The determinants of side branch compromise after main vessel stenting in coronary bifurcation lesions.

BACKGROUND AND AIM The purpose of this analysis was to determine the factors responsible for side branch (SB) ostial stenosis after main vessel stent implantation. METHODS Theoretical and bench-test bifurcation models with different lengths of carina were created. Bench-test experiments with a flexible bifurcation model were performed for the observation of changes in the bifurcation region after stent implantation. An angiographic analysis of 92 bifurcation lesions (84 patients) was performed to determine the role of theoretical parameters on SB compromise in practice. The theoretically predicted and actual SB compromise were compared in these patients. RESULTS Bench tests revealed a complex change in the bifurcation region with carina displacement, SB lateral walls stretch and main vessel - SB proximal angle decrease after main vessel stent placement. In an angiographic analysis, actually measured SB% diameter stenosis was larger than expected in 35 (38%) lesions and the measured stenosis was smaller than expected in 49 lesions. Independent predictors of difference between theoretically predicted and observed SB stenosis were carina length mismatch (OR = 2.568, CI 1.336-4.896), main branch reference diameter (OR = 0.314, CI 0.101-0.972), and proximal main vessel - SB angle change after stenting (OR = 0.926, CI 0.870-0.985). In a plot comparing the values of carina length mismatch and deviations from the prediction in SB ostial stenosis, 30% (n = 27) of cases were located in a zone with a shorter carina and more SB compromise than expected, suggesting the role of plaque shift in these cases. CONCLUSIONS The degree of SB jailing seems to be determined by carina deformation, the length of the carina, and plaque shifting.