Pre-Percutaneous Coronary Intervention C-Reactive Protein Levels and In-Stent Restenosis: A Systematic Review and Meta-Analysis.

Introduction: C-reactive protein (CRP) is an inflammatory biomarker, implicated in the pathogenesis of atherosclerotic lesion formation, plaque rupture, and coronary thrombosis. The relationship between preprocedural CRP levels and subsequent development of in-stent restenosis (ISR) after percutaneous coronary intervention (PCI) however remains uncertain. Against this background, we performed a systematic review and meta-analysis, investigating the association between baseline CRP levels and the incidence of ISR after PCI. Methods: Relevant published studies were identified following a PubMed, EMBASE, MEDLINE, Scopus and Web of Knowledge databases search until April 30, 2024. To be included, studies had to be original research with: (i) angiographically determined ISR group, (ii) angiographically or clinically determined no-ISR group, and (iii) CRP levels measured before the index PCI procedure for both groups. The mean difference in baseline CRP levels and associated 95% confidence interval (CI) between the ISR and no-ISR groups was ascertained for each included study. The pooled standard mean difference (SMD) and its 95% CI was derived after pooling study-level results using a random effects model, employing a Results: Out of a total of 1018 unique results, 19 studies, with a total sample size of 4744 patients (1154 restenosis cases/3590 controls), were included for quantitative synthesis. ISR group had higher baseline CRP levels (SMD = 0.41, 95% CI = 0.16, 0.66 mg/L, Conclusions: The present systematic review and meta-analysis suggests a significant association of elevated pre-PCI CRP with subsequent angiographically confirmed ISR. These results warrant further validation in dedicated large cohorts, ideally in a prospective setting.