Abstract Body (Do not enter title and authors here): Background: Extracorporeal cardiopulmonary resuscitation (eCPR) is increasingly being used for cardiac arrest refractory to conventional resuscitation. While data suggests the benefit of eCPR in select populations, there are scarce outcomes data for patients with in-hospital cardiac arrest (IHCA) compared to those with out-of-hospital cardiac arrest (OHCA).

Research Question: Do outcomes of eCPR differ between IHCA and OHCA?

Methods: Using the Nationwide Readmissions Database from 2016 to 2022, we analyzed in-hospital outcomes of adult patients who underwent eCPR for IHCA vs. OHCA using multivariable logistic regression and propensity score methods. The study cohort was identified using ICD-10 diagnostic and procedural codes.

Results: Of 4,365 patients treated with eCPR for cardiac arrest, 3,252 (74.5%) had OHCA and 1,113 (25.5%) had IHCA. During the study period, the proportion of patients with OHCA receiving eCPR significantly increased (p-trend<0.001). Patients with IHCA were older (54 vs. 53 years), more often female (37.8% vs. 33.1%) with a higher comorbidity burden, and less likely to have shockable rhythm. In-hospital mortality was higher in patients with IHCA compared to OHCA (66.5% vs. 56.4%, p<0.001). The length of hospital stay was longer, and the cost of hospitalization was higher for patients with IHCA vs. OHCA. After adjustment for comorbidities, IHCA was associated with higher mortality based on regression (odds ratio [OR], 1.56; 95% CI [confidence interval], 1.23-1.98) and propensity score-matched (OR, 1.62; 95% CI, 1.25-2.10) analyses. IHCA was associated with less major bleeding (OR, 0.73; 95% CI, 0.55-0.98) and less anoxic brain injury (OR, 0.75; 95% CI, 0.60-0.95) but higher risk of sepsis (OR, 1.65; 95% CI, 1.29-2.10).

Conclusion: In patients with cardiac arrest treated with eCPR, IHCA was associated with increased in-hospital mortality compared to OHCA. These findings suggest a need for further studies to guide patient selection in clinical practice for eCPR in IHCA.