Andrey Nailor, M.D.·Published 17 May 2012·13 min read
Key points
Stroke is the third most common overall cause of death and the leading cause of adult disability in the United States.
After a stroke or TIA, there is a high risk of stroke and of other serious vascular events.
Although prevention of stroke is the primary outcome of interest, many of the grades for the recommendations were chosen to reflect the existing evidence on the reduction of all vascular outcomes after stroke, including stroke, myocardial infarction (MI), and vascular death.
- Offer people who are overweight or obese advice and support to work towards achieving and maintaining a healthy weight. - Alcohol consumption: - Advise men to limit their alcohol intake to 3-4 units a day. - Advise women to limit their alcohol intake to 2-3 units a day. - Advise everyone to avoid binge drinking.
Stroke is the third most common overall cause of death and the leading cause of adult disability in the United States. New therapeutic interventions instituted in the period immediately after a stroke have revolutionized the approach to ischemic cerebrovascular disease. Recognition of a transient ischemic attack provides an opportunity to prevent a subsequent stroke. Specific stroke prevention treatment depends on the cause of the transient ischemic attack, its cerebrovascular localization and the presence of associated coexisting medical problems. Modification of stroke risk factors is the principal therapeutic approach. Antiplatelet agents and anticoagulants have been shown to be effective in reducing the occurrence of stroke in certain populations. Several well-designed studies have recently demonstrated the effectiveness of carotid endarterectomy in preventing strokes related to extracranial carotid artery disease.
Approximately 550,000 new strokes and 150,000 stroke-related deaths occur each year in the United States.1 About 80 percent of strokes are due to ischemic cerebrovascular disease, and the rest are attributable to hemorrhagic causes such as subarachnoid or intracerebral hemorrhage. Even though great strides have been made in the identification and treatment of risk factors for stroke and the development of new therapeutic interventions, ischemic stroke continues to be a significant public health problem.
A completed stroke is caused by irreversible brain injury secondary to the interruption of blood flow. In contrast, a transient ischemic attack (TIA) is a temporary focal neurologic deficit caused by the brief interruption of local cerebral blood flow. The prevalence of TIAs ranges from 1.6 to 4.1 percent, depending on gender and age. Stroke occurs in one third of patients who have a TIA.
Prevention of stroke may be classified as primary prevention if there is no previous history of stroke or transient ischaemic attack (TIA) and secondary prevention if there has been such an event.
The revised Joint British Societies' (JBS 2) guidelines on prevention of cardiovascular disease (CVD) in clinical practice recommend that cardiovascular disease prevention should focus equally on the following three groups of patients who are at high risk of cardiovascular disease
- People with established atherosclerotic CVD - People with diabetes mellitus (type 1 or 2) - Apparently healthy individuals at high risk (CVD risk of 20% or greater over 10 years) of developing symptomatic atherosclerotic disease
Well-documented and modifiable risk factors for stroke include hypertension, exposure to cigarette smoke, diabetes, atrial fibrillation (AF), dyslipidaemia, carotid artery stenosis, sickle cell disease, postmenopausal hormone therapy, poor diet, physical inactivity, and obesity - especially truncal obesity.
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Written and revised by
Andrey Nailor, M.D.
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- Abrupt onset of focal neurologic deficit of - Vascular origin - Lasts at least 24 hours
Transient Ischemic Attack (TIA)
- Temporary, abrupt onset of focal neurologic deficit - Vascular origin - Short duration - - Usually few seconds to less than 30 minutes - - May last up to 24 hours
After a stroke or TIA, there is a high risk of stroke and of other serious vascular events. Medical treatments with clear evidence of benefit include:
- Lowering blood pressure (BP) after all types of stroke or TIA. - Lowering blood cholesterol with a statin after ischaemic stroke or TIA. - Antiplatelet treatment after ischaemic stroke or TIA. - Warfarin instead of antiplatelet treatment in patients with ischaemic stroke or TIA who have AF and no contra-indications to anticoagulation.
