OBJECTIVES: Most economic models in heart failure have been structured using New York Heart Association (NYHA) class to define mutually exclusive health states. With this structure, no utility (i.e. effectiveness) gains are measured in patients who experience important changes in health status but remain in the same NYHA class. We sought to evaluate whether the Kansas City Cardiomyopathy Questionnaire (KCCQ) summary score can further discriminate between patients with lower and higher health utilities within a given NYHA class. METHODS: Repeated measures of NYHA class, KCCQ, and EQ-5D utility scores were available from patients enrolled in HF-ACTION, a randomized trial evaluating the effectiveness and safety of exercise training in addition to usual care compared to usual care alone in patients with chronic heart failure.  We used generalized estimating equations to regress utility scores on NYHA class and demographic characteristics and to evaluate the impact of adding the KCCQ summary score in the regression models.RESULTS: A total of 12,649 sets of assessments were available from 2331 patients. The mean age of the study cohort was 59 years at baseline, 72% were male, 61% were white, and 32% were black. When controlling for age, gender and race, estimated utilities were 0.84 (95% CI: 0.81-0.87) for NYHA class I, 0.80 (95% CI: 0.78-0.83) for class II, 0.75 (95% CI: 0.72-0.78) for class III, and 0.65 (95% CI: 0.61-0.69) for class IV.  A one-unit increase in the KCCQ summary score was associated with a 0.0044 (95% CI: 0.0042, 0.0045) increase in the utility weight, and its impact did not significantly vary across NYHA classes. CONCLUSIONS: Use of KCCQ summary score in addition to, or instead of, NYHA class may provide more discriminatory power in terms of estimating incremental gains in quality-adjusted life-years afforded by interventions for heart failure.