Clinical Impact of In-Stent Calcification in Coronary Arteries: Optical Coherence Tomography Study

Abstract

In-stent restenosis with neoatherosclerosis has been known as the predictor of target lesion revascularization (TLR) after percutaneous coronary intervention (PCI). However, impact of in-stent calcification (ISC) alone on clinical outcomes remains unknown since neoatherosclerosis by optical coherence tomography (OCT) includes both in-stent lipid and calcification. We aimed to assess an effect of ISC on clinical outcomes and clinical differences among different types of ISC. We included 126 lesions that underwent OCT-guided PCI and divided those into the ISC group (n=38) and the non-ISC group (n=88) according to the presence of ISC. The cumulative incidence of clinically-driven TLR (CD-TLR) was compared between the ISC and non-ISC groups. Impact of in-stent calcified nodule and nodular calcification on CD-TLR was evaluated in the Cox hazard model. The incidence of CD-TLR was significantly higher in the ISC group than in the non-ISC group (p=0.004). In the multivariate Cox hazard model, ISC was significantly associated with CD-TLR [hazard ratio (HR): 3.58; 95% confidence interval (CI): 1.33-9.65; p=0.01]. In-stent calcified nodule/nodular calcification and in-stent nodular calcification alone were also the factors significantly associated with CD-TLR (HR: 3.34; 95%CI: 1.15-9.65; p=0.03 and HR: 5.21; 95%CI: 1.82-14.91; p=0.002, respectively). ISC without in-stent calcified nodule/nodular calcification, which was defined as in-stent smooth calcification, was not associated with CD-TLR. In conclusion, ISC was associated with the higher rate of CD-TLR. Types of calcifications that led to the high rate of CD-TLR were in-stent calcified nodule/nodular calcification and in-stent nodular calcification alone but not in-stent smooth calcification. In-stent calcified nodule and nodular calcification should be paid more attention.