Explanation of the variance in quality of life and activity capacity of patients with heart failure by laboratory data

Abstract

Background This study was conducted to explain the variance in quality of life (QoL) and activity capacity of patients with congestive heart failure from pathophysiological changes as estimated by laboratory data.

Methods Peak oxygen consumption (peak VO₂) and ventilation (VE)/carbon dioxide output (VCO2) slope derived from cardiopulmonary exercise testing, plasma N-terminal prohormone of B-type natriuretic peptide (NT-proBNP), and echocardiographic markers [left atrium (LA), left ventricular ejection fraction (LVEF)] were measured in 62 patients with congestive heart failure, who also completed the Minnesota Living with Heart Failure Questionnaire and the Specific Activity Questionnaire. All regression models were adjusted for age and sex.

Results On linear regression analysis, peak VO₂ with P value less than 0.001, VE/VCO₂ slope with P value less than 0.01, LVEF with P value less than 0.001, LA with P = 0.001, and logNT-proBNP with P value less than 0.01 were found to be associated with QoL. On stepwise multiple linear regression, peak VO₂ and LVEF continued to be predictive, accounting for 40% of the variability in Minnesota Living with Heart Failure Questionnaire score. On linear regression analysis, peak VO₂ with P value less than 0.001, VE/VCO₂ slope with P value less than 0.001, LVEF with P value less than 0.05, LA with P value less than 0.001, and logNT-proBNP with P value less than 0.001 were found to be associated with activity capacity. On stepwise multiple linear regression, peak VO₂ and LA continued to be predictive, accounting for 53% of the variability in Specific Activity Questionnaire score.

Conclusion Peak VO₂ is independently associated both with QoL and activity capacity. In addition to peak VO₂, LVEF is independently associated with QoL, and LA with activity capacity.