New AHA/ASA Guideline on Primary Stroke Prevention

Pauline Anderson

October 31, 2014

New oral anticoagulants in patients with atrial fibrillation (AF), home blood pressure monitoring in patients with hypertension, smoking cessation, nonestrogen oral contraceptives for women experiencing migraine with aura, and the healthy Mediterranean diet for all patients.

These are among the new recommendations for primary prevention of stroke released by the American Heart Association (AHA)/American Stroke Association (ASA). The updated guideline was published online October 28 in Stroke.

Over the years, there have been numerous advances in preventing stroke, including medications to control blood pressure and lipids, anticoagulants for at-risk patients with AF, revascularization, smoking cessation program, and changes in diet and physical activity level, write the guideline authors, led by James F. Meschia, MD, professor and chair, neurology, Mayo Clinic, Jacksonville, Florida.

"With so many interventions, optimization of stroke prevention for individuals requires systems of care that identify risk factors as they emerge and that gain control of emerging risk factors safely, expeditiously, and cost-effectively."

The latest iteration of the guideline, which summarizes the evidence for established and emerging stroke risk factors, is an update of the last AHA statement, published in 2011. Targets for stroke prevention in the new document have been "reordered" to align with the AHA's "Life's Simple" public health campaign for cardiovascular health, the authors write.

Atrial Fibrillation

One of the most importance changes, Dr Meschia said, is the expansion of the recommendation for oral anticoagulants to include agents other than warfarin for patients with nonvalvular AF who are at acceptably low risk for hemorrhagic complications (options now include dabigatran, apixaban, and rivaroxaban as well as warfarin).

"We are now recognizing the important role of the novel oral anticoagulants as an alternative to warfarin," he told Medscape Medical News. "Not that they are superior, but we recognize that there is sufficient evidence to recommend them as an alternative for stroke prevention."

He stressed that "by no means are we saying that everyone needs to stop their warfarin and switch; what we're basically saying is that people now have options, and legitimate options."

Some patients with AF are "very reluctant" to take warfarin because of "the rigors" involved with frequent monitoring, he added.

Although public awareness is growing, gaps in the field include the underuse of anticoagulants by suitable patients with AF, particularly those who are elderly, the authors note.

Home Monitoring

The committee added several new recommendations pertaining to hypertension. One is self-monitoring of blood pressure.

"There's now a more explicit acknowledgement that home blood pressure monitoring is useful," said Dr Meschia. "This is important for a lot of reasons," including that it "empowers patients" and can lead to better blood pressure control, he said.

"It's an acknowledgment that the automated cuffs are getting better and are more reliable, and that with advancing technology, there are going to be greater and greater opportunities to monitor health variables, and fitness variables," he added.

Importantly, the committee decided to retain the target systolic blood pressure of 140 mmHg, regardless of age. "That's a little controversial," said Dr Meschia. "Some folks had recommended perhaps that in older individuals, that goal could be liberalized."

Other recommendations relating to hypertension are regular blood pressure screening and appropriate treatment of patients with hypertension, including lifestyle modification and pharmacologic therapy, and annual blood pressure screening and health-promoting lifestyle modification for patients with prehypertension.

Successful reduction of blood pressure is more important in reducing stroke risk than is the choice of a specific agent, and treatment should be individualized on the basis of other patient characteristics and medication tolerance, the authors stressed.

Women With Migraine

The updated document has new recommendations on migraine. The experts recommended smoking cessation in women with migraine headaches with aura and that these women use alternatives to oral contraceptives, especially those containing estrogen.

The guideline committee also focused on risk assessment tools, such as the AHA /American College of Cardiology (ACC) Risk Calculator. These tools, it said, may be useful in uncovering stroke risks, but treatment decisions should be considered in the context of a patient's overall risk profile.

According to the committee, all such tools have limitations. For example, newer risk factors, such as obstructive sleep apnea, that were not collected in older studies need to be considered, they said.

"Risk assessment tools should be used with care because they do not include all the factors that contribute to disease risk. Some potential for harm exists from unnecessary application of interventions that may result from inappropriate use of risk assessment tools or from the use of poorly adjudicated tools."

They also stressed that risk assessment tools need to be validated across age, sex, and race/ethnic groups.

Another new recommendation advocates for following a Mediterranean diet that is supplemented with nuts. Other dietary recommendations are to reduce intake of sodium and increase intake of potassium, and to follow the DASH-style diet, which emphasizes fruits, vegetables, low-fat dairy products, and reduced saturated fat.

Overweight and Obesity

The new guideline defines overweight and obesity on the basis of body mass index (BMI). The committee recommended weight reduction to lower blood pressure in patients who are overweight (BMI of 25 to 29 kg/m2) and obese (BMI over 30 kg/m2).

In the category of cigarette smoking, the committee deemed that community-wide or statewide bans of smoking in public spaces is reasonable for reducing the risk for stroke. The authors noted, however, a lack of data showing that participating in smoking cessation programs leads to a long-term reduction in stroke.

Because of its association with stroke risk, the committee recommended screening for sleep apnea through a detailed history, including physical examination, polysomnography where indicated, and structured questionnaires, this latest being a new element, said Dr Meschia. The committee noted, however, that while treating sleep apnea is reasonable, its effectiveness in preventing stroke is unknown.

Another new aspect of the updated guideline is that patients with asymptomatic carotid stenosis are encouraged to take daily aspirin and a statin. The previous guideline did not explicitly state this except in the perioperative and postoperative context.

Specific Circumstances

In the category of genetic factors, pharmacogenetic dosing of vitamin K antagonists should now be considered when therapy is initiated. The committee also slightly updated recommendations for prevention of stroke in a variety of other specific circumstances, including sickle cell disease.

According to background information in the guideline paper, about 795,000 Americans sustain a stroke each year, about 610,000 of them for the first time. This results in 6.8 million adult stroke survivors.

Stroke is a leading cause of functional impairment. Six months after a stroke, 26% of those age 65 years and older are dependent on others for their activities of daily living and 46% have cognitive deficits.

Effective primary prevention is the best approach for reducing the burden of stroke, said the authors. "Primary prevention is particularly important because >76% of strokes are first events," they write. "Fortunately, there are enormous opportunities for preventing stroke."

The authors cited an international case-control study of 6000 individuals that found 10 potentially modifiable risk factors explained 90% of the risk for stroke.

"[S]troke-prone individuals can readily be identified and targeted for effective interventions," they said.

The American Academy of Neurology affirms the value of these guidelines as an educational tool for neurologists. The guideline is endorsed by the American Association of Neurological Surgeons, the Congress of Neurological Surgeons, and the Preventive Cardiovascular Nurses Association.

Stroke. Published online October 28, 2014. Abstract

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