Control Other Risk Factors - Preventing Stroke: Stroke

Content provided by the Faculty of the Harvard Medical School

Control other risk factors

The impact of other risk factors may depend on your lifestyle and medical history.

Moderate your drinking

Alcohol plays a complex role in stroke. Moderate consumption (an average of one to two drinks a day for men and one drink a day for women) may actually lower the risk of ischemic stroke, just as it lowers the risk of heart disease. Researchers from Columbia University's College of Physicians and Surgeons in New York tracked the stroke rate of 677 people age 40 and older for 4 years and found that those who consumed 1 or 2 drinks a day had a 45% lower risk of ischemic stroke than those who drank no alcohol. It didn't seem to matter what kind of alcohol; the results were the same for wine, beer, and spirits. But heavy drinkers fared worse. Those who consumed seven or more drinks a day had nearly three times the risk of ischemic stroke. For hemorrhagic stroke, any amount of drinking appears to increase the risk by two to four times.

The reason moderate drinking may reduce the risk of ischemic stroke is that alcohol inhibits blood clotting and raises protective HDL cholesterol. But heavy drinking can cause heart rhythm disturbances and boost blood pressure, thereby increasing the likelihood of a stroke.

Weigh the risks of hormone therapy

The Women's Health Initiative found an increased risk of stroke among women who took either combined estrogen/progestin hormone therapy or estrogen-only therapy for menopause. The study also found an increased risk of blood clots from hormone therapy.

If you are considering hormone therapy to control menopausal symptoms, discuss the risks and benefits with your doctor. Using this therapy on a short-term basis to relieve troubling symptoms such as hot flashes is generally considered safe. If you have had an ischemic stroke or a TIA, the American Heart Association/American Stroke Association does not recommend hormone therapy.

There is no convincing evidence that most healthy women who use low-dose oral contraceptives have an increased risk of stroke. However, women taking the pill who smoke and have migraines, high blood pressure, or blood-clotting problems have a higher risk, especially if they have a family history of stroke. The contraceptive patch may pose a higher risk of blood clots than oral contraceptives because it delivers 60% more estrogen into the blood. The FDA is studying the issue.

Treat atrial fibrillation

Atrial fibrillation is a common arrhythmia, or heart rhythm disturbance that affects about two million people in the United States. For reasons that aren't fully understood, the upper chambers of the heart (the atria) quiver erratically. As a result, blood swirls around and pools inside the upper chambers, especially the left atrium. The stagnant blood in the left atrium may form clots that can cause a stroke if they break loose and make their way to the brain (see Figure 16).

Figure 16: Atrial fibrillation and stroke During atrial fibrillation, the upper chambers of the heart (atria) quiver rapidly rather than contract forcefully. Blood pools along the walls of the left atrium, eventually forming clots that may break free to travel through the left ventricle to the aorta. If the clot lodges in an artery to the brain, it may obstruct blood flow downstream and cause an ischemic stroke.

Experts estimate that atrial fibrillation, which is most common among people over 65, causes more than 75,000 strokes per year, or nearly 10% of all strokes. In the Framingham Heart Study, atrial fibrillation was blamed for 1 of every 4 strokes among people over 80. Taking medications that prevent blood clotting can reduce the risk of stroke by 68% in people with atrial fibrillation in addition to other stroke risk factors.

Prevent or treat other heart conditions

Having a heart attack (myocardial infarction) can cause an embolic stroke. The damaged part of the left ventricle (the lower chamber that pumps blood into the aorta) does not contract normally. Blood tends to pool along the nonfunctional area, permitting small clots to form. A blood clot may form at the site of the heart attack, then break off and, like a ball in a pinball machine, travel to the brain and lodge in a blood vessel there, cutting off the brain's blood supply. About 3%–4% of people who have a heart attack go on to have an embolic stroke, almost all of these occurring in the first month following the heart attack.

Stroke risk is also higher for people with other heart conditions that increase the chance of clot formation, such as congestive heart failure, left ventricular hypertrophy (a thickening of the wall of the left ventricle), valve disease, or arrhythmias. Proper treatment of these conditions can help prevent stroke.

Know your family medical history

As with many other illnesses, the risk of stroke runs in families. Genetic factors influence blood clotting and the development of atherosclerosis and hypertension, all of which affect the risk of stroke. Aneurysms and arteriovenous malformations, two conditions that cause hemorrhagic strokes, clearly have a genetic basis. But genes alone may not be at fault. In addition to sharing many genes, relatives may also share eating habits and other behaviors that can promote strokes. If you have a strong family history of stroke, talk with your doctor about preventive measures you should take.

Control sleep apnea

Obstructive sleep apnea is a life-threatening disorder, most common among overweight men, in which breathing stops hundreds of times each night. It occurs when the upper airway is blocked by excess tissue such as a large uvula, tongue, tonsils, fatty deposits, or a floppy rim at the back of the palate. The hallmark of this condition is heavy snoring, but many snorers do not have this problem.

Because up to 44% of strokes occur during sleep, some researchers believe that obstructive sleep apnea may trigger some TIAs or strokes. Some research has found that people who had these events were much more likely to have a history of sleep apnea than their healthy peers. So far, however, researchers have not yet established how obstructive sleep apnea may cause a stroke.

If apnea can't be reduced by losing weight, avoiding alcohol, and discontinuing medications that may suppress breathing, then ventilation, drugs, or surgery may be necessary.

Detect carotid bruit

Carotid bruit is an abnormal rushing sound made by blood flowing through a narrowed vessel. Doctors may be able to hear it when they press a stethoscope against either one of the carotid arteries, which run up the left and right sides of the neck. Although people who have carotid bruits have an elevated risk of heart disease and stroke, less than half of those with bruits actually have a significant obstruction or narrowing of the carotid artery. Many experts recommend that, after a bruit is detected, physicians perform a more sensitive ultrasound test (see "Doppler ultrasound").

Even if the carotid artery is not severely obstructed and you have not had a TIA or a stroke, you'll still need to take some preventive measures against stroke, such as quitting smoking, losing weight, exercising regularly, and improving your diet. Your doctor may also recommend that you take medication to reduce your blood pressure, cholesterol, or both. Your doctor will probably want to monitor the blockage by scheduling periodic ultrasounds.

If the narrowing increases, or if you develop symptoms, you may need carotid endarterectomy, surgery to remove the obstruction. This surgery is necessary if you have a narrowing that is severe enough to cause blood pressure in the affected artery to drop (see "Carotid endarterectomy"). If you are a candidate for carotid endarterectomy but the surgery is too risky for you, your doctor may prescribe warfarin, an anticoagulant, to help prevent stroke.

Last updated:	September 05, 2008