Relationships between brain perfusion and early recanalization after intravenous thrombolysis for acute stroke with large vessel occlusion

Thrombus composition and thrombolysis resistance in stroke

A State of the Art lecture titled "Thrombus Composition and Thrombolysis Resistance in Stroke" was presented at the ISTH Congress in 2022. Intravenous thrombolysis (IVT) remains the only pharmacologic option to re-establish cerebral perfusion at the acute phase of ischemic stroke. IVT is based on the administration of recombinant tissue plasminogen activator with the objective of dissolving fibrin, the major fibrillar protein component of thrombi. Almost 30 years on from its introduction, although the clinical benefits of IVT have been clearly demonstrated, IVT still suffers from a relatively low efficacy, with a rate of successful early recanalization below 50% overall. Analyses of thrombectomy-recovered acute ischemic stroke (AIS) thrombi have shown that apart from occlusion site, thrombus length, and collateral status, AIS thrombus structure and composition are also important modulators of IVT efficacy. In this article, after a brief presentation of IVT principle and current knowledge on IVT resistance, we review recent findings on how compaction and structural alterations of fibrin together with nonfibrin thrombus components such as neutrophil extracellular traps and von Willebrand factor interfere with IVT in AIS. We further discuss how these new insights could soon result in the development of original adjuvant therapies for improved IVT in AIS. Finally, we summarize relevant new data presented during the 2022 ISTH Congress.

Outcomes in minor stroke patients treated with intravenous thrombolysis

AIMS

Our study aimed to describe the short-, medium-, and long-term outcomes of intravenous thrombolysis in minor stroke, and to explore the relationship between thrombolysis and clinical outcomes.

METHODS

Our study included ischemic minor stroke patients (National Institutes of Health Stroke Scale score ≤ 5) within 4.5 h from symptom onset from the Third China National Stroke Registry (CNSR-III) between August 2015 and March 2018. The primary outcome was a favorable functional outcome, defined as a modified Rankin Scale (mRS) score of 0-1 at 3 months. The secondary outcomes included mRS score of 0-1 at discharge, 6 months, and 1 year. The safety outcomes were symptomatic intracerebral hemorrhage (sICH) at 24-36 h and all-cause mortality. The association between intravenous thrombolysis and clinical outcomes was studied using multivariable models.

RESULTS

A total of 1905 minor ischemic stroke patients were included. Overall 527 patients (28%) received intravenous t-PA (IV t-PA) and 1378 patients (72%) in the non-IV t-PA group. Of them, 18.85% (359/1905) participants had a disabled outcome (defined as mRS score ≥ 2) at discharge, 12.8% (242/1885) at 3 months, 13.9% (262/1886) at 6 months, and 13.9% (260/1871) at 1 year. In multivariable analysis, IV t-PA was associated with favorable functional outcomes at discharge (adjusted odds ratio [aOR] 1.49; 95% confidence interval [CI] 1.13-1.96; p = 0.004), 3 months (aOR 1.51; 95% CI 1.09-2.10; p = 0.01), 6 months (aOR 1.64; 95% CI 1.19-2.27; p = 0.003), and 1 year (aOR 1.52; 95% CI 1.10-2.10; p = 0.01). Symptomatic ICH occurred in 3 (0.6%) patients in IV t-PA versus 2 (0.1%) in the non-IV t-PA group. No significant differences were found in all-cause mortality between the two groups.

CONCLUSIONS

Intravenous t-PA may be safe and effective in minor stroke (NIHSS ≤ 5) within a 4.5-h window and further randomized controlled trials are warranted.

FLAIR Vascular Hyperintensities as a Surrogate of Collaterals in Acute Stroke: DWI Matters

BACKGROUND AND PURPOSE

FLAIR vascular hyperintensities are thought to represent leptomeningeal collaterals in acute ischemic stroke. However, whether all-FLAIR vascular hyperintensities or FLAIR vascular hyperintensities-DWI mismatch, ie, FLAIR vascular hyperintensities beyond the DWI lesion, best reflects collaterals remains debated. We aimed to compare the value of FLAIR vascular hyperintensities-DWI mismatch versus all-FLAIR vascular hyperintensities for collateral assessment using PWI-derived collateral flow maps as a reference.

