Effect of statins in stroke prevention

Treatment Approaches to Lacunar Stroke

Lacunar strokes are appropriately named for their ability to cavitate and form ponds or "little lakes" (Latin: lacune -ae meaning pond or pit is a diminutive form of lacus meaning lake). They account for a substantial proportion of both symptomatic and asymptomatic ischemic strokes. In recent years, there have been several advances in the management of large vessel occlusions. New therapies such as non-vitamin K antagonist oral anticoagulants and left atrial appendage closure have recently been developed to improve stroke prevention in atrial fibrillation; however, the treatment of small vessel disease-related strokes lags frustratingly behind. Since Fisher characterized the lacunar syndromes and associated infarcts in the late 1960s, there have been no therapies specifically targeting lacunar stroke. Unfortunately, many therapeutic agents used for the treatment of ischemic stroke in general offer only a modest benefit in reducing recurrent stroke while adding to the risk of intracerebral hemorrhage and systemic bleeding. Escalation of antithrombotic treatments beyond standard single antiplatelet agents has not been effective in long-term lacunar stroke prevention efforts, unequivocally increasing intracerebral hemorrhage risk without providing a significant benefit. In this review, we critically review the available treatments for lacunar stroke based on evidence from clinical trials. For several of the major drugs, we summarize the adverse effects in the context of this unique patient population. We also discuss the role of neuroprotective therapies and neural repair strategies as they may relate to recovery from lacunar stroke.

Prevention of cardiovascular complications of the metabolic syndrome: focus on pharmacotherapy

The metabolic syndrome increases the risk of atherothrombotic cardiovascular disease (CVD) and diabetes. In turn, diabetes promotes the development of atheroma and is regarded as a coronary heart disease risk equivalent. A multifactorial therapeutic strategy is advocated for patients with the metabolic syndrome to improve cardiovascular risk factor profiles and to reduce the chances of developing type 2 diabetes. Individual components of the syndrome must be addressed using safe, efficacious, and cost-effective measures. There is general agreement that lifestyle modifications, including control of body weight, avoidance of central adiposity, adoption of an antiatherogenic diet, and regular physical activity, are crucial. However, as the magnitude of the individual components of the metabolic syndrome increases with time, lifestyle measures are often insufficient. An individual with metabolic syndrome will often require drug treatment for hyperglycemia, atherogenic dyslipidemia, and high blood pressure, together with antiplatelet therapy. Reducing the need for polypharmacy is an increasingly important consideration for clinicians and the pharmaceutical industry; to date, no single therapy has emerged that targets the root cause(s) of the syndrome. HMG-CoA reductase inhibitors are important agents that reduce CVD morbidity and mortality, in people with impaired fasting glucose or metabolic syndrome. Selective cannabinoid receptor antagonists appear promising because they improve or attenuate several key defects of the syndrome. Thiazolidinediones and metformin are presently licensed for treatment of type 2 diabetes but may prove to have a broader role in future. Novel insulin-sensitizing drugs are under investigation. Drugs that act to prevent or reverse endothelial dysfunction may be of particular utility in preventing cardiovascular disease, especially if initiated before tissue damage has become irreversible. Insulin therapy, which has antiinflammatory and endothelial protective properties, has been shown to reduce morbidity and mortality in high-risk nondiabetic patients during critical illness. Potential synergy between different classes of drugs with metabolic and/or cardiovascular protective properties merits further investigation.

Stroke prevention: modifying risk factors

Risk factor modification remains as the principal aspect of care for stroke prevention. Understanding of risk factors has advanced and several options are now available to treat modifiable risk factors. However, effective treatment remains a challenging task in clinical practice. Prevention begins with awareness of risk factors by patients and clinicians. Risk factor assessment along with overall stroke risk estimation should be part of evaluation of patients with stroke, and used with careful clinical judgment. In this review, we discuss the impact of modifiable traditional vascular risk factors on ischemic stroke, interventions for stroke prevention, and evidence for early treatment of risk factors where available, as well as areas of research progress. Emphasis should be put on the education of patients, the community, and medical personnel. Future research in the field of genetic determinants of vascular risk factors and stroke will increase our understanding of the underlying mechanisms of cerebrovascular disease and likely result in development of new therapies and individualized programs for stroke prevention.

