Red Blood Cell Distribution Width and Stent Length Predict In-Stent Restenosis After Myocardial Infarction: A Retrospective Cohort Study

Summary

This study evaluated whether red blood cell distribution width and stent length predict in-stent restenosis after percutaneous coronary intervention using regression analysis and found that their combination improves predictive accuracy.

Abstract

This study investigated the predictive value of red blood cell distribution width (RDW) stent length for in-stent restenosis (ISR) drug-eluting stent implantation in patients with acute myocardial infarction. Reliable predictors of restenosis remain limited, highlighting the need for accessible clinical markers. A total of 170 patients who underwent stent implantation were included and classified into restenosis and nonrestenosis groups based on follow-up coronary angiography at 12 months. Clinical characteristics and laboratory parameters were compared between groups. Multivariate logistic regression and receiver operating characteristic analyses were performed to evaluate associations and predictive performance. The results showed that RDW and stent length were significantly higher in patients with restenosis and were independent predictors of restenosis risk. The combined use of these variables demonstrated improved predictive performance compared to using the variables individually. In conclusion, RDW and stent length are significant predictors of ISR and may serve as practical indicators for risk stratification in patients undergoing stent implantation.

Introduction

Percutaneous coronary intervention (PCI) is an important method for revascularization in patients with coronary heart disease. Emergency PCI is a crucial treatment approach for patients with acute ST-segment elevation myocardial infarction (STEMI)¹, and can significantly reduce the mortality rate of myocardial infarction². Although the implantation of drug-eluting stents has reduced the incidence of in-stent restenosis (ISR), this complication remains unresolved.

In recent years, red blood cell distribution width (RDW) has received increasing attention as a marker of inflammation in cardiovascular disease. A previous study shows that elevated RDW is closely related to poor prognosis in conditions such as coronary heart disease, heart failure, and acute myocardial infarction³. Another study has reported that elevated RDW levels before or after intervention are associated with ISR, reflecting the potential impact of systemic inflammatory status on vascular healing after stent implantation⁴. Stent length, as a procedural parameter, has also been reported to be associated with ISR, with longer stents linked to a higher incidence of restenosis^5,6.

Although RDW and stent length have been associated with ISR, current studies have several limitations. Most studies have focused on patients with stable coronary artery disease, such as stable or unstable angina, while relatively few have investigated patients with acute myocardial infarction. In addition, previous studies have mainly analyzed single indicators and lacked a systematic evaluation of the combined predictive value of these factors.

This study aimed to evaluate the association of RDW and stent length with ISR in patients with ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention, and to assess their individual and combined predictive value. These findings may provide a practical approach for risk assessment in clinical practice. To our knowledge, this study evaluates the combined predictive value of RDW and stent length for ISR specifically in patients with ST-segment elevation myocardial infarction, a population in which this relationship has been less extensively explored.

Protocol

This study was approved by the Ethics Committee of Chengdu Second People’s Hospital (Approval No. KYPJ2025553) and conducted in accordance with the Declaration of Helsinki. The requirement for informed consent was waived due to the study’s retrospective design.

A schematic of the study workflow (including patient selection, grouping, and analysis pipeline) is shown in Figure 1.

Figure 1. Study workflow for patient selection, grouping, and analysis. A total of 170 patients with ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention with drug-eluting stent implantation at Chengdu Second People’s Hospital (January 2022–January 2024) were included after application of inclusion and exclusion criteria. All eligible patients underwent 12-month follow-up coronary angiography and were categorized into the in-stent restenosis (ISR) group (n = 32) and the non-ISR group (n = 138). Clinical characteristics, stent-related parameters, and laboratory indices, including red blood cell distribution width (RDW), were collected. Statistical analyses included group comparison, multivariate logistic regression, and receiver operating characteristic (ROC) curve analysis to identify factors associated with ISR and evaluate predictive performance. Please click here to view a larger version of this figure.

Participant Selection
A total of 170 patients who underwent successful stent implantation (defined as residual stenosis <20%, thrombolysis in myocardial infarction (TIMI) grade 3 flow, no dissection, and no occlusion of major branches) in the cardiology department of our hospital from January 2022 to June 2024 were included. Among them, 132 were male and 38 were female, with an age range of 31–86 years (66.23 ± 12.26). Based on the results of 12-month follow-up coronary angiography, patients were divided into the ISR group and the non-ISR (control) group.

Patients were included if they met the following criteria: symptom onset within 24 h and admission meeting the diagnostic criteria of the Emergency Rapid Diagnosis and Treatment Guidelines for Acute Coronary Syndrome⁷; first successful single-vessel drug-eluting stent implantation (1–2 stents within one vessel); and completion of 12-month follow-up coronary angiography.

Patients were excluded if they had contraindications to PCI or a history of prior PCI or coronary artery bypass graft surgery; poor compliance preventing regular secondary prevention treatment; refusal to undergo follow-up coronary angiography; incomplete clinical or laboratory data; chronic obstructive pulmonary disease or other local or systemic infections; severe valvular disease, cardiomyopathy, congenital heart disease, autoimmune disease, hematologic disease, or advanced malignancy; severe liver or renal dysfunction; or death during the follow-up period. In addition, patients with chronic kidney disease stage 4–5 who were not undergoing dialysis were excluded, whereas those undergoing dialysis were included.

ISR was defined as ≥50% diameter stenosis within the stent or within 5 mm of its edges, assessed by quantitative coronary angiography. All angiograms were anonymized and coded. Two experienced interventional cardiologists, blinded to clinical data, independently evaluated ISR. Discrepancies were resolved by a third blinded senior expert.

