Abstract Body (Do not enter title and authors here): Background
Significant coronary artery disease has been suggested as the main cause of the refractory state among patients with out-of-hospital cardiac arrest (OHCA) and initial ventricular fibrillation (VF).
Research Question/Hypothesis
The aim of this study was to describe the coronary angiography findings in relation to degree of treatment refractoriness, measured as the number of shocks, among patients with shockable OHCA in Sweden.
We hypothesized that increasing number of shocks was associated with an increased prevalence of coronary artery disease (CAD) and more frequent percutaneous coronary intervention (PCI).

Methods
All patients with primary VF OHCA in Sweden between January 1, 2010, and December 31, 2019, who underwent coronary angiography, were included using three national registries. Patients were divided according to the number of delivered defibrillations and subgrouped according to presence of STEMI on ECG. Coronary angiography findings of acute occlusions, PCI performed, chronic total occlusions as well as multivessel disease were described in relation to level of refractoriness.

Results
In total, 3369 patients were included. Among them 67%/N=2270 required 1-3 defibrillations, 23%/N=758 4-6, 7%/N=222 7-9 and 4%/N=119 ≥10 defibrillations. There was no significant difference regarding acute coronary occlusions between the groups. The proportion of patients receiving PCI decreased with increased number of shocks (67%/N=1525 for 1-3 shocks, 58%/N=435for 4-6 shocks, 54%/N119 for 7-9 shocks and 55%/N=65 for ≥10 shocks). This was true for both subgroups with or without STEMI. Survival and neurological function decreased in accordance with increased need of defibrillations (74% to 35%; p=<0,001), a clear difference that was unaffected when adding coronary angiography findings as well as PCI in an adjusted multivariable model.

Conclusions
In this comprehensive study including all VF OHCA undergoing coronary angiography in Sweden, patients with an increased number of defibrillations have less coronary artery disease motivating PCI in relation to those receiving fewer defibrillations.