Prevalence, predictors, and outcomes of in-stent restenosis with calcified nodules

Background: Calcified nodules (CN) have been reported as being associated with stent failure including in-stent restenosis (ISR). However, there is no systematic study of this condition.

Aims: We aimed to clarify the prevalence, predictors, and midterm results of ISR lesions with CN.

Methods: We examined the clinical characteristics of 651 ISR lesions in patients who underwent percutaneous coronary intervention (PCI) with optical coherence tomography (OCT) between October 2008 and July 2016, and their 6- to 8-month follow-up angiography results. CN was defined as a high backscattering mass with small nodular calcium depositions which protruded into the vessel lumen.

Results: Thirty-two ISR lesions (4.9%) had CN. Multivariable analysis showed that calcified lesion (odds ratio [OR] 12.441, p<0.001), incomplete stent apposition (OR 3.228, p=0.005), haemodialysis (OR 3.633, p=0.024), and female gender (OR 3.212, p=0.036) were independently associated with ISR lesions with CN. Midterm follow-up was performed on 612 ISR lesions. Both ISR and target lesion revascularisation (TLR) rates were significantly higher in lesions with CN compared with those without CN (43.8% vs 25.0%, p=0.023; 37.5% vs 18.8%, p=0.020, respectively). However, multivariate analysis did not show the presence of CN as an independent predictor of re-TLR (OR 1.690, p=0.286).

Conclusions: The prevalence of ISR lesions with CN was 4.9%. Calcified lesions, incomplete stent apposition, haemodialysis, and female gender are probably associated with CN formation. ISR lesions with CN may have poor midterm outcomes compared with ISR lesions without CN.