So heart attack happens when you have a blockage in the arteries that supply the heart with the oxygen and nutrients that it needs to function normally. So there are different ways that this can happen. You can either have an acute occlusion of blood clot that forms rapidly, that causes a massive heart attack where you can potentially drop dead suddenly. Or this narrowing can happen over time with multiple risk factors. And as this narrowing is happening, you may experience chest discomfort with physical activity that gets worse over time as your arteries are narrowing to a close.