Rationale:
Cardiopulmonary exercise testing (CPET) in the heart failure (HF) population is a standard of care in both American and European clinics although the mode of exercise typically differs.
Objectives:
The purpose of the present study was to compare the prognostic characteristics of peak oxygen consumption (VO2) and the minute ventilation-carbon dioxide production (VE/VCO2) slope between two independent (American vs. European) HF groups.
Methodology:
One hundred and thirty-seven subjects underwent LE ergometry CPET at San Paolo Hospital in Milano, Italy (SPH). One hundred and six subjects underwent treadmill CPET at Virginia Commonwealth University in Richmond, Virginia (VCU).
Results:
Unpaired t-test results are reported SPH vs. VCU group throughout. Age (59.0 +/- 10.6 vs. 49.7 +/- 14.2), peak VO2 (16.4 +/- 4.5 vs. 14.8 +/- 5.2 mlO2*kg-1*min-1) and ejection fraction (33.8 +/- 11.3 vs. 27.7 +/- 13.1%) were significantly greater in the SPH group (P <.01). VE/VCO2 slope (34.2 +/- 8.2 vs. 35.3 +/- 8.5) was similar between groups (P >.05). There were 14 cardiac-related deaths over the one-year tracking period in both groups. ROC curve areas for peak VO2 were 0.78: SPH and 0.71: VCU (P <.01). Optimal prognostic threshold values for peak VO2 were 13.0 mlO2*kg-1*min-1 (sensitivity: 82%, specificity 79%) in the SPH group and 12.1 mlO2*kg-1*min-1 (sensitivity: 74%, specificity 64%) in the VCU group. ROC curve areas for VE/VCO2 slope were 0.82: SPH and 0.81: VCU (P <.001). The optimal prognostic threshold value for VE/VCO2 slope was 34.5 in both the SPH (sensitivity: 62%, specificity 86%) and VCU (sensitivity: 64%, specificity 86%) groups.
Conclusions:
Despite differences in mode of exercise, baseline and CPET characteristics and mortality rate, the prognostic characteristics of peak VO2 and VE/VCO2 slope were similar between the two centers. These results suggest that neither the mode of exercise or differences in subject characteristics between different centers negatively impact the prognostic utility of CPET responses in HF.