Stroke-prevention guidelines updated
MRI shows a stroke involving the left temporal-occipital region (green).
A person who has experienced one cerebrovascular event is at substantially increased risk of sustaining another. To help clinicians protect this vulnerable population, the American Heart Association (AHA) along with the American Stroke Association (ASA) recently issued Guidelines for the Prevention of Stroke in Patients with Stroke or Transient Ischemic Attack (Stroke. 2011;42:227-276), an update of a 2006 document.
These guidelines address the principal risk factors for stroke (BP, cholesterol, and comorbid diabetes), with detailed consideration of their relevance to recurrent events.
The latest revision, which incorporates findings of several recent major studies, includes new or modified recommendations for managing carotid artery stenosis, metabolic syndrome, and atrial fibrillation, says Bruce Ovbiagele, MD, director of the Olive View-UCLA Medical Center Stroke Program, and a member of the committee that wrote the guidelines.
The primary concern
"Blood pressure is the premier modifiable risk factor for a second stroke, as it is for a first stroke as well," says Dr. Ovbiagele. "Clinicians get the biggest bang for the buck by reducing BP."
Although many studies establish its efficacy in primary stroke prevention, relatively few have looked specifically at BP control for secondary prevention. This evidence supports the general recommendations promulgated by the The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7).
The guidelines endorse the JNC 7 definition of "normal" BP as <120/80 mm Hg but specify that, "An absolute target BP level and reduction are uncertain and should be individualized." The authors note that average BP reductions of approximately 10/5 mm Hg have generally been shown to be beneficial after stroke or transient ischemic attack (TIA), even for patients without diagnosed hypertension.
As long as BP is not "very low," some reduction might be considered, Dr. Ovbiagele notes. "The issue is treating risk, rather than hypertension."
Few studies comparing drug regimens in this population exist, but what data are available support the use of diuretics, with or without an ACE inhibitor. In actual practice, drug choice should be made with pharmacologic qualities, side-effect profile, and such patient factors as comorbid disease in mind.
Lifestyle changes (i.e., salt restriction; weight loss; aerobic exercise; and following a diet rich in fruits, vegetables, and low-fat dairy products) are "a reasonable part of comprehensive antihypertensive therapy," the authors write.
The AHA/ASA recommendations follow the general National Cholesterol Education Program guidelines for treating hypercholesterolemia with a regimen that includes lifestyle and diet modification as well as medication.
More specifically, statin therapy is recommended for post-stroke/TIA patients with LDL ≥100 mg/dL and evidence of atherosclerosis—even in the absence of known coronary heart disease—with a target reduction of 50%, or a level <70 mg/dL.
Consider niacin or gemfibrozil for patients with low levels of HDL, the guidelines advise.
The 2010 AHA/ASA guidelines include a section that addresses the metabolic syndrome. The authors do not advocate screening but recommend clinicians take an active approach toward all the syndrome component parts when diagnosed.
This approach would include counseling for lifestyle modification and medication—when necessary—to reduce high triglycerides, elevate low HDL, address abdominal obesity, improve glucose intolerance, and treat hypertension. Most of these concerns are addressed individually elsewhere in the guidelines, and questions surrounding the clinical utility of characterizing a more inclusive syndrome remain, the authors concede.