Table 4.
Multivariate Cox regression analysis for key patient characteristics and CPX variables in the overall group and peak RER subgroups.
| Overall group | ||
|---|---|---|
| Chi-square | p-Value | |
| VE/VCO2 slope | 109.50 | <0.001 |
| Residual chi-square | ||
| LVEF | 24.03 | <0.001 |
| HRR** | 12.49 | 0.001 |
| Peak VO2 | 9.17 | <0.01 |
| Beta-blockade | 5.09 | 0.02 |
| Peak RER < 1.00 | ||
| Chi-square | ||
| HRR** | 12.82 | <0.001 |
| Residual chi-square | ||
| VE/VCO2 slope | 9.43 | 0.001 |
| Peak RER 1.00–1.09 | ||
| Chi-square | ||
| VE/VCO2 slope | 13.20 | <0.001 |
| Residual chi-square | ||
| HRR** | 9.31 | <0.01 |
| Peak RER ≥ 1.10 | ||
| Chi-square | ||
| VE/VCO2 slope | 98.88 | <0.001 |
| LVEF | Residual chi-square 12.42 | 0.001 |
| Peak VO2 | 4.74 | 0.03 |
| Beta-blockade | 6.24 | <0.01 |
| HRR** | 4.35 | 0.04 |
CPX=cardiopulmonary exercise testing; VE/VCO2=minute ventilation/carbon dioxide production; LVEF=left ventricular ejection fraction; HRR**=heart rate recovery as a continuous variable; VO2=oxygen consumption.
Only variables retained in models are presented; the number of variables included in each model was different due to the number of events in each RER subgroup. Variables in each model included: overall group (age, heart failure etiology, beta-blocker use, LVEF, resting heart rate, peak VO2, VE/VCO2 slope, and HRR), peak RER<1.0 (peak VO2, VE/VCO2 slope, and HRR), peak RER 1.0–1.09 (LVEF, peak VO2, VE/VCO2 slope, and HRR), and peak RER≥1.10 (age, heart failure etiology, beta-blocker use, LVEF, resting heart rate, peak VO2, VE/VCO2 slope, and HRR).