AHA/ASA Guideline Guidelines for the Prevention of Stroke in ...

228 Stroke January 2011Stroke is a major source of mortality and morbidity in theUnited States. Survivors of a transient ischemic attack (TIA)or stroke represent a population at increased risk of subsequentstroke. Approximately one quarter of the 795 000 strokes thatoccur each year are recurrent events. The true prevalence of TIAis difficult to gauge because a large proportion of patients whoexperience a TIA fail to report it to a healthcare provider. 1 Onthe basis of epidemiological data defining the determinants ofrecurrent stroke and the results of clinical trials, it is possible toderive evidence-based recommendations to reduce stroke risk.Notably, much of the existing data come from studies withlimited numbers of older adults, women, and diverse ethnicgroups, and additional research is needed to confirm the generalizabilityof the published findings.The aim of this statement is to provide clinicians with themost up-to-date evidence-based recommendations for theprevention of ischemic stroke among survivors of ischemicstroke or TIA. A writing committee chair and vice chair weredesignated by the Stroke Council Manuscript OversightCommittee. A writing committee roster was developed andapproved by the Stroke Council with representatives fromneurology, cardiology, radiology, surgery, nursing, pharmacy,and epidemiology/biostatistics. The writing groupconducted a comprehensive review and synthesis of therelevant literature. The committee reviewed all compiledreports from computerized searches and conducted additionalsearches by hand. These searches are available on request.Searches were limited to English-language sources and humansubjects. Literature citations were generally restricted topublished manuscripts appearing in journals listed in IndexMedicus and reflected literature published as of August 1,2009. Because of the scope and importance of certainongoing clinical trials and other emerging information, publishedabstracts were cited for informational purposes whenthey were the only published information available, butrecommendations were not based on abstracts alone. Thereferences selected for this document are exclusively forpeer-reviewed papers that are representative but not allinclusive,with priority given to references with higher levelsof evidence. All members of the committee had frequentopportunities to review drafts of the document and reach aconsensus with the final recommendations. Recommendationsfollow the American Heart Association (AHA) and theAmerican College of Cardiology (ACC) methods of classifyingthe level of certainty of the treatment effect and theclass of evidence (Tables 1 and 2). 2Although prevention of ischemic stroke is the primaryoutcome of interest, many of the grades for the recommendationswere chosen to reflect the existing evidence on thereduction of all vascular outcomes after stroke or TIA, includingsubsequent stroke, myocardial infarction (MI), and vasculardeath. The recommendations in this statement are organized tohelp the clinician who has arrived at a potential explanation ofthe cause of ischemic stroke in an individual patient and isembarking on selection of a therapy to reduce the risk of arecurrent event and other vascular outcomes. Our intention is toupdate these statements every 3 years, with additional intervalupdates as needed, to reflect the changing state of knowledge onthe approaches to prevent a recurrent stroke.Definition of TIA and IschemicStroke SubtypesA TIA is an important predictor of stroke. The 90-day risk ofstroke after a TIA has been reported as being as high as 17%,with the greatest risk apparent in the first week. 3,4 Thedistinction between TIA and ischemic stroke has become lessimportant in recent years because many of the preventiveapproaches are applicable to both. 5 TIA and ischemic strokeshare pathophysiologic mechanisms, but prognosis may varydepending on severity and cause, and definitions are dependenton the timing and extent of the diagnostic evaluation. Byconventional clinical definitions, the presence of focal neurologicalsymptoms or signs lasting 24 hours has beendefined as a TIA. With more widespread use of modernimaging techniques for the brain, up to one third of patientswith symptoms lasting 24 hours have been found to have aninfarction. 5,6 This has led to a new tissue-based definition ofTIA: a transient episode of neurological dysfunction causedby focal brain, spinal cord, or retinal ischemia, without acuteinfarction. 5 Notably, the majority of studies described in thisguideline used the older definition. Recommendations providedby this guideline are believed to apply to both strokeand TIA regardless of which definition is used.The classification of ischemic stroke is based on thepresumed mechanism of the focal brain injury and the typeand localization of the vascular lesion. The classic categorieshave been defined as large-artery atherosclerotic infarction,which may be extracranial or intracranial; embolism from acardiac source; small-vessel disease; other determined causesuch as dissection, hypercoagulable states, or sickle celldisease; and infarcts of undetermined cause. 7 The certainty ofclassification of the ischemic stroke mechanism is far fromideal and reflects the inadequacy of the diagnostic workup insome cases to visualize the occluded artery or localize thesource of the embolism. The setting of specific recommendationsfor the timing and type of diagnostic workup forpatients with TIA or stroke is beyond the scope of theseguidelines; at a bare minimum, all stroke patients should havebrain imaging with computed tomography or magnetic resonanceimaging (MRI) to distinguish between ischemic andhemorrhagic events, and both TIA and ischemic strokepatients should have an evaluation sufficient to excludehigh-risk modifiable conditions such as carotid stenosis oratrial fibrillation (AF) as the cause of ischemic symptoms.I. Risk Factor Control for All Patients WithTIA or Ischemic StrokeA. HypertensionAn estimated 72 million Americans have hypertension, definedas a systolic blood pressure (BP) 140 mm Hg ordiastolic BP 90 mm Hg. 8 Overall, there is an associationbetween both systolic and diastolic BP and risk of strokewithout a clear threshold even at a systolic BP of115 mm Hg. 9 Meta-analyses of randomized controlled trialshave shown that BP lowering is associated with a 30% to 40%reduction in risk of stroke. 10–12 Risk reduction is greater withlarger reductions in BP without clear evidence of a drugclass–specific treatment effect. 12 Evidence-based recommen-Downloaded from stroke.ahajournals.org by on March 8, 2011