Remnant Cholesterol as a Predictor of Target-Vessel Failure in Patients With In-Stent Restenosis

Background: The clinical value of remnant cholesterol (RC) in patients with in-stent restenosis (ISR) who undergo percutaneous coronary intervention (PCI) is unknown. Therefore, this study aimed to clarify the association between increased RC levels and clinical prognosis in patients with ISR. Methods: This retrospective study enrolled 836 patients diagnosed with ISR. The study population was divided into four quartiles (Q1–Q4) according to median RC levels. Using a multivariate Cox proportional hazards model and Kaplan–Meier (KM) curve, the association between RC levels and the study endpoint, defined as target-vessel failure (TVF) within 3 years after PCI, was investigated. A discordance analysis was also performed with several definitions. Results: The KM curve showed an increased risk of TVF with elevated RC levels (p < 0.001). After adjustment, the RC level was identified as an independent predictor of TVF, regardless of whether the metric was considered as a continuous or categorical variable (hazard ratio (HR) = 1.37, 95% confidence interval (CI): 1.16–1.62; p < 0.001; HR = 3.43, 95% CI: 1.85–6.36; p < 0.001). Subgroup analysis showed that the RC-related TVF risk was more pronounced in patients with low-density lipoprotein cholesterol (LDL-C) <1.8 mmol/L (2.75 for each one standard deviation (SD) increase, 95% CI: 1.66–4.55; p for interaction < 0.001). In the discordance analysis, individuals with discordantly high RC levels rather than high LDL-C levels had an increased risk of TVF (HR = 2.02, 95% CI: 1.33–3.07; p < 0.001). Conclusions: An increased RC level was associated with an elevated risk of TVF in patients with ISR who underwent PCI. Further, the RC-related risk was more pronounced in patients with LDL-C levels <1.8 mmol/L.