Microcirculatory dysfunction at first medical contact predicts shock severity and clinical outcomes in cardiogenic shock

Background Cardiogenic shock (CS) remains associated with high morbidity and mortality. Early risk stratification at first medical contact (FMC) in the emergency department (ED) is critical for the timely management of CS. The Society for Cardiovascular Angiography and Interventions (SCAI) staging system improves risk stratification but does not directly reflect microcirculatory dysfunction, a key determinant of tissue perfusion and organ failure, which may occur despite apparently preserved macrocirculation. Sublingual microcirculation imaging enables real-time bedside visualization of microvascular perfusion. Whether microcirculatory parameters correlate with SCAI stage and predict adverse outcomes in emergency CS patients remains unclear. Purpose To investigate whether sublingual microcirculatory parameters assessed in the emergency department are associated with SCAI shock stage and predict adverse clinical outcomes in CS. Methods This retrospective single-center study included consecutive CS patients who underwent sublingual microcirculation assessment in the ED at FMC. Microcirculatory parameters included Microvascular Flow Index (MFI), Heterogeneity Index (HI), Proportion of Perfused Vessels (PPV), Perfused Vessel Density (PVD), Red Blood Cell velocity (RBCv), and Perfused Boundary Region (PBR). Their associations with SCAI stage and composite adverse outcome were evaluated using Spearman correlation and logistic regression. The composite outcome included SCAI stage deterioration, in-hospital mortality, mechanical circulatory support escalation, left ventricular assist device implantation, or heart transplantation. Results From May 1st, 2025, to January 30th, 2026, a total of 94 patients were included (age 59±17 years; 67.0% male; median Left Ventricular Ejection Fraction 27.5% [21.75%–35.25%]). SCAI distribution was A (25.5%), B (10.6%), C (58.5%), D (4.2%), and E (1.0%). Higher SCAI stages were associated with impaired microvascular flow, including lower MFI and RBC velocity, and increased flow heterogeneity. In univariate analysis, MFI, HI, and RBCv were associated with higher SCAI stages. In multivariate analysis, MFI remained independently associated with advanced SCAI stage (OR 0.312, 95% CI 0.134–0.729, p=0.007). Microcirculatory impairment was also associated with adverse clinical outcomes. Lower MFI (OR 0.435, 95% CI 0.210–0.902, p=0.025) and higher HI (OR 5.193, p=0.035) were associated with composite adverse events in univariate analysis. In multivariate analysis, MFI remained an independent predictor of adverse outcomes (OR 0.435, 95% CI 0.210–0.902, p=0.025). Conclusion Sublingual microcirculatory dysfunction is detectable at FMC in the ED and independently predicts CS severity and adverse clinical outcomes. Early microcirculatory assessment may provide incremental prognostic value beyond conventional staging, supporting improved risk stratification and early therapeutic decision-making in CS.