[Mechanism of lumen loss of the left circumflex ostium after main vessel stent implantation: observations by intravascular ultrasound].

Objective: To explore the mechanism of lumen loss of the left circumflex ostium after main vessel stent implantation.
Methods: Twenty-eight patients undergoing provisional T technique were enrolled in this study. Intravascular ultrasound (IVUS) examination was performed before and after main vessel stenting and kissing balloon post-dilatation to evaluate the geometrical changes of the vessels.
Results: The CSA of LCX ostium lumen decreased significantly from 5.9∓2 mm(2) to 4.9∓1.9 mm(2) (P<0.01) after the procedure, and the CSA of LCX ostium P and M increased from 5.4∓2.9 mmmm(2) to 5.7∓2.9 mm(2) (P=0.21) after the main vessel stenting. The changes in LCX ostium lumen CSA was correlated with the changes of LCX ostium EEM CSA but not the LCX ostium P and M CSA. After kissing balloon post-dilatation, the CSA of LCX ostium lumen increased from 4.9∓1.9 mm(2) to 5.5∓1.9 mm(2) (P<0.01) , and the CSA of LCX ostium P and M showed no obvious changes (5.7∓2.9 mmmm(2) vs 5.7∓2.6 mmmm(2), P=0.89). The changes of LCX ostium lumen CSA were correlated with the those of the LCX ostium EEM CSA (R=0.432, P=0.02).
Conclusion: After stent implantation from the LMCA to the LAD, most of lumen losses of the LCX are due to carina shift, and in occasional cases, plaque shift occurs from the distal LMCA to the ostium of the LCX. Kissing balloon technique can adjust carina shift but can not improve plaque shift.