Survivors of a transient ischemic attack (TIA) or stroke have an increased risk of another stroke, which is a major source of increased mortality and morbidity. Among the estimated 700 000 people with stroke in the United States each year, 200 000 of them are among persons with a recurrent stroke. The number of people with TIA, and therefore at risk for stroke, is estimated to be much greater. Epidemiological studies have helped to identify the risk and determinants of recurrent stroke, and clinical trials have provided the data to generate evidence-based recommendations to reduce this risk. Prior statements from the American Heart Association (AHA) have dealt with primary and secondary stroke prevention. Because most strokes are cerebral infarcts, these recommendations focus primarily on the prevention of stroke among the ischemic stroke or TIA group. Other statements from the AHA have dealt with acute ischemic stroke, subarachnoid hemorrhage (SAH), and intracerebral hemorrhage (ICH).
The aim of this new statement is to provide comprehensive and timely evidence-based recommendations on the prevention of ischemic stroke among survivors of ischemic stroke or TIA. A writing committee chair and vice chair were designated by the Stroke Council Manuscript Oversight Committee. A writing committee roster was developed and approved by the Stroke Council with representatives from neurology, cardiology, radiology, surgery, nursing, and health services research. The committee met in person and had a number of teleconferences to develop the outline and text of the recommendations. The writing group conducted a comprehensive review of the relevant literature. Although the complete list of keywords is beyond the scope of this section, the committee reviewed all compiled reports from computerized searches and conducted additional searching by hand. Searches were limited to English language sources and to human subjects. Literature citations were generally restricted to published manuscripts appearing in journals listed in Index Medicus and reflected literature published as of December 31, 2004. Because of the scope and importance of certain ongoing clinical trials and other emerging information, published abstracts were cited when they were the only published information available. The references selected for this document are exclusively for peer-reviewed papers that are representative but not all inclusive. All members of the committee had frequent opportunities to review drafts of the document, comment in writing or during teleconference discussions, and reach consensus with the final recommendations.
Blood pressure reduction- Prevent recurrent stroke, cardiovascular events - Benefit seen in hypertensives and normotensives
Absolute target blood pressure not defined
- Benefits seen with 10/5 mmHg reduction - CHEP <140/90 mmHg
Lifestyle modifications and pharmacologic therapy
- Diuretic+ACEI reasonable option - May begin > 24 hours post-stroke, depending on stability
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Although prevention of stroke is the primary outcome of interest, many of the grades for the recommendations were chosen to reflect the existing evidence on the reduction of all vascular outcomes after stroke, including stroke, myocardial infarction (MI), and vascular death. We have organized our recommendations in this statement to aid the clinician who has arrived at a potential explanation of the cause of the ischemic stroke in an individual patient and is embarking on therapy to reduce the risk of a recurrent event and other vascular outcomes. Our intention is to have these statements updated every 3 years, with additional interval updates as needed, to reflect the changing state of knowledge on the approaches to prevention of a recurrent stroke.
Diabetes and Stroke Risk
Established risk factor for ischemic stroke- Approximately two fold increased risk of stroke
Independent predictor of recurrent stroke
- 9.1% of recurrent stroke attributable to diabetes
Advise people to eat a diet in which:- Total fat intake is 30% or less of total energy intake. - Saturated fats are 10% or less of total energy intake. - Dietary cholesterol is less than 300 mg/day. - Saturated fats are replaced by monounsaturated and polyunsaturated fats.Burden of Illness
Stroke
- 3rd leading cause of death in Canada - 6% of all deaths in Canada
Stroke survivors
- 25% left minor disability - 40% left with moderate to severe disability - 10% require long-term care
A stroke survivor
- 20% chance of having another stroke over next 2 years
Dietary advice:
- Advise eating at least five portions of fruit and vegetables per day. - Advise eating at least two portions of fish per week, including a portion of oily fish. - Advise pregnant women to limit their intake of oily fish to two portions a week. - Do not routinely recommend omega-3 fatty acid supplements or plant sterols and stanols for primary prevention.
