When heart muscle recovers from damage, it forms scar tissue, meaning that its usefulness for cardiac functions afterward is compromised. The rest of the heart keeps working if the patient survives and recovers from the heart attack, as stated by the American Heart Association.
Part of a heart attack involves the blockage of blood supply to the heart. Those parts of the heart muscle that stop receiving blood undergo an injury. The amount of damage suffered by the heart muscle depends on the size of the part of the heart that the blocked artery had supplied as well as the time between the heart attack and the treatment, according to the American Heart Association.
Once the heart muscle begins to heal from the loss of blood, the damaged area develops scar tissue in a process that depends on the individual's rate of healing as well as the degree of the injury. Even though a significant portion of the heart may have suffered from injury, the rest of it keeps functioning. Even if the patient recovers, the remaining healthy heart muscle may not be able to pump blood as efficiently as before, potentially limiting activity for the patient. It is possible to limit further damage with the right lifestyle changes and other forms of treatment, notes the American Heart Association.