If you're like me, you probably don't mind having your picture taken, as long as the result is flattering and makes you look younger than you are. Well, brace yourself, because I'm going to urge you to pose for a picture that won't fudge the truth about your age.

It's called a heart scan and, by revealing how much calcium has accumulated in your arteries, it tells you exactly how old they are. The presence of any calcium indicates damage caused by plaque. When young, soft plaque (made up of cholesterol and other fats) in an artery bursts, it can cause a heart attack or even sudden death. Fortunately, most of the time it doesn't--it just causes a little hole in the vessel. To firm up the injury, your body dispatches calcium and other substances to form a scar. What these "healed" plaques tell us as they accumulate--and this is your calcium score--is how rapidly you are developing and rupturing the soft plaques. If your score is high, you can reduce your heart attack risk with medications and lifestyle modifications.

I recommend that men over age 40 and women over 50 who are at intermediate risk of a heart attack get the test. That means you have two or more of these risk factors: high blood pressure, high cholesterol, diabetes, obesity, sedentary lifestyle, smoking, or family history of disease. The majority of women over age 50 fall into that category. (Most insurance companies don't cover the cost--less than $400.)

So get your picture taken--of your heart, that is. Just remember to smile: You're doing yourself a big, big favor. Arthur Agatston, MD, a preventive cardiologist and an associate professor of medicine at the University of Miami Miller School of Medicine, conducted several groundbreaking studies on heart disease and wrote the international bestseller The South Beach Diet. He maintains a cardiology practice and research foundation in Miami Beach, FL.

To read Agatston's blog and ask him questions, visit prevention.com/dragatston.