Recurrent stroke prevention guidelines get an update

To give clinicians “the most up-to-date evidence based recommendations for the prevention of ischemic attack,” the American Heart Association and American Stroke Association published updated guidelines.

“Since the last update (in 2006), we’ve had results from several studies testing different inventions. We need to reevaluate the science every few years to optimize prevention.”

Approximately one-fourth of the nearly 800,000 strokes that occur each year in the United States are recurrences in patients who have already had a stroke or TIA.

New recommendations in the guidelines cover control of risk factors, interventions for atherosclerotic disease, antithrombotic therapies for cardioembolism, and use of antiplatelet drugs for noncardioembolic stroke.

While the clinical usefulness of screening patients for the metabolic syndrome remains controversial, the guidelines advise that if patients are already diagnosed as having the disorder, they should be counseled to improve their diet, exercise, and lose weight to reduce their stroke risk. The individual components of the metabolic syndrome that raise the risk of stroke — particularly dyslipidemia and hypertension — should be treated. Survivors of TIA or stroke who have diabetes should follow existing treatment guidelines for glycemic control and blood pressure management.

The writing committee recommended that patients with stenosis of the carotid artery or vertebral artery should receive optimal medical therapy, including antiplatelet drugs, statins, and risk factor modification. In patients whose TIA or stroke was due to 50 percent-99 percent stenosis of a major intracranial artery, they advised prescribing aspirin therapy (50-325 mg daily) over warfarin. Long-term maintenance of blood pressure at less than 140/90 mm Hg and total cholesterol at less than 200 mg/dL “may be reasonable,” they wrote. The usefulness of angioplasty, with or without stent placement, for an intracranial artery stenosis is not yet known in this population and is considered investigational. Extracranial-intracranial bypass surgery is not recommended.

For patients with atherosclerotic ischemic stroke or TIA who do not have coronary heart disease, the committee stated that “it is reasonable to target a reduction of at least 50 percent in LDL-C or target LDL-C level of less than 70 mg/dL.”

The guidelines recommended that patients who need anticoagulation therapy but cannot take oral anticoagulants should be given aspirin alone. They warn that the combination of aspirin plus clopidogrel “carries a risk of bleeding similar to that of warfarin and therefore is not recommended for patients with a hemorrhagic contraindication to warfarin.”

Any temporary interruption to anticoagulation therapy in patients who have atrial fibrillation and are otherwise at high risk for stroke calls for the use of bridging therapy with subcutaneous administration of low-molecular-weight heparin, according to the guidelines.

The committee members recommended caution in using warfarin in patients who have cardiomyopathy characterized by systolic dysfunction (a left ventricular ejection fraction of 35 percent or less) because of lack of proven benefit.

Evidence is also insufficient to establish whether anticoagulation therapy for secondary stroke prevention in patients who have a patent foramen ovale.

The guidelines also address secondary stroke prevention under a variety of special circumstances, such as cases of arterial dissection, hyperhomocysteinemia, hypercoagulable states, and sickle cell disease. They also detail management specific to women, particularly concerning pregnancy and the use of postmenopausal hormone replacement.