Stroke is a leading cause of death and disability in older persons. The National Stroke Association recently established an Advisory Board to review published guidelines and make a consensus statement about how the risk of having a stroke can be reduced.

The members of the Board identified the following risk factors: high blood pressure, a heart attack (myocardial infarction, or MI), raised blood cholesterol, the irregular heart beat known as atrial fibrillation, diabetes, narrowed carotid arteries, and 4 important lifestyle ingredient -- smoking, alcohol use, exercise and diet.

High Blood Pressure

This is the most prevalent and readily modifiable risk factor for stroke, as shown by numerous clinical trials. All persons diagnosed with high blood pressure must be treated effectively by their physician, most probably for the rest of their life. All persons should have their blood pressure checked on every visit to the doctor, and patients with high blood pressure should monitor their blood pressure at home. In older patients, borderline isolated systolic hypertension (where just the upper blood pressure reading is only slightly increased) deserves treatment to avoid cardiovascular effects such as stroke.

Myocardial Infarction (MI)

A stroke will occur in approximately 1% to 2% of patients who have had a heart attack -- the risk is greatest in the first month. An anti-platelet agent, like aspirin, reduces the risk by about 30%; aspirin is usually given to MI patients in any case, to help prevent a recurrence of MI. If there is persistent irregular heartbeat (atrial fibrillation) or impaired heart function, patients will be given an oral anticoagulant, such as warfarin.

Cholesterol-lowering agents, in particular "statin"-type drugs, decrease the risk of stroke after MI, and should therefore be given to patients after MI, even if they have normal cholesterol levels.

Irregular Heartbeat due to Atrial Fibrillation

Atrial fibrillation increases the risk of stroke about 6-fold, and about a third of the strokes in the elderly are attributed to this condition. Oral anticoagulants (warfarin) should therefore be given to all patients over 75 with atrial fibrillation. In younger patients, warfarin must be used if there are additional risk factors for stroke. Otherwise, atrial fibrillation patients should take aspirin.

Diabetes

Diabetes is a well-established risk factor for stroke, although there are no conclusive clinical studies showing that tight control of glucose levels reduces the risk for stroke. Nevertheless, all diabetic patients should have treatment directed at good control of their blood sugar, so as to reduce the complications which themselves can contribute to the risk of a stroke (e.g. atherosclerosis, high blood pressure).

Carotid Artery Disease

Atherosclerotic changes in the carotid artery increase the risk of a stroke, and the risk increases with the degree of narrowing. Surgical cleaning of the artery (carotid endarterectomy) should be done if the degree of narrowing reaches 60% or more. The surgical mortality of this surgery is about 3%, but the risk of stroke is reduced by about 20% to 60%.

Lifestyle Factors

Cigarette smoking: Smokers are about 1.5-times more likely to have a stroke than non-smokers, and heavy smokers are twice as likely to have a stroke than light smokers. Many clinical studies have shown that the benefits of stopping smoking are almost immediate, and increase with the duration of abstinence.

Alcohol use: It is now recognized that light to moderate drinking (1 to 2 drinks a day) can have a beneficial effect on the risk of having a stroke, through a variety of possible mechanisms. Heavy use of alcohol should be avoided, as it can have the opposite effect, as well as other health hazards.

Physical activity: Regular exercise lowers the risk of having a stroke, although it has not been shown that "more is better". The protective effect is probably due to beneficial effects of exercise on high blood pressure, diabetes and obesity, among other actions. Exercise at moderate intensity (e.g. brisk walking) for at least 30 minutes on at least five days a week is recommended -- consistency is more important than sporadic vigorous exertion.

Diet: Nutritional factors can play a role in the risk of stroke. For instance, sodium intake is associated with high blood pressure. Lack of folic acid, vitamins B6 or B12 may be associated with an increased risk of stroke. Fruits and vegetables can help through their antioxidant mechanisms and/or potassium content. To help prevent stroke (and other cardiovascular conditions) it is recommended that dietary fat (especially saturated fat) is limited to less than 30% of total dietary energy, with cholesterol as less than 10% of total energy, and that at least five servings of fruits and vegetables per day are taken. There must be adequate amounts of dietary fiber, calcium, beta-carotenes and antioxidants.

Comment

The family physician should ideally tailor recommendations for stroke prevention for the individual patient. Adherence to these recommendations is vital if one is to achieve the hoped-for protection. This means frequent follow-up visits to the physician and other health professionals (dietitians, life-style councilors, physiotherapists, etc). Without obvious symptoms, motivation for follow-through can be difficult.