Persistent hyperlactaemia is related to high rates of in-hospital adverse events and poor outcome in acute heart failure.

Background: Although lactate is a well-established marker in intensive care, our understanding of its utility in acute heart failure (AHF) is modest and based on studies with a single measurement of this marker. Aim: We aimed to investigate whether persistent elevation of lactate during hospitalisation is related to a higher risk of adverse events. Methods: We conducted a prospective study to assess AHF patients hospitalised in one cardiac centre. The diagnosis of persistent hyperlactataemia was based on two measurements of the marker (on admission and at 24 h of hospitalisation) and it was defined as lactate elevation (>= 2 mmol/L) at both time points. Results: The population consisted of 222 patients at a mean age of 70 +/- 13 years. Mean ejection fraction and creatinine level on admission were 37% +/- 16% and 1.36 +/- 0.51 mg/dL, respectively. The percentage of patients with elevated lactates on admission, at 24 h of hospitalisation, and persistent hyperlactataemia were 47%, 35%, and 24%, respectively. The group with persistent hyperlactataemia did not differ in most clinical and laboratory variables from the rest of the population. Patients with persistent hyperlactataemia had higher rate of adverse events during hospitalisation: worsening of heart failure (22.6% vs. 6.5%, p < 0.05), inotrope use (22.6% vs. 5.3%, p < 0.05), and increase of N-terminal pro-B-type natriuretic peptide at 48 h of hospitalisation (30% vs. 18%, p < 0.05). Persistent hyperlactataemia was an independent predictor of one-year mortality (hazard ratio 2.5, 95% confidence interval 1.5-4.3, p < 0.001). Conclusions: Persistent hyperlactataemia within the first 24 h of hospitalisation is a predictor of a worse outcome in AHF and is related to higher rates of in-hospital adverse events and one-year mortality.