Stroke : Risk Factors

by Food and Drug Administration (FDA)

(Page 2 of 4)

As Pagnotta discovered, stroke can strike without warning. After tests done during a six-day hospital stay, her doctors determined that her stroke likely occurred because of a combination of factors — she had started taking birth control pills for the first time three months earlier and she had a heart problem.

Pagnotta found out that she had a hole in her heart called patent foramen ovale (PFO). She also had an atrial septal aneurysm, a thinning of the wall between the two chambers of her heart. She had an embolic stroke, in which a clot travels to the brain. She says her doctors believe that a blood clot traveled from her heart, through the PFO, to her brain. A blood clot could move to other areas of the body and never pose a problem. But compared with other organs, the brain is much more sensitive to the interruption of blood supply.

A condition called atrial fibrillation also can increase the risk of having an embolic stroke. Normally, the atrium pumps blood into the ventricles, which then sends blood to the rest of the body. In atrial fibrillation, the atrium doesn't pump blood out properly. This increases the likelihood that blood will pool and clot in the atrium. If a piece of that clot breaks off, it can then be pumped to the brain.

Most strokes occur because blood clots develop directly in the brain. These are known as thrombotic strokes. The most common cause is atherosclerosis, a process in which fatty deposits form in the vessel walls of the brain. The process is similar to what happens in the heart for people with heart disease. This is why stroke and heart disease share some of the same controllable risk factors: high blood pressure, cigarette smoking, high cholesterol, diabetes, physical inactivity, and obesity. These factors raise the risk for plaque build-up in the arteries, which in turn raises the risk of the formation of blockages and blood clots. A stroke sometimes occurs because plaque develops in the carotid artery, the main blood vessel in the neck that leads to the brain.

Sacco says high blood pressure is perhaps the biggest risk factor for stroke. "There are too many people with uncontrolled high blood pressure," he says. "Especially given that it can be prevented and treated with behavior changes and medications.

"We want people to be aware of their stroke risk and take steps to address the risk factors they can control. We're all at risk. But no matter who you are, it is possible to lower your risk and help prevent a stroke from happening," Sacco says.

Men have a greater stroke rate than women, Sacco says, but women usually live longer and therefore more women are disabled or die from stroke each year. Having a family history of stroke and getting older also raise stroke risk. "African-Americans have twice the stroke incidence and mortality compared to whites," Sacco says, "and Hispanics also seem to be at greater risk." In addition, having one stroke or TIA increases the risk of having another stroke.

Leslie Virgil, 60, of New York City, had a mild stroke about five years ago with no lasting effects. "So I didn't think much about it," she says. "But now I see that the first one was like my body telling me: 'Watch out, because the big one is coming.'

"I had high blood pressure, diabetes, and high cholesterol, but I didn't make any changes. My mother had a stroke and so did my mother's brother."

Virgil experienced a second, major stroke in November 2004. Due to a blood clot on the left side of her brain, she lost function in her right leg. Her speech is still slurred. And she has difficulty concentrating and finding the right words to communicate sometimes.

Virgil entered the Rusk Institute of Rehabilitation Medicine, part of New York University Medical Center, in December 2004. She is working with a team of specialists to regain her strength. "My goal is to walk out of here," she says.

Now she takes medication to control blood pressure, cholesterol, and diabetes, and she has switched to a diet that's low in fat, cholesterol, and salt. "This stroke knocked some sense into me," Virgil says.

Small Window of Opportunity

When the FDA approved Activase (t-PA) in 1996, it was the first drug approved to treat acute ischemic stroke. Made by Genentech of South San Francisco, Calif., the drug is given intravenously to dissolve the clot or clots that are keeping blood from flowing to the brain. It improves the chance of recovery by up to 30 percent when used correctly. But there is a major limitation — the need to begin the treatment within three hours.

"The fraction of people who get treated with t-PA is very, very low, just a few percent of all stroke patients," says Marc Walton, M.D., Ph.D., director of the FDA's Division of Therapeutic Biological Internal Medicine Products. "The three-hour time window is very limiting. There is also a risk of causing intracranial bleeding. Research shows that for safety reasons, doctors are selecting patients carefully."

When someone suffers a stroke, doctors have to run tests to figure out which kind of stroke has occurred and whether the patient is a candidate for t-PA. Meanwhile, time is ticking away. "Hospitals are getting better at evaluating and treating patients with stroke symptoms quickly," Sacco says. "But we also need people to recognize the warning symptoms and get to the hospital sooner."

Most people don't go to the emergency room until more than 24 hours after they experience stroke symptoms, according to the NSA.

James Grotta, M.D., a professor of neurology and stroke program director at the University of Texas Medical School in Houston, says there is a host of reasons for the delay.

"Some people don't know the signs of stroke," Grotta says. "Other people call their doctor's office or a family member when they should call 911. Some people are embarrassed to call 911 or they go to bed and hope the symptoms will go away. Stroke symptoms also usually don't hurt, which is why some people try to ignore it. And there are geographical challenges when people are far away from a stroke center."

About the Author

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