Blood lactate shows weak and discordant associations with congestion indices but not with pulmonary congestion or adverse outcomes in acute heart failure

Introduction: Hyperlactatemia is commonly encountered in acute heart failure, but its mechanisms remain unclear. We aimed to explore the association between admission lactate and markers of congestion and adverse outcomes Methods: We retrospectively screened patients with acute heart failure who were admitted to the Internal Cardiology department and the Interventional Cardiology department at a teaching hospital. We assessed congestion indices: composite congestion score (CCS), estimated plasma volume status (ePVS), congestion score index (CSI) and NT-proBNP. Composite adverse outcomes were defined as treatment escalation or death. Results: We enrolled 225 patients with median age of 73 (65–83) years with ejection fraction of 39.0 (30.7–54.7) %. Median admission lactate was 1.8 (1.3–2.5) mmol/L with 87 patients had lactate concentration ≥2 mmol/L (38.7%). At admission, median values of congestion markers were CCS 6 (5–8) points, ePVS 5.5 (4.4–6.6), CSI 2 (1.3–3) points and NT-proBNP 7449 (3568–14447) pg/ml. Adverse outcomes occurred in 22 patients (9.8%). There was a weak correlation between lactate and CCS (r = 0.15, p = 0.022), ePVS (r = -0.26, p < 0.001) but not with CSI (r = -0.06, p = 0.340) and NT-proBNP (r = 0.1, p = 0.150). In multivariable analysis, CCS (OR=1.35, 95% CI: 1.04 – 1.79), log-transformed NT-proBNP (OR=2.30; 95% CI: 1.28 – 4.42) were independently associated with adverse outcomes but not admission lactate (OR=1.13, 95% CI: 0.91 – 1.30). Conclusion: In acute heart failure, blood lactate showed weak and discordant associations with different systemic congestion indices but was not associated with pulmonary congestion or adverse outcomes.