Drug therapy for the secondary prevention of stroke in hypertensive patients: current issues and options

Interplay between brain stem angiotensins and monocyte chemoattractant protein-1 as a novel mechanism for pressor response after ischemic stroke

Pressor response after stroke commonly leads to early death or susceptibility to stroke recurrence, and detailed mechanisms are still lacking. We assessed the hypothesis that the renin-angiotensin system contributes to pressor response after stroke by differential modulation of the pro-inflammatory chemokine monocyte chemoattractant protein-1 (MCP-1) in the rostral ventrolateral medulla (RVLM), a key brain stem site that maintains blood pressure. We also investigated the beneficial effects of a novel renin inhibitor, aliskiren, against stroke-elicited pressor response. Experiments were performed in male adult Sprague-Dawley rats. Stroke induced by middle cerebral artery occlusion elicited significant pressor response, accompanied by activation of angiotensin II (Ang II)/type I receptor (AT1R) and AT2R signaling, depression of Ang-(1-7)/MasR and Ang IV/AT4R cascade, alongside augmentation of MCP-1/C-C chemokine receptor 2 (CCR2) signaling and neuroinflammation in the RVLM. Stroke-elicited pressor response was significantly blunted by antagonism of AT1R, AT2R or MCP-1/CCR2 signaling, and eliminated by applying Ang-(1-7) or Ang IV into the RVLM. Furthermore, stroke-activated MCP-1/CCR2 signaling was enhanced by AT1R and AT2R activation, and depressed by Ang-(1-7)/MasR and Ang IV/AT4R cascade. Aliskiren inhibited stroke-elicited pressor response via downregulating MCP-1/CCR2 activity and reduced neuroinflammation in the RVLM; these effects were potentiated by Ang-(1-7) or Ang IV. We conclude that whereas Ang II/AT1R or Ang II/AT2R signaling in the brain stem enhances, Ang-(1-7)/MasR or Ang IV/AT4R antagonizes pressor response after stroke by differential modulations of MCP-1 in the RVLM. Furthermore, combined administration of aliskiren and Ang-(1-7) or Ang IV into the brain stem provides more effective amelioration of stroked-induced pressor response.

Secondary prevention of stroke in the elderly: a review of the evidence

BACKGROUND

Stroke is a major health problem with significant impact on the affected individuals and the whole community. In light of stroke being the leading cause of disability, the ageing of the population and the high incidence of stroke among the elderly, highlight the importance of primary and secondary prevention interventions among this group. The elderly generally have been underrepresented in clinical trials, creating many uncertainties and less optimal medical care for this group of patients.

OBJECTIVE

This review aims to make evidence-based management recommendations for secondary stroke prevention in the elderly.

METHODS

Secondary prevention-related primary literature was identified using MEDLINE and PubMed (1982 to present) with combinations of the following search terms being employed: antiplatelets, aspirin, atrial fibrillation, elderly, geriatrics, hypertension, lipids, secondary prevention, statins, stroke, and warfarin. In addition, the references of these articles were also reviewed.

RESULTS

Twenty-three clinical trials were included in this review, covering different aspects of secondary stroke prevention. Many of these trials were not specifically limited to the elderly, but conclusions related to their care can be derived from them. Although the American Heart Association/American Stroke Association guidelines suggest an equal benefit of aspirin, aspirin/dipyridamole, and clopidogrel in secondary prevention, the use of aspirin in the elderly may be preferred for reasons related to compliance and experience. Warfarin was largely avoided in the management of elderly stroke patients in the past, although available evidence demonstrates its efficacy and safety as a first choice for elderly patients with atrial fibrillation and presumed cardiac source of emboli. Lowering blood pressure among the elderly is an important aspect of secondary stroke prevention and can be achieved with the same agents used among younger age groups with a preference for a thiazide diuretic/angiotensin-converting enzyme inhibitor combination that has proven efficacy among elderly patients. Available evidence supports the use of statins among elderly patients with history of stroke or transient ischemic attack (TIA), and the derived benefit of treatment does not differ significantly from that in the younger age group. Elderly patients with 50% to 99% carotid artery stenosis and history of stroke or TIA should be considered for early carotid endarterectomy to reduce recurrent stroke.

CONCLUSION

Age should not be considered a barrier for the provision of optimal secondary prevention interventions. The available evidence supports similar and sometimes superior derived benefit from secondary preventive stroke measures in the elderly compared with that seen in younger patients.

Blockade of brain angiotensin II AT1 receptors ameliorates stress, anxiety, brain inflammation and ischemia: Therapeutic implications

