1.3 Bifurcation Lesions: What Are the Optimal Stenting Strategies, and Will Drug-Coated Balloons Change Them?

These proceedings summarize the educational activity of the 16th Biennial Meeting of the International Andreas Gruentzig Society held January 31-February 3, 2022 in Punta Cana, Dominican Republic

Faculty Disclosures     Vendor Acknowledgments

2022 IAGS Summary Document

Statement of the problem or issue

In large clinical studies and registries, bifurcation lesions consistently account for approximately 10%-15% of percutaneous coronary intervention (PCI) procedures. Bifurcation anatomy in clinical trials historically was categorized in simplified manner according to the Medina classification, which described involvement of the main vessel (MV) and the side branch (SB) using a 0-1 binary scheme. More recently, assessing bifurcation complexity has evolved, using the DEFINITION criteria, to include additional characteristics that help predict postprocedural major adverse cardiac events, and facilitate selection of a 2-stent or provisional-stent strategy. Considerable debate exists on this selection of optimal bifurcation stenting strategy. However, a provisional approach with proximal optimization technique is generally accepted as the favored initial strategy if the risk of SB occlusion is low. Due to unclear thresholds for defining SB significance, there is potential for overuse of 2-stent strategies. Achieving optimal stent expansion and final configuration using intracoronary image guidance is likely more important than the specific 2-stent technique employed. Further, key modifications to 2-stent strategies like double-kiss crush and double-kiss culotte have improved procedural and clinical outcomes. Emerging data support use of drug-eluting balloon (DEB) over plain old balloon angioplasty (POBA) for the SB in a provisional approach when drug-eluting stents are used for the MV.

Gaps in current knowledge

Knowledge gaps in bifurcation PCI are numerous and span anatomic phenotyping all the way to procedural optimization techniques. Noninvasive stress testing and imaging methods for ischemia detection do not readily delineate SB significance regarding size of distal myocardium at risk. Although the DEFINITION criteria are more comprehensive than Medina for differentiating simple from complex bifurcation lesions, it is unclear if use of 2-stent strategies will prevail even in complex anatomy given the apparent superiority of DEB, and whether availability of DEB might limit the need for up-front routine 2-stent techniques and enhance provisional approaches. How SB “compromise” is defined also needs clarification, including whether acute ischemic signs and symptoms, visual lesion and vessel assessment, and hemodynamic measurements can be translated into acute procedural success and improved longer-term clinical outcomes. A further important question here is whether SB compromise should be defined similarly for DEB and POBA. Intuitively, use of intracoronary imaging should result in procedural optimization and reduced risk of target-lesion failure, but which imaging modality and its enhancements (automated image interpretation, coregistration, etc) is preferred is unknown. With the dynamic nature of bifurcation PCI, the need for operator adaptation to the various outcomes of each of the numerous technical steps is required. How operator experience relates to outcomes for bifurcation lesions has not been examined but will need to be. Whether computational modeling or artificial intelligence (AI) can guide decisions in bifurcation PCI remains to be examined broadly clinically, but it has begun to be conceptually developed.

Possible solutions and future directions

Although not widely used currently, commercially available stress-rest imaging modalities that could assess SB disease specifically for significance include PET-CT and FFR-CT. In the future, coupling lesion-specific anatomy with myocardial blood flow might become standard, and perhaps alert the interventionalist to the highest-risk bifurcation cases. Until that time, angiographic scoring systems that estimate myocardium at risk, along with an intraprocedural assessment of acute ischemia, can be used to guide decisions on SB significance and need for intervention. With respect to the benefits of intraprocedural guidance using high-definition imaging, the findings of the 1200 patient OCTOBER (European Trial on Optical Coherence Tomography Optimized Bifurcation Event Reduction) trial are eagerly awaited (ClinicalTrials.gov identifier: NCT03171311). In this trial, which has nearly completed enrollment, randomization is stratified by bifurcation location (left main or non-left main) and by intended treatment strategy (provisional or 2-stent technique). Patients are randomized 1:1 to systematic OCT guidance using 1 of 5 complex stent implantation techniques, or to standard treatment with angiographic guidance and optional use of intravascular ultrasound. Recent advances in software for assessing coronary hemodynamics, such as AptiVue (Abbott), can provide operators with real-time feedback on stent expansion, as well as with nonhyperemic indices to assess ischemia, which can be applied to bifurcation PCI. Potential areas where AI can be applied in bifurcations include helping define optimal stent geometry, MV stent sizing, risk of SB compromise, and the suitability for dedicated bifurcation stent platforms or 2-stent techniques. Computational simulations of bifurcation PCI that utilize angiography-OCT fusion and plaque material properties for 3D patient-specific reconstruction are possible; however, at this time they are performed off-line rather than in real time. In the future, libraries of patient anatomies can be examined using computational simulations to derive possible treatment algorithms based on the expertise of practiced operators. The application of DEB to bifurcation PCI may reduce the problem of SB target-lesion recurrences, but this only scratches the surface of improving outcomes in this common lesion subset. For now, operators are encouraged to understand and optimize the stent techniques they currently are using in practice.