van Wezenbeek J, Canada JM, Ravindra K, et al. - Given the impact of a complex array of cardiac and extracardiac factors on impaired cardiorespiratory fitness (CRF) in heart failure (HF), researchers looked for the factors that can clinically determine CRF measured as peak oxygen consumption (peak VO₂) in HF patients. They used regression equations to define a peak VO₂ prediction model. They retrospectively analyzed 200 HF patients who finished treadmill cardiopulmonary exercise testing and had Doppler echocardiography and/or biomarker analysis on the same day. A stepwise linear regression analysis was performed using significant variables, after univariate linear regression analysis, to construct a multivariate peak VO₂ prediction model. The strongest predictors of impaired CRF that were identified in patients with HF across a wide range of left ventricular ejection fraction were age, systemic inflammation, oxygen carrying capacity, obesity, and elevated filling pressures. The prediction of peak VO₂ in HF patients was enabled by the proposed CRF model, which likely affords a tool to estimate peak VO₂ alterations over time.