Abstract 14481: Oxygen Consumption Flattening During Exercise in Heart Failure: Evidence for a Combined Low Cardiac Output and Inefficient Oxygen Extraction
Background: Cardiopulmonary exercise testing (CPET) is useful for an objective functional evaluation of heart failure (HF) patients, allowing to understand the physiological basis of exercise intolerance. A specific pattern of impaired performance and severe exercise limitation is the one showing an early flattening of oxygen uptake (VO2) to maximum.This has been though to be related to a significant cardiac output (CO) impairment but it is undefined whether an increased O2 extraction may compensate for.
Aim: to study the relationship between CO and O2 extraction in a population of HF reduced ejection fraction (HFrEF) with or without a flattened VO2/WR.
Methods: 116 HFrEF patients (mean age 63±11 y, male 70%, ischemic etiology 69%, mean LVEF 33±9%) underwent a maximal CPET (incremental ramp protocol) combined with exercise-echo. Peripheral extraction (C(a-v)O2) was non-invasively estimated by dividing CPET measured VO2 and echo-derived CO.
Results: Study population was divided into 2 groups according to VO2/WR relationship: Group A (n=95) linear VO2/WR and B (n=21) non-linear (flattened) VO2/WR. Despite similar rest condition (A vs B CO 3.6±1.2 vs 3.5±1.2 L/min, peak VO2 0.28±0.07 vs 0.27±0.07 L/min, C(a-v)O2 8±3 vs 9±5mL/100mL, p=ns), Group B patients had lower peak VO2 (1.04±0.33 vs 0.73±0.23 L/min, p=0.000) and slightly lower CO, even though non statistically significant (6.7±2.5 vs 5.8±2.1 L/min, p=ns), resulting in markedly reduced peak peripheral extraction (C(a-v)O2 17±5 vs 14±4mL/100mL, p=0.003) compared to Group A.
Conclusions: In a population of HFrEF, the flattening of VO2/WR relationship phenotype was associated with worse exercise performance and a quite unfavourable hemodynamic combination, i.e. a reduced CO increase and blunted peripheral O2 extraction prospecting the necessity of complex and comprehensive therapeutic interventions integrating central and peripheral cardiovascular targets
Author Disclosures: G. Generati: None. F. Bandera: None. E. Alfonzetti: None. M. Guazzi: None.
- © 2016 by American Heart Association, Inc.