A lot of people equate a heart attack with cardiac arrest, where the heart actually stops pumping blood and the patient suddenly collapses, but in reality, a heart attack refers to a complete blockage of blood flow to part of the heart, and is sometimes colloquially to refer to inadequate blood flow (the term is never really used clinically).

Also, heart attacks can present very differently in different people. A large number of people (especially women) have atypical presentations that may not include the classic sub-sternal chest pain, so the symptoms often get ignored or missed.