Abstract 2221: Lack of Neointimal Growth is a Predictor of Late Stent Thrombosis
Background-Late stent thrombosis (LST) has previously been shown to be associated with lack of reendothelialization in drug eluting stents (DES). Morphological factors determining endothelialization have not been established.
Methods-From a registry of 34 DES cases of > 30 days duration, stents with occlusive or sub-occlusive thrombi were compared to patent stents. Histologic sections were taken at 3 mm sections throughout the entire length of the stent. Neointimal thickness and endothelialization were assessed over each stent strut. Data are reported as stent length and the number of struts/stent section without neointimal coverage. To determine predictors for the occurrence of LST, multivariate analysis was applied and significant variables subsequently examined by discriminant function analysis.
Results-Of 34 patients with DES in place > 30 days, 18 had evidence of LST. Neointimal thickness was significantly correlated with percentage of endothelialization (r2 = 0.35, p < 0.0002) and was significantly lower in cases with mural thrombi compared to patent DES (0.10 ± 0.11 vs. 0.23 ± 0.18 mm, p < 0.01). The stent length without neointimal coverage and the number of uncovered stent struts/section were significantly greater in cases with LST compared to patent stents (see table⇓). Neointimal thickness and stent length without neointima were significantly correlated with LST. Following discriminant analysis, 27 cases were appropriately predicted and 7 misclassified (positive predictive value 80 %).
Conclusion-Absence of neointimal growth is associated with LST as it relates to a lack of reendothelialization and delay of arterial healing in DES. Diagnostic measurements of lacking neointimal coverage might be a valuable tool to predict LST.