MATERIALS AND METHODS

We retrospectively reviewed the registries of 6 large stroke centers and included all patients with acute stroke with anterior circulation large-vessel occlusion who underwent MR imaging with PWI before thrombectomy. Collateral status was graded from 1 to 4 on PWI-derived collateral flow maps and dichotomized into good (grades 3-4) and poor (grades 1-2). The extent of all-FLAIR vascular hyperintensities and FLAIR vascular hyperintensities-DWI mismatch was assessed on the 7 cortical ASPECTS regions, ranging from 0 (absence) to 7 (extensive), and associations with good collaterals were compared using receiver operating characteristic curves.

RESULTS

Of the 209 included patients, 133 (64%) and 76 (36%) had good and poor collaterals, respectively. All-FLAIR vascular hyperintensity extent was similar between collateral groups (P = .76). Conversely, FLAIR vascular hyperintensities-DWI mismatch extent was significantly higher in patients with good compared with poor collaterals (P < .001). The area under the curve was 0.80 (95% CI, 0.74-0.87) for FLAIR vascular hyperintensities-DWI mismatch and 0.52 (95% CI, 0.44-0.60) for all-FLAIR vascular hyperintensities (P < .001 for the comparison), to predict good collaterals. Variables independently associated with good collaterals were smaller DWI lesion volume (P < .001) and larger FLAIR vascular hyperintensities-DWI mismatch (P = .02).

CONCLUSIONS

In acute ischemic stroke with large-vessel occlusion, the extent of FLAIR vascular hyperintensities does not reliably reflect collateral status unless one accounts for DWI.

Association between the time of day at stroke onset and functional outcome of acute ischemic stroke patients treated with endovascular therapy

To investigate the association between time-of-day of stroke onset and functional outcome in patients with acute ischemic stroke(AIS) treated with endovascular thrombectomy(EVT). AIS patients treated with EVT between January 2013 and December 2018 were recruited and divided them into four 6-h interval groups according to the time-of-day of stroke onset. A total of 438 patients were enrolled, 3-month favorable outcome were achieved in 58.6%, 43.7%, 36.6%, and 30.5% of patients in the 00:00-06:00, 06:00-12:00, 12:00-18:00, and 18:00-24:00 groups, respectively (adjusted OR 0.61, 95% CI 0.40-0.93; p = 0.020). Compared with the 18:00-24:00 interval, patients in the 00:00-06:00 interval (adjusted OR 4.01, 95%CI 1.02-15.80, p = 0.047) and the 06:00-12:00 interval (adjusted OR 3.24, 95% CI 1.09-9.64, p = 0.034) were more likely to achieve favorable outcome. The time-of-day of stroke onset was not associated with 3-month mortality (adjusted p = 0.829), symptomatic intracerebral hemorrhage (sICH, adjusted p = 0.296), or early successful recanalization (adjusted p = 0.074). In conclusion, in AIS patients treated with EVT, those onsets either between 00:00 and 06:00 or between 06:00 and 12:00 appeared to be associated with a higher proportion of favorable outcomes at 3 months, but the time-of-day at stroke onset was not associated with the incidence of sICH, rate of early successful recanalization, or 3-month mortality.

Efficacy and safety of 3-n-butylphthalide combined with endovascular treatment in acute ischemic stroke due to large vessel occlusion

BACKGROUND

The drug 3-n-butylphthalide (NBP) was developed and approved in China, where it has been used to treat ischemic cerebrovascular diseases. It is also considered to have a neuroprotective effect. This study aimed to evaluate whether NBP combined with endovascular treatment (EVT) can improve the clinical outcome and safety in patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO).

METHODS

Data from three studies of patients treated with EVT for AIS due to LVO were combined in this study. Patients of LVO undergoing EVT were dichotomized into NBP and non-NBP subgroups. The primary efficacy outcome was the shift of the modified Rankin Scale (mRS) score at 90 days. The secondary efficacy outcome included favorable functional outcomes, functional independence, and excellent outcome (defined as an mRS score of 3 or less) at 90 days. Safety outcomes included mortality within 90 days and symptomatic intracranial hemorrhage (sICH) within 48 h.

