Increased circulating platelet-derived microparticles are associated with stent-induced vascular inflammation.

Inflammation as well as platelet activation at the site of local vessel-wall injury plays an essential role in the mechanism of restenosis after Percutaneous coronary intervention (PCI). Platelet-derived microparticles (PDMPs) released from activated platelets are thought to play a role in the inflammatory process, possibly interacting with leukocyte integrin Mac-1. We serially measured circulating PDMPs, high-sensitive C-reactive protein (hs-CRP) and activated Mac-1 on the surface of neutrophils in 61 patients undergoing coronary stenting. PDMPs, hs-CRP and Mac-1 increased after coronary stenting in a time-dependent manner with the maximum response at 48 h in coronary sinus blood (PDMPs: 10.3+/-8.9-32.8+/-13.8 U/ml; P<0.001, hs-CRP: 0.27+/-0.23-1.46+/-0.99 mg/dl; P<0.001, activated Mac-1, 134+/-19% relative increase, P<0.001). PDMPs were correlated with hs-CRP (R=0.58, P<0.001) and the relative increase in Mac-1 (R=0.69, P<0.001) 48 h after coronary stenting. Multiple regression analysis showed that each of PDMPs (R=0.40, P<0.05), hs-CRP (R=0.33, P<0.05) and Mac-1 (R=0.48, P<0.01) was an independent predictor of the late lumen loss. Coronary stenting enhanced circulating PDMPs in association with an inflammatory response in the injured vessel wall. PDMPs may be a useful marker for evaluation of stent-induced inflammatory status and a powerful predictor of restenosis equivalent to activated Mac-1.