Prevalence of Subclavian Artery Stent Fractures and Their Impact on Restenosis Development

Introduction - Stenting is the preferred, minimally invasive treatment for subclavian artery (SA) steno-occlusive disease. Stent fractures in the SA have not been assessed in large cohorts. Our aim was to determine the prevalence of SA stent fractures, identify predisposing factors, and analyse their impact on restenosis development. Methods - 120 patients (71 women; mean age: 59.4+/-9.0 years) with symptomatic significant SA stenosis who underwent stenting between 2002 and 2014 at our Department were included in the study. In 2016, patients were asked to return for a fluoroscopic examination of the implanted stents. Stent fractures were defined as type I: single-strut fracture, type II: > 2 strut fractures without deformation, type III: > 2 strut fractures with deformation, type IV: multiple strut fractures with acquired transection but without gap, and type V: multiple strut fractures with acquired transection with gap in the stent body. Colour duplex scan was used to monitor stent patency. In case of continuous variables t or Mann-Whitney U tests, while in case of categorical variables chi-square or Fisher exact tests were performed. Results - 122 stents were deployed (balloon-expandable, n = 94; self-expandable, n = 28). The median follow-up time was 81.4 (41.1-113.7) months. 43 (35.2%) stent fractures were detected (type I-II, n = 28; type III-V, n = 15). The difference between the fractured (n = 43) and non-fractured (n = 79) groups was non-significant regarding the atherosclerotic risk factors (age > 70 years, female sex, smoking, hypertension, hyperlipidemia, diabetes mellitus, obesity, chronic kidney disease), underlying pathology (atherosclerosis, restenosis, radiation-induced arteriopathy, vasculitis), lesion location, and stenosis grade. Calcifications, long lesions (> 20 mm), and long balloon-expandable stents (> 20 mm) were more common in the fractured than in the non-fractured groups (86.0% versus 43.0%, P < 0.001; 51.2% versus 20.3%, P < 0.001; 62.8% versus 40.5%, P = 0.036, respectively). The restenosis and reintervention rates were significantly higher in patients with type III-V fractures compared to those with type I-II fractures (60.0% versus 3.6%, P < 0.001; 46.7% versus 3.6%, P < 0.001, respectively). Conclusion - Fractures frequently occur. Lesion and stent characteristics have an influence on fracture rate. Complex fractures increase the risk of restenosis.