Clinical, respiratory, haemodynamic and metabolic determinants of lactate in heart failure.

BACKGROUND: Lactate is an end-product of anaerobic cell metabolism. Although lactate is believed to have prognostic significance in heart failure (HF), the data on the pathomechanisms that lead to lactate accumulation is scarce.

AIM: We aim to determine the clinical, respiratory, biochemical and haemodynamic correlates of lactate in HF.

METHODS: Patients hospitalised at one cardiac centre with a diagnosis of HF, who underwent haemodynamic monitoring, were included in the analysis.

RESULTS: The population consisted of 93 patients (44 acute HF (AHF) and 49 chronic HF (CHF)). The mean age, ejection fraction and lactate were: 60±13 (years), 33±17 (%), 1.4±0.9 (mmo/L), respectively. The mean CI (cardiac index), RAP (right atrial pressure) and PCWP ( pulmonary capillary wedge pressure) were: 2.2±0.5 (l/min/m2), 8.7±6 (mmHg) and 18±6 (mmHg), respectively. AHF patients had significantly higher: RAP, heart rate, NTproBNP and creatinine compared to the CHF group. Both heart rate (HR) and natriuretic peptide were correlated with lactate. Among haemodynamic indices, lactate correlated with CI (r = -0.25, p = 0.01). We found no correlation between lactate and RAP or PCWP (both p >0.05). There was no relationship between lactate and peripheral blood gases. Lactate was strongly correlated with mixed venousoxygen saturation (svO2) (r=-0.61, p <0.05). HR, svO2 and systemic vascular resistance (SVR) were found to be independent determinants of lactate.

CONCLUSIONS: Lactate accumulation in HF is not a result of respiratory disturbances or hypoxaemia. Among haemodynamic indices, cardiac index is correlated with lactate. The strongest determinants of lactate included svO2, SVR and HR.