Persons who survive a stroke or transient ischemic attack (TIA) are at increased risk of subsequent stroke; approximately 25% of the 795,000 annual strokes in the United States are recurrent events. The American Heart Association/American Stroke Association recently published evidence-based primary and secondary ischemic stroke prevention guidelines.
Conclusions. Antihypertensive medications have been demonstrated to reduce the incidence of recurrent stroke and vascular events in patients with and without hypertension. However, no threshold blood pressure for benefit has been determined.
Although diabetes is a risk factor for initial stroke, the role of diabetes as a risk for recurrent stroke is less clear.
There are few data supporting the efficacy of nonstatin cholesterol-reducing medications in prevention of stroke recurrence. Nor has the benefit of screening for metabolic syndrome in persons with stroke been proven. No guidance is provided regarding the use of dabigatran, as it was not approved prior to completion of the guideline.
Aspirin, ticlopidine and the combination of dipyridamole plus aspirin are all effective antiplatelet agents for secondary stroke prevention. No studies have compared clopidogrel to placebo for this indication, and head-to-head studies against other antiplatelet agents have not demonstrated equivalence.
There are no clinical trials demonstrating that changing from one antiplatelet agent to another, or increasing the dose, following a TIA or stroke is beneficial in reducing recurrence.
Implementation. The minimum evaluation of a patient for acute stroke or TIA should include a brain MRI or CT to distinguish hemorrhagic from ischemic events, and testing to exclude modifiable risk factors for recurrence, such as carotid stenosis or atrial fibrillation.
Beginning 24 hours or more after a TIA or stroke, blood pressure should be reduced to help prevent recurrent stroke and other vascular events. Current data suggest that diuretics with or without ACE inhibitors are useful; however, few data exist comparing antihypertensive classes for the prevention of recurrent stroke.
Statin therapy, in conjunction with lifestyle modification as detailed in the third edition of the National Cholesterol Education Program guidelines, is recommended to reduce LDL cholesterol to less than 100 mg/dL for secondary stroke prevention. It is reasonable to aim for a 50% reduction in LDL or a target LDL of less than 70 mg/dL.
Behavioral modifications such as smoking cessation, limiting alcohol intake to moderate or low levels, and introducing moderate-intensity physical exercise have been shown to be effective in reducing stroke risk.
Persons with a history of TIA or ischemic stroke within the past 2 weeks to 6 months should be considered for carotid endarterectomy or stenting for ipsilateral carotid stenosis of 50%-99%, if the periprocedural risk of morbidity and mortality is less than 6%. There is no routine indication for revascularization for stenosis less than 50%.
Optimal medical therapy, including antiplatelet agents and statins, and risk-factor modification, are recommended for all patients with symptomatic carotid, vertebrobasilar, and intracranial atherosclerosis/stenosis.
Extracranial-intracranial bypass is not recommended for treatment of symptomatic intracranial atherosclerosis. Angioplasty and stent placement for patients with symptomatic high-grade intracranial stenosis is considered investigational.
Warfarin therapy aimed at a target international normalized ratio (INR) of 2.5 (range 2.0-3.0) is recommended for stroke prevention in patients with paroxysmal or permanent atrial fibrillation. Aspirin alone is recommended in patients with atrial fibrillation who are unable to take oral anticoagulants.
Bridging anticoagulation with low-molecular-weight heparin is recommended for patients at the highest risk for stroke (defined as having a stroke or TIA within 3 months, a CHADS2 score of at least 5, a mechanical cardiac valve, and rheumatic valve disease) in circumstances in which oral anticoagulation must be temporarily interrupted.
Patients with TIA or ischemic stroke and acute myocardial infarction complicated by left ventricular mural thrombus should be anticoagulated to a target INR of 2.5 for a minimum of 3 months. However, warfarin has no demonstrated benefit for secondary stroke prevention in the presence of systolic cardiac dysfunction alone.
Long-term warfarin therapy with a target INR of 2.5 is reasonable for secondary stroke prevention in patients with rheumatic mitral valve disease. Antiplatelet agents should not be combined with warfarin due to additional bleeding risk.
Antiplatelet agents are reasonable for secondary stroke prevention in patients with nonrheumatic native valve disease, mitral annular calcification, and mitral valve prolapse in the absence of atrial fibrillation.
Warfarin with a target INR of 3.0 is recommended for prevention of stroke in patients with mechanical heart valves. The addition of aspirin at 75-100 mg/day is reasonable in those who have had TIA or stroke despite adequate oral anticoagulation and in whom the bleeding risk is not excessive.