Preexisting statin use is associated with greater reperfusion in hyperacute ischemic stroke

Transdiagnostic In Vivo Magnetic Resonance Imaging Markers of Neuroinflammation

Accumulating evidence suggests that inflammation is not limited to archetypal inflammatory diseases such as multiple sclerosis, but instead represents an intrinsic feature of many psychiatric and neurological disorders not typically classified as neuroinflammatory. A growing body of research suggests that neuroinflammation can be observed in early and prodromal stages of these disorders and, under certain circumstances, may lead to tissue damage. Traditional methods to assess neuroinflammation include serum or cerebrospinal fluid markers and positron emission tomography. These methods require invasive procedures or radiation exposure and lack the exquisite spatial resolution of magnetic resonance imaging (MRI). There is, therefore, an increasing interest in noninvasive neuroimaging tools to evaluate neuroinflammation reliably and with high specificity. While MRI does not provide information at a cellular level, it facilitates the characterization of several biophysical tissue properties that are closely linked to neuroinflammatory processes. The purpose of this review is to evaluate the potential of MRI as a noninvasive, accessible, and cost-effective technology to image neuroinflammation across neurological and psychiatric disorders. We provide an overview of current and developing MRI methods used to study different aspects of neuroinflammation and weigh their strengths and shortcomings. Novel MRI contrast agents are increasingly able to target inflammatory processes directly, therefore offering a high degree of specificity, particularly if used in conjunction with multitissue, biophysical diffusion MRI compartment models. The capability of these methods to characterize several aspects of the neuroinflammatory milieu will likely push MRI to the forefront of neuroimaging modalities used to characterize neuroinflammation transdiagnostically.

Effect of drug interventions on cerebral hemodynamics in ischemic stroke patients

The ischemic penumbra is sensitive to alterations in cerebral perfusion. A myriad of drugs are used in acute ischemic stroke (AIS) management, yet their impact on cerebral hemodynamics is poorly understood. As part of the Cerebral Autoregulation Network led INFOMATAS project (Identifying New Targets for Management and Therapy in Acute Stroke), this paper reviews some of the most common drugs a patient with AIS will come across and their potential influence on cerebral hemodynamics with a particular focus being on cerebral autoregulation (CA). We first discuss how compounds that promote clot lysis and prevent clot formation could potentially impact cerebral hemodynamics, before focusing on how the different classes of antihypertensive drugs can influence cerebral hemodynamics. We discuss the different properties of each drug and their potential impact on cerebral perfusion and CA. With emerging interest in CA status of AIS patients, either during or soon after treatment when timely reperfusion and salvageable tissue is at its most critical, the properties of these pharmacological agents may be relevant for modelling cerebral perfusion accuracy and for setting individualised treatment strategies.

Statins Use and Outcome of Acute Ischemic Stroke Patients after Systemic Thrombolysis

AIM

The aim of this was to study the effects of statins and their intensity on symptomatic intracranial hemorrhage (sICH) and outcome after IV thrombolysis (IVT) for acute ischemic stroke (AIS).

METHODS

We retrospectively reviewed the medical records and cerebrovascular images of all the patients treated with IVT for AIS in our center in a 10-year period. Patients were further characterized as any statin users versus non-users on admission to the emergency department. Statins were categorized in high intensity or low intensity statin based on its propensity to reduce lower low-density cholesterol by ≥45% or <45%, respectively. Safety and discharge modified Rankin Score were compared between statin users versus non-users and also between high-intensity versus low-intensity groups.

RESULTS

A total of 834 patients received IVT for AIS in our center during a 10-year period. Multivariate models were adjusted for age, NIH Stroke Scale at admission, INR, and history of DM and atrial fibrillation. There was no association between odds of sICH and any statin use (OR = 0.52 [0.26-1.03], p = 0.06). In multivariate model, any statin use was not associated with odds of poor outcome (Table 4: OR = 1.01 [0.79-1.55], p = 0.57). There was no significant association between odds of sICH among patients on high-intensity statin compared to low intensity statin (multivariate model OR = 0.39 [0.11-1.40], p = 0.15). There was 47% reduced odds of poor outcome among patients on high-intensity statin as compared to low-intensity statin (OR = 0.53[0.32-0.88] p = 0.01). However, this significant association was lost in the multivariate model (OR = 0.60 [0.35-1.05], p = 0.07).

