Predictors of Stent Underexpansion for Severely Calcified Lesions After Debulking.

Background: There are few studies regarding the predictors of stent underexpansion (SUE) in post-debulking calcified lesions. We investigated predictors of SUE in severely calcified lesions after debulking using optical coherence tomography-guided rotational atherectomy (RA) or orbital atherectomy (OA).

Methods and results: As a post hoc analysis of the DIRO trial, we compared various parameters, including calcium and lipid parameters (lipid-rich plaque, thin cap fibroatheroma [TCFA], maximum lipid arc, mean lipid arc, lipid length, and lipid volume index), between groups with adequate stent expansion (ASE) and SUE. To find predictors of SUE, multivariable analysis was performed using significant factors from the univariable analysis. We also evaluated adverse events 8 months after the procedure. The SUE group consisted of 57 (65.5%) patients. After suitable debulking of severely calcified lesions using RA or OA, there was no correlation between calcium parameters and SUE; however, the lipid parameters of maximum lipid arc ≥224° and TCFA were significantly and independently correlated with SUE Approximately 45% of severely calcified lesions contained lipid-rich plaques. Adverse events occurred more frequently in the SUE than ASE group.

Conclusions: The role of calcium parameters in predicting SUE in severely calcified lesions after suitable debulking using RA or OA is weak; however, maximum lipid arc and TCFA are important predictors of SUE.