In-stent Restenosis of the Carotid Artery: Revised Velocity Thresholds
Why 'Native' Thresholds Cannot Be Applied
In a stented artery, the wall compliance is altered, so the velocity thresholds for in-stent restenosis are higher than for a native carotid artery. Additionally, a mismatch between the stent and artery diameter itself locally increases PSV at the stent and its distal end—but without a 'turbulent trail'. This is not restenosis.
Criteria for Significant In-stent Restenosis
According to Mohabat et al., the criteria for significant stent restenosis are: PSV >280 cm/s and RAR >4.5 (sensitivity 93%, specificity 99%).
Other data suggest even higher thresholds for ≥70% restenosis: PSV ≥395 cm/s or RAR ≥5.1.
| Criterion | Threshold | Source |
|---|---|---|
| Significant Restenosis | PSV >280 cm/s and RAR >4.5 | Mohabat et al. |
| Restenosis ≥70% | PSV ≥395 cm/s or RAR ≥5.1 | other data |
How to Differentiate True Restenosis from Artifact
True restenosis results in flow acceleration with post-stenotic turbulence and dampening of the distal spectrum throughout. Local acceleration without a turbulent trail reflects a stent/artery diameter mismatch and is not restenosis.
The key to diagnosis: acceleration + post-stenotic turbulence + distal dampening indicates restenosis; isolated local acceleration without a turbulent trail is an artifact of diameter mismatch.
Frequently asked questions
What thresholds should be used for significant in-stent restenosis?
According to Mohabat et al.: PSV >280 cm/s and RAR >4.5 (sensitivity 93%, specificity 99%).
Are there stricter thresholds for ≥70% restenosis?
Yes, other data suggest PSV ≥395 cm/s or RAR ≥5.1.
Why can't native thresholds be applied in a stent?
Altered wall compliance elevates velocities; thresholds for stented arteries are higher than native ones.
How to differentiate diameter mismatch artifact from true restenosis?
Diameter mismatch causes local acceleration without a turbulent trail. True restenosis is acceleration with post-stenotic turbulence and distal dampening.