Many people have no knowledge of any prior heart problems. Other people may notice their first symptoms some time after a heart attack, a viral illness, or delivering a baby. Usually the weakness takes years to develop, but occasionally cardiomyopathy can lead to an enlarged heart within weeks. For some patients, coronary artery disease or poor function nof the heart's valves are the causes of the heart weakness. In addition, use of alcohol, cocaine or amphetamines can weaken the heart muscle.
Some hormone imbalances can also contribute to cardiomyopathy.
In many cases the original injury cannot be identified because it occurred so long ago. Salt can worsen the symptoms of cardiomyopathy by increasing retention of excess fluid. Alcohol consumption can cause further weakening of the heart muscle. When physical activity becomes severely limited because of weakness or shortness of breath, the whole body becomes deconditioned and is further limited. The first symptom is often a decreased ability to exercise due to early fatigue or shortness of breath.