Short-term risk of recurrent stroke in symptomatic carotid near-occlusion: pooled analysis of three cohort studies

Carotid near-occlusion (CNO) is a severe carotid stenosis causing distal internal carotid artery (ICA) diameter reduction, classifiable as with or without full collapse. Whether full collapse confers an especially high short-term recurrent stroke risk is debated, and no prior pooled analysis has quantified the ultra-early (0-2 day) risk.

Pooled individual patient data from 3 prospective cohort studies (TransAtlantic Carotid Near-Occlusion Study [TACNOS], UCC [Umeå Carotid Cohort], CAsi Oclusión Sintomática [CAOS]). The primary outcome was ipsilateral ischaemic stroke or retinal infarction within 90 days, censored at revascularisation. Full collapse was defined by visual appearance and by measurement (distal ICA ≤ 2.0 mm and/or ICA ratio ≤ 0.42). Cox regression and pre-specified sensitivity analyses addressing ascertainment bias and informative censoring were performed.

A total of 360 patients with symptomatic CNO were included. The 90-day recurrent stroke risk was 16.4% (95% CI, 11.7%-21.1%), with 5.9% within the first 2 days. Per-cohort rates differed markedly (TACNOS 23.9%, UCC 22.3%, CAOS 8.1%; I2 = 77%, P = .012). By visual appearance (n = 333), 90-day stroke risk did not differ by collapse status (adjHR 1.5; 95% CI, 0.8-2.9). By measurement (n = 219), full collapse was associated with higher stroke risk (adjHR 2.0; 95% CI, 1.0-3.9). For both definitions, full collapse strongly predicted 0-2 day recurrence (adjHR 4.0; 95% CI, 1.5-10.5 and adjHR 4.8; 95% CI, 1.8-12.8). Full collapse combined with TIA identified a subgroup with 90-day stroke risk of 37.8% (by appearance) and 50.4% (by measurement).

Findings should be interpreted in the context of substantial between-study heterogeneity and informative censoring; sensitivity analyses confirmed the robustness of the estimates.

Carotid near-occlusion with full collapse carries a markedly elevated risk of stroke recurrence within 48 h, supporting dedicated trials of urgent revascularisation strategies. In exploratory analysis, presentation with TIA appeared to identify a particularly high-risk subgroup, a hypothesis-generating observation that requires independent validation.