Dilated cardiomyopathy is a disease of the heart muscle, usually starting in your heart's main pumping chamber (left ventricle). The ventricle stretches and thins (dilates) and can't pump blood as well as a healthy heart can. The term "cardiomyopathy" is a general term that refers to the abnormality of the heart muscle itself.
Dilated cardiomyopathy might not cause symptoms, but for some people it can be life-threatening. A common cause of heart failure — the heart's inability to supply the body with enough blood — dilated cardiomyopathy can also contribute to irregular heartbeats (arrhythmias), blood clots or sudden death.
The condition affects people of all ages, including infants and children, but is most common in men ages 20 to 60.