Etiologic Workup in Cases of Cryptogenic Stroke: A Systematic Review of International Clinical Practice Guidelines.

Background and Purpose- Identifying the etiology of acute ischemic stroke is essential for effective secondary prevention. However, in at least one third of ischemic strokes, existing investigative protocols fail to determine the underlying cause. Establishing etiology is complicated by variation in clinical practice, often reflecting preferences of treating clinicians and variable availability of investigative techniques. In this review, we systematically assess the extent to which there exists consensus, disagreement, and gaps in clinical practice recommendations on etiologic workup in acute ischemic stroke. Methods- We identified clinical practice guidelines/consensus statements through searches of 4 electronic databases and hand-searching of websites/reference lists. Two reviewers independently assessed reports for eligibility. We extracted data on report characteristics and recommendations relating to etiologic workup in acute ischemic stroke and in cases of cryptogenic stroke. Quality was assessed using the AGREE II tool (Appraisal of Guidelines for Research & Evaluation). Recommendations were synthesized according to a published algorithm for diagnostic evaluation in cryptogenic stroke. Results- We retrieved 16 clinical practice guidelines and 7 consensus statements addressing acute stroke management (n=12), atrial fibrillation (n=5), imaging (n=5), and secondary prevention (n=1). Five reports were of overall high quality. For all patients, guidelines recommended routine brain imaging, noninvasive vascular imaging, a 12-lead ECG, and routine blood tests/laboratory investigations. Additionally, ECG monitoring (>24 hours) was recommended for patients with suspected embolic stroke and echocardiography for patients with suspected cardiac source. Three reports recommended investigations for rarer causes of stroke. None of the reports provided guidance on the extent of investigation needed before classifying a stroke as cryptogenic. Conclusions- While consensus exists surrounding standard etiologic workup, there is little agreement on more advanced investigations for rarer causes of acute ischemic stroke. This gap in guidance, and in the underpinning evidence, demonstrates missed opportunities to better understand and protect against ongoing stroke risk. Registration- URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42019127822.

Non-pharmacological interventions for the reduction and maintenance of blood pressure in people with prehypertension: a systematic review protocol.

INTRODUCTION: Prehypertension is defined as blood pressure that is above the normal range but not high enough to be classed as hypertension. Prehypertension is a warning of development of hypertension as well as a risk for cardiovascular disease, heart attack and stroke. In the UK, non-pharmacological interventions are recommended for prehypertension management but no reviews have focused on the effectiveness of these types of interventions solely in people with prehypertension. Therefore, the proposed systematic review will assess the clinical effectiveness and cost-effectiveness of non-pharmacological interventions in reducing or maintaining blood pressure in prehypertensive people. METHODS AND ANALYSIS: This systematic review will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The databases/trial registries that will be searched to identify relevant randomised controlled trials (RCTs) and economic evaluations include Medline, EMBASE, CINAHL, PsycINFO, CENTRAL, the WHO International Clinical Trials Registry Platform, ClinicalTrials.gov, Cochrane Library, Scopus and the International HTA Database. Search terms have been identified by the team including an information specialist. Three reviewers will be involved in the study selection process. Risk of bias will be evaluated using the Cochrane risk-of-bias tool for RCTs and the Consensus Health Economic Criteria list for economic evaluations. Findings from the included studies will be tabulated and synthesised narratively. Heterogeneity will be assessed through visual inspection of forest plots and the calculation of the χ2 and I2 statistics and causes of heterogeneity will be assessed where sufficient data are available. If possible, we plan to investigate differential effects on specific subgroups and from different types of interventions using meta-regression. Where relevant, the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) will be used to assess the certainty of the evidence found. ETHICS AND DISSEMINATION: Ethical approval is not needed. Results will be published in a peer-reviewed journal, disseminated via the wider study website and shared with the study sites and participants. REGISTRATION DETAILS: The review is registered with PROSPERO (CRD420232433047).

Risk reduction intervention for raised blood pressure (REVERSE): protocol for a mixed-methods feasibility study.