CONCLUSION

Our study does not show any significant association between risk of sICH and poor outcome after IVT for patients on prior statin therapy. We also did not find significant association between the risk of sICH and poor outcome after IVT and the intensity of the stain used.

Statins in Neuro-ophthalmology

Statins are effective and well-tolerated hypolipidaemic agents which have been increasingly studied for their pleiotropic immunomodulatory and anti-inflammatory effects. Statins have potential therapeutic benefit in a range of neuro-ophthalmological conditions but may also induce or exacerbate certain neurological disorders. This literature review examines evidence from clinical and in vitro studies assessing the effects of statins in myasthenia gravis, myopathy, multiple sclerosis, neuromyelitis optica, idiopathic intracranial hypertension (pseudotumour cerebri), migraine, giant cell arteritis, Bell's palsy, ocular ischaemia, stroke, Alzheimer's disease and Parkinson's disease.

The Benefits and Risks of Statin Therapy in Ischemic Stroke: A Review of the Literature

Statins are effective cholesterol-lowering drugs for reducing the risks of mortality and morbidity of cardiovascular diseases. Increasing evidence has shown that statin use is associated with a significant beneficial effect in patients with ischemic stroke. Both pre-stroke and post-stroke statin use has been found to be beneficial in ischemic stroke. Furthermore, good adherence is associated with a better clinical outcome, and statin withdrawal is associated with a poor functional outcome in patients with ischemic stroke. High-intensity statin therapy is advocated for the treatment of ischemic stroke. However, there are concerns regarding the adverse effects associated with statin use in ischemic stroke such as intracranial hemorrhage. In this review, we summarize the beneficial effect of statin use in ischemic stroke and discuss the potential risks associated with statin therapy.

Transporter-Mediated Delivery of Small Molecule Drugs to the Brain: A Critical Mechanism That Can Advance Therapeutic Development for Ischemic Stroke

Ischemic stroke is the 5th leading cause of death in the United States. Despite significant improvements in reperfusion therapies, stroke patients still suffer from debilitating neurocognitive deficits. This indicates an essential need to develop novel stroke treatment paradigms. Endogenous uptake transporters expressed at the blood-brain barrier (BBB) provide an excellent opportunity to advance stroke therapy via optimization of small molecule neuroprotective drug delivery to the brain. Examples of such uptake transporters include organic anion transporting polypeptides (OATPs in humans; Oatps in rodents) and organic cation transporters (OCTs in humans; Octs in rodents). Of particular note, small molecule drugs that have neuroprotective properties are known substrates for these transporters and include 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (i.e., statins) for OATPs/Oatps and 1-amino-3,5-dimethyladamantane (i.e., memantine) for OCTs/Octs. Here, we review current knowledge on specific BBB transporters that can be targeted for improvement of ischemic stroke treatment and provide state-of-the-art perspectives on the rationale for considering BBB transport properties during discovery/development of stroke therapeutics.

Lipid Control and Beyond: Current and Future Indications for Statin Therapy in Stroke

OPINION STATEMENT

Statins are a group of lipid-lowering agents that are competitive inhibitors of the enzyme 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase that have been used to reduce cholesterol levels and prevent cardiovascular events. Statins have been also shown to reduce the risk of stroke. In this review, we cover the role of statins in cerebrovascular disease through lipid-lowering mechanisms and other "pleiotropic" effects that provide protection against cerebrovascular events and potentially contribute to improve functional outcome after stroke.

Reperfusion Beyond 6 Hours Reduces Infarct Probability in Moderately Ischemic Brain Tissue

BACKGROUND AND PURPOSE

We aimed to examine perfusion changes between 3 and 6 and 6 and 24 hours after stroke onset and their impact on tissue outcome.

METHODS

Acute ischemic stroke patients underwent perfusion magnetic resonance imaging at 3, 6, and 24 hours after stroke onset and follow-up fluid-attenuated inversion recovery at 1 month to assess tissue fate. Mean transit time prolongation maps (MTTp=MTT-[median MTT of contralateral hemisphere]) were obtained at 3 (MTTp3 h), 6 (MTTp6 h), and 24 hours (MTTp24 h). Perfusion changes between 3 and 6 hours (ΔMTTp3_6) and 6 and 24 hours (ΔMTTp6_24) were calculated. A 2-step analysis was performed to evaluate the impact of ΔMTTp3_6 and ΔMTTp6_24 on tissue fate. First, a voxel-based multivariable logistic regression was performed for each individual patient with MTTp3 h, ΔMTTp3_6, and ΔMTT6_24 as independent variables and tissue fate as outcome. Second, Wilcoxon signed-rank tests on logistic regression coefficients were performed across patients to evaluate whether ΔMTTp3_6 and ΔMTT6_24 had significant impact on tissue fate for varying severities of baseline perfusion.

