Biological basis for statin therapy in stroke prevention

Protective Effects of Different Classes, Intensity, Cumulative Dose-Dependent of Statins Against Primary Ischemic Stroke in Patients with Type 2 Diabetes Mellitus

PURPOSE OF REVIEW

The aim of this study is to investigate the protective effects of different statin classes, intensity, and cumulative dose-dependent against primary ischemic stroke in patients with T2DM.

RECENT FINDINGS

The Cox hazards model was used to evaluate statin use on primary ischemic stroke. Case group: T2DM patients who received statins; control group: T2DM patients who received no statins during the follow-up. Adjusted hazard ratio (aHR) for primary ischemic stroke was 0.45 (95% CI: 0.44 to 0.46). Cox regression analysis showed significant reductions in primary ischemic stroke incidence in users of different statin classes. Corresponding aHRs (95% CI) were 0.09 to 0.79 for pitavastatin, rosuvastatin, atorvastatin, pravastatin, simvastatin, fluvastatin, and lovastatin. Multivariate analyses indicated significant reductions in primary ischemic stroke incidence for patients who received different cumulative defined daily doses (cDDDs) per year (cDDD-year). Corresponding aHRs (95% CI) were 0.17 to 0.77 for quartiles 4 to 1 of cDDD-years, respectively (P for trend < .0001). Optimal intensity daily dose of statin use was 0.89 DDD with the lowest aHR of primary ischemic stroke compared with other DDDs. Persistent statin use reduces the risk of primary ischemic stroke in T2DM patients. Higher cDDD-year values are associated with higher reductions in primary ischemic stroke risk in T2DM patients.

Statin use prior to ischemic stroke onset is associated with decreased in-hospital mortality

Statins can reduce the risk of stroke in at-risk populations and improve survival after acute ischemic stroke (AIS) among patients with previous statin use. This study aimed to investigate the impact of statin use before AIS onset on in-hospital mortality and identify the factors related to in-hospital mortality among patients with and without previous statin use. A retrospective cohort study of all patients with AIS attending hospital from June 1, 2008 to December 31, 2008. Data were collected from medical records including demographic information, diagnostic information, risk factors, previous statin use, and vital discharge status. Chi-square, Fisher's exact tests, student's t-test, and Mann-Whitney U test, whatever appropriate, were used to test the significance between the variables, and multiple logistic regression was used to identify factors associated with in-hospital mortality. Altogether, 386 patients with AIS were studied, of which 113 (29.3%) had a documented previous statin use. A total of 62 (16.1%) patients with AIS died in hospital. In-hospital mortality was significantly lower among previous statin users (P = 0.013). The presence of atrial fibrillation (AF) increased in-hospital mortality among patients with or without previous statin use. The independent predictors for in-hospital mortality among AIS patients without previous statin use were the presence of diabetes mellitus (P = 0.047), AF (P = 0.045), and renal impairment (P < 0.001). The prophylactic administration of statins significantly reduces post-AIS in-hospital mortality. Furthermore, the identification of predictors of in-hospital mortality might reduce death rates and enhance the application of specific therapeutic and management strategies to patients at a high risk of dying.

Prevention and management of stroke in very elderly patients

As the average human lifespan extends and medical care improves, there are more individuals above the age of 80 years who have a high quality of life. However, these very elderly individuals are particularly susceptible to stroke. Identifying ways to optimise the treatment and prevention of acute stroke in these much older people will increasingly be a priority for health-care providers, research funding agencies, and policy makers in years to come. Despite substantial advances in stroke research, with several therapeutic drugs being able to enhance clinical outcomes in people with stroke or who are at risk of stroke, the very elderly seem to receive fewer vascular protection interventions that have been shown to be effective in younger individuals. Although there has been an under-representation of the very elderly in studies of stroke therapy, these treatments might be of benefit to this group of patients. Indeed, emerging data indicate that the use of several of these therapies in routine clinical practice in the very elderly can be effective.

