New Cerebral Microbleeds and Mechanism of Post-Thrombolysis Remote Intracerebral Hemorrhage: "Red Meets White" Revisited

Cerebral microbleeds and asundexian in non-cardioembolic ischemic stroke: Secondary analyses of the PACIFIC-STROKE randomized trial

BACKGROUND AND AIMS

Cerebral microbleeds are magnetic imaging resonance (MRI) markers of hemorrhage-prone cerebral small vessel disease that predict future risk of ischemic stroke and intracranial hemorrhage (ICrH). There exist concerns about the net benefit of antithrombotic therapy in patients with microbleeds. We aimed to investigate the effects of an oral factor-XIa inhibitor (asundexian), that is hypothesized to inhibit thrombosis without compromising hemostasis, on the development of new microbleeds over time and interactions between microbleeds and asundexian treatment on clinical outcomes. We additionally assessed associations between baseline microbleeds and the risks of clinical and neuroimaging outcomes in patients with non-cardioembolic ischemic stroke.

METHODS

This is a secondary analysis of the PACIFIC-STROKE, international, multi-center Phase 2b double-blind, randomized clinical trial. PACIFIC-STROKE enrolled patients aged ⩾ 45 years with mild-to-moderate non-cardioembolic ischemic stroke who presented within 48 h of symptom onset for whom antiplatelet therapy was intended. Microbleeds were centrally adjudicated, and participants with an interpretable T2*-weighted sequence at their baseline MRI were included in this analysis. Patients were randomized to asundexian (10/20/50 mg daily) versus placebo plus standard antiplatelet treatment. Regression models were used to estimate the effects of (1) all pooled asundexian doses and (2) asundexian 50 mg daily on new microbleed formation on 26-week MRIs. Cox proportional hazards or regression models were additionally used to estimate interactions between treatment assignment and microbleeds for ischemic stroke/transient ischemic attack (TIA) (primary outcome), and ICrH, all-cause mortality, hemorrhagic transformation (HT), and new microbleeds (secondary outcomes).

RESULTS

Of 1746 participants (mean age, 67.0 ± 10.0; 34% female) with baseline MRIs, 604 (35%) had microbleeds. During a median follow-up of 10.6 months, 7.0% (n = 122) had ischemic stroke/TIA, 0.5% (n = 8) ICrH, and 2.1% (n = 37) died. New microbleeds developed in 10.3% (n = 155) of participants with adequate follow-up MRIs and HT in 31.4% (n = 345). In the total sample of patients with adequate baseline and 26-week follow-up MRIs (n = 1507), new microbleeds occurred in 10.2% of patients assigned to any asundexian dose and 10.5% of patients assigned to placebo (OR, 0.96; 95% CI, 0.66-1.41). There were no interactions between microbleeds and treatment assignment for any of the outcomes (p for interaction > 0.05). The rates of new microbleeds, HT, and ICrH were numerically less in patients with microbleeds assigned to asundexian relative to placebo. The presence of microbleeds was associated with a higher risk of HT (aOR, 1.6; 95% CI, 1.2-2.1) and new microbleeds (aOR, 4.4; 95% CI, 3.0-6.3).

CONCLUSION

Factor XIa inhibition with asundexian appears safe in patients with non-cardioembolic ischemic stroke and hemorrhage-prone cerebral small vessel disease marked by microbleeds on MRI. These preliminary findings will be confirmed in the ongoing OCEANIC-STROKE randomized trial.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04304508.

Predictors of new remote cerebral microbleeds after IV thrombolysis for ischemic stroke

OBJECTIVE

To assess the frequency, associated factors, and underlying vasculopathy of new remote cerebral microbleeds (CMB), as well as the risk of concomitant hemorrhagic complications related to new CMBs, after IV thrombolysis (IVT) in acute stroke patients.

METHODS

We conducted an observational study using data from our local thrombolysis registry. We included consecutive stroke patients with MRI (3T)-based IVT and a follow-up MRI the next day between 2008 and 2017 (n = 396). Only CMBs located outside of the ischemic lesions were considered. We also performed a meta-analysis on new CMBs after IVT that included 2 additional studies.

RESULTS

In our cohort, new remote CMBs occurred in 16/396 patients (4.0%) after IVT and the distribution was strictly lobar in 13/16 patients (81%). Patients with preexisting CMBs with a strictly lobar distribution were significantly more likely to have new CMBs after IVT (p = 0.014). In the random-effects meta-analysis (n = 741), the pooled cumulative frequency of new CMBs after IVT was 4.4%. A higher preexisting CMB burden (>2) was associated with a higher likelihood of new CMBs (odds ratio [OR] 3.6, 95% confidence interval [CI] 1.3-10.3) and new CMBs were associated with the occurrence of remote parenchymal hemorrhage (OR 28.8, 95% CI 8.6-96.4).

