Prognostic impact of the addition of ventilatory efficiency to the Seattle Heart Failure Model in patients with heart failure.
BACKGROUND
The Seattle Heart Failure Model (SHFM) is a multivariable model with proven prognostic value. Cardiopulmonary exercise testing (CPX) and neurohormonal markers (eg, B-type natriuretic peptide [BNP]) are also well accepted assessment techniques in the HF population and have both demonstrated robust prognostic value. The purpose of this investigation was to assess the combined prognostic value of the SHFM and CPX.


METHODS AND RESULTS
This study included all 453 patients enrolled in the Multicenter In-Sync Randomized Clinical Evaluation (MIRACLE) trial. Baseline SHFM and CPX were used. Both peak oxygen consumption (VO(2)) and ventilatory efficiency (VE/VCO(2)) were determined. In a univariate Cox proportional model analysis, SHFM and log-transformed peak VE/VCO(2) were stronger predictors of 6-month mortality (both P < .001) than log-transformed BNP (P = .013) or peak VO(2) (P = .066). In a multivariable Cox proportional hazards model, neither peak VO(2) nor BNP were independent predictors when added to the SHFM (P > .1). Conversely, peak VE/VCO(2) was a strong independent predictor when added to the SHFM, with an increase in the Cox proportional hazards model Wald χ(2) from 22.7 for SHFM alone to 33.8 with inclusion of log-transformed peak VE/VCO(2) (P < .0001) and significant changes in the net reclassification improvement and integrated discrimination index (both P < .002).


CONCLUSIONS
These results indicate that the SHFM and peak VE/VCO(2) work synergistically to improve prognostic resolution. Further investigation is needed to continue to optimize multivariable prognostic models in patients with HF, a chronic disease population that continues to suffer from a high adverse event rate despite advances in medical care.