Researchers at the University of Hong Kong (HKU) found that the 12-month restenosis rate after carotid artery stenting (CAS) is about 26.3 percent, with a history of radiotherapy and post-dilatation balloon diameter being associated with higher restenosis risk, but restenosis rarely caused new neurological events.
The prospective study, carried out between January 2007 and December 2022, included a total of 120 consecutive CAS procedures performed in 102 patients at the Queen Mary Hospital’s vascular centre. All patients (male, 80 percent; mean age, 66.9 years; age range, 39–85 years) with carotid artery disease (CAD) received dual antiplatelet therapy (DAPT) consisting of aspirin 100 mg and clopidogrel 75 mg daily for 1 week before CAS. DAPT was continued for 3 months postoperatively, followed by lifelong clopidogrel monotherapy. All patients were followed according to a standardized prospective protocol, with clinical assessment and carotid duplex ultrasonography every 6 months. [Hong Kong Med J 2026;32:309-316]
During the study period, 89 patients underwent unilateral CAS, 13 underwent bilateral CAS, and three of those treated with bilateral CAS underwent multiple stenting procedures. CAS was performed in 45 (37.5 percent) symptomatic cases and 75 (62.5 percent) asymptomatic cases. The mean interval between two CAS procedures in the same patient was 13.9 months. The mean follow-up duration was 6.7 ± 4.2 years. Hypertension was present in 64.2 percent of the patients, diabetes mellitus in 24.2 percent, ischaemic heart disease in 13.3 percent, and 61.7 percent had previous neck radiotherapy.
Among 110 evaluable cases, 53.6 percent remained patent without restenosis at the most recent follow-up scan, whereas 46.4 percent (including bilateral and/or reintervention CAS procedures) developed ≥50 percent restenosis, of which 26.3 percent occurred within 1 year postoperatively. The mean time to development of ≥50 percent restenosis was 94.9 ± 31.9 months. No ischaemic stroke occurred within 30 days postoperatively. However, among patients with restenosis, five subsequently experienced ipsilateral stroke and two of these died of stroke or related complications.
Comparison of comorbidity profiles associated with restenosis found higher prevalence of hypertension in patients without restenosis (74.6 vs 50.9 percent, p=0.01), and higher prevalences of nasopharyngeal carcinoma (62.7 vs 42.4 percent; p=0.03) and previous neck radiotherapy (74.5 vs 47.5 percent; p=0.004) in patients who developed restenosis. Patients with restenosis also had a significantly greater mean number of stents (1.1 vs 1.4 stents; p=0.001) and longer mean stent length (43.6 vs 56.0 mm; p=0.001).
According to the authors, the paucity of data on risk factors associated with in-stent restenosis after CAS in Asian patients prompted the study.
“Although the underlying mechanism for increased restenosis risk is not well understood, it is speculated that aggressive oversizing during post-dilation can cause greater intimal injury and promote more severe restenosis,” wrote the authors. “Caution should be exercised when selecting the appropriate balloon size for post-stenting dilation.”