The frequency and clinical characteristics of in-stent restenosis due to calcified nodule development after coronary stent implantation

The purpose of this study was to evaluated the clinical characteristics of calcified nodule-like in-stent restenosis (ISR) lesions using optical coherence tomography (OCT) in vivo. A total of 124 ISR lesions that were treated with a repeat coronary intervention under OCT guidance were included in this analysis. ISR neointimal morphology was classified as “calcified nodule-like ISR”, that appeared as a high-backscattering protruding mass with an irregular surface covered by signal-rich bands, or “non-calcified nodule-like ISR”. The maximum arc and thickness of calcium behind the stent struts was also measured. Of the 124 ISR lesions, calcified nodule-like ISR was observed in 11 lesions (9%). OCT analysis data showed that the maximum arc of calcium and the maximum calcium thickness behind the stent were significantly larger in the calcified nodule-like ISR lesions than in the non-calcified nodule-like ISR lesions (269 ± 51 vs. 179 ± 92°, p