“What are the symptoms of heart muscle damage?”

The symptoms of heart muscle damage depends on the severity of the damage. Severity is based on the amount of muscle that is damaged, how badly damaged, and where in the heart the damaged muscle is. How badly damaged is based on the kind of damage. The damage can be due to lack of oxygen, due either to blockage of the arteries supplying blood to the heart muscle or a demand for oxygen that is so excessive that the arteries cannot supply it. (Don't forget, the heart is the only organ whose energy supply is dependent on its own activity.) The damage may also be due to tumors in the heart, inflammation in the heart due to infections or noninfectious inflammatory disease. The damage may be due to damage to the nerves supplying the heart.

Almost any disease that occurs in the human body can affect the heart and may damage heart muscle. Various nutritional/vitamin deficiencies can affect the heart. Emotional and psychological issues can have a very damaging effect on heart muscle mediated through the nervous system. Hormonal diseases such as hyperthyroidism can affect the heart. The list is endless and embodies that entire field of medicine and cardiology.



You can see that you have asked a very complicated question for which there is no simple answer. I will assume the most general interpretation of your question: when you say "damaged" you mean weakened. Then the symptom would be shortness of breath on exertion. That is the most straightforward answer to your question. Other symptoms that could occur depending on all the factors I mentioned above are palpitations, lightheadedness, chest pain, sudden blacking out. I hope this is at least a start to the answer of your question.

The most common symptom is shortness of breath. Other symptoms are weakness, fatigue, chest discomfort, swelling of the lower extremities progressing to the abdomen and upper extremities. Blue color of the lips and nails may also be seen. This all depends on how much heart muscle is damaged.