Poor adaptation to stress, alterations in cerebrovascular function and excessive brain inflammation play critical roles in the pathophysiology of many psychiatric and neurological disorders such as major depression, schizophrenia, post traumatic stress disorder, Parkinson's and Alzheimer's diseases and traumatic brain injury. Treatment for these highly prevalent and devastating conditions is at present very limited and many times inefficient, and the search for novel therapeutic options is of major importance. Recently, attention has been focused on the role of a brain regulatory peptide, Angiotensin II, and in the translational value of the blockade of its physiological AT(1) receptors. In addition to its well-known cardiovascular effects, Angiotensin II, through AT(1) receptor stimulation, is a pleiotropic brain modulatory factor involved in the control of the reaction to stress, in the regulation of cerebrovascular flow and the response to inflammation. Excessive brain AT(1) receptor activity is associated with exaggerated sympathetic and hormonal response to stress, vulnerability to cerebrovascular ischemia and brain inflammation, processes leading to neuronal injury. In animal models, inhibition of brain AT(1) receptor activity with systemically administered Angiotensin II receptor blockers is neuroprotective; it reduces exaggerated stress responses and anxiety, prevents stress-induced gastric ulcerations, decreases vulnerability to ischemia and stroke, reverses chronic cerebrovascular inflammation, and reduces acute inflammatory responses produced by bacterial endotoxin. These effects protect neurons from injury and contribute to increase the lifespan. Angiotensin II receptor blockers are compounds with a good margin of safety widely used in the treatment of hypertension and their anti-inflammatory and vascular protective effects contribute to reduce renal and cardiovascular failure. Inhibition of brain AT(1) receptors in humans is also neuroprotective, reducing the incidence of stroke, improving cognition and decreasing the progression of Alzheimer's disease. Blockade of AT(1) receptors offers a novel and safe therapeutic approach for the treatment of illnesses of increasing prevalence and socioeconomic impact, such as mood disorders and neurodegenerative diseases of the brain.

[Prevention of stroke: what is evidence based?]

On the background of aging population an increase of patients suffering from stroke has to be expected during the next years and decades. Strokes are the 3rd leading cause of death and reason for disability in Germany and many other countries. An effective treatment of the modifiable risk factors hypertension, hyperlipidemia, diabetes mellitus, atrial fibrillation, smoking, alcohol consumption, and adipositas is of enormous impact. Due to the linear relationship between blood pressure and risk of stroke, the treatment of hypertension is the most important and effective one in primary as well as in secondary prevention. Treatment with platelet inhibitors plays an additional important role in secondary prevention. Patients with atrial fibrillation should receive an effective oral anticoagulatory therapy when there are certain risk factors.

Blood pressure lowering treatment for preventing stroke recurrence: a systematic review and meta-analysis

BACKGROUND

While hypertension is a leading risk factor for an initial stroke, the role of blood pressure lowering to prevent subsequent stroke is less clear. The results of recent large clinical trials investigating effects of antihypertensive agents in patients with a history of stroke have not shown a significant benefit; findings that are at odds with previous data. Our meta-analysis systematically evaluates the available, relevant trials to examine the role of antihypertensive drugs in preventing recurrent stroke.

METHODS

MEDLINE, CENTRAL, and ClinicalTrials.gov were systematically searched and bibliographies from key reports were examined. All randomized, placebo-controlled trials that tested blood pressure lowering agents in patients with stroke or transient ischemic attack were identified. The results from these trials were combined and meta-analyses were performed.

RESULTS

Ten studies were found to contain relevant endpoints and presented data allowing meta-analysis. Agents that lowered blood pressure reduced recurrent stroke (OR 0.71, 95% CI 0.59-0.86, P = 0.0004) and cardiovascular events (OR 0.69, 95% CI 0.57-0.85, P = 0.0004) in patients with a previous stroke or TIA. These agents did not affect the rate of myocardial infarction (OR 0.86, 95% CI 0.73-1.01, P = 0.07) or all-cause mortality (OR 0.95, 95% CI 0.83-1.07, P = 0.39) in this patient population.

CONCLUSION

Despite recent large trials showing no significant effect, in patients that have experienced a TIA or stroke, blood pressure lowering agents reduced the occurrence of subsequent stroke and cardiovascular events. The rate of myocardial infarction and all-cause mortality was unchanged.

A combined role of calcium channel blockers and angiotensin receptor blockers in stroke prevention

Stroke is a leading cause of death and disability worldwide. The importance of lowering blood pressure for reducing the risk of stroke is well established. However, not all the benefits of antihypertensive treatments in stroke can be accounted for by reductions in BP and there may be differences between antihypertensive classes as to which provides optimal protection. Dihydropyridine calcium channel blockers, such as amlodipine, and angiotensin receptor blockers, such as valsartan, represent the two antihypertensive drug classes with the strongest supportive data for the prevention of stroke. Therefore, when combination therapy is required, a combination of these two antihypertensive classes represents a logical approach.

Systemic delivery of umbilical cord blood cells for stroke therapy: a review

PURPOSE

This review paper summarizes relevant studies, discusses potential mechanisms of transplanted cell-mediated neuroprotection, and builds a case for the need to establish outcome parameters that are critical for transplantation success. In particular, we outline the advantages and disadvantages of systemic delivery of human umbilical cord blood (HUCB) cells in the field of cellular transplantation for treating ischemic stroke.

METHODS

A MEDLINE/PubMed systematic search of published articles in peer-reviewed journals over the last 25 years was performed focusing on the theme of HUCB as donor graft source for transplantation therapy in neurological disorders with emphasis on stroke.

RESULTS

Ischemic stroke remains a leading cause of human death and disability. Although stroke survivors may gain spontaneous partial functional recovery, they often suffer from sensory-motor dysfunction, behavioral/neurological alterations, and various degrees of paralysis. Currently, limited clinical intervention is available to prevent ischemic damage and restore lost function in stroke victims. Stem cells from fetal tissues, bone marrow, and HUCB has emerged in the last few years as a potential cell transplant cell source for ischemic stroke, because of their capability to differentiate into multiple cell types and the possibility that they may provide trophic support for cell survival, tissue repair, and functional recovery.

CONCLUSION

A growing number of studies highlight the potential of systemic delivery of HUCB cells as a novel therapeutic approach for stroke. However, additional preclinical studies are warranted to reveal the optimal HUCB transplant regimen that is safe and efficacious prior to proceeding to large-scale clinical application of these cells for stroke therapy.