Abstract Body (Do not enter title and authors here): Background
Cardiogenic shock (CS) complicating acute myocardial infarction (AMI) is associated with high mortality. Transient myocardial stunning seen after out-of-hospital cardiac arrest (OHCA) often presents similar clinical characteristics as CS upon hospital arrival. OHCA involves a sudden cessation of circulation followed by a low-flow period during resuscitation, while CS involves prolonged myocardial dysfunction leading to hypoperfusion. The Society for Cardiovascular Angiography and Interventions (SCAI) proposed five distinct shock stages, further refined by the Cardiogenic Shock Working Group (CSWG). OHCA typically places patients in SCAI stage E, but this study abandoned that automatic classification.

Methods
This post hoc analysis of the BOX trial data involved comatose OHCA patients with a presumed cardiac cause. Patients were classified using the CSWG-SCAI shock classification upon hospital admission without automatically assigning OHCA patients to stage E. Invasive arterial and pulmonary arterial measurements were taken within the first 72 hours of ICU admission. Cardiac Index (CI), cardiac power output (CPO), and perfusion pressure (mean arterial pressure minus central venous pressure) were calculated.

Results
The results demonstrated that 31.6% of the 789 included patients were classified as SCAI class B/C, 29.9% as SCAI class D, and 38.5% as SCAI class E. One-year mortality for SCAI classes was as follows: B/C (21.3%), D (34.3%), and E (48.4%), with a p-value of <0.001 (Figure 1). There was no difference in CI and CPO within the first 72 hours of the ICU stay between SCAI classes. The first recorded perfusion pressure differed between SCAI class B/C and E (63.4±14.3 mmHg vs. 60±14.1 mmHg and 60.9±14.2 mmHg, respectively, p=0.008). This difference was only found at the first measurement. As lactate levels are a variable of SCAI classification, it was anticipated that there would be a significant difference in lactate at arrival. This difference in lactate remained at 36 hours after admission (1.3±0.7 mmol/L vs. 1.6±0.8 mmol/L and 1.9±1.1 mmol/L, respectively, p<0.001), but not thereafter. A higher proportion of patients developed acute kidney injury (AKI) as the SCAI classification increased (20%, 31% and 48%, respectively, p<0.001).

Conclusion
One-year mortality increased with increasing SCAI classes but hemodynamic parameters within the first 72 hours of treatment did not differ between groups.