Lactate clearance as a prognostic marker in cardiogenic shock: a retrospective study from a tertiary cardiac intensive care unit

Abstract Background Cardiogenic shock (CS) carries a persistently high in-hospital mortality exceeding 40–50%. Accurate and dynamic markers of perfusion are essential for early risk stratification and treatment optimization. Recent recommendations support lactate clearance (LC) as a key marker of shock trajectory, being an easily accessible bedside marker to guide management decisions, including mechanical support (MCS). Methods Retrospective observational study in the cardiac intensive care unit (CICU) of a tertiary centre, including consecutive adults admitted with CS between 2017 and 2024. Patients without lactate measurements at admission, 6h, and 24h were excluded. Demographic, clinical data, SCAI stage, and aetiology of CS (acute myocardial infarction–related (AMI-CS), heart failure-related (HF-CS), or secondary-CS) were collected. Outcomes included mortality at 30 days and 1 year. LC was calculated as the relative percentage change in lactate from baseline to each time point. A significant LC was defined as a reduction 10%, and lactate normalization as lactate 2 mmol/L at 24h. Results A total of 251 patients were included (mean age 68.5±16 years; 66% male). Most presented with AMI-CS (54%), and initial SCAI stages C and D accounted for 86% of admissions. Median CICU stay was 6 3–13 days. MCS was required in 34%. At admission, median lactate was 3.4 2.1–5.4 mmol/L, decreasing to 2.2 1.4–3.8 mmol/L at 6h, and 1.6 1.1–2.5 mmol/L at 24h. LC 10% at 6h was observed in 65% of patients, while 64% achieved lactate 2 mmol/L by 24h (Figure 1). Early LC 10% at 6h was associated with a trend toward lower 30-day mortality (42% vs. 53%, p = 0.06) and more frequent lactate normalization at 24h (69% vs. 58%, p = 0.07). LC normalization at 24h was strongly associated with reduced CICU mortality (26% vs. 62%, p0.001). Kaplan–Meier survival analysis demonstrated that both 6h and 24h LC predicted 30-day and 1-year survival, with 24h clearance showing the highest discrimination (Figure 2). In patients with MCS, baseline lactate was higher (3.7 2.2–6.2 vs. 3.2 1.9–5.1 mmol/L), as expected. At 6 hours, 20 out of 85 patients without a lactate clearance (LC) 10% were receiving MCS. Of these 20 patients under MCS, 50% achieved lactate normalization by 24 hours. In a subgroup analysis by aetiology, AMI-CS patients were more frequently treated with MCS compared to other forms (p 0.05). The association between LC at 6h and 24h and survival persisted across all etiologic subgroups. Conclusion In this real-world cohort of CS patients, LC within the first 24 hours was a robust prognostic marker of survival. Both early (6h) and 24h LC correlated with lower mortality, with 24h providing the strongest predictive value for short- and mid-term outcomes, independent of aetiology or MCS use. These findings reinforce the role of serial lactate monitoring as an accessible and powerful tool to assess trajectory and guide management in CS.Lactate Clearance Kaplan–Meier survival analysis