RESULTS

A total of 1820 patients undergoing EVT were included in this study; 628 (37.5%) patients received NBP treatment, whereas 1138 (62.5%) did not. After adjusting for multiple factors, NBP was associated with the improvement of functional outcomes at 90 days (adjusted common odds ratio [OR]: 1.503; 95% confidence interval (CI): 1.254-1.801; p < 0.001). NBP was associated with a higher rate of 90-day favorable outcomes (adjusted OR: 1.589; 95% CI: 1.251-2.020; p < 0.001) and a lower rate of 90-day mortality (adjusted OR: 0.486 [95% CI: 0.372-0.635]; p < 0.001). sICH occurred in 74 of 682 (10.9%) patients in the NBP group and 155 of 1126 (13.8%) patients in the non-NBP group; no statistical difference was detected (adjusted OR: 0.787 [95% CI: 0.567-1.092]; p = 0.152).

CONCLUSION

Among patients with AIS due to LVO, NBP combined with EVT is associated with better functional outcomes and reduced mortality risk without increasing the risk of sICH.

Cohort study on the differential expression of inflammatory and angiogenic factors in thrombi, cerebral and peripheral plasma following acute large vessel occlusion stroke

Inflammation plays an important role in the pathogenesis of stroke. The differential expression of inflammatory and angiogenic factors in thrombi and plasma remain undefined. In this observational cohort study, we evaluated angiogenic factors and inflammatory cytokines, in cerebral thrombi, local cerebral plasma (CP), and peripheral plasma (PP) in patients with acute ischemic stroke. Protein analysis of thrombi, CP and PP were used to measure angiogenic and inflammatory proteins using electrochemiluminescence. Our data indicate that VEGF-A, VEGF-C, bFGF, IL-4, IL-13, IL-1β, IL-2, IL-8, IL-16, IL-6 and IL-12p70 were higher in the thrombi of acute ischemic stroke patients than in the CP and PP of stroke patients. Moreover, the protein levels of GM-CSF were lower in the PP than in the CP and the clot. Moreover, VEGF-D, Flt-1, PIGF, TIE-2, IL-5, TNF-β, IL-15, IL-12/IL-23p40, IFN-γ and IL-17A were higher in PP and CP than in thrombi. Our results show that cytokines mediating the inflammatory response and proteins involved in angiogenesis are differentially expressed in thrombi within the cerebral and peripheral circulations. These data highlight the importance of identifying new biomarkers in different compartments of the circulatory system and in thrombi that may be used for the diagnosis and treatment of stroke patients.

Hypoperfusion Intensity Ratio Predicts Infarct Growth After Successful Thrombectomy for Distal Medium Vessel Occlusion

BACKGROUND AND PURPOSE

This study evaluated whether quantitative measurement of collaterals by the hypoperfusion intensity ratio (HIR) on baseline computed tomography perfusion (CTP) correlated with infarct growth and clinical outcome after successful endovascular recanalization of acute ischemic stroke (AIS) caused by primary distal medium vessel occlusions (DMVO).

METHODS

We performed a retrospective analysis of consecutive AIS patients who underwent an initial CTP and were successfully recanalized by thrombectomy (modified thrombolysis In cerebral infarction 2b or 3) for DMVO. We evaluated the association of baseline HIR with infarct growth and clinical outcome.

RESULTS

Between January 2018 and January 2021, 40 patients with an AIS caused by a DMVO were successfully recanalized by MT (65%, 26/40 female, median age 72 years, range 65-83 years). Baseline HIR was strongly correlated with infarct growth after successful recanalization (r = 0.501, p = 0.001). An HIR<0.3 was the optimal threshold for good collaterals using ROC analysis. Patients with HIR ≥ 0.3 had higher infarct growth compared to HIR < 0.3 (23.8 mL, IQR: 9.1-45.1 vs. 7.2 mL, interquartile range (IQR): 4.2-11.7, relative risk 7.9, p = 0.024 in multivariate analysis); their clinical outcome was poorer in univariate analysis (75%, 21/28 patients with a 3 months modified Rankin scale of 0-2 vs. 33%,4/12, p < 0.017, odds ratio (OR) 6.0, 1.37-26.20) but it did not remain significant in multivariate analysis (p = 0.107).

CONCLUSION

Good collaterals on initial CTP assessed by an HIR < 0.3 are associated with less infarct growth after successful recanalization of AIS caused by a DMVO.

