Circulating neuregulin1‐β in heart failure with preserved and reduced left ventricular ejection fraction

AIMS: Neuregulin1‐β (NRG1‐β) is released from microvascular endothelial cells in response to inflammation with compensatory cardioprotective effects. Circulating NRG1‐β is elevated in heart failure (HF) with reduced ejection fraction (HFrEF) but not studied in HF with preserved EF (HFpEF). METHODS AND RESULTS: Circulating NRG1‐β was quantified in 86 stable patients with HFpEF (EF ≥45% and N‐terminal pro‐brain natriuretic peptide >300 ng/L), in 86 patients with HFrEF prior to and after left ventricular assist device (LVAD) and/or heart transplantation (HTx) and in 21 healthy controls. Association between NRG1‐β and the composite outcome of all‐cause mortality/HF hospitalization in HFpEF and all‐cause mortality/HTx/LVAD implantation in HFrEF with and without ischaemia assessed as macrovascular coronary artery disease was assessed. In HFpEF, median (25th–75th percentile) NRG1‐β was 6.5 (2.1–11.3) ng/mL; in HFrEF, 3.6 (2.1–7.6) ng/mL (P = 0.035); after LVAD, 1.7 (0.9–3.6) ng/mL; after HTx 2.1 (1.4–3.6) ng/mL (overall P < 0.001); and in controls, 29.0 (23.1–34.3) ng/mL (P = 0.001). In HFrEF, higher NRG1‐β was associated with worse outcomes (hazard ratio per log increase 1.45, 95% confidence interval 1.04–2.03, P = 0.029), regardless of ischaemia. In HFpEF, the association of NRG1‐β with outcomes was modified by ischaemia (log‐rank P = 0.020; P (interaction) = 0.553) such that only in ischaemic patients, higher NRG1‐β was related to worse outcomes. In contrast, in patients without ischaemia, higher NRG1‐β trended towards better outcomes (hazard ratio 0.71, 95% confidence interval 0.48–1.05, P = 0.085). CONCLUSIONS: Neuregulin1‐β was reduced in HFpEF and further reduced in HFrEF. The opposing relationships of NRG1‐β with outcomes in non‐ischaemic HFpEF compared with HFrEF and ischaemic HFpEF may indicate compensatory increases of cardioprotective NRG1‐β from microvascular endothelial dysfunction in the former (non‐ischaemic HFpEF), but this compensatory mechanism is overwhelmed by the presence of ischaemia in the latter (HFrEF and ischaemic HFpEF).