What is a silent heart attack?

My ignorance, but I just assumed that most people know when they are having a heart attack. I assumed that you feel excruciating pain in your chest and your arm. Well I recently asked someone who had a heart attack and was surprised. In fact, I read that almost 50% of people having a heart attack don't know they are having a heart attack.

I thought that silent heart attacks were rare but after reading some articles on CNN I found that there not so rare.

A concern that I'm having being that heart disease runs in my family is how do you know when your having a heart attack or when tightness in your chest is just gas and not a heart attack? When do I go see a doctor? My risk for heart attack is low but there is a family history and that's when I worry. When do I go see a doctor?

So I've learned that a silent heart attack means that that absence of pain but not the absence of damage to the heart and arteries.

Most physicians would probably encourage undergoing preventive screening when you have 2 to 3 risk factors such as smoking, diabetes, high blood pressure, and obesity. For me getting answers to questions about screening for risk of heart attack is where I've decided to start.