Will i need to have heart disease, to have a heart attack?

Not necessarily: Most of the time, people who get heart attacks have heart disease, namely where there are blockages in the arteries that supply the heart muscle. But, in some rare cases, people without blocked arteries can get heart attacks as well: like people with clotting disorders, or Cocaine abusers.

Atherosclerosis yes: In general: depends on one's personal risks smoking, obesity, hypertension, hyperlipemia, diabetes , family history. Drug abuse may also cause. Simply, one blocks the feeding artery to part of the heart muscle and low flow, or no flow causes ischemia which cause death of the heart cells, which is a heart attack! myocardial infarction is the medical term.Ekg and lab tests show the damage.