Abstract 13253: Pattern of Cardiac Output vs O2 Uptake Ratio During Maximal Exercise in Heart Failure With Reduced Ejection Fraction: Pathophysiological Insights
Background: the oxygen uptake (VO2) response to exercise, measured during cardiopulmonary exercise testing (CPET), has prognostic value in heart failure (HF). The increase in VO2 is due to the increase in cardiac output (CO) and arterial-mixed venous oxygen content difference (C(a-v)O2). How much (C(a-v)O2) contribute to VO2 increase may be estimated by the CO/VO2 ratio. Aim: To study the cardiac and functional phenotype associated with CO/VO2 ratio at peak exercise in HF with reduced ejection fraction (HFrEF).
Methods: 104 HFrEF patients (mean age 64±11 y, male %, ischemic etiology 68%, mean LVEF 34±9%) underwent a maximal CPET (incremental ramp protocol) combined with exercise-echo.
Results: Study population was divided into 2 groups according to the peak exercise CO/VO2 (cutoff 0.49, CO/VO2 median value) Group A (n=52) with CO/VO2 <049 and B (n=52) with CO/VO2 ≥0.49. Despite similar peak VO2 (13.8 vs 12.6 mL/min/kg p=ns) patients with impaired CO exercise response (Group A) showed worse cardiac remodeling (LVEDV indexed 101±33 vs 91±23 mL/m2 p=0.09, E/e’28±15 vs 22±11 p=0.02) and more severe mitral regurgitation at rest and peak exercise (ERO rest 22±10 16±9 mm2 p=0.02, peak 33±13 vs 25±12 mm2 p=0.03). Group A patients exhibited also more impaired right ventricular function (TAPSE rest 17±5 vs 19±4 mm p=0.0001, peak 19±5 vs 21±4 p=0.04) associated with ventilatory inefficiency (VE/VCO2 slope 36±11 vs 31±7 p=0.01). The two Groups presented with similar average Hb levels. Conclusions: In advanced HF population, the worse exercise performance is associated witha reduced CO /VO2 ratio during maximal exercise, that for a similar peak VO2 as compared to the population with a high CO/VO2 ratio, is suggestive of "optimal" peripheral O2 extraction as compensation to a reduced O2 delivery.
Author Disclosures: G. Generati: None. F. Bandera: None. M. Pellegrino: None. V. Labate: None. F. Carbone: None. E. Alfonzetti: None. M. Guazzi: None.
- © 2015 by American Heart Association, Inc.