INTRODUCTION: Around 40% of adults have pre-hypertension (blood pressure between 120-139/80-89), meaning they are at increased risk of developing hypertension and other cardiovascular disease-related conditions. There are limited studies on the management of pre-hypertension; however, guidance recommends that it should be focused on lifestyle modification rather than on medication. Self-monitoring of blood pressure could allow people to monitor and manage their risk status and may allow individuals to modify lifestyle factors. The purpose of this study is to determine the feasibility and acceptability, to both healthcare professionals and people with pre-hypertension, of blood pressure self-monitoring. METHODS AND ANALYSIS: A prospective, non-randomised feasibility study, with a mixed-methods approach will be employed. Eligible participants (n=114) will be recruited from general practices, pharmacies and community providers across Lancashire and South Cumbria. Participants will self-monitor their blood pressure at home for 6 months and will complete questionnaires at three timepoints (baseline, 6 and 12 months). Healthcare professionals and participants involved in the study will be invited to take part in follow-up interviews and a focus group. The primary outcomes include the willingness to engage with the concept of pre-hypertension, the acceptability of self-monitoring, and the study processes. Secondary outcomes will inform the design of a potential future trial. A cost-analysis and cost-benefit analysis will be conducted. ETHICS AND DISSEMINATION: Ethics approval has been obtained from London-Fulham NHS Research Ethics Committee, the University of Central Lancashire Health Ethics Review Panel and the HRA. The results of the study will be disseminated via peer-reviewed publications, feedback to service users and healthcare professionals, and to professional bodies in primary care and pharmacy. TRIAL REGISTRATION NUMBER: ISRCTN13649483.

Brain inflammation is induced by co-morbidities and risk factors for stroke.

Chronic systemic inflammatory conditions, such as atherosclerosis, diabetes and obesity are associated with increased risk of stroke, which suggests that systemic inflammation may contribute to the development of stroke in humans. The hypothesis that systemic inflammation may induce brain pathology can be tested in animals, and this was the key objective of the present study. First, we assessed inflammatory changes in the brain in rodent models of chronic, systemic inflammation. PET imaging revealed increased microglia activation in the brain of JCR-LA (corpulent) rats, which develop atherosclerosis and obesity, compared to the control lean strain. Immunostaining against Iba1 confirmed reactive microgliosis in these animals. An atherogenic diet in apolipoprotein E knock-out (ApoE(-/-)) mice induced microglial activation in the brain parenchyma within 8 weeks and increased expression of vascular adhesion molecules. Focal lipid deposition and neuroinflammation in periventricular and cortical areas and profound recruitment of activated myeloid phagocytes, T cells and granulocytes into the choroid plexus were also observed. In a small, preliminary study, patients at risk of stroke (multiple risk factors for stroke, with chronically elevated C-reactive protein, but negative MRI for brain pathology) exhibited increased inflammation in the brain, as indicated by PET imaging. These findings show that brain inflammation occurs in animals, and tentatively in humans, harbouring risk factors for stroke associated with elevated systemic inflammation. Thus a "primed" inflammatory environment in the brain may exist in individuals at risk of stroke and this can be adequately recapitulated in appropriate co-morbid animal models.

Etiologic workup in cases of cryptogenic stroke: protocol for a systematic review and comparison of international clinical practice guidelines.

BACKGROUND: Stroke is a leading cause of death and disability worldwide. Identifying the aetiology of ischaemic stroke is essential in order to initiate appropriate and timely secondary prevention measures to reduce the risk of recurrence. For the majority of ischaemic strokes, the aetiology can be readily identified, but in at least 30% of cases, the exact aetiology cannot be determined using existing investigative protocols. Such strokes are classed as 'cryptogenic' or as a stroke of unknown origin. However, there exists substantial variation in clinical practice when investigating cases of seemingly cryptogenic stroke, often reflecting local service availability and the preferences of treating clinicians. This variation in practice is compounded by the lack of international consensus as to the optimum level and timing of investigations required following a stroke. To address this gap, we aim to systematically review and compare recommendations in evidence-based clinical practice guidelines (CPGs) that relate to the assessment and investigation of the aetiology of ischaemic stroke, and any subsequent diagnosis of cryptogenic stroke. METHOD: We will search for CPGs using electronic databases (MEDLINE, Health Management Information Consortium (HMIC), EMBASE, and CINAHL), relevant websites and search engines (e.g. guideline specific websites, governmental, charitable, and professional practice organisations) and hand-searching of bibliographies and reference lists. Two reviewers will independently screen titles, abstracts and CPGs using a pre-defined relevance criteria form. From each included CPG, we will extract definitions and terms for cryptogenic stroke; recommendations related to assessment and investigation of the aetiology of stroke, including the grade of recommendations and underpinning evidence. The quality of the included CPGs will be assessed using the AGREE II (Appraisal of Guidelines for Research and Evaluation) tool. Recommendations across the CPGs will be summarised descriptively highlighting areas of convergence and divergence between CPGs. DISCUSSION: To our knowledge, this will be the first review to systematically compare recommendations of international CPGs on investigating the aetiology of ischaemic stroke. The findings will allow for a better understanding of international perspectives on the optimum level of investigations required following a stroke and thus contribute to achieving greater international consensus on best practice in this important and complex area. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42019127822.

Clinical outcome following acute ischaemic stroke relates to both activation and autoregulatory inhibition of cytokine production.

