How long does heart disease last?

I don't know but brain damage occurs after 3 minutes.

Heart failure means that your heart can no longer pump blood adequately through the heart and out to the rest of the body. The blood literally "backs up" into the pulmonary system (lungs) and your lungs become too fluid filled to exchange oxygen and carbon dioxide. This process deprives your body's tissues/organs from the oxygen it needs and they begin to fail. This can be a very slow process if it is a chronic condition, or it can occur very quickly depending on how quickly the heart function is failing, and why (example: heart failure due to chronic high blood pressure or heart attack which results in heart tissue death)