Independent and Added Value of Cardiopulmonary Exercise Testing to New York Heart Association Classification in Patients With Heart Failure

Abstract

Purpose: The objective of this study was to evaluate the independent and added value of a cardiopulmonary exercise test (CPX) to New York Heart Association (NYHA) functional analysis in patients with heart failure (HF) and ejection fraction (EF) <50%.

Methods: Patients (n = 613) with HF and EF < 50% underwent CPX and were followed for 28 ± 17 mo with respect to primary outcomes (death or heart transplantation).

Results: Mean patient age was 56 ± 12 yr, and 64% were male. Most patients were classified as NYHA class II (41%). The composite rate of primary outcomes was 12%; death occurred in 9%, and heart transplant in 4%. Independent predictors of primary outcomes were: EF (HR = 0.95: 95% CI, 0.92-0.98; P = .001) and NYHA (HR = 2.06: 95% CI, 1.54-2.75; P < .0001). When added to the model, peak oxygen uptake (V˙ O2peak ) was an independent predictor (HR = 0.90: 95% CI, 0.84-0.96; P = .001), as was the percentage of predicted V˙ O2peak (HR = 0.03: 95% CI, 0.007-0.147; P < .001), minute ventilation/carbon dioxide production slope (HR = 1.02: 95% CI, 1.01-1.04; P = .012), and CPX score (HR = 1.16: 95% CI, 1.06-1.27; P = .001).

Conclusions: CPX variables were independent predictors of HF prognosis, even when controlled by NYHA functional class. Despite being independent predictors, the value added to NYHA classification was modest and lacked statistical significance.