BACKGROUND: As critical mediators of local and systemic inflammatory responses, cytokines are produced in the brain following ischaemic stroke. Some have been detected in the circulation of stroke patients, but their role and source is unclear. Focusing primarily on interleukin(IL)-1-related mechanisms, we serially measured plasma inflammatory markers, and the production of cytokines by whole blood, from 36 patients recruited within 12 h and followed up to 1 year after acute ischaemic stroke (AIS). RESULTS: Admission plasma IL-1 receptor antagonist (IL-1ra) concentration was elevated, relative to age-, sex-, and atherosclerosis-matched controls. IL-1beta, soluble IL-1 receptor type II, tumour necrosis factor (TNF)-alpha, TNF-RII, IL-10 and leptin concentrations did not significantly differ from controls, but peak soluble TNF receptor type I (sTNF-RI) in the first week correlated strongly with computed tomography infarct volume at 5-7 days, mRS and BI at 3 and 12 months. Neopterin was raised in patients at 5-7 d, relative to controls, and in subjects with significant atherosclerosis. Spontaneous IL-1beta, TNF-alpha and IL-6 gene and protein expression by blood cells was minimal, and induction of these cytokines by lipopolysaccharide (LPS) was significantly lower in patients than in controls during the first week. Minimum LPS-induced cytokine production correlated strongly with mRS and BI, and also with plasma cortisol. CONCLUSION: Absence of spontaneous whole blood gene activation or cytokine production suggests that peripheral blood cells are not the source of cytokines measured in plasma after AIS. Increased plasma IL-1ra within 12 h of AIS onset, the relationship between sTNF-RI and stroke severity, and suppressed cytokine induction suggests early activation of endogenous immunosuppressive mechanisms after AIS.

Variability of the systemic acute phase response after ischemic stroke.

Despite apparent relationships between ischemic stroke and the acute phase response (APR), considerable variation in the APR exists between individuals. We therefore performed post-hoc analysis of individual APR profiles in 31 patients with ischemic stroke in relation to volume of brain infarction. Patients with ischemic stroke had serial blood samples taken within 12 h, and up to 12 months of symptom onset, for analysis of plasma C-reactive protein (CRP) and interleukin-6 (IL-6). Computed tomography (CT) brain infarct volume was measured at 5 to 7 days (median 23.9 cm(3)). An increase in plasma CRP after the admission sample was evident in 94% of patients by day 5 to 7 (median increase 558% of admission value). CRP response, assessed as area under the curve between admission and day 5 to 7, correlated strongly (r=0.62, p<0.001) with CT infarct volume. Those with greater infarct volumes had more evidence of infection, either prior to or during the first week after stroke. The pattern of response was similar for IL-6, although only 77% showed an increase in plasma IL-6 after the admission sample (median increase 148% of admission value). These data suggest that, although infection and other factors may contribute to systemic inflammation, the extent of acute brain injury after ischemic stroke is a major factor influencing the magnitude and variability of the APR.

An early and sustained peripheral inflammatory response in acute ischaemic stroke: relationships with infection and atherosclerosis.

Central nervous system and peripheral inflammation is important in the responses to ischaemic stroke, and may also predispose to its development. We aimed to identify (1) the extent to which a peripheral inflammatory response is activated in patients following acute stroke, and (2) whether there was evidence for preexisting peripheral inflammation. Thirty-six patients with ischaemic stroke within 12 h of onset of symptoms had serial blood samples taken up to 12 months for analysis of markers of inflammation. Thirty-six control subjects, individually matched for age, sex and degree of atherosclerosis, were also studied. Median C-reactive protein (CRP) was elevated, relative to controls (2.08 mg/l), from admission (4.31 mg/l) (p

Peak plasma interleukin-6 and other peripheral markers of inflammation in the first week of ischaemic stroke correlate with brain infarct volume, stroke severity and long-term outcome.

BACKGROUND: Cerebral ischaemia initiates an inflammatory response in the brain and periphery. We assessed the relationship between peak values of plasma interleukin-6 (IL-6) in the first week after ischaemic stroke, with measures of stroke severity and outcome. METHODS: Thirty-seven patients with ischaemic stroke were prospectively recruited. Plasma IL-6, and other markers of peripheral inflammation, were measured at pre-determined timepoints in the first week after stroke onset. Primary analyses were the association between peak plasma IL-6 concentration with both modified Rankin score (mRS) at 3 months and computed tomography (CT) brain infarct volume. RESULTS: Peak plasma IL-6 concentration correlated significantly (p < 0.001) with CT brain infarct volume (r = 0.75) and mRS at 3 months (r = 0.72). It correlated similarly with clinical outcome at 12 months or stroke severity. Strong associations were also noted between either peak plasma C-reactive protein (CRP) concentration or white blood cell (WBC) count, and all outcome measures. CONCLUSIONS: These data provide evidence that the magnitude of the peripheral inflammatory response is related to the severity of acute ischaemic stroke, and clinical outcome.