Estimated plasma volume in heart failure with reduced ejection fraction: ACE inhibitors versus angiotensin receptor/neprilysin inhibitor in follow up

Abstract Background Estimated plasma volume status (ePVs) has been considered a biological surrogate for congestion and has been shown to be associated with post-discharge outcomes in patients with heart failure with reduced ejection fraction (HFrEF). The plasma volume status can be easily estimated by the index of the PVs according to the haemoglobin and haematocrit levels. Purpose The aim of the study was to examine the change in ePVs and N-terminal pro B-type natriuretic peptide (NT-proBNP) levels during the 12-month follow up of HFrEF patients treated with ACE inhibitors (ACEi) and angiotensin receptor/neprilysin inhibitor (ARNI). Methods We included all patients treated or diagnosed with HFrEF in our hospital from May 2021 to February 2022 and prescribed with either ACEi or ARNI among complete guideline-directed medical therapy (GDMT). We used Strauss-derived Duarte formula [ePVs= (100-Hct%) ÷ Hb] to estimate PVs during the initiation of GDMT and after 12-month follow up. Results This registry-based study included 619 patients with HFrEF, out of which 278 were prescribed with ACEi (ACEi group) and 273 with ARNI (ARNI group). There were no differences between the groups regarding age (ACEi 68 vs. ARNI 67 years, p=0.09), however, ACEi group had significantly more women (30% vs. 26% of patients, p=0.02). Patients in ACEi group were more likely to have ischemic cardiomyopathy (61 vs. 49%, p<0.01), higher estimated glomerular filtration rate (72 vs. 64 L/min/1.73m², p=0.01), while patients in ARNI group were more likely to be NYHA III class (40 vs. 48%, p=0.04). Initial ePVs (4.23 for ACEi vs. 4.20 for ARNI, p=0.46), NT-proBNP levels (3357.5 for ACEi vs. 2786 for ARNI, p=0.08), and left ventricular ejection fraction (median 35% for ACEi vs. 35% for ARNI, p=0.49) did not significantly differ between the groups. After the 12-month follow up, the change in ePVs was similar between the groups (-0.22 for ACEi vs. -0.19 for ARNI, p=0.93). Reduction of NT-proBNP levels was more prominent in ACEi group (1750.5 vs. 858.5 pg/mL, p=0.01). Mortality rate did not differ between the groups during 12-month follow up (9.71% in ACEi vs. 8.42% in ARNI, p=0.60). Conclusion In HFrEF patients both ACEi and ARNI reduced ePV and NTproBNP levels during 12-month follow up. ACEi were more potent in reducing NT-proBNP levels. Despite the more prominent reduction in NT-proBNP levels, no significant difference was observed in mortality rate during follow up between the groups.