Abstract Body (Do not enter title and authors here): Background Field activation of patients with ST-segment elevation myocardial infarction (STEMI) by Emergency Medical Services (EMS) during the COVID-19 (COVID) pandemic era involved a change in policy whereby patients underwent COVID-19 testing in the emergency department (ED) prior to Percutaneous Coronary Intervention (PCI) versus bypassing the ED to the Catheterization (Cath) Lab.

Research Question We aimed to compare In-Hospital Mortality and other performance metrics of field activated STEMI patients at a large rural health system during the COVID era to pre and post pandemic periods.

Methods Retrospective single-center (Essentia Health, Duluth, MN, USA) cohort study of consecutive patients with STEMI activation identified in the field by EMS prior to the COVID era (5/27/2018–3/26/2020), during the 22 months of the COVID testing policy (3/27/2020–1/25/2022), and post-COVID when ED bypass resumed (1/ 26/2022–11/26/2023). The main outcomes of this study were in-hospital mortality and common STEMI system performance metrics.

Results A total of 373 consecutive field activated STEMI cases were included (pre COVID [N =132], COVID [N = 104], post COVID [N = 137]). Pre COVID, 40.9% of EMS activated STEMI cases stopped in the ED prior to the Cath Lab, 97.1% during the COVID era, and 51.1% in the post-COVID era (p<0.0001 between pre COVID and COVID era). The median door to device time was increased from 32.5 (15-75 total range) 39 (18-122) min p= 0.042. The time from symptom onset to device placement was increased from 140 (63-806) to 170 (63-934) min p=0.0054. The time from 1^st positive EKG to device time was increased from 80 (32-157) to 94 (43-197) min p=0.046. The first medical contact to device, 911 call to device, and symptoms onset to 911 call times during COVID era showed increasing trend as compared to pre-COVID times but were not statistically significant. The unadjusted In-hospital mortality rates for EMS identified STEMI during the pre-COVID era, COVID era, and post-COVID era were 6.1%, 8.7%, and 7.3%, respectively (p=ns). Most times metrics returned to the pre-COVID levels in the post-COVID phase.

Conclusion In the rural setting, EMS activated STEMI patients had longer times to reperfusion during the COVID-19 era as compared to pre COVID due to the stop at the ED. The delayed reperfusion did not significantly reflect in in-hospital mortality, likely due to low number of events. Larger cohort multi-center studies on this issue is warranted.