Microembolic signals and clinical outcome in patients with acute stroke--a prospective study

Microembolic Signals Detected by Transcranial Doppler Predict Future Stroke and Poor Outcomes

BACKGROUND AND PURPOSE

Although transcranial Doppler detects microembolic signals (MES) in numerous settings, the practical significance of such findings remains unclear.

METHODS

Clinical information from ischemic stroke or transient ischemic attack patients (n = 248) who underwent embolic monitoring from January 2015 to December 2018 was obtained.

RESULTS

MES were found in 15% of studies and ischemic recurrence was seen in 11% of patients (over 7 ± 6 days). Patients with MES had more lacunes than those without MES (1 ± 3 vs. 1 ± 2, P = .016), were more likely to have ischemic recurrence (37% vs. 6%, P < .001), undergo a future revascularization procedure (26% vs. 10%, P = .005), have a longer length of stay (9 vs. 4 days, P = .043), and have worse functional disability at discharge (modified Rankin Scale 3-6, 66% vs. 34%, P < .001). After controlling for several relevant cofactors, patients with MES were more likely to have ischemic recurrence (HR 4.90, 95% CI 2.16-11.09, P < .001), worse functional disability (OR 3.31, 95% CI 1.22-8.99, P = .019), and longer length of stays (β = .202, P < .001).

CONCLUSIONS

MES may help to risk stratify patients as their presence is associated with ischemic recurrence and worse outcomes.

Microemboli After Successful Thrombectomy Do Not Affect Outcome but Predict New Embolic Events

Background and Purpose- We aimed to determine if microemboli after endovascular thrombectomy correlate with unfavorable outcomes despite successful recanalization. Methods- This is a prospective multicenter study of consecutive patients with ischemic stroke and occlusion of anterior circulation vessels (terminal internal carotid or main trunk of the middle cerebral artery/first-order branch of the main trunk of the middle cerebral artery segments of middle cerebral artery) after successful thrombectomy (modified Treatment In Cerebral Ischemia grades 2b-3). Microembolic signals (MES) were assessed by 30 minutes of transcranial Doppler monitoring within 72 hours of the last-seen-well time. Major outcomes included modified Rankin Scale at 90 days and infarct volume on head computed tomography at 24 hours. We also assessed early outcomes based on National Institutes of Health Stroke Scale variation and recurrence of stroke, transient ischemic attack, or systemic embolism within 90 days. Results- Among 111 patients, MES were detected in 43 (39%), with a median rate of 4 counts/h (interquartile range 2-12). The occurrence of MES was not associated with a significant difference in modified Rankin Scale (ordinal shift analysis, adjusted odds ratio, 1.06 [95% CI, 0.48-2.34] P=0.85) nor in functional independence (modified Rankin Scale, 0-2: adjusted odds ratio, 0.52 [95% CI, 0.19-1.39] P=0.19). Patients with and without MES had similar infarct volumes (adjusted beta, 11.2 [95% CI, -46.6 to +22.9] P=0.51) on 24-hour computed tomography. MES did predict new embolic events (adjusted Cox hazard ratio, 6.78 [95% CI, 1.63-27.8] P=0.01). Conclusions- MES detected by transcranial Doppler following endovascular treatment of anterior circulation occlusions do not predict clinical or radiological outcome. However, such emboli are an independent marker of recurrent embolic events within 90 days.

Microembolic signal monitoring of TOAST‑classified cerebral infarction patients

The aim of the present study was to investigate the effects of microembolic signals (MES) on post‑stroke neurological deficits, stroke recurrence and survival in patients with acute cerebral infarction (CI). Patients with acute CI were enrolled consecutively and classified etiologically into the following 4 subtypes using the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification: i) Cardioembolism (CE); ii) large‑artery atherosclerosis (LA); iii) small‑vessel disease (SVD); and iv) stroke of other etiology, including other and undetermined etiologies. The MES of cerebral arteries were monitored by transcranial doppler (TCD), carotid atherosclerotic lesions were detected by color Doppler sonography and extracranial and intracranial magnetic resonance angiography were performed. Next, the severity of neurological deficits was evaluated using National Institutes of Health Stroke Scale (NIHSS) scores. Cases of stroke recurrence and post‑stroke mortality were recorded. A total of 135 patients were recruited, including 33 with CE, 49 with LA, 24 with SVD and 29 with stroke of other etiology. A significant difference in the incidence of MES was identified between the 4 subtypes (P=0.025). The occurrence of positive MES was found to markedly correlate with a history of coronary heart disease (P<0.001) and antithrombotic treatment (P=0.045) and increased levels low density lipoprotein (P=0.036). Compared with patients with negative MES, no significant changes in NIHSS scores were found in patients with positive MES on days 1 and 7 following admission. The incidence of recurrent stoke and post‑stroke mortality was elevated 3 months from the onset of CI. In conclusion, a significant difference in the occurrence of MES was identified between subtypes of patients with acute CI. The incidence of recurrent stroke and mortality was increased among patients with positive MES 3 months from onset.