Association of Intravenous Alteplase, Early Reperfusion, and Clinical Outcome in Patients With Large Vessel Occlusion Stroke: Post Hoc Analysis of the Randomized DIRECT-MT Trial

BACKGROUND

The added value of intravenous alteplase in reperfusing ischemic brain tissue in patients undergoing endovascular treatment and directly presented to an endovascular treatment-capable hospital is uncertain. We conducted this post hoc analysis of a randomized trial (DIRECT-MT [Direct Intraarterial Thrombectomy in Order to Revascularize Acute Ischemic Stroke Patients With Large Vessel Occlusion Efficiently in Chinese Tertiary Hospitals: A Multicenter Randomized Clinical Trial]) to explore the association of intravenous alteplase, early (preendovascular treatment) reperfusion, and clinical outcome and to determine factors which may modify alteplase treatment effect on early reperfusion.

METHODS

In this post hoc analysis of the DIRECT-MT randomized trial comparing intravenous alteplase before endovascular treatment versus endovascular treatment only, 623 of 656 randomized patients, with adequate angiographic evaluation for early reperfusion assessment, were included. The association of intravenous alteplase and early reperfusion (defined as expanded Thrombolysis in Cerebral Infarction score ≥2a on angiogram) was assessed using unadjusted comparisons and multivariable logistic regression.

RESULTS

Among 623 patients included (317 received intravenous alteplase and 306 did not), early reperfusion occurred in 91 (15%) patients and was associated with better functional outcome (modified Rankin Scale score, 0-2 of 49/91 [54%] versus 178/531 [34%]; adjusted odds ratio, 1.92 [95% CI, 1.15-3.21]; P<0.001). Intravenous alteplase was independently associated with early reperfusion (59/317 [19%] versus 32/306 [10%]; adjusted odds ratio, 2.06 [95% CI, 1.27-3.33]; P=0.003), and the alteplase effect was modified by time from randomization to groin puncture (dichotomized by median, ≤33 minutes; adjusted odds ratio, 1.06 [95% CI, 0.53-2.10] versus >33 minutes; adjusted odds ratio, 4.07 [95% CI, 1.86-8.86]; Pinteraction=0.012).

CONCLUSIONS

For patients with large vessel occlusion directly presenting to an endovascular treatment-capable hospital, intravenous alteplase increases early reperfusion when endovascular treatment gets delayed more than approximately half an hour. Thus, intravenous alteplase should be considered if endovascular treatment delays are anticipated by the treating medical team.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03469206.

Negative correlation between early recovery and lipoprotein-associated phospholipase A2 levels after intravenous thrombolysis

Objective

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is considered a biomarker for systemic inflammation and the risk of myocardial infarction and stroke. However, little is known about the effect of acute vascular events on marker levels. The purpose of this study was to assess the potential association of early recovery with Lp-PLA2 levels in patients with acute ischemic stroke (AIS) after intravenous thrombolysis (IVT).

Methods

Forty-three consecutive AIS patients who had their first stroke and were hospitalized within 5 hours of the onset of stroke were enrolled. All patients were treated with IVT using alteplase or urokinase. Plasma Lp-PLA2 levels were measured within 24 hours after IVT. Variables that showed a significant association with Lp-PLA2 in univariate analysis were included in the multivariate ordered logistic regression model.

Results

Early recovery was associated with Lp-PLA2 levels after IVT, and Lp-PLA2 levels tended to decrease with increased probability of early recovery. This study is the first to report a negative correlation between early recovery and Lp-PLA2 levels after IVT.

Conclusion

Early recovery after IVT was negatively correlated with Lp-PLA2 A2 levels.

EphrinB2-EphB2 signaling for dendrite protection after neuronal ischemia in vivo and oxygen-glucose deprivation in vitro

In order to rescue neuronal function, neuroprotection should be required not only for the neuron soma but also the dendrites. Here, we propose the hypothesis that ephrin-B2-EphB2 signaling may be involved in dendritic degeneration after ischemic injury. A mouse model of focal cerebral ischemia with middle cerebral artery occlusion (MCAO) method was used for EphB2 signaling test in vivo. Primary cortical neuron culture and oxygen-glucose deprivation were used to assess EphB2 signaling in vitro. siRNA and soluble ephrin-B2 ectodomain were used to block ephrin-B2-Ephb2 signaling. In the mouse model of focal cerebral ischemia and in neurons subjected to oxygen-glucose deprivation, clustering of ephrin-B2 with its receptor EphB2 was detected. Phosphorylation of EphB2 suggested activation of this signaling pathway. RNA silencing of EphB2 prevented neuronal death and preserved dendritic length. To assess therapeutic potential, we compared the soluble EphB2 ectodomain with the NMDA antagonist MK801 in neurons after oxygen-glucose deprivation. Both agents equally reduced lactate dehydrogenase release as a general marker of neurotoxicity. However, only soluble EphB2 ectodomain protected the dendrites. These findings provide a proof of concept that ephrin-B2-EphB2 signaling may represent a novel therapeutic target to protect both the neuron soma as well as dendrites against ischemic injury.

