ABC | Volume 114, Nº2, February 2020

Original Article Gonçalves et al. Prediction of CPET in HF patients with AF Arq Bras Cardiol. 2020; 114(2):209-218 Table 4 – Univariate Cox proportional-hazards analysis (CPET parameters) Characteristics All SR AF Wald Hazard ratio 95% CI p Wald Hazard ratio 95% CI p Wald Hazard ratio 95% CI p Initial HR 0.220 1.006 0.983-1.029 0.639 2.265 1.024 0.993-1.056 0.132 1.414 0.977 0.940-1.015 0.234 Maximal HR 6.259 0.982 0.967-0.996 0.012 0.644 0.992 0.974-1.011 0.422 5.706 0.973 0.951-0.955 0.017 Maximal HR(%) predicted 8.343 0.962 0.937-0.968 0.004 1.864 0.975 0.941-1.011 0.172 5.590 0.958 0.924-0.993 0.018 Delta HR during exercise 10.141 0.969 0.951-0.988 0 .001 3.324 0.979 0. 956-1.002 0.068 6.527 0.960 0.930-0.991 0.011 HHR1 22.484 0.837 0.778-0.901 < 0 .001 15.623 0.829 0 .755-0.910 < 0 .001 5.939 0.869 0 .777-0.973 0.015 Initial SBP 13.913 0.946 0.919-0.974 < 0 .001 8.317 0.951 0 .919-0.984 0.004 4.346 0.939 0.885-0.996 0.037 Maximal SBP 21.896 0.959 0.943-0.976 < 0 .001 12.029 0.964 0 .945-0.984 0 .001 7.205 0.954 0. 922-0.987 0.007 Duration of CPET (min) 26.781 0.756 0.681-0.841 < 0 .001 20.636 0.730 0 .637-0.836 < 0 .001 4.009 0.838 0 .704-0.996 0.048 SR: sinus rhythm; AF: atrial fibrillation; CI: confidence interval; HR: heart rate; HHR1: heart rate recovery in the first minute after finishing CPET; SBP: systolic blood pressure; CPET: cardiopulmonary exercise test. AUC value (0.906) followed by predicted pVO 2 (%) (0.903), with OUES with the lower AUC value (0.798). Despite these numerical differences, no statistically significant difference was found when the Hanley & McNeil test was applied to compare the different AUC values of the CPET parameters. In the AF group, predicted pVO 2 (%) (0.878) and pVO 2 (0.869) had the highest AUC values. Similarly to the SR group, OUES had the lowest AUC value (0.833), but no statistically significant difference was found when the Hanley & McNeil test was applied to compare these parameters. The Hanley & McNeil test was applied for comparing each CPET AUC parameter in the AF versus SR groups as well, with no statistically significant difference found. Multivariate Cox analysis (Table 5) showed that when pVO 2 and the VE/VCO 2 slope are analysed together, significant differences were found between SR and AF groups. In the SR group, pVO 2 lost his predictive power (p = 0.280) while the VE/VCO 2 slope remained predictive of the primary outcome (p = 0.001). In the AF group, the VE/VCO 2 slope lost its predictive power (p = 0.398) and pVO 2 showed a trend towards the prediction of the primary outcome (p = 0.091). Similar results were found in the multivariate Cox analysis of predicted pVO 2 (%) and the VE/VCO 2 slope in the AF group (p = 0.094 and p = 0.145, respectively), while in the SR group there was a difference, since predicted (%) pVO 2 (p = 0.006) and VE/VCO 2 slope (p = 0.033) kept their predictive power (p = 0.006), while pVO 2 had not (p = 0.280). OUES lost its predictive power in the multivariate Cox analysis in both SR and AF groups when compared with pVO 2 (p = 0.948 and p = 0.539, for SR and AF group respectively) Table 5 – Multivariate Cox analysis of CPET 1 prognostic parameters Multivariate Cox analysis SR AF Hazard ratio 95% CI p Hazard ratio 95% CI p 1) pVO 2 vs VE/VCO 2 slope pVO 2 0.910 0.766-1.080 0.280 0.759 0.551-1.045 0.091 VE/VCO 2 slope 1.117 1.045-1.194 0.001 1.050 0.937-1.177 0.398 2) pVO 2 (%) predicted vs VE/VCO 2 slope pVO 2 (%) 0.933 0.888-0.981 0.006 0.942 0.879-1.010 0.094 VE/VCO 2 slope 1.070 1.005-1.139 0.033 1.078 0.974-1.193 0.145 3) OUES 5 vs VE/VCO 2 slope OUES 1.508 0.388-5.864 0.553 0.624 0.056-6.975 0.701 VE/VCO 2 slope 1.170 1.090-1.256 < 0.001 1.123 1.002-1.258 0.046 4) pVO 2 vs. OUES pVO 2 0.742 0.597-0.922 0.007 0.623 0.482-0.907 0.014 OUES 1.061 0.183-6.153 0.948 2.335 0.156-34.907 0.539 SR: sinus rhythm;AF: atrial fibrillation; CPET: cardiopulmonary exercise test; CI: confidence interval; pVO2: peak O2 consumption; OUES: oxygen uptake efficiency slope. 213