Most of us are happy to make adjustments in our lives now if we know they may reduce our chances of developing health problems later. That's why knowing our risk for medical problems is so important. We may not be able to change certain risk factors, such as age or heredity, but many are within our control.

Yet according to a survey conducted by the Alliance, more than three-fourths of Americans are unaware of one of the main risk factors for stroke. Atrial fibrillation causes nearly one out of every five strokes in the U.S., but we haven't yet tuned in to its importance.

What is atrial fibrillation?

Atrial fibrillation is a type of irregular heartbeat. If someone is suffering from AF, the upper chambers of their heart - the atria - quiver. A normal heartbeat is between 60 and 80 beats per minute. During AF, the atria may beat between 350 and 600 times per minute - up to ten times faster than normal.

An effective cardiovascular system relies on the heart beating efficiently and regularly. When it doesn't, blood can pool in the heart and form clots. If these clots become loose and travel through the bloodstream, they could lodge in blood vessels in the brain and cause a stroke.

More than 60 percent of those surveyed by the Alliance correctly identified atrial fibrillation as a type of irregular heartbeat. But when it comes to AF and stroke, most Americans aren't making the connection. Almost two-thirds of respondents believed that AF is a risk factor for heart attack. It's true that - if left unchecked - AF could ultimately damage the heart and lead to heart failure. But AF is not among the risk factors cited for heart disease.

Atrial fibrillation is, however, listed by the National Stroke Association as a major risk factor for stroke. Yet eighty-one percent of the respondents didn't know that people suffering from this disorder are among those most at risk. The fact is, strokes related to AF account for nearly 15 to 20 percent of strokes in the U.S.

Not only do AF patients find themselves at greater risk for having a stroke, these patients also tend to have more disabling first strokes than those without AF, and people with AF are 70 percent more likely to die from their stroke than people without AF.

How is atrial fibrillation recognized and treated?

Atrial fibrillation is often discovered during routine medical exams because people who have it may not notice any signs. But for those who do, symptoms include an irregular pulse and heart palpitations, which feel like a "flopping" in the chest. AF sufferers might also experience dizziness, sweating and chest pain or pressure, difficulty catching a breath, or a feeling of overall weakness.

Because many people do not have symptoms, the National Stroke Association recommends that everyone, especially those over 55, check their heartbeats once a month. If you notice your heartbeat has an irregular rhythm, talk to your doctor.

Most of the survey respondents were right when they said that strokes due to AF can often be prevented. But when asked for the most effective way to prevent them, more than half incorrectly answered lowering cholesterol.

Only 35 percent answered correctly: treatment with blood-thinning medications is actually the most effective way to prevent strokes due to AF. In fact, long-term use of these drugs - also known as anticoagulants - in patients with AF and other stroke risk factors may reduce the risk of stroke by 68 percent. Experts also recommend treating AF aggressively with therapies that return the irregular heartbeat to normal.

As we age, we're more and more at risk for developing atrial fibrillation. Studies estimate that more than two million people in the U.S. suffer from atrial fibrillation. Almost three-fourths of them are between the ages of 65 and 85. Yet surprisingly, most of the survey respondents over the age of 65 did not place themselves within the age group at highest risk for AF-related stroke.

Ultimately, atrial fibrillation is a treatable condition. So if you suffer from AF, be sure to discuss treatment options with your doctor. He or she will probably want to treat the disorder aggressively to curb your risk for stroke.