(532) Relationship Between Blood Volume Measures and Cardiopulmonary Exercise Testing Performance in Advanced Heart Failure

PurposeDirect measurement of blood volume provides better assessment and guides management of congestion in patients with heart failure (HF). The impact of congestion using surrogate measures from blood volume analysis (BVA) on cardiopulmonary responses to exercise in HF is unknown.MethodsThis is a prospective two-center study enrolling consecutive patients with advanced HF who underwent cardiopulmonary exercise test (CPET) with invasive hemodynamic assessment and BVA. Total blood volume (TBV), red blood cell volume (RBCV) and plasma volume (PV) were measured using indicator dilution technique with an I131-tagged albumin tracer. The BVA reports absolute values and %-deviation from ideal values. Absolute values were indexed to 70 kg of weight. The association between BVA measures and CPET parameters was assessed using Pearson correlation.ResultsTotal of 40 patients (mean age 54.7 years, 30% female, 53% African American, 33% HFrEF) were included. Mean TBV, RBCV and PV were 4263 ± 807, 1586 ± 443 and 2676 ± 536 ml/70 kg respectively. Mean peak oxygen consumption (VO2) was 11.7 ± 3.5 mL/kg/min with % predicted maximal VO2 52.0 ± 16.7 %. The minute ventilation/carbon dioxide production (VE/VCO2) slope was 35.0 ± 9.8. Respiratory exchange ratio (RER) was 1.03 ± 0.16. There was a moderate correlation between RBCV and peak VO2 (r=0.340, p=0.03). We observed a moderate correlation between VE/VCO2 and TBV (r=0.333, p=0.04), PV (r=0.355, p=0.02) and PV %deviation (r=0.323, p=0.04). There was no correlation between BVA measures and % predicted VO2 or RER.ConclusionHigher degree of volume congestion assessed by TBV and PV is associated with worse VE/VCO2 slope but not other CPET parameters in patients with advanced HF. The impact of volume congestion on other HF-related clinical outcomes warrants further investigation. Direct measurement of blood volume provides better assessment and guides management of congestion in patients with heart failure (HF). The impact of congestion using surrogate measures from blood volume analysis (BVA) on cardiopulmonary responses to exercise in HF is unknown. This is a prospective two-center study enrolling consecutive patients with advanced HF who underwent cardiopulmonary exercise test (CPET) with invasive hemodynamic assessment and BVA. Total blood volume (TBV), red blood cell volume (RBCV) and plasma volume (PV) were measured using indicator dilution technique with an I131-tagged albumin tracer. The BVA reports absolute values and %-deviation from ideal values. Absolute values were indexed to 70 kg of weight. The association between BVA measures and CPET parameters was assessed using Pearson correlation. Total of 40 patients (mean age 54.7 years, 30% female, 53% African American, 33% HFrEF) were included. Mean TBV, RBCV and PV were 4263 ± 807, 1586 ± 443 and 2676 ± 536 ml/70 kg respectively. Mean peak oxygen consumption (VO2) was 11.7 ± 3.5 mL/kg/min with % predicted maximal VO2 52.0 ± 16.7 %. The minute ventilation/carbon dioxide production (VE/VCO2) slope was 35.0 ± 9.8. Respiratory exchange ratio (RER) was 1.03 ± 0.16. There was a moderate correlation between RBCV and peak VO2 (r=0.340, p=0.03). We observed a moderate correlation between VE/VCO2 and TBV (r=0.333, p=0.04), PV (r=0.355, p=0.02) and PV %deviation (r=0.323, p=0.04). There was no correlation between BVA measures and % predicted VO2 or RER. Higher degree of volume congestion assessed by TBV and PV is associated with worse VE/VCO2 slope but not other CPET parameters in patients with advanced HF. The impact of volume congestion on other HF-related clinical outcomes warrants further investigation.