Heart attacks are caused (pretty much 99% of the time) by a long, long history of inactivity, smoking and bad diet and alcoholism, which lead to things like high cholesterol, dyslipidemia and hypercalcemia in your arteries, which lead to blockages over a period of a few decades, and left untreated can cause blood clots
in your coronary arteries leading to the
heart, hence leading to a
heart attack since fresh blood is essentially cut off, starving your heart of oxygen.