Immunohistochemical study on distribution of NF-kappaB and p53 in gerbil hippocampus after transient cerebral ischemia: effect of pitavastatin

We investigated the immunohistochemical alterations of the transcription nuclear factor kappa-B (NF-kappaB) and transcription factor p53 in the hippocampus after transient cerebral ischemia in gerbils. We also examined the effect of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor pitavastatin against the alterations of NF-kappaB, p53 and neuronal nuclei in the hippocampus after ischemia. Severe neuronal damage was observed in the hippocampal CA1 neurons 5 and 14 days after ischemia. In the present study, the increase of NF-kappaB immunoreactivity in glial cells and p53 immunoreactivity in neurons preceded neuronal damage in the hippocampal CA1 sector after ischemia. Thereafter, NF-kappaB immunoreactivity was induced highly in reactive astrocytes and microglia of the hippocampal CA1 sector where severe neuronal damage was observed. Our immunohistochemical study showed that pitavastatin prevented the alterations of NF-kappaB and p53 in the hippocampal CA1 sector 5 days after transient ischemia. Furthermore, our results with neuronal nuclei immunostaining indicate that pitavastatin dose-dependently prevented the neuronal cell death in the hippocampal CA1 sector 5 days after transient cerebral ischemia. These results suggest that the up-regulations of NF-kappaB in glia and p53 in neurons can cause neuronal cell death after ischemia. Our findings also support the hypothesis that NF-kappaB- and/or p53-mediated neuronal cell death is prevented through decreasing oxidative stress by pitavastatin. Thus, NF-kappaB and p53 may provide an attractive target for the development of novel therapeutic approaches for brain stroke.

Lipids and stroke: the opportunity of lipid-lowering treatment

Dyslipemia is a clear risk factor (RF) for ischemic heart disease and peripheral artery disease, but its relation with ischemic stroke (IS) is not so clear. HMG-CoA reductase inhibitor drugs or statins (simvastatin, atorvastatin, pravastatin) reduce the relative risk of IS by between 18 and 51% in patients with IHD, in patients with high vascular disease risk and in hypertensive patients with other RFs, acute coronary syndrome, and type 2 diabetes mellitus. According to the guidelines for use, statins are indicated in the majority of patients with IS since the risk is equivalent to that of IHD or high vascular disease risk. In view of the existing clinical evidence of benefit, it would not seem unreasonable to proceed with treatment of patients using statins while awaiting specific studies justifying their use. The non-lipid-lowering mechanisms of the statins and results of studies, such as the Heart Protection Study, provide evidence for widening the indications of statins beyond the prevention of dyslipemia, as a new therapeutic approach in the prevention of IS in patients with plasma levels of total cholesterol or low density lipoproteins currently considered within the normal distribution. The neuroprotective role, which these drugs may play in the acute phase of cerebral ischemia, remains to be clarified, but very recent evidence suggests that such patients may also benefit.

HMG CoA reductase inhibitors reduce ischemic brain injury of Wistar rats through decreasing oxidative stress on neurons

Statins possess neuroprotective effect against ischemic damage, but how they protect neurons is not exactly made clear. We speculated that anti-oxidative property of statins is implicated, and investigated statins' influences on the oxidative neuronal damage in the brain after ischemia. After 14 days of atorvastatin, pitavastatin, simvastatin, or vehicle administration, 90 min of middle cerebral artery occlusion was imposed on Wistar rats. The production of 4-hydroxynonenal (HNE) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), both of which are oxidative stress markers, as well as infarction formation were investigated at 1 day after the reperfusion. In the vehicle group, massive infarction was confirmed and HNE and 8-OHdG are robustly produced. In the statins-treated group, the infarction was smaller and the HNE and 8-OHdG production was less prominent than the vehicle group. Among the statins investigated, simvastatin was most effective for reducing oxidative stress and infarction volume, which may be brought by its highly lipophilic property. Reduction of oxidative stress by statins may be one main reason in ameliorating ischemic brain damage in rats.

Favorable Outcome of Ischemic Stroke in Patients Pretreated with Statins

Background and Purpose— Statins may be beneficial for patients with acute ischemic stroke. We tested the hypothesis that patients pretreated with statins at the onset of stroke have less severe neurological effects and a better outcome.

