Known also as silent ischemia or silent myocardial infarction, silent heart attacks are often overlooked because they occur with minimal, unrecognized, or no symptoms at all.

And they’re more common than you might think: About 170,000 silent heart attacks occur each year, according to the American Heart Association.

Most often, silent heart attacks are only recognized later, when the person undergoes an EKG — often for another reason — and is found to have suffered a heart attack.

But even though it went unrecognized at the time of the event, a silent heart attack increases the risk of a second heart attack, as well as stroke, cardiac arrest, and congestive heart failure. A recent study published in the American College of Cardiology found a 35 percent increase of heart failure in people with silent heart attacks, and the risk was even higher in people in their early 50s or younger.

Symptoms of silent heart attack include:

• Chest discomfort

• Clamminess, or cold sweat

• Indigestion or feeling nauseated

• Feeling lightheaded

• Shortness of breath after exercise, which can be passed off too easily as “feeling winded”

• Feeling like you strained a muscle in your chest or upper back

• Prolonged, excessive fatigue

The risk factors for a silent heart attack are the same as for a heart attack, so if you have these risk factors, you need to be aware of the possibility of having a silent heart attack as well.