Abstract 2784: Detection Of Eosinophils In Thrombectomy Aspirates From Patients With Late Stent Thrombosis: Predictor Of Hypersensitivity?
Background: Localized hypersensitivity reaction is one of the causes of late stent thrombosis (LST) consisting of intense eosinophilic infiltrates and lymphocytes within the arterial wall and in regions of thrombus close to the lumen. However, histologic examination of coronary thrombectomies from patients with late stent thrombosis has not been studied previously.
Methods: Histologic examination of thrombi aspirated from patients with LST compared to patients with AMI (without stenting) was performed to evaluate for the presence of eosinophils and other inflammatory cells associated with thrombosis. Sixteen thrombectomy aspirates from 16 patients were submitted; 8 were harvested from patients with LST (defined as thrombosis occurring > 30 days post implantation) and 8 were obtained from patients with AMI and served as the control group. Of the 8 patients in the LST group, 6 had DES (4 Cypher and 2 Taxus stents) and 2 had BMS. Eosinophil counts were performed for each specimen and recorded as total eosinophil number and eosinophil fraction expressed as total eos/total white blood cells.
Results: The greatest number of eosinophils was observed in the Cypher group (range: 2- 441) followed by Taxus (range: 30 –135) and was least in the BMS and AMI control group (range: 2–25 and 2– 43 respectively). The total mean eosinophil count for Cypher (n = 4) was 139.7 compared to 82.5 for Taxus (n = 2) followed by BMS (13.5) (n = 2) and the control group (11.4) (n = 8). The mean fraction of eosinophils was highest in the Cypher group (0.14) followed by Taxus (0.11), BMS and control (both = .04). Of the 4 thrombi from the Cypher group, one demonstrated a much higher percentage of eosinophils (49%) compared to the others; clinical follow up for this patient revealed 2 episodes of LST after stent implantation with positive remodeling of the vessel wall demonstrated by IVUS and OCT suggesting a localized hypersensitivity reaction.
Conclusion: Histologic analysis of thrombi aspirated from patients with DES LST may be a valuable method to determine the underlying etiology of hypersensitivity in patients with LST.