Treatment Plan
The PCI procedure and perioperative management were performed according to current clinical guidelines⁸. Postoperative secondary prevention followed established guidelines⁹, including dual antiplatelet therapy, lipid-lowering therapy, and other standard treatments.

PCI procedure:
All procedures were performed via the radial artery approach. Lesion preparation was conducted based on angiographic characteristics. Drug-eluting stents (DESs; Resolute Integrity [zotarolimus-eluting] or Promus Premier [everolimus-eluting]) were implanted. Post-dilation was performed at high pressure, and final angiography confirmed residual stenosis <20% and TIMI grade 3 flow.

Perioperative medication:
Patients received loading doses of antiplatelet therapy before PCI (aspirin 300 mg, clopidogrel 300 mg, or ticagrelor 180 mg). During PCI, unfractionated heparin (70–100 IU/kg) was administered for anticoagulation. After PCI, patients received aspirin (100 mg once daily), clopidogrel (75 mg once daily), or ticagrelor (180 mg once daily), along with statins (atorvastatin 20 mg once daily), and other medications as clinically indicated.

Postoperative management and follow-up:
Patients received health education to improve adherence and were instructed to continue secondary prevention therapy, including dual antiplatelet therapy for at least 12 months. Follow-up visits were conducted at 1, 3, 6, and 12 months after PCI.

Coronary angiography follow-up:
Repeat coronary angiography was performed in patients with suspected ischemic symptoms, including persistent or recurrent chest pain, chest tightness, decreased exercise tolerance, or dynamic electrocardiographic changes. In asymptomatic patients, routine follow-up angiography was performed at 12 months. For patients undergoing multiple angiographic evaluations, only the first follow-up angiography was included in the analysis. Among the cases of ISR, some were identified during symptom-driven angiographic evaluation, while others were detected during routine 12-month follow-up; however, the exact proportions were not separately analyzed in this study and may introduce potential detection bias. Variability in follow-up timing was not adjusted analytically and is acknowledged as a potential source of bias.

General Data Collection
Demographic and clinical data, including age, sex, height, weight, and body mass index, were recorded. Smoking status (≥1 cigarette/day for >1 year), hypertension, and type 2 diabetes were documented. Medication use during follow-up, including type and adherence, was recorded. Stent length was obtained from procedural records and defined as the total implanted stent length per target vessel. Medication adherence was assessed based on outpatient follow-up records and patient self-report. Coronary angiographic data included target vessel, lesion location, lesion type, and lesion severity. Stent-related data included implantation site, stent type, stent length (obtained from procedural records), and stent diameter.

Hematological Index Detection
Laboratory data were collected during the first PCI hospitalization. Blood lipid measurements were performed after an 8–12 h fasting period. Parameters included complete blood count (white blood cell count, neutrophil percentage, lymphocyte percentage, hemoglobin, RDW, and platelet count), creatinine, albumin (ALB), and lipid profile (triglycerides [TG], total cholesterol [TCHO], low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], apolipoprotein A1, and apolipoprotein B). Calculated ratios included TCHO/HDL-C, apolipoprotein A1/B, and RDW/ALB. All measurements were performed in the hospital central laboratory using automated analyzers according to manufacturer protocols.

RDW measurement procedure: 2–3 mL of venous blood was collected in ethylenediaminetetraacetic acid–anticoagulated tubes. Samples were mixed and analyzed using an automated hematology analyzer for cell counting and RDW calculation. All laboratory measurements were performed using the analyzers listed in the Table of Materials according to manufacturer protocols.

Statistical Methods
All statistical analyses were performed using SPSS version 27.0. Baseline characteristics, hematological indices, and stent-related parameters were compared between the ISR and non-ISR (control) groups. Quantitative variables were tested for normality using the Shapiro–Wilk test. Normally distributed data were expressed as mean ± standard deviation and compared using the independent samples t-test. Non-normally distributed data were expressed as median (P₂₅, P₇₅) and compared using the rank-sum test. Categorical variables were expressed as percentages and compared using the χ² test. Univariate and multivariate logistic regression analyses were performed to identify factors associated with ISR. Variables included in the multivariate logistic regression model were selected based on clinical relevance and results of univariate analysis, and all selected variables were entered simultaneously using the enter method. Receiver operating characteristic (ROC) curves were constructed to evaluate the predictive performance of RDW, stent length, and their combination. A two-sided P < 0.05 was considered statistically significant.

Results

Incidence of ISR and Baseline Characteristics
A total of 170 patients with STEMI who underwent emergency PCI and stent implantation were followed for 12 months, and all patients underwent coronary angiography re-examination. Among them, 32 patients developed ISR, while 138 patients did not develop ISR and served as the comparison (non-ISR) group. The baseline characteristics of the two groups were comparable, with no significant differences observed. However, stent length was greater in the ISR group...

Discussion

Previous studies have demonstrated the prognostic significance of RDW in various cardiovascular diseases. In the present study, RDW levels prior to intervention and stent length were independently associated with DES restenosis in patients with acute ST-segment elevation myocardial infarction. In addition, the combined use of these two indicators showed higher predictive efficacy than either parameter alone. These findings extend existing evidence by demonstrating the combined predictive value of RDW and stent length spe...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
	Philips	Azurion 7 M12	Coronary angiography imaging system used for diagnostic and follow-up angiography
	Mindray	BriCyte-E6	Hematology analyzer used for complete blood count and RDW measurement
	Hitachi, Japan	Hitachi 008 AS	Biochemical analyzer used for measurement of lipid profiles, creatinine, and albumin
	Medtronic	Resolute Integrity	Drug-eluting stent used for coronary stent implantation
	Boston Scientific	Promus Premier	Drug-eluting stent used for coronary stent implantation
	IBM	SPSS v27.0	Statistical software used for data analysis