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

Abstract

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<0.01 and 989±174 vs. 684±241μm, p<0.01, respectively). The enlargement of the stent area was significantly larger in the calcified nodule-like ISR lesions than in the non-calcified nodule-like ISR lesions (1.6±2.3 vs. 0.7±1.3 mm2, p=0.02). As a result, the enlargement of the lumen area tended to be larger in the calcified group (2.8±1.7 vs. 2.4±1.3 mm2, p=0.3). Calcified nodule-like neointima within the stent could develop in approximately 10% of all ISR lesions, especially within stents deployed in severely calcified lesions.