Impact of three-dimensional characteristics of the left main coronary artery bifurcation on outcome of crush stenting

Abstract

Background: Crush stenting with drug-eluting stents is used to treat left main coronary artery (LMCA) bifurcations. However, the rate of restenosis at the left circumflex (LCX) artery ostium is high. The impact of the three-dimensional (3D) structure of LMCA bifurcation on the outcome of crush stenting with respect to restenosis has not been described.

Objectives: This study examined the stent expansion, deformity, overlapping, and apposition after crush stenting of LMCA bifurcations.

Methods: Bare metal stents were crushed at LMCA bifurcations in a 3D model that reproduced actual angles, such that the stent deployed from the LMCA to the left anterior descending (LAD) artery crushed the stent deployed from the LMCA to the LCX, followed by kissing balloon inflation. The stents were inspected under fluoroscopy and endoscopy. The effect of the bifurcation angle on stent expansion was also examined.

Results: In the 3D model, one stent overlapped the other in the distal LMCA, in contrast to the nearly parallel position of the stents observed in a separate two-dimensional model. When the LAD stent overlapped the LCX stent, the latter was crushed on the myocardial side of the vessel, and an unstented segment was observed on the nonmyocardial side, at the LCX ostium. When the overlap was reversed, the LCX stent was crushed on the nonmyocardial side and an unstented segment was observed on the myocardial side. A narrow LMCA-LCX angle was associated with less expansion of the LCX stent at the ostium than more distally, and with a higher likelihood of incomplete stent apposition.

Conclusions: Overlap of the LAD stent over, as opposed to under, the LCX stent was associated with close apposition of the stent to the vessel on the myocardial side, at the ostium of the LCX artery, where atherosclerotic plaques are likely to be present. The spatial plaque burden and bifurcation angle should be closely examined before crush stenting, and segments should not be left unstented over large plaques.