Abstract Body (Do not enter title and authors here): Background
The optimal anticoagulation strategy in patients with cardiogenic shock (CS) undergoing mechanical circulatory support (MCS) with Impella remains an area of ongoing debate. While bivalirudin has demonstrated favorable outcomes in percutaneous coronary interventions, its comparative effectiveness against unfractionated heparin in the setting of Impella-supported Cardiogenic shock is poorly defined.

Methods
We conducted a retrospective cohort study using the TriNetX research network, including adults with cardiogenic shock supported by Impella (2016–2023). Patients were stratified by anticoagulant use (bivalirudin vs. heparin) and matched 1:1 using propensity scores based on >50 clinical and treatment variables. The primary outcome was all-cause mortality; secondary outcomes included renal replacement therapy, mechanical ventilation, major bleeding, thromboembolic events, stroke/TIA, and ECMO use. A pre-specified subgroup analysis was conducted in acute myocardial infarction (AMI) patients.

Results
Following propensity matching (n=1,124 per group), there was no significant difference in all-cause mortality between bivalirudin and heparin (46.9% vs. 46.7%; HR 0.97; p=0.675). Bivalirudin was associated with a significantly lower rate of hemodialysis (8.5% vs. 16.1%; HR 0.50; p<0.001), but a higher incidence of mechanical ventilation (26.2% vs. 16.4%; HR 1.62; p<0.001). Rates of major bleeding, thromboembolic events, and ECMO use were comparable. Findings were consistent in the AMI subgroup (n=671 per arm), with reduced hemodialysis and increased mechanical ventilation in the bivalirudin group, without mortality difference.

Conclusion
In Impella-supported cardiogenic shock, bivalirudin was associated with less renal replacement therapy, possibly due to lower thrombotic burden, while heparin was linked to lower mechanical ventilation rates, perhaps reflecting milder illness severity. Despite these differences, survival was similar between groups. These findings highlight the need for randomized trials to clarify optimal anticoagulant strategies.