Time-weighted lactate as a predictor of adverse outcome in acute heart failure

The role of dynamic changes in lactate concentrations on prognosis in acute heart failure has been poorly investigated. The aim of this study was to explore the predictive value of 24 h time-weighted lactate (LAC_TW ) in patients with acute heart failure.

Ninety-six consecutive acute heart failure patients presenting to the Emergency Department of San Paolo Hospital, Naples, Italy, were prospectively enrolled. Arterial blood lactate was measured at admission and during the following 24 h at random time intervals. LAC_TW was obtained by the sum of the average lactate values among consecutive time points multiplied by the intervals between consecutive time points and dividing the sum by the total time (24 h). The outcome was a composite of need of admission to the intensive care unit, hospitalization duration >7 days, or intra-hospital death. Admission lactate, maximum measured lactate, and LAC_TW were collected. Univariate and multivariate Cox regression analysis was applied to determine the hazard ratio (HR) of developing the outcome. Forty-three patients experienced the pre-specified outcome. In sex-adjusted and age-adjusted multivariable analysis, LAC_TW predicted the outcome occurrence (HR: 1.51, 95% confidence interval: 1.24, 1.84, P < 0.001). Risk stratification analysis based on LAC_TW tertiles demonstrated a gradual increase in risk of developing the outcome (HR: 17.32, 95% confidence interval: 2.30, 130.23, P = 0.006) for the highest LAC_TW tertile.

In acute heart failure patients, 24 h LAC_TW had a significant independent predictive value for adverse intra-hospital outcome. LAC_TW could be a useful index at identifying high-risk patients who may require a more aggressive treatment during hospitalization.