CONCLUSIONS

New remote CMBs after IVT occurred in 4% of stroke patients, mainly had a strictly lobar distribution, and were associated with IVT-related hemorrhagic complications. Preexisting CMBs with a strictly lobar distribution and a higher CMB burden were associated with new CMBs after IVT, which may indicate an underlying cerebral amyloid angiopathy.

Impact of Microbleeds on Outcome Following Recanalization in Patients With Acute Ischemic Stroke

Background and Purpose- We analyzed the association between cerebral microbleeds (CMBs) and clinical outcome in acute ischemic stroke patients and especially in a subgroup of patients with successful recanalization. Methods- A total of 1532 acute ischemic stroke patients treated with intravenous thrombolysis or mechanical thrombectomy were enrolled in this prospective cohort study. The primary outcome was measured using the modified Rankin Scale at 3 months, according to the CMB status based on magnetic resonance imaging at admission. Favorable outcome was defined as functional independence with modified Rankin Scale scores of 0 to 2. Secondary outcomes included the occurrence of symptomatic intracranial hemorrhage. Results- There was no statistically significant association between the presence of CMB and favorable outcome at 3 months when considering all patients (44.3% versus 37.6%; P=0.121). In patients with recanalization, the number of patients with favorable outcomes was significantly higher in the CMB-negative than in the CMB-positive group (57.0% versus 36.0%; P<0.001). In the final multivariate analysis, the presence of CMB, and in particular high CMB burden (≥5), and lobar location, were significantly associated with less favorable 3-month outcomes (odds ratio=0.57; 95% CI, 0.33-0.97; P=0.038) and symptomatic intracranial hemorrhage (odds ratio=3.21; 95% CI, 1.37-7.49; P=0.007) in patients with recanalization. In the analysis of subgroups, a statistically significant interaction was found between CMB presence and recanalization in predicting functional outcomes at 3 months. Conclusions- These results indicate that the presence of CMBs, and especially high burden and lobar location, are independent predictors of poor 3-month clinical outcomes and may increase symptomatic intracranial hemorrhage risk in acute ischemic stroke patients with recanalization. Our findings suggest that CMBs lead to more unfavorable effects in patients with recanalization after large vessel occlusion than in those without recanalization.

Pretreatment cerebral microbleeds and symptomatic intracerebral hemorrhage post-thrombolysis: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Cerebral microbleeds (CMBs) are a possible predictor of symptomatic intracranial hemorrhage (sICH) and poor function outcome (PFO). We aimed to investigate the presence of CMBs on increased incidence of sICH and PFO in acute ischemic stroke patients receiving intravenous thrombolysis (IVT) treatment.

METHODS

We searched PubMed, EMBASE, and Cochrane Library from 1 January 1997 to 13 May 2018, for relevant studies and calculated the pooled relative risk (RR) for the incidence of sICH and PFO in patients with CMBs versus those without after IVT.

RESULTS

We included 2407 participants from nine studies. The cumulative sICH incidence was higher in patients with CMBs (6%, 95% CI 4-8%) than that in patients without CMBs (4%, 95% CI 2-6%) with pooled RR 1.51 (95% CI, 1.04-2.21; P = 0.031). Four studies including 1550 patients reported data on 3- to 6-month PFO. The cumulative PFO incidence was higher in patients with CMBs (53%, 95% CI 47-59%) than that in patients without CMBs (41%, 95% CI 36-46%) with pooled RR 1.25 (95% CI 1.11-1.41; P = 0.000).

CONCLUSIONS

The pretreatment CMBs were associated with increased incidence of sICH and PFO in acute ischemic stroke patients receiving IVT. However, it was not convincing enough to set the presence of CMBs as contraindication to IVT.

Remote Intracerebral Hemorrhage Following Intravenous Thrombolysis in Pregnancy at 31 Weeks Gestation: A Case Report and Review of the Literature

INTRODUCTION

Intravenous recombinant tissue-type plasminogen activator thrombolysis in pregnancy for acute ischemic stroke is infrequent. As a rare complication of thrombolysis, remote intracerebral hemorrhage (rICH) whose mechanisms are unclear has not gained enough attention until now.

CASE REPORT

We present here a case of 26-year-old pregnant woman at 31 weeks gestation who suffered from sudden onset right-sided hemiparesis and slurred speech. She successfully received intravenous recombinant tissue-type plasminogen activator thrombolysis within 2.5 hours from stroke onset. Further workup demonstrated multiple and bilateral acute cerebral infarcts due to cardioembolism. At 6 hours after thrombolysis, multifocal intracerebral hemorrhages were developed in her left cerebellum and right temporal cortex, remote from the initial infarct areas. However, the patient achieved a final complete recovery of symptoms. Despite diffusion-weighted imaging could not confirm infarct in the areas of hemorrhages, multiple cerebral embolism was suggested to be involved in the etiology of rICH.