Methods— We prospectively included consecutive patients with ischemic stroke of <24-hour duration. We recorded demographic data, vascular risk factors, Oxfordshire Classification, National Institutes of Health Stroke Scale (NIHSS) score, admission blood glucose and body temperature, cause (Trial of Org 10172 in Acute Treatment [TOAST] criteria), neurological progression at day 3, previous statin treatment, and outcome at 3 months. We analyzed the data using univariate methods and a logistic regression with the dependent variable of good outcome (modified Rankin Scale [mRS] 0 to 1, Barthel Index [BI] 95 to 100).

Results— We included 167 patients (mean age 70.7±12 years, 94 men). Thirty patients (18%) were using statins when admitted. In the statin group, the median NIHSS score was not significantly lower and the risk of progression was not significantly reduced. Favorable outcomes at 3 months were more frequent in the statin group (80% versus 61.3%, P =0.059 with the mRS; 76.7% versus 51.8%, P =0.015 with the BI). Predictors of favorable outcome with the BI were: NIHSS score at admission (OR: 0.72; CI: 0.65 to 0.80; P <0.0001), age (OR: 0.96; CI: 0.92 to 0.99; P =0.017), and statin group (OR: 5.55; CI: 1.42 to 17.8; P =0.012).

Conclusions— Statins may provide benefits for the long-term functional outcome when administered before the onset of cerebral ischemia. However, randomized controlled trials will be required to evaluate the validity of our results.

Stroke and neurodegenerative disorders. 1. acute stroke evaluation, management, risks, prevention, and prognosis11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors(s) or upon any organization with which the author(s) is/are associated

This self-directed learning module highlights recent developments in the acute care of stroke patients, prediction of outcome after stroke, evaluation of risk factors, secondary prevention of stroke, and the evaluation of the young adult with stroke. It is part of the study guide on stroke and neurodegenerative disorders in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation. This article contains sections on the acute evaluation and management of the stroke patient, prediction of functional outcome after stroke, and secondary prevention of stroke. Special emphasis is given to the evaluation of the young adult with stroke.

OVERALL ARTICLE OBJECTIVES

(a) To summarize the acute evaluation and management of stroke, particularly in the young stroke patient; and (b) to review the risk factors for stroke and secondary prevention measures.

Cardiovascular disease prevention

In this chapter, we have reviewed many of the steps necessary for effective CHD risk reduction. The first step in the office setting is to assess the individual CHD risk. This combines the evaluation of current CHD or a "secondary risk equivalent" with the counting of risk factors and in many cases, the absolute risk calculation. The next steps are to consider each of the major modifiable risk factors (hypertension, dyslipidemia, diabetes mellitus, smoking status) to set goals for each and then work to achieve those goals through lifestyle changes and medication therapy. We reviewed each of these risk factors in detail and then turned to a discussion of emerging risk factors that may help "fine-tune" the risk assessment in some borderline cases. We also discussed additional non-invasive testing that is available to the clinician to help refine the assessment of current burden of disease. Finally, we discuss some of the barriers that exist on both a global and local level to effective treatment of CHD risk factors.

Advantages of lipid-lowering therapy in cerebral ischemia: role of HMG-CoA reductase inhibitors

Dyslipemia as a risk factor for ischemic stroke and indications for statins in the prevention of ischemic stroke are revised. The role of cholesterol levels as a risk factor for ischemic stroke is controversial. This could be due to failures in the design of early epidemiological studies. Recent studies, however, do suggest a clearer risk relationship between cholesterol levels and ischemic stroke. Studies conducted on the prevention of ischemic heart disease (IHD) with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), using pravastatin and simvastatin, unequivocally show reductions in overall mortality, cardiovascular mortality, acute myocardial infarction and other coronary events. These studies show a reduction in the risk of ischemic stroke, and although relative risk reduction is great, absolute risk reduction is low; the reasons for this are analyzed. Apart from lipid mechanisms, statins act on the atheroma plaque; they have antithrombotic and possibly neuroprotecting properties. Statins reduce the number of strokes due to the decrease of atherothrombotic strokes, cardioembolic strokes secondary to IHD, and lacunar strokes related to atherothrombosis and probably to microatheromas. Although there are currently no specific studies available on the secondary prevention of stroke with statins, which are required to clarify certain points, according to European and American guidelines for prevention, statins would be indicated in the secondary prevention of atherothrombotic stroke, and in cardioembolic and lacunar stroke associated with clinical or silent atherosclerosis (IHD, peripheral artery disease). Patients with ischemic stroke of other etiologies, except for stroke in the young or other unusual causes, are patients with a high vascular risk (cardiac and cerebral) owing to the stroke itself, age and other vascular risk factors, and they should also be treated with statins, at least from the point of view of primary prevention of IHD. Natural statins (pravastatin and simvastatin) play an essential part in secondary prevention of ischemic stroke, together with antiaggregants, anticoagulants, angiotensin-converting enzyme inhibitors and the treatment of other vascular risk factors.

