The new study was carried out by researchers at the University of California at San Francisco.
They surveyed 3,500 people who all had a history of heart problems, and were at an increased risk of a future cardiac event such as a heart attack.
They were asked questions about their knowledge of their own risk, heart attack symptoms, etc.
Out fo the entire group, 44% were rated at a very low knowledge level across the baord, with the majority not even knowing they had an increased risk of having a cardiac event such as a heart attack.