Post-Carotid Stent Imaging Surveillance
Perform carotid duplex ultrasound surveillance at 1 month, 6 months, and then annually after carotid artery stenting to detect restenosis and ensure long-term patency. 1
Initial Post-Procedure Imaging
Obtain the first duplex ultrasound within 1 month after CAS to establish a baseline, assess technical success, and identify any acute complications such as residual stenosis or early thrombosis. 1, 2
This initial imaging is critical because it can detect technical issues from the procedure itself, which occur in approximately 1% of cases and represent incomplete revascularization rather than true restenosis. 1
Subsequent Surveillance Schedule
Perform follow-up duplex ultrasound at 6 months after the initial 1-month study to detect early in-stent restenosis, which typically occurs within 18 months and is primarily due to neointimal hyperplasia. 1
Continue annual surveillance thereafter to monitor for late restenosis (occurring ≥5 years post-procedure) caused by progressive atherosclerosis, and to assess contralateral disease progression. 1
Once stability has been established over an extended period, surveillance at longer intervals may be appropriate, and termination of surveillance is reasonable when the patient is no longer a candidate for intervention. 1
Velocity Criteria for Significant In-Stent Restenosis
Use stent-specific velocity thresholds when interpreting post-CAS duplex studies, as standard non-stented artery criteria significantly overestimate restenosis. 1
Peak systolic velocity ≥3 m/s and end-diastolic velocity ≥1.4 m/s indicate ≥70% in-stent restenosis requiring angiographic verification for potential intervention. 1
Be aware that "normal" in-stent velocities vary by stent design—open-cell stents (more conformable) versus closed-cell stents (greater bending stiffness) produce different flow characteristics. 1
Clinical Follow-Up Requirements
Perform formal neurological examination within 24 hours before and after CAS, and document findings at each surveillance visit to assess for delayed neurological events. 1
Clinical follow-up plays an equally important role as imaging surveillance in assessing both periprocedural complications and long-term stroke prevention efficacy. 1
Restenosis Rates and Clinical Significance
In-stent restenosis after CAS is usually clinically asymptomatic, though presentations as stroke or TIA may occur, particularly with an isolated hemisphere or rapid progression. 1
Recent meta-analysis of 20 RCTs showed no increase in late ipsilateral stroke with restenosis after CAS, contrasting with CEA where significant restenosis (70-99%) increased late ipsilateral stroke risk (OR 3.87,95% CI 1.96-7.67). 1
Restenosis rates vary by stent design, with braided stents showing higher risk (OR 2.71 for first restenosis, OR 3.11 for recurrent restenosis) compared to other designs. 1
Risk Factors Requiring Enhanced Surveillance
Consider more frequent monitoring in patients with clinical risk factors for restenosis, including:
- Diabetes mellitus 1
- Dyslipidemia 1
- Female gender 1
- Chronic kidney disease 1
- Active smoking 1
- Residual stenosis after the primary procedure 1
- Contralateral stenosis >50% 1
Critical Pitfalls to Avoid
Never apply non-stented artery velocity criteria to stented arteries, as this leads to significant overestimation of in-stent restenosis and unnecessary interventions. 1
Do not delay the 1-month surveillance study, as early detection of technical issues or acute thrombosis is essential for preventing stroke and allows for timely intervention. 1, 2
Recognize that first-generation single-layer stents may fail to effectively sequestrate atherosclerotic lesions, potentially allowing continued intra-stent plaque growth that manifests as late restenosis. 1
Ensure patient compliance with post-procedural antiplatelet regimen (DAPT with aspirin and clopidogrel for at least 1 month), as this minimizes thrombosis and restenosis risk. 1