Correlation Between decreased mixed venous oxygen saturation and increased B-type natriuretic peptides independent of hemodynamics in pre-heart failure/heart failure patients

Previous studies have shown that natriuretic peptides (NPs) respond to hypoxia. Mixed venous oxygen saturation (SvO₂) reflects the oxygen balance and may indicate pulmonary hypoxia. In this study, we investigated whether NPs are influenced by SvO₂ and whether this effect differs between A-type natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) in heart failure patients, using structural equation modeling (SEM). We examined 179 patients with pre-heart failure/heart failure who underwent Swan-Ganz catheterization, and investigated the relationship between NP levels and various clinical parameters, including SvO₂. The path model showed that pulmonary artery wedge pressure (PAWP) and administration of angiotensin receptor-neprilysin inhibitor (ARNI) were significantly positively associated with ANP (PAWP: standardized regression coefficient [St. β] =0.281, P = 0.002; ARNI administration: St. β=0.396, P < 0.001). PAWP and ischemic heart disease (IHD) were positively associated with BNP, whereas the estimated glomerular filtration rate (eGFR) and SvO₂ were negatively associated with BNP (PAWP: St. β =0.370, P < 0.001; IHD: St. β =0.241, P < 0.001; eGFR: St. β =-0.209, P = 0.003; SvO₂: St. β =-0.528, P < 0.001). ANP was not associated with arterial oxygen saturation (SaO₂) or SvO₂, whereas BNP showed a negative relationship with SvO₂ but was not associated with SaO₂. Thus, an increased BNP, but not ANP, correlates strongly with decreased SvO₂, an indicator of hypoxia before pulmonary circulation, independent of hemodynamic indices.