Symptomatic carotid atheroma inflammation Lumen-stenosis score compared with Oxford and Essen risk scores to predict recurrent stroke in symptomatic carotid stenosis

Background: The Oxford Carotid Stenosis tool (OCST) and Essen Stroke Risk Score (ESRS) are validated to predict recurrent stroke in patients with and without carotid stenosis. The Symptomatic Carotid Atheroma Inflammation Lumen stenosis (SCAIL) score combines stenosis and plaque inflammation on fluorodeoxyglucose positron-emission tomography (18FDG-PET). We compared SCAIL with OCST and ESRS to predict ipsilateral stroke recurrence in symptomatic carotid stenosis.

Patients and methods: We pooled three prospective cohort studies of patients with recent (<30 days) non-severe ischaemic stroke/TIA and internal carotid artery stenosis (>50%). All patients had carotid 18FDG-PET/CT angiography and late follow-up, with censoring at carotid revascularisation.

Results: Of 212 included patients, 16 post-PET ipsilateral recurrent strokes occurred in 343 patient-years follow-up (median 42 days (IQR 13-815)).Baseline SCAIL predicted recurrent stroke (unadjusted hazard ratio [HR] 1.96, CI 1.20-3.22, p = 0.007, adjusted HR 2.37, CI 1.31-4.29, p = 0.004). The HR for OCST was 0.996 (CI 0.987-1.006, p = 0.49) and for ESRS was 1.26 (CI 0.87-1.82, p = 0.23) (all per 1-point score increase). C-statistics were: SCAIL 0.66 (CI 0.51-0.80), OCST 0.52 (CI 0.40-0.64), ESRS 0.61 (CI 0.48-0.74). Compared with ESRS, addition of plaque inflammation (SUVmax) to ESRS improved risk prediction when analysed continuously (HR 1.51, CI 1.05-2.16, p = 0.03) and categorically (ptrend = 0.005 for risk increase across groups; HR 3.31, CI 1.42-7.72, p = 0.006; net reclassification improvement 10%). Findings were unchanged by further addition of carotid stenosis.

Conclusions: SCAIL predicted recurrent stroke, had discrimination better than chance, and improved the prognostic utility of ESRS, suggesting that measuring plaque inflammation may improve risk stratification in carotid stenosis.