Comparative Value of NYHA Functional Class and Quality-of-Life Questionnaire Scores in Assessing Heart Failure

PURPOSE: To assess the relationships between New York Heart Association (NYHA) functional class, quality of life, aerobic capacity (peak oxygen uptake, (V) over dotO(2)), ventilatory efficiency (minute ventilation/carbon dioxide production slope, VE/(V) over dotcO(2) slope), and brain natriuretic peptide (BNP) in creating a model for predicting peak (V) over dotO(2). METHODS: Cardiopulmonary exercise testing was performed in 62 patients. A baseline blood sample was taken to measure the N-terminal prohormone BNP (NT-proBNP). Patients also completed the Minnesota Living with Heart Failure Questionnaire (MLHF) and the Specific Activity Questionnaire (SAQ), and NYHA functional class was determined. RESULTS: NYHA functional class correlated more strongly with SAQ score than with MLHF score. Peak (V) over dotO(2) and VE/(V) over dotcO(2) slope had stronger associations with NYHA functional class and SAQ score than with MLHF score. NT-proBNP plasma levels correlated more significantly with NYHA functional class and SAQ score (both P < .001) than with MLHF score. Using multiple linear regression analysis adjusted for age and sex, SAQ score, NT-proBNP, and etiology of heart failure had significant independent relationships with peak (V) over dotO(2), explaining 63% of its variability (adjusted R-2 = 0.596). CONCLUSIONS: Cardiopulmonary exercise variables and plasma NT-proBNP are associated more with NYHA functional class and SAQ score than with MLHF score. When combined, SAQ score, NT-proBNP, and etiology of heart failure can satisfactorily predict peak oxygen uptake.