Run for It: Use of Cardiopulmonary Exercise Testing for Hemodynamic Assessment in Advanced Heart Failure

PURPOSE Cardiopulmonary exercise testing (CPET) is an underutilized resource in the assessment of advanced heart failure (HF) after listing for heart transplant (HT). Currently, the ISHLT recommends repeating right heart catheterization (RHC) periodically after HT listing. The objective of this study was to assess whether CPET metrics could reliably predict hemodynamic pressures. METHODS Patients with pre-transplant RHC and CPET measured within 3 months of each other were included. Pearson correlation between CPET and hemodynamic variables were calculated. We applied a Random Forest method to develop a prediction model with demographics and CPET metrics for each hemodynamic variable. In addition, we ranked the input variables in terms of their relative importance, defined as the relative reduction in accuracy or, equivalent relative increase in RMSE. RESULTS 102 patients were included. Of those, 65 had a CI ≥2 and 37 had a CI< 2 LPM. Mean peak oxygen consumption (pVO2) was 12.2±2.8 ml/kg/min, with a %predicted 45.8%±11.4%, a respiratory exchange ratio (RER) 1.12±0.11 and a VE/VCO2 slope 41.4±10.4. When comparing HF etiologies, RER was lowest in those with ischemic cardiomyopathy (ICMP 1.08±0.1, DCMP 1.1±0.11, Other 1.16±0.11, p=0.029). There were no differences in pVO2, %predicted or VE/VCO2 slope. The cross-correlation analysis stratified by CI is shown in Fig 1A. We found modest correlations in the low CI group between VE/VCO2 slope and diastolic PA pressure (r=0.44), VE/VCO2 slope and mean PA pressure (r=0.42), and pVO2 and CI (r=0.37). When combining CPET data and demographic data, we were able to rank the importance of each predictor within in each model (Fig 1B). CONCLUSION Using CPET data as a surrogate for invasive hemodynamics in those listed for HT is feasible. The use of serial exercise testing may allow a safer means to monitor patients and determine the timing of more aggressive support prior to HT.