Could you have a heart attack -- and not know it?

A close up of a mans heart while he's suffering a heart attack. — Shortness of breath and chest pain can be early indicators of a heart attack. boonchai wedmakawand / Getty Images

The lights dim in your favorite movie theater. You have your popcorn, Goobers and the largest soda you've ever seen. You're ready to watch the hero battle corruption for the good of all mankind -- to risk it all and lose his one true love in the process. He overcomes the odds and defeats the unscrupulous enemy. Alone and exhausted, his true love returns to reclaim the man that she cannot live without. Suddenly, our hero clutches his chest, doubles over and has trouble breathing. He drops to his knees and lays in his lover's arms. Before he goes, he manages a final farewell -- "I did it all for you." Then his tired, broken heart gives out once and for all. The curtain falls -- not a dry eye in the house.

If only all heart attacks were like they are in the movies. Unfortunately, that's not how they typically go down. A heart attack isn't very complicated. Your heart, like all muscles, needs blood to function properly. Blood is carried throughout the body through blood vessels and larger arteries. When the coronary arteries that supply blood to your heart get blocked, you're likely to have a heart attack. These arteries become blocked because of a buildup of something called plaque. Plaque may build if:

you're overweight
you don't exercise
your diet has too much fat and cholesterol
you're stressed
you smoke
you drink alcohol in excess
you have a history of heart disease in your family

These factors put you at risk for plaque buildup, called atherosclerosis, and eventually a heart attack. Once that plaque builds up, it can rupture and completely block the artery, cutting off the blood supply to your heart.

Some of the common symptoms of a heart attack are:

sweating
shortness of breath
chest pressure
chest pain
prolonged squeezing in your chest area
pain shooting through arms, shoulders, back or jaw
nausea and vomiting

Women may also experience additional symptoms when they have heart attacks, and no one is quite sure why. The symptoms include clammy skin, dizziness, a burning sensation in the chest and unexplained fatigued. About 1.2 million Americans have heart attacks each year, and it's the leading killer of both men and women. About a third of these victims die before they ever get to the hospital. This is because you can actually have a heart attack and never realize it. It's called a "silent" heart attack, and it happens more often than you might think.

Silent Heart Attack

Sometimes people have heart attacks and never know it. It's called the silent heart attack, when someone either shows no symptoms at all or ignores or misinterprets the symptoms until the pain goes away. Because the key to recovering from a heart attack is by restoring the blood flow to the heart as quickly as possible, silent heart attacks are even more deadly. In fact, twice as many people die from the silent type of heart attack as those who experience the typical variety [source: silentheartattack.org].

What's going on here in most cases is something called ischemia -- when blood that normally flows to a part of the body is temporarily restricted. When this happens to the heart it's called cardiac ischemia. A temporary loss of blood flow to the heart causes chest pain, or angina, which is basically a warning sign that something bad could happen shortly. This is where things get a little tricky. Sometimes there's no angina. This is called silent ischemia and it leads to the silent heart attack. That's the trouble with silent ischemia -- there are no symptoms.

In other cases, the heart attack isn't completely pain free, but the symptoms are overlooked or misinterpreted as heartburn, standard angina that goes away, a pulled muscle or even overall fatigue. This is largely explained away by the fact that some people have higher pain thresholds, and others are embarrassed by the fact that they may be in trouble and just want to wait until the pain subsides. One odd symptom that's never been fully explained in regular and silent heart attacks is a feeling of impending doom. In silent attacks, this is often misinterpreted as stress or anxiety.

It may be hard to comprehend, but about 25 percent of all heart attacks are silent. This is probably due in part to how heart attacks are portrayed in movies and on television. A study by the British Heart Association shows that one in four people in England get their information on heart attacks from what they see on the big and small screen [source: The Guardian]. Besides the fact that they can kill you, silent heart attacks also increase the risk of dementia for men. A Dutch study reports that men who experienced silent attacks are more than twice as likely to suffer from dementia as those who have never had an attack at all. If it doesn't kill you, you may not even realize you had an attack until your doctor discovers the damage at your next physical.

If you're at risk for a heart attack, you should get checked out for silent ischemia. Your doctor will ask you questions about your own and your family's medical history and put you on a treadmill to jog while your heart function is monitored by an electrocardiogram (ECG) machine. In this test, doctors are looking at how your heart rate and blood pressure increase during exercise, a good indicator of how your blood is flowing. You'll also likely get a blood test for cardiac enzymes. These are proteins that are released when the heart is damaged. Aside from this preventive screening, your best course of action is to know the symptoms of a heart attack and pay attention if you experience any of them. Call paramedics immediately if you feel chest pain, have shortness of breath or are unusually fatigued and they'll walk you through the proper course of action. Ignoring these signs because of embarrassment or shame can kill you.

Could you have a heart attack -- and not know it?

Silent Heart Attack

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