Millions of Americans have a heart rhythm disorder that's a leading cause of stroke. With atrial fibrillation, an electrical problem in the heart, the upper chambers cannot pump right, so blood pools and then clots can break off and trigger strokes. Meanwhile, the lower chambers may beat too rapidly, resulting in heart failure.

The common heart arrythmia is the subject of Saturday's Deseret News/Intermountain Healthcare Hotline. From 10 a.m. to noon, interventional cardiologists Dr. John Day and Dr. Brian Crandall, both of Intermountain Medical Center, will answer phoned-in questions. Call 1-800-925-8177. You can also e-mail hotline@desnews.com.

Day uses the word "epidemic" to describe the large increase in the number of atrial fibrillation cases that he and colleagues are seeing. And while he points out that age is a risk factor you can't do much about, there are other things you can impact. High blood pressure, for instance, "puts a lot of wear and tear on the heart. It causes it to misfire and go into arrythmia." Obesity forces the heart to work too hard. You can do something about that. Sleep apnea is another cause of atrial fibrillation — and it's related to obesity and heart disease. It's also treatable.

Diabetes, thyroid disease, chronic lung problems, excessive use of alcohol or stimulants — they are all risk factors for arrhythmia. And any heart condition can increase the likelihood of atrial fibrillation, although some are more likely to cause it than others. Sometimes, there's no clear cause.

Risk may go away once a heart defect is repaired, said Crandall.

It's tricky in that a number of things can cause symptoms, which may include dizziness, shortness of breath, palpitations, trouble exercising, chest discomfort or stroke or mini-stroke. Initially, the duo say, the symptoms come and go on their own. But eventually it's apt to become entrenched. And it also gets harder to treat.

The condition is usually diagnosed with an EKG while symptoms are active. If it comes and goes, a doctor may have you wear a heart monitor until an episode occurs.

Because of the pooling blood and the risk a clot will break off, the blood thinner warfarin (Coumadin) is a staple of treatment, "but one that everyone hates," Day said. Warfarin is "difficult to manage and you have to watch diet closely. It's a medication that patients and health-care providers don't like. But it's also needed, he said.

There are a couple of other classes of medicines used early on as well. One type slows down the chaos, while the other type helps control rhythm, said Crandall. Over time, though, the medicines tend to lost their effectiveness and doctor and patient must do something else.