The progression of chronic heart failure (CHF) is related to ongoing myocyte loss, which can be detected by cardiac troponin T (cTnT). We examined the prevalence and prognostic value of increased cTnT concentrations in serial blood specimens from patients with severe CHF. Clinical, echocardiographic, and 6-minute walk test data were collected prospectively at baseline and at 1 year in 115 outpatients (mean age, 61+/-11 years; 75% men; 62% coronary heart disease) with CHF and a left ventricular ejection fraction <40%. Blood samples were collected at baseline and at 3, 6, and 12 months of follow-up. cTnT concentrations > or =0.02 ng/mL were considered abnormal, and a Tn index (highest cTnT measurement/0.02 ng/mL) was calculated. In 62 patients (54%), cTnT was consistently <0.02 ng/mL (group 1); 28 (24%) had a single abnormal cTnT result (group 2); and 25 (22%) had > or =2 abnormal cTnT results (group 3). At 18 months, CHF hospitalization-free survival was 63%, 46%, and 17%, respectively (P=0.0001). In a Cox proportional-hazards model, hospitalization for worsening CHF in the previous year (HR=2.1; 95% CI, 1.1 to 4.1), functional class III-IV (HR=2.3; 95% CI, 1.1 to 4.6), and number of abnormal cTnT samples (HR=1.6; 95% CI, 1.1 to 2.4) were independently associated with prognosis. A cTnT rise of 0.020 ng/mL in any sample was associated with an excess of 9% (95% CI, 1% to 18%) in the incidence of combined end point. Abnormal cTnT concentrations were detected in >50% of outpatients with advanced CHF. This ongoing myocardial necrosis was a strong predictor of worsening CHF, suggesting a role of cTnT-based monitoring to identify high-risk patients.