RESULTS

Perfusion change was common during both time periods: 85% and 81% of patients had perfusion improvement during 3- to 6- and 6- and 24-hour time intervals, respectively. ΔMTT3_6 significantly influenced 1-month infarct probability across a wide range of baseline perfusion (MTTp 0-15 s). ΔMTT6_24 also impacted 1-month infarct probability, but its influence was restricted to tissue with milder baseline ischemia (MTTp 0-10 s).

CONCLUSIONS

Brain tissue with mild to moderate ischemia can be salvaged by reperfusion even after 6 hours. Such tissue could be targeted for intervention beyond current treatment windows.

Statins in Acute Ischemic Stroke: A Systematic Review

BACKGROUND AND PURPOSE

Statins have pleiotropic effects of potential neuroprotection. However, because of lack of large randomized clinical trials, current guidelines do not provide specific recommendations on statin initiation in acute ischemic stroke (AIS). The current study aims to systematically review the statin effect in AIS.

METHODS

From literature review, we identified articles exploring prestroke and immediate post-stroke statin effect on imaging surrogate markers, initial stroke severity, functional outcome, and short-term mortality in human AIS. We summarized descriptive overview. In addition, for subjects with available data from publications, we conducted meta-analysis to provide pooled estimates.

RESULTS

In total, we identified 70 relevant articles including 6 meta-analyses. Surrogate imaging marker studies suggested that statin might enhance collaterals and reperfusion. Our updated meta-analysis indicated that prestroke statin use was associated with milder initial stroke severity (odds ratio [OR] [95% confidence interval], 1.24 [1.05-1.48]; P=0.013), good functional outcome (1.50 [1.29-1.75]; P<0.001), and lower mortality (0.42 [0.21-0.82]; P=0.0108). In-hospital statin use was associated with good functional outcome (1.31 [1.12-1.53]; P=0.001), and lower mortality (0.41 [0.29-0.58]; P<0.001). In contrast, statin withdrawal was associated with poor functional outcome (1.83 [1.01-3.30]; P=0.045). In patients treated with thrombolysis, statin was associated with good functional outcome (1.44 [1.10-1.89]; P=0.001), despite an increased risk of symptomatic hemorrhagic transformation (1.63 [1.04-2.56]; P=0.035).

CONCLUSIONS

The current study findings support the use of statin in AIS. However, the findings were mostly driven by observational studies at risk of bias, and thereby large randomized clinical trials would provide confirmatory evidence.

Perihematoma cerebral blood flow is unaffected by statin use in acute intracerebral hemorrhage patients

Statin therapy has been associated with improved cerebral blood flow (CBF) and decreased perihematoma edema in animal models of intracerebral hemorrhage (ICH). We aimed to assess the relationship between statin use and cerebral hemodynamics in ICH patients. A post hoc analysis of 73 ICH patients enrolled in the Intracerebral Hemorrhage Acutely Decreasing Arterial Pressure Trial (ICH ADAPT). Patients presenting <24 hours from ICH onset were randomized to a systolic blood pressure target <150 or <180 mm Hg with computed tomography perfusion imaging 2 hours after randomization. Cerebral blood flow maps were calculated. Hematoma and edema volumes were measured planimetrically. Regression models were used to assess the relationship between statin use, perihematoma edema and cerebral hemodynamics. Fourteen patients (19%) were taking statins at the time of ICH. Statin-treated patients had similar median (IQR Q25 to 75) hematoma volumes (21.1 (9.5 to 38.3) mL versus 14.5 (5.6 to 27.7) mL, P=0.25), but larger median (IQR Q25 to 75) perihematoma edema volumes (2.9 (1.7 to 9.0) mL versus 2.2 (0.8 to 3.5) mL, P=0.02) compared with nontreated patients. Perihematoma and ipsilateral hemispheric CBF were similar in both groups. A multivariate linear regression model revealed that statin use and hematoma volumes were independent predictors of acute edema volumes. Statin use does not affect CBF in ICH patients. Statin use, along with hematoma volume, are independently associated with increased perihematoma edema volume.

