Abstract Body: Background: Ventricular fibrillation (VF) - induced cardiac arrest is a frequent complication of ST-segment elevation myocardial infarction (STEMI). Although larger infarct sizes (IS) are associated with a higher risk of VF, there has been no investigation into the influence of VF itself on IS. To address this knowledge gap, we analyzed the impact of VF on IS in patients and 2 experimental models.

Methods: From the prospective cohort HIBISCUS-STEMI, 30 STEMI patients with VF were matched on common determinants of IS in a 1:2 ratio with patients without VF. The primary endpoint was IS, assessed using the 48-hour area under the curve (AUC) for troponin. We compared IS in pigs with/without spontaneous VF during STEMI (n=15/group), and in an isolated rat heart model of acute myocardial infarction with/without electrically induced VF (n=7/group); IS was assessed using the ratio of the area of necrosis (AN) to the area at risk (AAR).

Results: While patient characteristics were similar after matching (including AAR), IS was 33% lower in the VF group than in the control group (troponin AUC 1.6 [0.5-3.3] 10⁶ vs. 2.4 [0.9-4.1] 10⁶ arbitrary units; p=0.049). In pigs, IS was lower (p<0.01) in the VF group (24% [11-40]) than in controls (71% [48-75]). In the isolated heart model, IS was lower (p<0.05) in the VF group (9% [7-15]) than in controls (42% [38-44]).

Conclusion: When common determinants of IS are comparable, the occurrence of VF prior to MI reperfusion is associated with significantly smaller IS.