Microemboli-monitoring during the acute phase of ischemic stroke: is it worth the time?

Background

The prevalence of microembolic signals (MES) during the acute phase of ischemic stroke and its influence on outcome is not well studied. The aim of our study was to determine the prevalence of MES, the different factors that are associated with the presence of MES and the association between MES and outcomes in stroke patients investigated within 6 hours after the onset of ischemic stroke.

Methods

We included unselected ischemic stroke patients who underwent microemboli-monitoring within six hours after stroke onset. Microemboli-monitoring of both middle cerebral arteries (MCA) was done for a period of 1 hour using 2-MHz probes applied over the trans-temporal window. Prevalence of MES, predictors for the presence of MES and the association between MES and various outcome factors were analyzed.

Results

Forty patients were included. The mean age of the patients was 70 years. The prevalence of either ipsilateral or contralateral MES were 25% (n = 10). The predictors for the presence of MES were older age (OR 9; p = 0.03), higher NIHSS (OR 28; p = 0.02), intracranial stenosis (OR 10; p = 0.04) and embolic stroke (large-artery atherosclerosis and cardioembolism on TOAST classification) (OR 7; p = 0.06). MES were not independently associated with short-term functional outcome, long-term mortality or future vascular events.

Conclusions

MES are moderately frequent following acute ischemic stroke. Microemboli-monitoring helps to better classify the stroke etiology. However, the presence MES did not have any prognostic significance in this study.

Detection of microembolic signals using power M-mode Doppler sonography in acute stroke patients with intracranial artery stenosis

PURPOSE

Microembolic signals (MES) can be detected in a variety of clinical situations using conventional transcranial Doppler (TCD) sonography. We studied the prevalence of positive MESs in acute stroke patients with intracranial artery stenosis using power M-mode Doppler (PMD) sonography and also tested the feasibility of this new technique.

METHOD

Thirty-three consecutive acute ischemic stroke or transient ischemic attack patients with intracranial large artery occlusive disease were enrolled. PMD/TCD monitoring for 30 minutes was used for MES detection downstream of the stenotic artery within 1 week after stroke onset. Clinical risk factors in emboli-positive and emboli-negative patients were assessed.

RESULTS

MESs were detected in 21% (7/33) of patients. No significant differences were found in clinical risk factors between emboli-positive and emboli-negative patients.

CONCLUSION

PMD sonography to detect MESs in acute stroke patients is feasible and may be used in future clinical trials regarding MES detection.

Microembolic signals within 24 hours of stroke onset and diffusion-weighted MRI abnormalities

BACKGROUND

The clinical relevance of the microembolic signals (MES) detected by transcranial Doppler sonography (TCD) in acute stroke remains unclear. In a prospective study the authors analyzed the relationship between MES and the findings on diffusion-weighted magnetic resonance imaging (DWI) in acute stroke patients.

METHODS

We performed TCD for a period of 30 min to detect MES in patients within 24 h of stroke onset, and DWI was done within the initial 7 days. MES were assessed from Doppler waves obtained from the middle cerebral artery contralateral to the side of the neurological deficits. The acute ischemic lesions observed on DWI were classified by their diameter (small, medium or large) and by their site (cortical, superficial perforator territory, internal borderzone or deep perforator territory).

RESULTS

We obtained Doppler waves from 39 vessels in 37 patients; 2 patients had bilateral deficits. MES were detected in 12 vessels (MES-positive group) and not detected in 27 vessels (MES-negative group). No significant differences in clinical features were observed between the 2 groups. The number of small lesions was significantly higher in the MES-positive group than in the MES-negative group (p = 0.02). The numbers of cortical and superficial perforator infarcts were significantly higher in the MES-positive group than in the MES-negative group (p = 0.002 and 0.02, respectively).

CONCLUSION

In acute ischemic stroke, MES detected by TCD in the acute phase may produce small cortical and subcortical lesions found on DWI.