Lactate-to-albumin ratio and 28-day mortality in acute myocardial infarction with cardiogenic shock

Background Acute myocardial infarction complicated by cardiogenic shock (AMI-CS) remains associated with high short-term mortality. The lactate-to-albumin ratio (LAR), reflecting tissue hypoperfusion and systemic inflammation, has been associated with adverse outcomes in critically ill populations, but its prognostic relevance in AMI-CS warrants further evaluation. Methods In this retrospective dual-cohort study, patients with AMI-CS were identified from the MIMIC-IV database and an independent coronary care unit cohort. The primary outcome was 28-day all-cause mortality. Cox regression models were used to assess the association between LAR and mortality. Non-linear relationships were explored using restricted cubic splines. The incremental value of LAR beyond conventional risk assessment was also evaluated. The prespecified multivariable model incorporating LAR was externally evaluated in an independent cohort. Results A total of 778 patients from MIMIC-IV and 201 patients from the external cohort were included. Higher LAR was independently associated with increased 28-day mortality (HR per 1-SD: 1.39, 95% CI 1.27–1.52, P < 0.001). A significant non-linear relationship was observed across the range of LAR values. Addition of LAR to the SOFA score provided modest incremental prognostic information, although reclassification effects were not consistent between events and non-events. The prespecified multivariable model incorporating LAR achieved an AUC of 0.713 in the external cohort. Conclusions LAR was independently associated with 28-day all-cause mortality in patients with AMI-CS and showed a significant non-linear relationship with mortality. LAR provided modest additional prognostic information beyond conventional risk assessment, although reclassification effects were not consistent across events and non-events. LAR may serve as a complementary marker for early prognostic assessment, although its clinical utility and generalizability require further evaluation.