Early Lactate Trajectories and Outcomes in Veno-Arterial Extracorporeal Membrane Oxygenation-Supported Cardiogenic Shock: A Multicenter Study.

In this multicenter retrospective study (Chinese Society of Extracorporeal Life Support [CSECLS] registry), we evaluated early lactate trajectories in 1,465 adults with cardiogenic shock surviving greater than 24 hours on veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Unsupervised k-means clustering of serial lactates (baseline, 4 hours, 24 hours) defined four metabolic phenotypes. The "Persistent High" phenotype (5.7%) exhibited refractory hyperlactatemia (median 24 hour lactate 17.0 mmol/L) and the highest in-hospital mortality (85.7% vs. 27.9% in the "Low Stable" group; p < 0.001). Notably, this persistent hyperlactatemia occurred despite comparable ECMO flow indices (2.8 vs. 2.6 L/min/m2) and preserved venous oxygen saturation (72.2% ≥ 50%). The "Persistent High" trajectory independently predicted mortality (adjusted hazard ratio [HR]: 6.36, 95% confidence interval [CI]: 4.83-8.36) and severe organ failure, with findings reproduced in an external validation cohort (MIMIC-IV, n = 136). In conclusion, persistent hyperlactatemia during VA-ECMO may reflect impaired systemic oxygen utilization rather than insufficient macrocirculatory flow. Early trajectory-based phenotyping helps identify a refractory state of flow-metabolism decoupling, signaling a high-risk subgroup where conventional flow escalation alone may be insufficient.