Aggressive blood pressure control and stroke prevention: role of calcium channel blockers

Cerebrovascular disease is a major cause of morbidity and mortality worldwide and its prevalence is expected to increase as a result of projected demographic trends. Stroke is one of the leading causes of disability and death of over 30 million people each year worldwide. Hypertension is the most important modifiable risk factor for stroke. Recent data indicate that treatment with antihypertensive drugs reduces the incidence of all strokes in men (by 34%), women (by 38%), the elderly (by 36%), including those older than 80 years (by 34%), younger persons, those with systolic and diastolic hypertension, persons with isolated systolic hypertension, and those with a history of stroke or transient ischemic attack (by 28%). Furthermore, several large, prospective, randomized, clinical outcome trials have shown that calcium channel blockers (CCBs) are effective and safe antihypertensive drugs compared with placebo and reduce the cardiovascular morbidity and mortality of treated patients. Moreover, when CCBs were compared with conventional antihypertensive drugs they demonstrated similar blood pressure-lowering effects and similar reductions in cardiovascular morbidity and mortality, with the exception of a higher incidence of heart failure and fatal myocardial infarction in some studies. Considering all the evidence available today, however, these drugs should be considered safe for the treatment of the uncomplicated hypertensive patient in combination with other drugs. They can also be used as first-line therapy for older, stroke-prone hypertensive patients. The aim of this review is to summarize the role of CCBs in the prevention of stroke.

Stroke

Stroke is the second most common cause of death and major cause of disability worldwide. Because of the ageing population, the burden will increase greatly during the next 20 years, especially in developing countries. Advances have occurred in the prevention and treatment of stroke during the past decade. For patients with acute stroke, management in a stroke care unit, intravenous tissue plasminogen activator within 3 h or aspirin within 48 h of stroke onset, and decompressive surgery for supratentorial malignant hemispheric cerebral infarction are interventions of proven benefit; several other interventions are being assessed. Proven secondary prevention strategies are warfarin for patients with atrial fibrillation, endarterectomy for symptomatic carotid stenosis, antiplatelet agents, and cholesterol reduction. The most important intervention is the management of patients in stroke care units because these provide a framework within which further study might be undertaken. These advances have exposed a worldwide shortage of stroke health-care workers, especially in developing countries.

High-dose statin therapy for secondary prevention of stroke: stroke prevention by aggressive reduction in cholesterol levels study review

It has been shown that HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase inhibitors (statins) lower the incidence of a first stroke in patients with coronary heart disease, diabetes, or risk factors for cardiovascular disease. However, it is unknown whether statin therapy could reduce the incidence of a second stroke in patients without evidence of heart disease. This article reviews the results of the Stroke Prevention by Aggressive Reduction in Cholesterol Levels trial, a prospective, randomized, multicentered, double-blind, placebo-controlled, international trial designed to examine the effect of high-dose atorvastatin on secondary stroke prevention. Trial participants (4,731) had experienced a stroke or transient ischemic attack within 1 to 6 months before randomization into the study. Over the 5-year follow-up period, incidence of second stroke or transient ischemic attack was significantly reduced in the atorvastatin treatment group compared with the placebo group. In addition, high-dose atorvastatin therapy significantly decreased major coronary artery and other negative cardiovascular events. The reduction in incidence of secondary stroke was specific to ischemic stroke as opposed to hemorrhagic stroke. Results of the trial are clinically significant and support extension of the latest secondary stroke prevention guidelines to include statin therapy for those patients without coronary heart disease.

Statin therapy and stroke prevention: what was known, what is new and what is next?

PURPOSE OF REVIEW

Randomized trials have shown that statins may reduce the risk of primary stroke. There is no evidence however that statins can reduce recurrent stroke incidence.

RECENT FINDINGS

In the SPARCL trial, patients with a recent stroke or transient ischemic attack randomized to atorvastatin 80 mg/day had a significant 16% relative risk reduction of stroke, and a 35% reduction in major coronary events compared with placebo. This was obtained despite 25% of the placebo arm patients receiving a commercially-available statin outside of the trial. Post-hoc analysis used blinded LDL-cholesterol measurements as a marker of adherence to lipid-lowering therapy. Compared with the group with no change or an increase in LDL-cholesterol (the group adherent to placebo or not taking a statin), the group with over 50% reduction in LDL-cholesterol had a significant 31% reduction in stroke. The next step is to define whether achieving LDL-cholesterol below 70 mg/dl is better than a standard dose of statin (LDL around 100-110 mg/dl) in the secondary prevention of stroke.

SUMMARY

Statins are effective in reducing both first-ever and recurrent stroke, and this effect seems driven by the extent of LDL-cholesterol lowering.

Atorvastatin in prevention of stroke and transient ischaemic attack

Besides blood pressure-lowering drugs and, in certain circumstances, antithrombotic agents, statins are among the most effective drugs in reducing the risk of stroke in populations of patients at high vascular risk, as well as the risk of major coronary events. In secondary prevention of stroke, statins clearly reduced the risk of major coronary events. In the SPARCL (Stroke Prevention by Aggressive Reduction in Cholesterol Levels) trial, compared with placebo, the patients with a recent stroke or transient ischaemic attack without coronary heart disease randomised to atorvastatin 80 mg/day had a significant 16% relative risk reduction of stroke and a 35% reduction in the risk of major coronary events. This was obtained despite the fact that 25% of patients allocated to the placebo arm were prescribed a commercially available statin outside the trial. A post-hoc analysis used blinded low-density lipoprotein cholesterol (LDL-C) measurements (taken at study visits during the trial) as a marker of adherence to lipid-lowering therapy. Compared with the group with no change or an increase in LDL-C (the group adherent to placebo or not taking a statin), the group with >or= 50% reduction in LDL-C had a significant 31% reduction in the risk of stroke. The next step is to define whether or not achieving a LDL-C of < 70 mg/dl is better than a standard dose of statin (LDL approximately 100 - 110 mg/dl) in the secondary prevention of stroke. Statins are effective in reducing both first-ever and recurrent stroke, and this effect seems driven by the extent of LDL-C lowering.

