Mid-term risk factor analysis and predictors of restenosis in patients undergoing carotid artery stenting

INTRODUCTION: This study investigated the timing and risk factors of restenosis (≥50% stenosis) in patients undergoing carotid artery stenting (CAS). METHODS: This retrospective case series included patients who underwent CAS between January 2007 and December 2022 at a tertiary referral vascular centre in Hong Kong. Patient demographics, co-morbidities, operative details, and clinical and radiological surveillance findings were reviewed. Univariate and multivariable Cox regression analyses were performed. RESULTS: In total, 120 CAS procedures (13 bilateral) were performed in 102 patients. Overall, 80% of patients were male (mean age: 66.9 years), and 45 (37.5%) were symptomatic preoperatively. The mean follow-up duration was 6.7 ± 4.2 years. Post-procedure, ipsilateral stroke occurred in 10 (8.3%) cases; the stroke-related mortality rate was 2.5%. In all, 51 (46.4%) of 110 evaluable cases developed restenosis, of which 29 (26.3%) occurred within 1 year postoperatively. The mean time to ≥50% restenosis development was 94.9 months. Univariate Cox regression analysis showed that a history of nasopharyngeal carcinoma (hazard ratio [HR]=2.12; P=0.01) and previous neck radiotherapy (HR=2.96; P<0.001) were significantly associated with higher restenosis risk. A greater number of stents, longer stent length, and post-dilation balloon diameter >5.5 mm (all P<0.001) were linked to higher restenosis risk. In multivariable Cox regression analysis, a history of radiotherapy (HR=3.72; P=0.01) and larger post-dilation balloon diameter (HR=2.10; P=0.01) remained associated with higher restenosis risk. CONCLUSION: The 12-month restenosis rate was 26.3%, although restenosis rarely caused new neurological events. A history of radiotherapy and larger post-dilation balloon diameter were associated with higher restenosis risk.