Thirty-eight HF patients (24 men and 14 women; 59 to 81 years; mean, 68 years) with left ventricular EF of <40% were selected from the First Affiliated Hospital of Dalian Medical University to collect the blood samples and medical record information. Furthermore, patients associated with infectious disease, immunological disease, pulmonary disease, and malignancy were not included. HF medication consisted of angiotensin converting enzyme (ACE) inhibitors (81%), diuretics (73%), digitalis (68%), and β blockers (42%). Their clinical and hemodynamic situations were stable, with no change in medication in the last month before the study. Controls subjects were 38 donors who received health examination (18 men and 20 women; 58 to 67 years old; mean, 62 years) without any history of cardiac disease. Both serum and plasma were collected to examine biochemical factors. For serum sampling, fresh blood samples without any anticoagulant were immediately immersed in ice for 1 hour before centrifugation (1000g at 4°C for 10 min). For plasma sampling, EDTA was added and samples were immediately centrifuged (1000g at 4°C) for 15 min.