ABCD risk score does not predict the presence of cerebral microemboli in patients with hyper-acute symptomatic critical carotid artery stenosis

Introduction: ABCD risk score and cerebral microemboli detected by transcranial Doppler (TCD) have been separately shown to the predict risk of recurrent acute stroke. We studied whether ABCD risk score predicts cerebral microemboli in patients with hyper-acute symptomatic carotid artery stenosis. Participants and methods: We studied 206 patients presenting within 2 weeks of transient ischaemic attack or minor stroke and found to have critical carotid artery stenosis (≥50%). 86 patients (age 70±1 (SEM: years), 58 men, 83 Caucasian) had evidence of microemboli; 72 (84%) of these underwent carotid endarterectomy (CEA). 120 patients (age 72±1 years, 91 men, 113 Caucasian) did not have microemboli detected; 102 (85%) of these underwent CEA. Data were analysed using X and Mann–Whitney U tests and receiver operating characteristic (ROC) curves. Results: 140/206 (68%: 95% CI 61.63 to 74.37) patients with hyper-acute symptomatic critical carotid stenosis had an ABCD risk score ≥4. There was no significant difference in the NICE red flag criterion for early assessment (ABCD risk score ≥4) for patients with cerebral microemboli versus those without microemboli (59/86 vs 81/120 patients: OR 1.05 ABCD risk score ≥4 (95% CI 0.58 to 1.90, p=0.867)). The ABCD risk score was <4 in 27 of 86 (31%: 95% CI 21 to 41) embolising patients and in 39 of 120 (31%: 95% CI 23 to 39) without cerebral microemboli. After adjusting for pre-neurological event antiplatelet treatment (APT), area under the curve (AUC) of ROC for ABCD risk score showed no prediction of cerebral microemboli (no pre-event APT, n=57: AUC 0.45 (95% CI 0.29 to 0.60, p=0.531); preevent APT, n=147: AUC 0.51 (95% CI 0.42 to 0.60, p=0.804)). Conclusions: The ABCD score did not predict the presence of cerebral microemboli or carotid disease in over one-quarter of patients with symptomatic critical carotid artery stenosis. On the basis of NICE guidelines (refer early if ABCD ≥4), assessment of high stroke risk based on ABCD scoring may lead to inappropriate delay in urgent treatment in many patients. INTRODUCTION The risk of recurrent stroke following first transient ischaemic attack (TIA) or minor stroke is highest during the first 7–14 days. On the basis of evidence that the benefit of surgery is greatest if performed within 2 weeks after the last ischaemic event, the major NICE clinical guideline recommends that patients with symptomatic carotid artery stenosis have urgent endarterectomy within 2 weeks. Transcranial Doppler (TCD)-detected microemboli have provided direct evidence of thromboembolism as the main mechanism of symptomatic carotid artery disease. TCDdetected cerebral microembolic signals (MES) predict short-term stroke risk in patients with symptomatic carotid stenosis. The ABCD risk prognostic scoring system predicts who is likely to be at increased risk of suffering a recurrent early stroke following onset of an initial stroke/ TIA, irrespective of the mechanism for acute stroke or TIA. The ABCD risk score is based on standard cardiovascular risk factors, including history of diabetes, in addition to clinical features of carotid disease. Several major clinical guidelines 11 recommend that patients with an ABCD risk score ≥4 should be assessed within 24 hours and those with an ABCD risk score <4 should be evaluated within a week of symptoms onset. ABCD risk score and the presence of cerebral microemboli predict risk of early recurrence of stroke. The association between ABCD risk score and cerebral microemboli has not been studied. We therefore aimed to explore whether the ABCD risk score predicts the presence of cerebral microemboli in patients with hyper-acute symptomatic critical carotid artery stenosis. 41 Saedon M, et al. Stroke and Vascular Neurology 2017;2:e000073. doi:10.1136/svn-2017-000073 Open Access Warwick Medical School, University of Warwick, Coventry, UK University Hospitals Coventry Warwickshire NHS Trust, Coventry, UK Fellowship of Postgraduate Medicine, London, UK Yale School of Medicine, New Haven, Connecticut, USA