The bifurcated anatomy is highly variable and PCI of bifurcation lesions is associated with increased procedural costs, greater complication rates and worse outcomes compared with PCI of simple coronary lesions. While progress has been made, more research and consensus need to occur.
To stent or not to stent
Since the NORDIC Bifurcation and BBC One studies several years ago found similar or worse results for a two-stent (main branch and side branch) versus a one-stent approach (main branch only), the interventional community has shied away from routine stenting of the side branch in bifurcation lesions. Implanting one stent rather than two, while reserving the option to rescue the side branch, reduces procedure time and complications, and decreases the risk for in-stent restenosis and stent thrombosis. Still, questions remain.
When should the side branch be stented? Should it always be pre-dilated? What technique is best for two stents—kissing, cullote, T, crush? How should dedicated bifurcation or side branch stents be used? What is the value of intravascular ultrasound (IVUS) or fractional flow reserve (FFR)?
“There is tremendous variation in anatomy, as well as concern about how much myocardium is in jeopardy,” says Michael A. Kutcher, MD, director of interventional cardiology at Wake Forest Baptist University Medical Center in Winston-Salem, N.C. “Under the best of circumstances, there is still a high restenosis rate regardless of the technique, and bifurcation stenting with drug-eluting stents has a higher rate of stent thrombosis than in simple lesions. It’s a very hard niche of cardiology.”
In an editorial, Waksman and Bonello detailed the “nearly endless anatomic and morphologic configurations of bifurcation types” (J Am Coll Cardiol Intv 2008;1;366-368). Adding to the complexity of developing standardized protocols is the challenge in designing a clinical trial that will determine the optimal treatment strategy. “The variability in anatomy, morphology, technique and learning curve makes it almost impossible to have a reproducible and reliable trial free of deviation that can detect the preferred strategy,” they wrote.
Niemelä et al from the NORDIC Bifurcation III study, however, recently reported favorable results for main vessel stenting without final kissing balloon dilatation (FKBD) compared with FKBD (Circulation 2011;123:79-86). At six months of follow-up in the randomized trial, they found that the “simple main vessel stenting technique without FKBD provides excellent clinical results that are similar to those of the more complex strategy of main vessel stenting with FKBD.” Definite stent thrombosis was 0.4 percent in both groups, but researchers called for longer follow-up “to obtain a reliable assessment of the risk of stent thrombosis.”
Is imaging the key?
Given the lack of consensus for an optimal strategy, some operators will use IVUS, which “can be helpful in locating plaque, defining the area that needs to be treated and, additionally, in optimizing stent sizing and deployment,” says Ajay J. Kirtane, MD, an assistant professor of internal medicine in the division of cardiology at Columbia University College of Physicians and Surgeons in New York City.
IVUS utilization is relatively low and varies from operator to operator, but at Columbia, dedicated IVUS technologists make it easier to employ. Kirtane says they use IVUS in bifurcation lesions in about 30 to 50 percent of cases. Yet, there is some debate on the use of IVUS, as studies have not produced definitive data that the technique improves clinical outcomes. Some interventionalists say those studies are flawed, but the bottom line is that the data do not yet support the routine use of IVUS, Kirtane says.
Angiographic classifications of plaque location and severity are currently used, but these are rarely accurate and IVUS might be the better tool, according to Oviedo et al (Circ Cardiovasc Interv 2010;3:105-112). Researchers used IVUS to evaluate plaque distribution in left main coronary artery bifurcations and found that the disease was rarely focal and that both sides of the flow divider (carina) were always disease-free, contrary to angiography-based notions. They proposed an IVUS classification for bifurcation lesions illustrating longitudinal and circumferential spatial plaque distribution.
FFR is another technique that, since the results of the FAME trial came out in 2008, has found a small niche in bifurcation stenting. FFR uses