Serum interleukin-6 in congestive heart failure secondary to idiopathic dilated cardiomyopathy.

Increased serum interleukin-6 (IL-6) was associated with a higher incidence of New York Heart Association functional classes III to IV and worse left ventricular function during follow-up. Patients with elevated serum IL-6 had poor prognosis. These results reinforce the concept that increased serum IL-6 may also play an important role in disease progression.