Predictors of in-stent restenosis in patients undergoing percutaneous coronary intervention

Abstract

Objectives: Clinical, angiographic, and biochemical factors associated with in-stent restenosis were retrospectively analyzed in patients undergoing percutaneous coronary intervention.

Materials and methods: Patients who had undergone follow-up angiography for de novo lesions six months after bare metal stent (BMS) and nine months after drug eluting stent (DES) implantation were retrospectively analyzed. Demographic, angiographic, and clinical parameters were collected from our patient database: In-stent restenosis (ISR) was defined as >50% narrowing of stent lumen or coronary artery 5 mm adjacent to stent edges. Retrospectively 319 patients with a mean age of 57.6 years were included in this study.

Results: In-stent restenosis occurred in 26.6% of the patients with drug-eluting stent and 36.5% of the patients with bare-metal stent implanted. Tobacco use was significantly more frequent among patients with in-stent restenosis.

Conclusion: In-stent restenosis rates in our study is consistent with the literature. Studies are ongoing to overcome this challenging problem.

Introduction

Percutaneous coronary intervention (PCI) is the most commonly preferred approach in most patients.[5] In-stent restenosis (ISR), defined as >50% narrowing of stent lumen or coronary artery 5 mm adjacent to stent edges, is a restricting complication of PCI leading to repeat revascularization. Inflammation, patient characteristics, and mechanical factors have been characterized as predictors of ISR.[6-9]

In this study, we retrospectively analyzed the effect of clinical, angiographic, and biochemical factors on ISR in patients who underwent PCI.

Patients and Methods

Patients who had undergone control angiogram six months after bare metal stent (BMS) and nine months after drug eluting stent (DES) implantation for de-novo lesions at Istanbul University Cardiology Institute between October 2007-April 2008 and January 2011- April 2012 were retrospectively analyzed. Patients without control angiogram (n=181),
patients with only coronary balloon angioplasty (n=46), and stent implantation to bypass graft veins (n=20) were excluded from the study. Demographic, angiographic, and clinical parameters were collected from our patient database: Gender, age, primary indication for PCI, creatinine, diabetes mellitus (DM), history of coronary artery disease (CAD), history of heart failure, history of cerebrovascular disease, dyslipidemia, tobacco use, and hypertension. In-stent restenosis (ISR) was defined as >50% narrowing of stent lumen or coronary artery 5 mm adjacent to stent edges.

The study was conducted with the approval of the Local Research Ethics Committee. A written informed consent was obtained from each patient. The study was conducted in accordance with the principles of the Declaration of Helsinki.

Statistical analysis
Continuous variables were expressed as mean ± standard deviation and categorical variables were expressed as percentage (%). Categorical variables were compared using the chi-square test. Student’s t-test was used to compare the continuous variables. All analyses were performed using SPSS for Windows version 15.0 software (SPSS, Inc., Chicago, Illinois, USA). A two-sided value less than 0.05 was considered statistically significant within a 95% confidence interval (CI).

Results

A total of 319 patients with a mean age of 57.6 years were included in this retrospective study. Demographic and clinical characteristics are presented in Table 1. The angiographic characteristics of our patient population is demonstrated in Table 2. In-stent restenosis occurred in 99 patients (31%) of the entire group. Patients were divided into two groups according to ISR. Table 3 compares the clinical characteristics of patients with and without ISR. Table 4 compares the angiographic characteristics of patients with and without ISR. Tobacco usage was significantly more frequent among patients with ISR. Dyslipidemia was significantly more common in patients without ISR. There was no difference in angiographic and stent characteristics between the groups.

Discussion

In this study, factors associated with ISR were investigated in our population. In our study, ISR prevalence was 31%. In-stent restenosis occurred in 26.6% of the patients with DES and 36.5% with BMS. Although there is limited data on the prevalence of ISR in our country, ISR occurred in 27.9% of patients who underwent BMS implantation in our clinic between 1995 and 1996.[10] Drug-eluting stents were developed to lower the frequency of ISR. In our study population, although patients with DES implantation had lower rate of ISR, this difference did not attain significance. High rate of ISR in the DES group may be attributed to smaller stent diameter, longer stents, and complex coronary interventions.

Previous studies have reported female gender is associated with higher rates of ISR,[11] however, in our study, there was no significant difference between genders according to ISR.

Use of tobacco leads to endothelial disfunction, inflammation, and aggravation of cardiovascular disease.[12,13] Turak et al.[14] investigated the role of neutrophil/lymphocyte ratio in predicting BMS restenosis and reported smoking was an associated factor of ISR. In our study, tobacco use was significantly more common in patients with ISR although we did not have any data on continuous tobacco use until follow-up angiography.

Patients with dyslipidemia in our study group had significantly lower rates of ISR. This finding seemed conflicting as statins have a protective effect on neointimal hyperplasia and this finding may be attributed to statin use among patients with dyslipidemia.[15]

We investigated the target vessel as a potential factor for ISR. Stent implantation of the left anterior descending artery showed predisposition towards ISR.[16]

In conclusion, the ISR rates determined in our study was consistent with the literature. Studies are ongoing to overcome this challenging problem.

The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

The authors received no financial support for the research and/or authorship of this article.

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