The many roles of statins in ischemic stroke

Stroke is the third leading cause of human death. Endothelial dysfunction, thrombogenesis, inflammatory and oxidative stress damage, and angiogenesis play an important role in cerebral ischemic pathogenesis and represent a target for prevention and treatment. Statins have been found to improve endothelial function, modulate thrombogenesis, attenuate inflammatory and oxidative stress damage, and facilitate angiogenesis far beyond lowering cholesterol levels. Statins have also been proved to significantly decrease cardiovascular risk and to improve clinical outcome. Could statins be the new candidate agent for the prevention and therapy in ischemic stroke? In recent years, a vast expansion in the understanding of the pathophysiology of ischemic stroke and the pleiotropic effects of statins has occurred and clinical trials involving statins for the prevention and treatment of ischemic stroke have begun. These facts force us to revisit ischemic stroke and consider new strategies for prevention and treatment. Here, we survey the important developments in the non-lipid dependent pleiotropic effects and clinical effects of statins in ischemic stroke.

Ischemia-reperfusion injury in stroke

Despite ongoing advances in stroke imaging and treatment, ischemic and hemorrhagic stroke continue to debilitate patients with devastating outcomes at both the personal and societal levels. While the ultimate goal of therapy in ischemic stroke is geared towards restoration of blood flow, even when mitigation of initial tissue hypoxia is successful, exacerbation of tissue injury may occur in the form of cell death, or alternatively, hemorrhagic transformation of reperfused tissue. Animal models have extensively demonstrated the concept of reperfusion injury at the molecular and cellular levels, yet no study has quantified this effect in stroke patients. These preclinical models have also demonstrated the success of a wide array of neuroprotective strategies at lessening the deleterious effects of reperfusion injury. Serial multimodal imaging may provide a framework for developing therapies for reperfusion injury.

Role of statin in atrial fibrillation-related stroke: an angiographic study for collateral flow

BACKGROUND

Currently, intensive lipid lowering is recommended in patients with atherosclerotic ischemic stroke or transient ischemic attack. However, the role of statin in cardioembolic stroke is unclear. We investigated the association of statin with pretreatment collateral status in cardioembolic stroke.

METHODS

A collaborative study from two stroke centers in distinct geographic regions included consecutive patients with acute middle cerebral artery (MCA) infarction due to atrial fibrillation (AF) who underwent cerebral angiography. The relationship between pretreatment collateral grade and the use/dose of statin at stroke onset was assessed. The angiographic collateral grade was evaluated according to the ASITN/SIR Collateral Flow Grading System.

RESULTS

Ninety-eight patients (76 statin-naïve, 22 statin users) were included. Compared with statin-naïve patients, statin users were older and more frequently had hypertension, hyperlipidemia and coronary heart disease. Excellent collaterals (grade 3-4) were more frequently observed in statin users (11 patients, 50%) than in statin-naïve patients (21 patients, 27.6%; p = 0.049). The use of atorvastatin 10 mg equivalent or higher doses of statin was associated with excellent collaterals (p for trend = 0.025). In multiple regression analysis, prestroke statin use was independently associated with excellent collaterals (odds ratio, 7.841; 95% confidence interval, CI, 1.96-31.363; p = 0.004).

CONCLUSIONS

Premorbid use of statin in AF patients is associated with excellent collateral flow. Although most statin trials excluded patients with cardioembolic stroke, our data suggests the possibility that statin may be beneficial in AF-related stroke

Dose-related effects of statins on symptomatic intracerebral hemorrhage and outcome after thrombolysis for ischemic stroke

BACKGROUND AND PURPOSE

The aim of our study was to assess whether statins have dose-dependent effects on risk of symptomatic intracerebral hemorrhage (sICH) and outcome after intravenous thrombolysis for ischemic stroke.

METHODS

We pooled data from 2 European intravenous thrombolysis registries. Statin doses were stratified in 3 groups according to the attainable lowering of cholesterol levels (low dose: simvastatin 20 mg or equivalent; medium dose: simvastatin 40 mg or equivalent; and high dose: simvastatin 80 mg or equivalent). sICH was defined according to the European Cooperative Acute Stroke Study. Modified Rankin Scale score 0 to 2 at 3 months was considered a favorable outcome.