Physical activity:
- Advise people to take 30 minutes of at least moderate-intensity exercise a day at least five days a week. - Encourage people who cannot manage this to exercise at their maximum safe capacity. - Recommend exercise that can be incorporated into everyday life, such as brisk walking, using stairs and cycling. - Tell people that they can exercise in bouts of 10 minutes or more throughout the day. - Take into account the person's needs, preferences and circumstances. - Agree goals and provide written information about the benefits of activity and local opportunities to be active.
Weight management:
- Offer people who are overweight or obese advice and support to work towards achieving and maintaining a healthy weight. - Alcohol consumption: - Advise men to limit their alcohol intake to 3-4 units a day. - Advise women to limit their alcohol intake to 2-3 units a day. - Advise everyone to avoid binge drinking.
Smoking cessation:
- Advise all people who smoke to stop. - If people want to stop: - Offer support and advice. - In addition, provide medication to help with smoking cessation when indicated.
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Definition of TIA and Ischemic Stroke Subtypes
The distinction between TIA and ischemic stroke has become less important in recent years because many of the preventive approaches are applicable to both groups. They share pathogenetic mechanisms; prognosis may vary, depending on their severity and cause; and definitions are dependent on the timing and degree of the diagnostic evaluation. By conventional clinical definitions, if the neurological symptoms continue for > 24 hours, a person has been diagnosed with stroke; otherwise, a focal neurological deficit lasting < 24 hours has been defined as a TIA. With the more widespread use of modern brain imaging, many patients with symptoms lasting < 24 hours are found to have an infarction. The most recent definition of stroke for clinical trials has required either symptoms lasting > 24 hours or imaging of an acute clinically relevant brain lesion in patients with rapidly vanishing symptoms. The proposed new definition of TIA is a "brief episode of neurological dysfunction caused by a focal disturbance of brain or retinal ischemia, with clinical symptoms typically lasting less than 1 hour, and without evidence of infarction." TIAs are an important determinant of stroke, with 90-day risks of stroke reported as high as 10.5% and the greatest stroke risk apparent in the first week.
Ischemic stroke is classified into various categories according to the presumed mechanism of the focal brain injury and the type and localization of the vascular lesion. The classic categories have been defined as large-artery atherosclerotic infarction, which may be extracranial or intracranial; embolism from a cardiac source; small-vessel disease; other determined cause such as dissection, hypercoagulable states, or sickle cell disease; and infarcts of undetermined cause. The certainty of the classification of the ischemic stroke mechanism is far from ideal and reflects the inadequacy or timing of the diagnostic workup in some cases to visualize the occluded artery or to localize the source of the embolism. Recommendations for the timing and type of diagnostic workup for TIA and stroke patients are beyond the scope of this guideline statement.
- What is the optimal anti-thrombotic agent? - What is the optimal blood-pressure lowering strategy? - What is the optimal lipid-lowering strategy? - What the optimal strategy to control diabetes?
Risk Factor Control for All Patients With TIA or Ischemic Stroke
Hypertension It is estimated that ~50 000 000 Americans have hypertension. There is a continuous association between both systolic and diastolic blood pressures (BPs) and the risk of ischemic stroke. Meta-analyses of randomized controlled trials confirm an approximate 30% to 40% stroke risk reduction with BP lowering. Detailed evidence-based recommendations for the BP screening and treatment of persons with hypertension are summarized in the American Stroke Association Scientific Statement on the Primary Prevention of Ischemic Stroke and the AHA Guidelines for Primary Prevention of Cardiovascular Disease and Stroke: 2002 Update and are detailed in the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-7). JNC-7 stresses the importance of lifestyle modifications in the overall management of hypertension. Systolic BP reductions have been associated with weight loss; the consumption of a diet rich in fruits, vegetables, and low-fat dairy products; regular aerobic physical activity; and limited alcohol consumption.
Although a wealth of data from a variety of sources support the importance of treatment of hypertension for primary cardiovascular disease prevention in general and in stroke in particular, only limited data directly address the role of BP treatment in secondary prevention among persons with stroke or TIA. There is a general lack of definitive data to help guide the immediate management of elevated BP in the setting of acute ischemic stroke; a cautious approach has been recommended, and the optimal time to initiate therapy remains uncertain.