Pluripotential mechanisms of cardioprotection with HMG-CoA reductase inhibitor therapy

Treatment with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors has been accompanied by a reduced risk of cardiovascular events. Rapid onset of clinical benefit and weak correlations between plasma low density lipoprotein-cholesterol levels and coronary lumen change or cardiovascular events indicates that nonlipid mechanisms are involved in this beneficial effects with HMG-CoA reductase inhibitors. Furthermore, more rapid onset of clinical benefit with HMG-CoA reductase inhibitors in patients with acute coronary syndromes or acute myocardial infarction than in those with stable coronary heart disease suggest that HMG-CoA reductase inhibitors facilitate repair of ruptured or ulcerated atherosclerotic plaque, facilitate plaque stabilization and/or reduce thrombus formation on ruptured plaques. Treatment with HMG-CoA reductase inhibitors improved endothelial dysfunction in patients with hypercholesterolemia and this improvement in endothelial function was not correlated with reduction in total serum cholesterol levels. Similarly, reduction in endothelial pre-proendothelin mRNA expression and endothelin synthesis and blood pressure lowering with HMG-CoA reductase inhibitors occurred independent of lipid-lowering. Finally, HMG-CoA reductase inhibitors increased endothelial nitric oxide levels i.e. upregulated endothelial nitric oxide synthetase expression via post-transcriptional mechanisms and prevented its down-regulation by oxidized LDL-C. HMG-CoA reductase inhibitors have been shown to modulate the immune response by inhibiting activation of immune-competent cells such as macrophages, and antigen presentation to macrophages by T cells. Treatment with HMG-CoA reductase inhibitors can reduce expression, production and circulating levels of chemokines (monocyte chemoattractant protein-1) and proinflammatory cytokines [tumor necrosis factoralpha, interleukin (IL)-6 and IL-1beta]. HMG-CoA reductase inhibitors reduced inflammation in human atheroma: significantly fewer macrophages and T cells, less oxidized LDL-C and higher collagen content. In addition, treatment with HMG-CoA reductase inhibitor led to decreased cell death within the atheroma. Treatment with these agents also reduced expression of inducible cellular adhesion molecules, decreased secretion of metalloproteinases by macrophages, reduced vascular smooth muscle cell apoptosis. Lastly, HMG-CoA reductase inhibitors appear to have important effects on the thrombogenesis: reduced expression of tissue factor production and activity; increased production of tissue factor package inhibitor; decreased platelet thrombus formation and improved fibrinolysis as a result of lowered plasminogen activator inhibitor-1 levels. As the pluripotential cardioprotective mechanisms of HMG-CoA reductase inhibitors are further elucidated, it is envisaged that treatment with HMG-CoA reductase inhibitors will be initiated earlier and more frequently in patients with hypercholesterolemia.

Basic mechanisms of stroke prevention with lipid-lowering therapy

Cholesterol-lowering therapy has not been considered an important risk factor for stroke; however, lipid-lowering therapies reduce cerebrovascular events in patients with coronary heart disease (CHD). The basic mechanisms of cerebrovascular protection have emphasized reduced atheroemboli from the left ventricle and aortic arch, delayed carotid artery disease progression, stabilization of vulnerable carotid atherosclerotic plaque, and improvement in cerebral blood flow.