Vascular responses to coronary calcification following implantation of newer-generation drug-eluting stents in humans: impact on healing

AIMS: Vascular calcification is routinely encountered in percutaneous coronary intervention (PCI) and severe coronary calcification is a known predictor of in-stent restenosis and stent thrombosis. However, the histopathologic mechanisms behind such events have not been systematically described. METHODS AND RESULTS: From our registry of 1211 stents, a total of 134 newer-generation drug-eluting stents (DES) (Xience, Resolute-Integrity, PROMUS-Element, and Synergy) with duration of implant >/=30 days were histologically analysed. The extent of calcification of the stented lesions was evaluated radiographically and divided into severe (SC, n = 46) and non-severely calcified lesions (NC, n = 88). The percent-uncovered struts per section {SC vs. NC; median 2.4 [interquartile range (IQR) 0.0-19.0] % vs. 0.0 (IQR 0.0-4.6) %, P = 0.02} and the presence of severe medial tears (MTs) (59% vs. 44%, respectively, P = 0.03) were greater in SC than NC. In addition, SC had a higher prevalence of >/=3 consecutive struts lying directly in contact with surface calcified area (3SC) (52% vs. 8%, respectively, P < 0.0001). Multivariate analysis demonstrated that sections with duration of implantation