Defining an Algorithm for Long-Term Duplex Ultrasound Surveillance after Carotid Intervention

Carotid duplex ultrasound (DUS) surveillance imaging is used to evaluate for development of restenosis in the ipsilateral carotid artery and disease progression in the contralateral artery. The timing and duration of routine long-term DUS surveillance has not been well-defined. Further, the interpretation and application of DUS using velocity criteria has evolved over time both for endarterectomy and stenting. We sought to define a clinically useful algorithm for a surveillance protocol for all patients who undergo carotid interventions. A prospective observational study was performed on all patients following carotid intervention, including carotid endarterectomy, transfemoral carotid artery stenting, and transcarotid revascularization from 2012-2023 at a single academic center. Data collected included procedure date and type, DUS dates, and degree of carotid artery stenosis using velocity criteria. Internal carotid artery PSV <130 cm/s with visible plaque was categorized as 1%-49% stenosis. PSV >130 cm/s with ICA/CCA ratio >2 was categorized as 50%-69% stenosis. PSV >230 cm/s, EDV >130 cm/s, and ICA/CCA ratio >4 was categorized as 70%- 99% stenosis. Absent flow was interpreted as occlusion, although a confirmatory study was performed where clinically indicated. Restenosis and contralateral progression were recorded if DUS met criteria after at least two consecutive studies or if a patient became symptomatic. A total of 409 carotid interventions, of which 311 met inclusion criteria, were identified. Patients were 64% male/36% female, 83.0% White, 7.1% Hispanic, 6.4% other. Hemodynamically significant restenosis (>50%) occurred in 3.5% (n = 11) of patients up to 39 months postoperatively, three symptomatic for TIA and eight asymptomatic. Two required reintervention for asymptomatic >70% restenosis and one for symptomatic 50%-69% restenosis. Twenty-one patients (6.8%) developed progression up to 59.1 months postoperatively, 11 of whom underwent intervention (6 symptomatic, 5 asymptomatic). Intervention for 50%-69% symptomatic progression occurred at an earlier interval (37.8 months) than asymptomatic patients (54.7 months). Intervention for >70% symptomatic progression occurred at 31.51 months and 18.02 months for asymptomatic progression. Serial bilateral carotid artery DUS surveillance is useful in long-term monitoring for ipsilateral restenosis, but more so for contralateral progression up to 5 years post-procedurally. Intervention indications for contralateral progression may be best guided by symptomatic status at this time. However, it is likely that the utility of DUS velocity and ICA ratio criteria to guide management decision needs further exploration prior to applying to all carotid intervention types, and cost analysis is necessary to further advocate for a specific surveillance duration.