PeakVO2-cardiac Output Relationship During Exercise In Seniors Who Are Sedentary, Athletic, And HFpEF Patients: 265 Board #86 May 31 9

PURPOSE: The purpose of this study was to evaluate the relationship between O2 uptake (VO2) and cardiac output (Qc) during exercise in seniors who were sedentary, athletic, and Patients with HFpEF. METHODS: Based on lifestyle physical activity level categorization, elderly-sedentary seniors (n=27, 69±5 yrs) and elderly-athletic seniors (n=25, 68±3 yrs), and patients with heart failure with preserved ejection fraction (HFpEF) (n=24, 71±7 yrs) were selected and underwent cardiopulmonary exercise testing. A modified Astrand-Saltin incremental treadmill protocol was performed to determine VO2 and ventilatory gas exchange using the Douglas bag technique. Cardiac output (Qc) was measured with the C2H2 rebreathing method. Peak arterial-venous O2 difference (peak AV-O2 diff) was calculated by Fick equation (peak VO2 divided by peak Qc). The slope of the relationship between changes in VO2 and Qc during exercise was calculated by [INCREMENT]Qc/[INCREMENT]VO2. RESULTS: Peak VO2 and peak Qc was lower in HFpEF group than the other groups (peak VO2: HFpEF: 13.1±3.6; vs. Sedentary: 23.5±4.4; vs. Athlete: 39.5±5.3 ml/kg/min, P<0.001 (ANOVA) as was peak Qc: HFpEF: 12.7±4.1; vs. Sedentary: 14.8±4.1; vs. Athlete: 19.0±6.0 L/min, P<0.001 (ANOVA)). Peak AV-O2 diff in HFpEF group was the smallest in the 3 groups (HFpEF: 9.7±2.3; vs. Sedentary: 12.2±3.0; vs. Athlete: 14.3±3.6 %, P<0.0001 (ANOVA)), and the Athlete group was greater than the Sedentary group (P=0.04 (Wilcoxon rank-sum)). The relationship between Qc and VO2 (slope of [INCREMENT]Qc/[INCREMENT]VO2) is shown in Figure. CONCLUSIONS: Both reduced Qc and AV-O2 diff contribute significantly to the impairment of exercise capacity in HFpEF through Qc is augmented for a given VO2. Lifelong exercise training enhances Qc and peak AV-O2 diff in the elderly population and normalizes Qc/VO2 relationship.Figure