Micro-embolic signal monitoring in stroke subtypes: A systematic review and meta-analysis of 58 studies

Abstract

Introduction Micro-embolic signals (MESs) detected using transcranial Doppler (TCD) help in risk stratification in stroke patients. A systematic review and meta-analysis were performed to estimate the prevalence of MES and its association with stroke recurrence, functional outcome, and mortality in different stroke subtypes. Methods A comprehensive literature search was conducted before 26th January 2021 in PubMed, Embase, Google Scholar, Cochrane Library, and ClinicalTrials.gov . Studies were identified that used TCD to detect MES in stroke/TIA patients. Pooled prevalence and odds ratio (OR) along with 95% confidence interval (95% CI) were calculated for different outcome measures. The entire statistical analysis was conducted in R version 3.6.2. Findings Fifty-eight studies involving 5123 patients (1329 MES+, 3794 MES−) were included in our meta-analysis. The pooled prevalence of MES among all acute stroke/TIA patients was 30% (95% CI 25-34%). The pooled prevalence adjusted after the trim-and-fill analysis among all acute stroke/TIA patients was 18% (95% CI 14-23%). The prevalence of MES was high among all stroke subtypes except in patients with small vessel disease (SVD). In patients with new-onset stroke/TIA, the presence of MES was associated with a high risk of recurrence of cerebral ischemia (OR 4.03; 95% CI 2.38-6.82). Although no significant association was observed for the presence of MES with increased mortality (OR 2.37; 95% CI 0.75-7.50) and poor functional outcome (OR 2.11; 95% CI 0.20-22.50) among patients with new-onset stroke/TIA, this could only be determined in a smaller sample size of 477 patients. Conclusions Our meta-analysis showed a 30% prevalence of MES following acute stroke/TIA. The presence of MES increased the chance of recurrence of cerebral ischemia but was not associated with poor functional outcomes and mortality in the studied subgroup.

Detection of microemboli in patients with acute ischaemic stroke and atrial fibrillation suggests poor functional outcome

“…21 MES detected through TCD monitoring can serve as a surrogate for future ischaemic lesions and subsequent ischaemic events. 11,12,17 New cerebral ischaemic lesions, even if not linked to a sudden clinical event, predict new neurological deficits, including cognitive impairment. 23…”

“…Numerous studies have been unable to find evidence supporting the association between MES and poor outcomes following a stroke. 17 However, many of these studies encompassed various stroke types, often including patients with small vessel disease, which clearly doesn’t align with the recording of microembolism in the primary stem of the middle cerebral artery. Most cases that tested positive for MES in prior studies were likely associated with carotid atherosclerosis, and the prognosis for these patients significantly differs from those with atrial fibrillation.…”

“…This percentage aligns with the findings of a recent meta-analysis encompassing all MES studies in acute stroke. 17 However, it must be noted that the majority of previous studies involving patients with AF did not account for the use of anticoagulants, which significantly influences the occurrence of MES.…”

“…21 MES detected through TCD monitoring can serve as a surrogate for future ischaemic lesions and subsequent ischaemic events. 11,12,17 New cerebral ischaemic lesions, even if not linked to a sudden clinical event, predict new neurological deficits, including cognitive impairment. 23 We must acknowledge that the size of the study cohort was relatively small, resulting in large confidence intervals for the calculated odds ratio.…”

European Stroke Organisation (ESO) Guidelines on Moyamoya angiopathy Endorsed by Vascular European Reference Network (VASCERN)

“…Regarding the latter, there are some studies describing the finding of microembolic signals (MES) or high intensity transient signals (HITS) using transcranial Doppler in patients with MMA, [116][117][118] which could represent embolic risk. 119 One retrospective study in a small population of MMA observed a reduction of MES after antiplatelet administration or regimen change. 120 Direct embolism has been even also visualised during surgery in a MMA patient.…”