Correlation Between Pressure And Volume In Ambulatory Heart Failure: Sex-specific Analysis

Introduction Discordance of pressure and volume in heart failure (HF) has been recognized and poses a challenge to the management of congestion in HF. Differences in cardiac structure and physiology exist between women and men with HF. Sex differences in the pressure-volume relationship in HF have not been described. Methods This was a prospective two-center study enrolling consecutive patients with chronic ambulatory HF undergoing initial implantation of an implantable pulmonary artery pressure monitor (CardioMEMS). All patients underwent blood volume analysis (BVA) using the indicator dilution technique with an I131-tagged albumin tracer. The BVA report provides absolute values and percent deviation from ideal values. Estimated stressed blood volume (eSBV) were presented as mL/70 kg body weight to account for differences in patient sizes. Baseline characteristics and hemodynamics were compared between sexes. Linear regression was performed to assess correlation between volume and pressure measures based on sex. Results A total of 20 (13 male and 7 female) patients were included. There were no differences in age (62.7 ± 13.9 vs. 58.6 ± 12.5 years), black race (46% vs. 14%), BMI (30.1 ± 4.3 vs. 30.5 ± 5.9 kg/m2), LVEF (31.9 ± 12.5 vs. 38.4 ± 18.2%) between men and women, respectively. Men had higher absolute total blood volume (TBV) (6137 ± 1234 vs. 4213 ± 949 mL, p=0.002) and a trend toward higher TBV percent deviation (5.5 ± 17.5 vs. -8.9 ± 14.2%, p=0.08). There was no difference in eSBV between men and women (2024 ± 506 vs. 2201 ± 460 mL). There was lack of correlation between diastolic pulmonary artery pressure (PADP) and TBV both in men (R2=0.005, p=0.81) and women (R2=0.024, p=0.74) (Figure). There was a strong correlation between PADP and eSBV in men (R2=0.51, p=0.006) but not in women (R2=0.029, p=0.72). Conclusions Despite similar baseline characteristics, men had higher absolute TBV and greater TBV percent deviation compared to women with similar eSBV. Discordance between pressure and volume measures was observed in both men and women, except for eSBV and PADP in men. Further studies to identify clinical implications of pressure-volume phenotypes are warranted.