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

Background Cardiogenic shock (CS) carries a high in-hospital mortality exceeding 40–50%. Accurate and rapidly responding markers of perfusion are essential for early risk stratification and treatment optimization. Recent SCAI recommendations evidence supports lactate clearance (LC) as a key marker of shock trajectory, being an easily accessible bedside marker to guide management decisions, including mechanical circulatory support (MCS). Methods Retrospective observational study including consecutive CS patients admitted to the CICU between 2017 and 2024. Demographic, clinical, and laboratory data, SCAI stage, and aetiology of CS were collected. Lactate measurements at admission, 6h, and 24h were obtained, and patients with any missing values were excluded. A significant LC was defined as a reduction >10%, and lactate normalization as lactate <2 mmol/L at 24h. Outcomes included mortality at 30 days and 1 year. Survival analysis was conducted using Kaplan–Meier estimates, with group comparisons performed by the log-rank test. Results A total of 251 patients were analysed (mean age 69±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. Mortality reached 41% in the CICU, 45% during the index hospitalization, and 53% at one year. In Cox regression analysis, only lactate normalization at 24 hours independently predicted both CICU mortality (HR 0.245, 95% CI 0.165–0.365; p < 0.001) and in-hospital mortality (HR 0.277, 95% CI 0.190–0.402; p < 0.001). Kaplan–Meier survival analysis demonstrated that both LC > 10% at 6h and lactate normalization at 24h predicted 30-day and 1-year survival, with 24h normalization demonstrating the greatest separation of survival curves. In patients supported with MCS, baseline lactate levels were higher (3.7 [2.2–6.2] vs. 3.2 [1.9–5.1] mmol/L), as expected. At 6h, 20 out of 85 patients without a LC >10% were receiving MCS. Of these, 50% achieved lactate normalization by 24h. In subgroup analysis by aetiology, the association between LC at 6h and 24h and survival persisted across all etiologic subgroups. Conclusion In this contemporary cohort of cardiogenic shock patients, early lactate clearance demonstrates a strong association with improved survival. Specifically, lactate normalization at 24 hours is highly discriminatory and independently associated with significantly reduced in-hospital and 1-year mortality across all aetiologies. These findings underscore the utility of dynamic lactate monitoring as a crucial bedside marker for risk stratification and real-time assessment of therapeutic efficacy in the management of cardiogenic shock.