Abstract Body (Do not enter title and authors here): Background
The pulmonary artery catheter (PAC) is used for hemodynamic monitoring, but its impact on patient outcomes, especially in cardiogenic shock (CS), is controversial. Several studies have shown no significant benefits and noted complications, leading to a decline in PAC use. However, PAC use appears to have increased recently in guiding management decisions in CS. Our study aims to assess the clinical characteristics and outcomes of CS patients receiving PACs versus not.

Methods
We included patients with CS admitted to a tertiary academic medical center between May 2015 and December 2023. Variables were compared using Kruskal-Wallis, chi-squared, and Fisher's exact tests. Hemodynamic parameters were collected from either right heart catheterization or from a PAC. Endpoints included native heart survival to discharge, durable left ventricular assist device (LVAD) implantation, heart transplant (HTx), and 30-day and 1-year survival from discharge.

Results
The study group consisted of 742 patients with CS. Of these, 385 (52%) received a PAC and 357 (48%) did not. The baseline characteristics of the two groups are shown in Table 1A . PAC patients had more severe shock, worse hemodynamics, and higher rates of temporary mechanical circulatory support (MCS) use. Hemodynamic measurements at shock onset differed, with PAC patients having higher right atrial pressures and lower cardiac index by Fick. Clinical outcomes and MCS related complications are shown in Table 1B. There was no significant difference in native heart survival at discharge, but HTx and durable LVAD implantation was higher in the PAC group. PAC placement was associated with longer hospital stays and more MCS related complications, including bleeding and hemolysis. The 30-day survival rate was similar between groups, and 1-year survival was marginally higher in the PAC group.

Conclusion
PAC patients exhibited more severe clinical characteristics, longer hospital stays, higher rates of temporary MCS use and complications, durable LVAD implantation, and HTx. Short-term survival rates were similar, but 1-year survival was slightly better for PAC patients. Further studies are needed to provide clearer insights into PAC use in CS.