The core/penumbra model: implications for acute stroke treatment and patient selection in 2021

Despite major advances in prevention, ischaemic stroke remains one of the leading causes of death and disability worldwide. After centuries of nihilism and decades of failed neuroprotection trials, the discovery, initially in non-human primates and subsequently in man, that ischaemic brain tissue termed the ischaemic penumbra can be salvaged from infarction up to and perhaps beyond 24 h after stroke onset has underpinned the development of highly efficient reperfusion therapies, namely intravenous thrombolysis and endovascular thrombectomy, which have revolutionized the management of the acute stroke patient. Animal experiments have documented that how long the penumbra can survive depends not only on time elapsed since arterial occlusion ('time is brain'), but also on how severely perfusion is reduced. Novel imaging techniques allowing the penumbra and the already irreversibly damaged core in the individual subject to be mapped have documented that the time course of core growth at the expense of the penumbra widely differs from patient to patient, and hence that individual physiology should be considered in addition to time since stroke onset for decision-making. This concept has been implemented to optimize patient selection in pivotal trials of reperfusion therapies beyond 3 h after stroke onset and is now routinely applied in clinical practice, using computed tomography or magnetic resonance imaging. The notion that, in order to be both efficient and harmless, treatment should be tailored to each patient's physiological characteristics represents a radical move towards precision medicine.

Baseline Cerebral Ischemic Core Quantified by Different Automatic Software and Its Predictive Value for Clinical Outcome

Purpose

This study aims to investigate the agreement of three software packages in measuring baseline ischemic core volume (ICV) and penumbra volume (PV), and determine their predictive values for unfavorable clinical outcome in patients with endovascular thrombectomy (EVT).

Methods

Patients with acute ischemic stroke who underwent computed tomographic perfusion (CTP) were recruited. Baseline CTP measurements including ICV and PV were calculated by three software packages of IntelliSpace Portal (ISP), Rapid Processing of Perfusion and Diffusion (RAPID), and fast-processing of ischemic stroke (F-STROKE). All patients received EVT, and the modified Rankin scale (mRS) at 90 days after EVT was assessed to determine the clinical outcomes (favorable: mRS = 0-2; unfavorable: mRS = 3-6). The agreement of CTP measurements among three software packages was determined using intraclass correlation coefficient (ICC). The associations between CTP measurements and unfavorable clinical outcome were analyzed using logistic regression. Receiver operating characteristic curves were conducted to calculate the area under the curve (AUC) of CTP measurements in predicting unfavorable clinical outcome.

Results

Of 223 recruited patients (68.2 ± 11.3 years old; 145 males), 17.0% had unfavorable clinical outcome after EVT. Excellent agreement between F-STROKE and RAPID was found in measuring ICV (ICC 0.965; 95% CI 0.956-0.973) and PV (ICC 0.966; 95% CI 0.956-0.973). ICVs measured by three software packages were significantly associated with unfavorable clinical outcome before (odds ratios 1.012-1.018, all P < 0.01) and after (odds ratios 1.003-1.014, all P < 0.05) adjusted for confounding factors (age, gender, TOAST classification, and NIHSS on admission). In predicting unfavorable clinical outcome, ICV measured by F-STROKE showed similar performance to that measured by RAPID (AUC 0.701 vs. 0.717) but higher performance than that measured by ISP (AUC 0.629).

Conclusions

The software of F-STROKE has excellent agreement with the widely used analysis tool of RAPID in measuring ICV and PV. The ischemic core volume measured by both F-STROKE and RAPID is a stronger predictor for unfavorable clinical outcome after EVT compared to ISP.

Case series demonstrating the value of computed tomography perfusion in differentiating ischemic strokes from seizures in patients with isolated aphasia

The value of computed tomography perfusion (CTP) imaging in suspected stroke patients who are not candidates for mechanical thrombectomy is promising. This case series demonstrates how CTP imaging aided in distinguishing seizure from stroke in 5 patients who presented to the emergency department with acute onset of isolated aphasia.