LAUSR

Serum lactate is a marker for the presence and severity of imbalances between tissue oxygen supply and demand. There are only scare data regarding the significance of arterial lactate in PE patients. We sought to explore the significance of venous serum lactate as a short- and long-term predictor of adverse outcomes. We prospectively enrolled 570 patients with topographically-confirmed pulmonary embolism, hospitalized in our center during 2016–2019. Patient's data was collected using an electronic medical record and follow-up interviews via telephone. The combined end point of hemodynamic instability, shock, mechanical ventilation, or need for CPR was prospectively documented during hospitalization as well as 1-year mortality. The analysis included 461 consecutive patients with available clinical data including venous lactate. The median age was 69 years, and 262 (58%) were female. Median serum lactate levels were 21 mg/dL (IQR 16–31). The composite endpoint was documented in 92 patients (20%), and lactate levels above 21 mg/dl had a higher incidence of the composite end point (26% vs, 14%, p=0.002). Similar findings were seen when adding either the need for escalating therapy (44% vs. 24%, p<0.001), in-hospital mortality (31% vs. 16%, p=0.001) or 30-day mortality (27% vs. 21%, p<0.001) to the previous composite. One-year mortality was significantly higher in the higher lactate group (17% vs 5%, p<0.001), and a lactate level above 21 mg/dL was independently associated with 1-year mortality in a Cox-regression model adjusted for age, gender and a history of heart failure or malignancy, HR 2.5 (95% CI 1.7–3.9). In subgroup analyses, lactate levels were associated with 1-year mortality regardless of age or gender. Similar predictive trends for 1-year mortality were seen in patients stratified by diabetes status, a current malignancy, PE risk and right-ventricle abnormalities (see figure). Venous serum lactate levels are associated with a myriad of in-hospital adverse outcomes, as well as long-term mortality. In a 1-year follow-up, a higher lactate level was predictive of mortality across various subgroups, with higher hazard ratios seen specifically in lower-risk patients. Further studies are needed in order to evaluate the possible prognostic role of the change in serum lactate during PE management. Elevated lactate and 1-year mortality Type of funding source: None