Compared With Provisional Stenting, Double-Kissing Crush Technique Reduces Left Main Disease Events at 1 Year

DENVER, CO—PCI of true distal left main (LM) bifurcation lesions with a planned double-kissing (DK) crush two-stent strategy compared with provisional stenting results in less target lesion failure at 1 year, according to the results of the randomized DKCRUSH-V trial presented here at TCT 2017. The findings were largely driven by lower rates of target vessel MI and definite/probable stent thrombosis, researchers say.

“The present randomized study has for the first time evaluated clinical and angiographic outcomes after treatment of true distal LM bifurcation lesions with the DK crush planned two-stent technique versus a [provisional stenting] approach,” lead investigator Shao-Liang Chen, MD (Nanjing Medical University, China), and colleagues conclude in their paper published simultaneously today in the Journal of the American College of Cardiology.

Previous studies comparing a one- versus two-stent approach for bifurcation lesions once favored the former, but newer research using second-generation DES has swayed opinion that maybe the latter is the way to go, although several techniques exist to do so. For left main bifurcations, the DK crush strategy, which involves side stenting and two kissing balloon inflations, has been shown to result in fewer adverse events than culotte stenting.

For the DKCRUSH-V trial, Chen et al randomized 482 patients with true distal unprotected LM bifurcation lesions (72.2% with unstable angina; mean Syntax score 30.6) to either provisional (n = 242) or DK crush stenting (n = 240) at 26 centers in China, Indonesia, Thailand, Italy, and the United States between December 2011 and February 2016.

At 1 year, the risk of the primary endpoint of target lesion failure (composite of cardiac death, target-vessel MI, or clinically driven TLR) was lower in the DK-crush arm than in those treated with provisional stenting (5.0% vs 10.7%; HR 0.42; 95% CI 0.21-0.85). The two-stent strategy also resulted in lower rates of target-vessel MI (0.4% vs 2.9%; P = 0.03) and definite or probable stent thrombosis (0.4% vs 3.3%; P = 0.02) compared with provisional stenting, and there were trends toward less clinically driven TLR and angiographic restenosis within the LM complex. However, there were no differences in cardiac or all-cause mortality between the study groups.

‘No Pain, No Gain’

In an accompanying editorial, Emmanouil Brilakis, MD, PhD; M. Nicholas Burke, MD; and Subhash Banerjee, MD (Minneapolis Heart Institute, MN), write that the DK crush technique “is a perfect illustration of the ‘no pain, no gain’ concept” as the strategy is “more challenging than provisional stenting, but will benefit the patients, which is what matters the most.”

Notably, participating operators needed to have performed at least 300 PCIs per year for at least 5 years, including on 20 LM lesions. To be included, the operators also had to perform between three and five DK crush cases that were reviewed and approved by the study steering committee.

“These numbers are unrealistic for many US operators, because the median annual PCI volume in the United States is 59 cases and 44% of US operators perform < 50 PCIs per year,” they write. “Although there is ongoing controversy about the impact of PCI volume on outcomes, concentrating [unprotected LM] PCI cases to centers experienced in performing complex PCI would likely improve outcomes, regardless of technique used.”

There is also a substantial learning curve for these procedures similar to chronic total occlusion interventions, the editorialists point out. This will require “teaching, adequate practice, and ideally, confirmation that adequate results are achieved using intravascular imaging,” they argue. Of note, IVUS was only used in 42% of the cases in DKCRUSH-V.

To perform DK crush stenting, “you really have to have excellent wiring technique,” Roxana Mehran, MD (Icahn School of Medicine at Mount Sinai, New York, NY), who was not involved with the study, said during a press conference. “It’s really a more advanced complex procedure, and I don’t know that a learning curve has been established anywhere. . . . You shouldn’t undertake a procedure in which you are uncomfortable with multiple wiring and rewiring of the crushed stent.”

Notably, Mitchell Krucoff, MD (Duke University Medical Center, Durham, NC), also commenting in the press conference, noted that trainees often learn procedures like DK crush stenting outside of the LM. “Once you have experience with bifurcation techniques, then implications to the left main would be a rational sort of next step,” he said.

Regardless of which stenting technique an operator chooses with these lesions, “understanding how to perform these procedures and being really good at [them] is extremely important,” Mehran added.

The ongoing EBC MAIN study, which is leaving the choice of stenting technique—either culotte, DK minicrush, and T or T plus protrusion stenting—to operator discretion in unprotected LM bifurcations, should lend more insight to this topic with results expected late next year, Brilakis, Burke, and Banerjee write.

For now, “it is our strong belief that coronary interventionalists will demonstrate an evidence-based ‘growth mindset’ and will adopt DK crush as their standard strategy for treating [unprotected LM] bifurcations,” they conclude.

Provisional Proficiency Questioned

In an email, David Hildick-Smith, MD (Royal Sussex Brighton Hospital, England), commented to TCTMD that the fact that 39.7% and 47.1% percent of patients in the provisional stenting arm received predilatation in the side branch—although it was discouraged—and a side branch stent, respectively, “may have influenced results.”

Cindy Grines, MD (Northwell Health, North Shore University Hospital, Manhasset, NY), agreed. “Oh my god, that's really high,” she said of the percentage of patients in the provisional stenting arm who also received a side-branch stent. “That's the problem,” Grines told TCTMD. “We are very biased. We have this occulostenotic reflex. We think, ‘oh, this [circumflex] is so important, we need to treat it.’ But in fact, we don't know that. There's been no physiologic testing to determine do we need to treat it or don't we, and this is a good example of how we could have harmed the patients by treating them so aggressively.”

She also disagreed with the editorialists that DK crush should become the preferred method for treating LM bifurcation lesions. “First of all, we don't really know how to do the technique. Secondly, it seems to me that the outcomes in the provisional arm were worse than what I would have expected,” Grines observed. “What we need to do is compare the outcomes in this provisional arm [with] the outcomes in the provisional arm from EXCEL. If they were equally as harmful, then maybe we're right. Maybe we need to change our strategy.”

Given that the operators in DKCRUSH-V were extremely proficient in DK crush stenting, “maybe they are not as skilled at the provisional,” she suggested, comparing this situation to the debate over radial versus femoral access. “Radial looks really, really good, but in part the reason it looks good is because we've lost our femoral skills,” Grines said.

Hildick-Smith, too, said that the editorialists “go too far in recommending this as the technique of choice for left main bifurcations. They have been enthusiastic, but I don’t think they have critically appraised the study very much.” Additionally, while he said he doesn’t doubt the study findings, “there is a significant difference between European and Chinese outcomes with two-stent versus provisional technique results, and we still have a lot to learn about quite why that is.”

As for a much larger trial looking at different stenting techniques for these lesions on an even more international scale, Grines agreed it would be worth the effort. But given that these are strategies of already-approved stents, funding would be an issue, she said.

Note: Study co-authors Martin B. Leon, MD, and Gregg W. Stone, MD, are faculty members of the Cardiovascular Research Foundation, the publisher of TCTMD.