Comparison of biochemical effects of statins and fish oil in brain: the battle of the titans

Neural membranes are composed of glycerophospholipids, sphingolipids, cholesterol and proteins. The distribution of these lipids within the neural membrane is not random but organized. Neural membranes contain lipid rafts or microdomains that are enriched in sphingolipids and cholesterol. These rafts act as platforms for the generation of glycerophospholipid-, sphingolipid-, and cholesterol-derived second messengers, lipid mediators that are necessary for normal cellular function. Glycerophospholipid-derived lipid mediators include eicosanoids, docosanoids, lipoxins, and platelet-activating factor. Sphingolipid-derived lipid mediators include ceramides, ceramide 1-phosphates, and sphingosine 1-phosphate. Cholesterol-derived lipid mediators include 24-hydroxycholesterol, 25-hydroxycholesterol, and 7-ketocholesterol. Abnormal signal transduction processes and enhanced production of lipid mediators cause oxidative stress and inflammation. These processes are closely associated with the pathogenesis of acute neural trauma (stroke, spinal cord injury, and head injury) and neurodegenerative diseases such as Alzheimer disease. Statins, the HMG-CoA reductase inhibitors, are effective lipid lowering agents that significantly reduce risk for cardiovascular and cerebrovascular diseases. Beneficial effects of statins in neurological diseases are due to their anti-excitotoxic, antioxidant, and anti-inflammatory properties. Fish oil omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, have similar anti-excitotoxic, antioxidant and anti-inflammatory effects in brain tissue. Thus the lipid mediators, resolvins, protectins, and neuroprotectins, derived from eicosapentaenoic acid and docosahexaenoic acid retard neuroinflammation, oxidative stress, and apoptotic cell death in brain tissue. Like statins, ingredients of fish oil inhibit generation of beta-amyloid and provide protection from oxidative stress and inflammatory processes. Collective evidence suggests that antioxidant, anti-inflammatory, and anti-apoptotic properties of statins and fish oil contribute to the clinical efficacy of treating neurological disorders with statins and fish oil. We speculate that there is an overlap between neurochemical events associated with neural cell injury in stroke and neurodegenerative diseases. This commentary compares the neurochemical effects of statins with those of fish oil.

Statins--treatment option for central nervous system autoimmune disease?

Statins, inhibitors of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase, are well-established agents to lower cholesterol levels and prevent cardiovascular morbidity. Independent of their lipid-lowering properties, statins have been shown to exert pleiotropic immunomodulatory effects in various animal models of human autoimmune disease. In experimental autoimmune encephalomyelitis, a murine model for multiple sclerosis, statins prevented disease onset and even reversed paralysis when treatment was initiated after experimental autoimmune encephalomyelitis was fully established. Furthermore, well-tolerated oral statins were recently shown to exert synergistic benefit in experimental autoimmune encephalomyelitis in combination with existing agents for multiple sclerosis therapy. Based primarily on these encouraging results, statins are now being tested in clinical trials as a monotherapy for multiple sclerosis, as well as in combination with approved disease-modifying therapies.

Stroke prevention and statin treatment

Randomized trials with statins have shown a modest but significant absolute reduction in the incidence of stroke in patients with a previous myocardial infarction. The reasons for the positive statin effect on stroke endpoint are unclear, because a link between serum cholesterol level and stroke never has been established. However, positive results of statin trials were mainly obtained in patients with an average or a low serum cholesterol level. Statins have a good overall safety profile. Statins reduced stroke incidence in high-risk (mainly coronary heart disease, diabetics, and hypertensives) population even with a normal baseline blood cholesterol level. In patients with prior strokes, statins reduce the incidence of coronary events, but it is not yet proven if drugs of this class actually reduce the incidence of recurrent strokes in terms of secondary prevention.

The effect of infections and vaccinations on stroke risk

There is increasing evidence that, in addition to conventional risk factors, acute and chronic infectious diseases increase the risk of stroke. Acute infection, mainly respiratory, and both bacterial and viral infection, represent temporarily active trigger factors for cerebral ischemia. Chronic infectious diseases that may increase the risk of stroke include periodontitis, chronic bronchitis and infections with microbial antigens, such as Helicobacter pylori and Chlamydia pneumoniae. From observational studies, there is evidence that vaccination against influenza is associated with a reduced risk of stroke, myocardial infarction and all-cause mortality. This report provides an overview on the influence of infection on stroke risk and potential anti-infective strategies that may play a future role in stroke prevention.