Preinterventional peak monocyte count and in-stent intimal hyperplasia after coronary stent implantation in human coronary arteries

Background: The mechanism of restenosis after stent implantation principally is neointimal hyperplasia. There is evidence that monocytes play a important role in in-stent restenosis (ISR) after stent implantation. Hypothesis: This study assessed the relationship between preinterventional peak monocyte count and neointimal growth after successful stent implantation. Methods: We performed coronary stent implantation in 85 patients (85 de novo lesions). Peripheral blood sample was obtained in all patients every 12 h before coronary angiography for measurement of peripheral monocytes. All patients received angiographic and intravascular ultrasound (IVUS) follow-up at 6 months after stenting. Results: The preinterventional circulating monocyte count was significantly higher in the ISR group than that in the group without ISR (654 ± 62/vs. 461 ± 222/mm³, p < 0.001) and was significantly higher in the reintervention group than that in the no-reintervention group (660 ± 72/vs. 470 ± 216/mm³, p < 0.001). The incidence of ISR and repeat intervention associated with preinterventional monocyte count was highest among the patients in the highest tertile, who were at a 2.64-fold increased risk of ISR and 3.22-fold increased risk of repeat intervention compared with the patients in the lowest tertile. A significant positive correlation was found between preinterventional peak monocyte count and preinterventional plaque and media cross-sectional area and follow-up neointima area (r = 0.311, p = 0.007, r = 0.465, p < 0.001, respectively). The neointima area associated with preinterventional monocyte count was largest among the patients in the highest tertile, that is, 2-fold larger than that of the patients in the lowest tertile (p < 0.001) and 1.44-fold larger than that of the patients in the middle tertile (p = 0.001). Conclusion: Our results suggest that circulating preinterventional monocytes play a principal role in the process of in-stent neointimal growth after successful stent implantation.