A systematic review focused on the relationship between BP reduction and the secondary prevention of stroke and other vascular events. The analysis included 7 published, nonconfounded, randomized controlled trials with a combined sample size of 15 527 participants with ischemic stroke, TIA, or ICH randomized from 3 weeks to 14 months after the index event and followed up for 2 to 5 years. No relevant trials tested the effects of nonpharmacological interventions. Treatment with antihypertensive drugs has been associated with significant reductions in all recurrent strokes, nonfatal recurrent stroke, MI, and all vascular events with similar, albeit nonsignificant, trends toward a reduction in fatal stroke and vascular death. These results were seen in studies that recruited patients regardless of whether they had hypertension.
Diabetes
Diabetes is estimated to affect 8% of the adult population. It is frequently encountered in stroke care, being present in 15%, 21%, and 33% of patients with ischemic stroke. Diabetes is a clear risk factor for stroke. The data supporting diabetes as a risk factor for recurrent stroke, however, are more sparse. Diabetes mellitus (DM) and age were the only significant independent predictors of recurrent stroke in a population-based study of stroke from Rochester, Minn. In another community-based stroke study, the Oxfordshire Stroke Project, diabetes was 1 of 2 factors independently associated with stroke recurrence (hazard ratio [HR] 1.85; 95% CI, 1.18 to 2.90; P<0.01), and investigators estimated that 9.1% (95% CI, 2.0 to 20.2) of the recurrent strokes were attributable to diabetes. In the evaluation of 2-year stroke recurrence in the Stroke Data Bank, patients at the lowest risk had no history of diabetes. Furthermore, diabetes has been shown to be a strong determinant for the presence of multiple lacunar infarcts in 2 different stroke cohorts.
Most of the available data on stroke prevention in patients with diabetes are on the primary rather than secondary prevention of stroke. Multifactorial approaches with intensive treatments to control hyperglycemia, hypertension, dyslipidemia, and microalbuminuria have demonstrated reductions in the risk of cardiovascular events. These intensive approaches included behavioral measures and the use of a statin, ACEI, ARB, and antiplatelet drug as appropriate. Primary stroke prevention guidelines have emphasized the more rigorous control of BP among both type 1 and type 2 diabetics with lower targets of 130/80 mm Hg. Tight control of BP in diabetics has been shown to reduce the incidence of stroke significantly. In the United Kingdom Prospective Diabetes Study (UKPDS), diabetic patients with controlled BP (mean BP, 144/82 mm Hg) had a 44% reduced relative risk (RR) of stroke compared with diabetics with poorer BP control (mean BP, 154/87 mm Hg; 95% CI, 11 to 65; P=0.013). Intensive treatment of hypertension also significantly reduced the risk of the combined end point of MI, sudden death, stroke, and peripheral vascular disease by 34% (P=0.019). Additional clinical trials have corroborated the risk reduction in stroke and/or cardiovascular events with BP control in diabetics. Although most of these studies did not reach the goal BP of 130/80 mm Hg, epidemiological analyses suggest a continual reduction in cardiovascular events to a BP of 120/80 mm Hg.
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Ralph L. Sacco, MD, MS, FAHA, FAAN, Chair; Robert Adams, MD, FAHA, Vice Chair; Greg Albers, MD; Mark J. Alberts, MD, FAHA; Oscar Benavente, MD; Karen Furie, MD, MPH, FAHA; Larry B. Goldstein, MD, FAHA, FAAN; Philip Gorelick, MD, MPH, FAHA, FAAN; Jonathan Halperin, MD, FAHA; Robert Harbaugh, MD, FACS, FAHA; S. Claiborne Johnston, MD, PhD; Irene Katzan, MD, FAHA; Margaret Kelly-Hayes, RN, EdD, FAHA; Edgar J. Kenton, MD, FAHA, FAAN; Michael Marks, MD; Lee H. Schwamm, MD, FAHA; Thomas Tomsick, MD, FAHA
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