RESULTS

Among 1446 patients analyzed (median age, 75 years; median initial National Institutes of Health Stroke Scale score, 11; 54% men), 317 (22%) used statins before intravenous thrombolysis. Of them, 120 patients had low-dose, 134 medium-dose, and 63 high-dose statin therapy. sICH occurred in 4% of patients (n=53). Frequency of sICH was 2%, 6%, and 13% in patients with low-, medium-, and high-dose statin treatment, respectively (P<0.01). Adjusted odds ratio (OR) for sICH was 2.4 (95% confidence interval [CI], 1.1-5.3) and 5.3 (95% CI, 2.3-12.3) for patients with medium- and high-dose statins compared with non-statin users. Statin users more often achieved favorable outcome compared with non-statin users (58% versus 51%; P=0.03). An independent association of statin use with favorable outcome was detected (adjusted OR, 1.8; 95% CI, 1.3-2.5). The association was maintained when stratifying for statin dose, although it was not significant in the high-dose group anymore (OR, 1.7; 95% CI, 0.9-3.2).

CONCLUSIONS

We observed an association between increasing dose of statin use and risk of sICH after intravenous thrombolysis. Nevertheless, there was an overall beneficial effect of previous statin use on favorable 3-month outcome.

Short-term high-dose effect of lovastatin on thrombolysis by rt-PA in a human whole-blood in vitro clot model

High-dose hydroxymethylglutaryl coenzyme. A reductase inhibitor (statin) administration reduces neuronal injury and improves outcomes in experimental models of acute ischemic stroke, and has been shown to be safe in a phase 1 dose-escalation study using lovastatin at doses higher than currently approved for daily use. Statins also affect the hemostatic system by upregulating t-PA expression and decreasing plasminogen activator inhibitor (PAI-1) expression, platelet adhesion and thrombus formation in animal models. Since a thrombolytic agent, recombinant tissue plasminogen activator (rt-PA), is currently the only FDA-approved therapy for use in ischemic stroke patients, it is important to ascertain whether high statin doses impact the efficacy of rt-PA. The main goal of this study was to evaluate the effect of a high dose of lovastatin and its active form, lovastatin hydroxy acid, on rt-PA thrombolysis in an in vitro model. Percentage clot lysis was measured in the presence and absence of rt-PA in three different treatment groups: lovastatin, lovastatin hydroxy acid, and ethanol. The effect of ethanol on clot lysis was studied since ethanol was used to disperse the highly hydrophobic lovastatin. The decrease in clot width over time was measured using microscopic imaging of an in vitro human whole blood clot model; an approximately 400 μm diameter clot was formed on suture silk, suspended in human fresh frozen plasma (hFFP) and exposed to treatment. In the absence of rt-PA, clot lysis did not show statistically significant differences in the percentage clot lysis between different treatment groups (p=0.103). In the presence of rt-PA, clot lysis was greater than in the absence of rt-PA for all groups, but there were no statistically significant differences between treatment groups (p=0.385). In this in vitro study, high doses of lovastatin neither impaired nor enhanced the lytic efficacy of rt-PA.

Statins and cerebral hemodynamics

HMG-CoA reductase inhibitors (statins) are associated with improved stroke outcome. This observation has been attributed in part to the palliative effect of statins on cerebral hemodynamics and cerebral autoregulation (CA), which are mediated mainly through the upregulation of endothelium nitric oxide synthase (eNOS). Several animal studies indicate that statin pretreatment enhances cerebral blood flow after ischemic stroke, although this finding is not further supported in clinical settings. Cerebral vasomotor reactivity, however, is significantly improved after long-term statin administration in most patients with severe small vessel disease, aneurysmal subarachnoid hemorrhage, or impaired baseline CA.

Neuroprotective effects of statins: evidence from preclinical and clinical studies

OPINION STATEMENT

The benefits of statins for both primary and secondary prevention of ischemic stroke are clearly established. Evidence is accumulating that statin withdrawal after ischemic stroke may lead to worse outcome and that initiation of statins after ischemic stroke may reduce mortality and improve outcome. Current treatment guidelines recommend starting statins before discharge in patients with stroke related to atherosclerosis or who have elevated cholesterol. The primary treatment question then is not if to start statins in most ischemic stroke patients, but when. Our recommendation would be start a statin as soon as the patient passes a dysphagia screen and can safely take oral medication. Based on the results of the Heart Protection Study and the SPARCL trial, either simvastatin 40 mg or atorvastatin 80 mg are appropriate alternatives. Clinical trials are needed to demonstrate unequivocal efficacy of improved outcome and to determine if lower doses may have this effect. Additionally, improved outcome needs to be established in cardioembolic stroke patients before routine use of statins in this stroke subtype can be recommended.