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. Many people with cardiomyopathy simply limit their activity without realizing the reason. When the condition becomes more severe, sufferers begin to build up extra fluid in their body, which can cause shortness of breath with rest or minimal exertion. Many patients notice difficulty breathing, particularly when lying down at night.