A new study of patients receiving care for acute heart failure at the Rambam Health Care Campus in Haifa, Israel, investigated how their clinical outcomes might be affected by high lactate levels and primary acid-base disorders.
A new survey of clinical outcomes in patients with a primary diagnosis and hospitalization for acute heart failure (AHF) – whether new onset or worsening of HF – notes that it There are higher mortality risks in the presence of hyperlactatemia and certain disturbances of blood acidity. base balance, especially respiratory acidosis.
All patients (N=4012 with normal blood pressure [≥90 mm Hg]; arterial blood gases measured at hospital admission) received care in the Cardiology Department of the Rambam Healthcare Campus in Haifa, Israel, between January 2005 and December 2016, the primary outcome of the study being hospital mortality. Secondary endpoints were in-hospital mortality or the need for inotropic/vasopressor therapy (eg, dopamine, dobutamine, epinephrine, milrinone, norepinephrine, neosynephrine, or vasopressin).
The findings of the study appeared last month in European Heart Journal: acute cardiovascular care.
“In AHF, several mechanisms can affect lactate production or clearance. Severe HF is considered one of the most common causes of lactic acidosis,” the study authors wrote. “However , few data are available on the clinical significance of elevated lactate levels and acid-base abnormalities in AHF.”
Thirty-eight percent of the overall patient cohort (mean [SD] age, 75  years) had hyperlactatemia, a condition characterized by a mild/moderate increase in blood lactate levels in the absence of metabolic acidosis, which itself had a strong positive correlation with hyperglycemia. Additionally, patients classified as having acidosis had the highest prevalence of hyperlactatemia (43.7%), followed by patients with alkalosis (42.0%) or normal blood pH (31.0%).
For their study, the authors used these definitions:
- Elevated blood lactate: ≥ 2 mmol/L
- Acidosis: pH
- Alkalosis: pH > 7.44
- Hypoxemia: PaO2
- Hypercapnia: PaCO2 > 44 mm of mercury
- Low bicarbonate content: HCO3
They also used multivariate logistic regression to determine the relationships between lactate levels and acid-base status with in-hospital mortality, and from this they show a 49% higher risk of in-hospital mortality among 16, 4% and 11.1% of their cohort who had and did not have hyperlactatemia (odds ratio adjusted [aOR], 1.49; 95% CI, 1.22-1.82; P
Moreover, the risk of hospitalization is even higher in the presence of acidosis and alkalosis, respectively, compared to normal blood pH: 148% (aOR, 2.48; 95% CI, 1.95- 3.16; P P
When comparing the risk of in-hospital death for people with normal lactate versus acidosis or alkalosis, the numbers still showed high, but lower risks: 18.1% and 10.4%, respectively.
Overall, the authors determined that patients with lactate measurements compared to those without such a measurement on file were considered to be at high risk due to their generally older age (P P P
Additionally, the group with lactate data on file had an in-hospital mortality rate that was nearly 5 times higher than patients without these measures (P
“Increased Lactate Levels [are] primarily due to increased production or decreased elimination of lactic acid,” the authors wrote. “In HF, the prevailing paradigm suggests that increased lactate concentrations indicate conditions of anaerobic glycolysis at the cellular level and a marker of end-organ hypoperfusion and/or hypoxia.”
However, accelerated aerobic glycolysis can also lead to hyperlactatemia independent of tissue oxygen availability, they added, and they believe their findings support the hypothesis that hyperlactatemia could be a sign of increased metabolic rate. and sympathetic activation.
“Abnormal lactate levels appear to be generated by impaired oxygen transport and tissue ischemia in a subset of cases, whereas in others elevated lactate more likely results from other mechanisms, including sympathetic stimulation,” the authors concluded. “Lactate is a marker of disease severity and is independently associated with in-hospital mortality in AHF.”
Bar O, Aronson D. Hyperlactatemia and acid-base disturbances in normotensive patients with acute heart failure. Eur Heart J Acute cardiovascular care. Published online February 16, 2022. doi:10.1093/ehjacc/zuac005