Plaque Echolucency and the Risk of Ischaemic Stroke in Patients with Asymptomatic Carotid Stenosis Within the First Asymptomatic Carotid Surgery Trial (ACST-1).
Level 3 - non-randomized controlled study
Post-hoc observational cohort analysis of an RCT medical-therapy arm evaluating a prognostic factor.
PubMed 26725253 · doi:10.1016/j.ejvs.2015.11.013
What was done
A post-hoc prognostic analysis was performed in 814 patients with asymptomatic carotid stenosis who had been randomized to medical therapy alone in the Asymptomatic Carotid Surgery Trial-1 (ACST-1). Baseline carotid plaque appearance was classified as definitely echolucent (> 25% soft plaque) or nonecholucent (< 25% soft plaque). Kaplan-Meier survival curves and adjusted models were used to compare cumulative ipsilateral ischaemic stroke rates between the groups over 5- and 10-year follow-up periods.
What was found
During the first 5 years of follow-up, the cumulative risk of ipsilateral ischaemic stroke was significantly higher in patients with definitely echolucent plaques (8.0%; 95% CI 6.4–9.6) compared with nonecholucent plaques (3.1%; 95% CI 2.1–4.1; p = .009). Following adjustment for other risk factors, echolucency was associated with a 2.5-fold increased risk of ipsilateral ischaemic stroke (hazard ratio 2.52; 95% CI 1.20–5.25; p = .014). At 10 years, stroke risk did not significantly differ (p = .233), coinciding with a sharp rise in lipid-lowering therapy in years 5–10 that was prescribed significantly more often to patients with echolucent plaques (p = .001).
Why it matters
Carotid plaque echolucency on ultrasound can identify a subgroup of asymptomatic carotid stenosis patients at substantially higher medium-term stroke risk who might benefit preferentially from revascularization.
Limits
The study was a post-hoc analysis with a low total number of stroke events. Plaque characterization relied on categorical visual assessment rather than automated quantitative grayscale analysis. Changing medical management over time, particularly differential statin adoption in later years, confounded 10-year risk comparisons.
Cited by
- supports Carotid intima-media thickness (CIMT) ultrasound imaging is able to detect soft, non-calcified plaque in the carotid artery wall.