It strikes without warning and the symptoms are subtle. But every year, more than 25,000 Americans die from what's called a "silent" heart attack.
It happened to Frank Burke.
"I would feel a weird sensation in my chest a vibration that felt like gas or something. I would go buy a sprite soda, I would drink it, I would burp, I would feel fine and I would continue on what I was doing just never paid attention to it," Burke said.
During a recent routine medical procedure, Burke learned that 'weird feeling' was in fact an indication of a heart attack he'd suffered 8 months earlier.
"I had no idea, of course," Burke added.
People at risk for a silent heart attack can appear to be perfectly healthy.
"That's why we usually categorize this type of patient as a non-complainer. So if they have something, they think, 'Oh, I'm out of shape,' so even if they have symptoms, they don't contribute these symptoms to their heart. They say, 'Oh, I need more work out,' rather than say, 'I might have a heart problem,'" said cardiologist Dr. Michael Shen.
The symptoms of a silent heart attack can include shortness of breath with exertion, which some may dismiss as a result of their increased activity. Other symptoms include discomfort in the stomach, which could be excused as 'Just something I ate.' A third symptom could include light headedness, which some may think is just a result of being tired or hungry.
Doctor Shen said if a patient has atypical symptoms combined with heart disease risk factors such as high cholesterol, diabetes, high blood pressure or smoking, they may be referred for some form of cardiac imaging.
"Imaging will reflect the whole process of heart attack from acute phase to later on delayed phase," said Dr. Shen. "So you can see the whole process and what's involved."
Through exercise, diet and medication, Burke is making every effort to protect against another silent heart attack.
"I definitely pay closer attention now," said Burke.
If you have one or more of risk factors for heart disease and experience any of the atypical symptoms of a heart attack, call 911. Don't try to get to the hospital on your own.
A recent study showed that the flu vaccine may reduce the risk of having a heart attack or stroke among those with heart disease.
Some researchers believe the vaccine helps break up plaque in the arteries.