Based on previous studies on insulin resistance and cardiovascular diseases, we believe that the insulin resistance metabolic score also has certain predictive value for the prognosis of in-stent restenosis after coronary stent implantation. The main purpose of this study is to explore the predictive effect of the insulin resistance metabolic score on in-stent restenosis after coronary stent implantation and to discuss a reasonable control level.

Coronary atherosclerotic heart disease, especially acute myocardial infarction, remains the leading cause of death worldwide. Despite the development and improvement of percutaneous coronary intervention (PCI) and drug therapy, which have significantly improved survival rates and clinical outcomes, the unresolved problem of in-stent restenosis (ISR) remains a key factor limiting the therapeutic effect. Therefore, identifying and studying the risk factors and formation mechanisms of in-stent restenosis is an important clinical step in preventing and treating in-stent restenosis. Moreover, an increasing number of studies have shown that IR may have a significant impact on the occurrence and progression of in-stent restenosis (ISR). The traditional quantitative techniques for assessing IR are limited by cost, time, and manpower, while new biomarkers overcome these limitations and become a clinically feasible alternative with cardiovascular disease prediction capabilities. However, there is currently no large amount of data to prove the relationship between metabolic syndrome-insulin resistance (METS-IR) and in-stent restenosis (ISR). Therefore, we designed a retrospective study on patients with recurrent chest pain after percutaneous coronary intervention to evaluate the potential association between subepithelial restenosis (ISR) and metabolic syndrome-insulin resistance (METS-IR), thereby providing a basis for evaluating METS-IR as a possible risk indicator for ISR in patients after percutaneous coronary intervention.

Inclusion Criteria:

• Age ≥45 years
• Patients with a history of percutaneous coronary intervention (PCI) with stent implantation
• Patients who underwent repeat coronary angiography during follow-up
• Complete clinical data available, including echocardiography, 24-hour ambulatory electrocardiogram, NT-proBNP, liver and kidney function tests, and blood biochemical tests

Exclusion Criteria:

• Previous coronary artery bypass grafting
• Lesions treated only with balloon angioplasty without stent implantation
• Clinical manifestations of heart failure, structural cardiomyopathy, congenital heart disease, or significant valvular heart disease
• Severe hepatic or renal dysfunction, such as estimated glomerular filtration rate <30 mL/min/1.73 m²
• Incomplete clinical or angiographic data

We retrospectively collected the clinical data of patients with recurrent chest pain after PCI and requiring repeated angiography from January 2022 to November 2025, which were obtained from electronic medical records.