Comparative value of NYHA functional class and quality-of-life questionnaire scores in assessing heart failure

To assess the relationships between New York Heart Association (NYHA) functional class, quality of life, aerobic capacity (peak oxygen uptake, (.)VO2), ventilatory efficiency (minute ventilation/carbon dioxide production slope, VE/(.)VCO2 slope), and brain natriuretic peptide (BNP) in creating a model for predicting peak (.)VO2).

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.

NYHA functional class correlated more strongly with SAQ score than with MLHF score. Peak (.)VO2 and VE/(.)VCO2 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 (.)VO2, explaining 63% of its variability (adjusted R(2) = 0.596).

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.