to the “step crush technique” it is less cumbersome; furthermore, in the minicrush technique recrossing, balloon inflations and kissing inflations occur only once and not twice such as in the two-step procedure9-10.
Thirdly, as shown in the silicone phantom by Ormiston7, gaps in stent coverage sometimes occur with kissing balloon postdilatation after standard crush deployment, but are significantly less common with minicrush. They occur in the-side branch stent, usually on the side opposite to the crushed portion of the stent; they are due to the postdilatation side-branch balloon, which pushes struts aside. When comparing standard crush with minicrush side-branch, ostial coverage by metal struts was reduced in the original work by Ormiston from 47% (39-53) to 36% (31-40), p<.002 7. Also, separate stent inflations rather than simultaneous stent inflation, as in the standard crush, may favour more homogenous and complete stent coverage; with this “ballooning crushing” there is less risk that the main-vessel stent will be deformed and potentially unapposed to the vessel wall and thus predisposed to restenosis.
Fourthly, following standard crush deployment, the two layers of crushed side-branch stent, in addition to a layer of main branch struts, form three layers of struts. The limited length of 1-2mm of stent that is crushed with minicrush – instead of the 3-4mm of the standard crush – determines minimal overlap of struts; indeed, this may be associated with more complete endothelialisation and reduced risk of thrombosis.
Alfredo R Galassi, Davide Tomasello, Davide Capodanno et al from the Ferrarotto Hospital, University of Catania, Italy, are the authors of the study.
References
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