A heart attack occurs when an artery supplying your heart with blood and oxygen becomes blocked. Fatty deposits build up over time, forming plaques in your heart's arteries. If a plaque ruptures, a blood clot can form and block your arteries, causing a heart attack.

How do heart attacks feel?

Most heart attacks involve discomfort in the center or left side of the chest that lasts for more than a few minutes or that goes away and comes back. The discomfort can feel like uncomfortable pressure, squeezing, fullness, or pain. Feeling weak, light-headed, or faint. You may also break out into a cold sweat.

Do heart attacks happen immediately?

Symptoms of a heart attack may be immediate and intense. More often, though, symptoms start slowly and persist for hours, days or weeks before a heart attack. Unlike with sudden cardiac arrest, the heart usually does not stop beating during a heart attack.