Mechanism of Percutaneous Revascularization for Coronary Bifurcation Disease

Percutaneous coronary intervention of bifurcation lesion remains a challenge, even in the
era of drug eluting stents (DES). Bifurcation interventions, when compared with
non-bifurcation interventions, have a lower rate of procedural success and a higher rate of
restenosis regardless of the techniques or technologies used. Although stenting of
individual non-bifurcated lesion has been shown to be superior to balloon angioplasty,
stenting of both branches seems to offer no advantage over stenting of the main branch (MB)
alone. The recent introduction of DES has resulted in a lower event rate and reduction of MB
restenosis in comparison with historical controls. However, reports suggest that restenosis
at the side branch (SB) ostium continues to be elevated. Intravascular ultrasound (IVUS)
studies have shown that stent dimensions are important predictors of restenosis even with
DES. Recently published observational data of IVUS analysis of bifurcation lesions treated
with “crush“ technique has shown the smallest minimum stent area at the SB ostium. This may
contribute to a higher restenosis rate. Plaque shift and insufficient covering of the SB
ostium may also play a major role in a development of SB restenosis. The belief that plaque
shift occurs during bifurcation stenting is challenged by the fact that plaque is mainly
located opposite to the side branch ostium as demonstrated by IVUS and anatomical studies.
Further, the occurrence of plaque shift in bifurcation lesions has never been scientifically
investigated. Finally, bending and twisting of the coronary arteries at the bifurcation
should be taken into account in the mechanism of SB restenosis because of continuous vessel
wall injury by the rigid stent and potential stent fractures. Bifurcation represents an
extreme model of vessel bending and twisting because the vessels beyond the bifurcation are
in different path/orientation and different heart walls. A better understanding of the
mechanisms of bifurcation intervention and restenosis is essential for the development of a
successful technique and dedicated technologies for this challenging scenario. Despite
multiple retrospective studies and various ingenious techniques, a true prospective
mechanistic investigation remains lacking in the field of bifurcation. The main objectives
of this study are define frequency of plaque shift phenomenon and impact on flow dynamics in
the side branch as assessed by IVUS, and evaluate acute and late side branch ostial vessel
reaction to balloon angioplasty and DES.