CONCLUSIONS

rICH is different from local intracerebral hemorrhage in its risk factors, neurological outcomes, and underlying mechanisms. Patients with rICH may have favorable outcomes and multiple cerebral embolism is still one of the important mechanisms for postthrombolytic rICH.

Microbleeds, Cerebral Hemorrhage, and Functional Outcome After Stroke Thrombolysis

Background and Purpose—

We assessed whether the presence, number, and distribution of cerebral microbleeds (CMBs) on pre-intravenous thrombolysis MRI scans of acute ischemic stroke patients are associated with an increased risk of intracerebral hemorrhage (ICH) or poor functional outcome.

Methods—

We performed an individual patient data meta-analysis, including prospective and retrospective studies of acute ischemic stroke treated with intravenous tissue-type plasminogen activator. Using multilevel mixed-effects logistic regression, we investigated associations of pre-treatment CMB presence, burden (1, 2–4, ≥5, and >10), and presumed pathogenesis (cerebral amyloid angiopathy defined as strictly lobar CMBs and noncerebral amyloid angiopathy) with symptomatic ICH, parenchymal hematoma (within [parenchymal hemorrhage, PH] and remote from the ischemic area [remote parenchymal hemorrhage, PHr]), and poor 3- to 6-month functional outcome (modified Rankin score >2).

Results—

In 1973 patients from 8 centers, the crude prevalence of CMBs was 526 of 1973 (26.7%). A total of 77 of 1973 (3.9%) patients experienced symptomatic ICH, 210 of 1806 (11.6%) experienced PH, and 56 of 1720 (3.3%) experienced PHr. In adjusted analyses, patients with CMBs (compared with those without CMBs) had increased risk of PH (odds ratio: 1.50; 95% confidence interval: 1.09–2.07; P =0.013) and PHr (odds ratio: 3.04; 95% confidence interval: 1.73–5.35; P <0.001) but not symptomatic ICH. Both cerebral amyloid angiopathy and noncerebral amyloid angiopathy patterns of CMBs were associated with PH and PHr. Increasing CMB burden category was associated with the risk of symptomatic ICH ( P =0.014), PH ( P =0.013), and PHr ( P <0.00001). Five or more and >10 CMBs independently predicted poor 3- to 6-month outcome (odds ratio: 1.85; 95% confidence interval: 1.10–3.12; P =0.020; and odds ratio: 3.99; 95% confidence interval: 1.55–10.22; P =0.004, respectively).

Conclusions—

Increasing CMB burden is associated with increased risk of ICH (including PHr) and poor 3- to 6-month functional outcome after intravenous thrombolysis for acute ischemic stroke.

Risk factors are different for deep and lobar remote hemorrhages after intravenous thrombolysis

Background and purpose

Remote parenchymal haemorrhage (rPH) after intravenous thrombolysis is defined as hemorrhages that appear in brain regions without visible ischemic damage, remote from the area of ischemia causing the initial stroke symptom. The pathophysiology of rPH is not clear and may be explained by different underlying mechanisms. We hypothesized that rPH may have different risk factors according to the bleeding location. We report the variables that we found associated with deep and lobar rPH after intravenous thrombolysis.

Methods

This is a descriptive study of patients with ischemic stroke who were treated with intravenous thrombolysis. These patients were included in a multicenter prospective registry. We collected demographic, clinical and radiological data. We evaluated the number and distribution of cerebral microbleeds (CMB) from Magnetic Resonance Imaging. We excluded patients treated endovascularly, patients with parenchymal hemorrhage without concomitant rPH and stroke mimics. We compared the variables from patients with deep or lobar rPH with those with no intracranial hemorrhage.

Results

We studied 934 patients (mean age 73.9±12.6 years) and 52.8% were men. We observed rPH in 34 patients (3.6%); 9 (0.9%) were deep and 25 (2.7%) lobar. No hemorrhage was observed in 900 (96.6%) patients. Deep rPH were associated with hypertensive episodes within first 24 hours after intravenous thrombolysis (77.7% vs 23.3%, p<0.001). Lobar rPH were associated with the presence of CMB (53.8% vs 7.9%, p<0.001), multiple (>1) CMB (30.7% vs 4.4%, p = 0.003), lobar CMB (53.8% vs 3.0%, p<0.001) and severe leukoaraiosis (76.9% vs 42%, p = 0.02).

Conclusions

A high blood pressure within the first 24 hours after intravenous thrombolysis is associated with deep rPH, whereas lobar rPH are associated with imaging markers of amyloid deposition. Thus, our results suggest that deep and lobar rPH after intravenous thrombolysis may have different mechanisms.