Change Of Heart

By Christine Gorman

The drama begins with a noise you can't hear. Your doctor places a stethoscope over your chest and detects a faint murmur or a distinctive clicking sound whenever your heart contracts. "There may be something wrong with one of your valves," he says. "I'd like you to get some ultrasound tests." Seven days and several hundred dollars later, you learn you have mitral-valve prolapse, a condition in which the tiny flaps of tissue that keep blood from flowing backward between the chambers on the left side of the heart don't close completely. Even though you feel fine, your insurance company jacks up your premiums, citing research from the past 20 years that shows you're at greater risk of dying suddenly or suffering a stroke. Your dentist makes you take antibiotics every time you get your teeth cleaned to prevent a potentially fatal infection of your defective valve. And your family starts treating you like an invalid.

At least you're not alone. There's a shelf full of medical reference books all in agreement that mitral-valve prolapse affects about 1 in 10 Americans--an estimated 27 million people--and is even more common among young women.

But guess what? The reference books, your insurance company and maybe even your dentist are wrong. Mitral-valve prolapse is neither as prevalent nor as dangerous as it has been portrayed, according to two studies in the current issue of the New England Journal of Medicine. Although the more severe forms of the condition can cause life-threatening complications, most folks who have been told they have it can probably stop worrying about their tickers.

The new findings show how important it is for researchers to look at the whole population and not just patients in university hospitals, where the worst cases are usually referred. By examining a broad cross section of adults in the long-running Framingham Heart Study, Dr. Lisa Freed and her colleagues found only 2.4% of subjects had mitral-valve prolapse and that half those cases consisted of less harmful variations on normal cardiac design. They also found the condition to be equally uncommon among women and men.

It turns out the anomaly is easy to misdiagnose. "Just because you have a click doesn't make you sick," says Dr. Robert Levine, a cardiologist at Massachusetts General Hospital in Boston and a co-author of both of last week's reports. Because the mitral valve is shaped like a saddle when the heart is beating--something that Levine discovered 10 years ago--an ultrasound scan can indicate a bulging of the valve where none actually exists. Since then he has determined that the front-to-back view is more reliable than the side-to-side one. (Both views are standard on ultrasound exams of the heart.)

If you've been told you have mitral-valve prolapse, it makes sense to ask your doctor to check again, particularly if it was diagnosed several years ago. That may be as simple as reviewing the tapes of your last ultrasound exam. If you do have mitral-valve prolapse but no thickening of the valves or backflow of blood into the left atrium, you probably don't need to take antibiotics before most dental procedures, according to the latest guidelines. Still, be sure to alert your doctor if you experience shortness of breath, a racing heartbeat or light-headedness.

For more on mitral-valve prolapse, visit our website at time.com/personal You can e-mail Christine at gorman@time.com