Abstract 20241: Better Parameters of Ventilation-co2 Output Relationship Predict Death in Chf Patients
Introduction: Measures of ventilation-co2 output relationship have been shown to be more prognostic than peak O2 uptake in assessing life expectancy in patients with chronic heart failure (CHF).
Hypothesis: Because both the ratios (Ve/Vco2) and slopes (Ve-vs-Vco2) of ventilation-co2 output of differing durations can be used, we aim to ascertain which measurements of ventilation-co2 output relationship best predicted CHF life expectancy.
Methods: 271 CHF patients with NYHA class II-IV underwent incremental cardiopulmonary exercise testing (CPET) and were followed-up for a median duration of 479 days. Four different linear regression Ve-vs-Vco2 slopes were calculated from warm-up exercise onset to: 180s, anaerobic threshold (AT), ventilatory compensation point (VCP); and peak exercise. Five Ve/Vco2 ratios were calculated for the following durations: rest (120s), warm-up (30s), AT (60s), lowest value (90s), and peak exercise (30s). Death or heart transplant were considered end-points. Multiple statistical analyses were performed.
Results: CHF patients had high lowest Ve/Vco2 (41.0±9.2, 141±30%pred), high Ve/Vco2 at AT (42.5±10.4, 145±35%pred), and high Ve-vs-Vco2 slope to VCP (37.6±12.1, 126±41%pred). The best predictor of death was a higher lowest Ve/Vco2 (≥42, ≥141%pred), whereas the Ve-vs-Vco2 slope to VCP was less variable than other slopes. At all time periods, the Ve/Vco2 ratios differed between survival and death groups (p<0.05) with significant AUC (p≤0.002). The highest AUC (0.712) was lowest Ve/Vco2 or highest Vco2/Ve, the next highest AUC (0.708) was Ve/Vco2 at AT (p <0.001). The AUC values of Ve-vs-Vco2 slopes were high to low in the following order from start to: VCP (0.701, p<0.001), AT (0.684, p<0.01); unloaded (0.662, p<0.01); and peak exercise (0.624, p<0.05).
For death prognosis in 6 months, %pred values were superior: for longer times, absolute values were superior.
Conclusions: The increased lowest Ve/Vco2 ratio easily identifiable and simply measured during exercise, is the best measurement to assess the ventilation-co2 output relationship in prognosticating death in CHF patients.
Author Disclosures: X. Sun: None. J. Hasen: None. W. Stringer: None. K. Wasserman: None. Y. Yao: None. S. Hu: None.
- © 2014 by American Heart Association, Inc.