Abstract 258: Age, Sex And Survival Of Ventricular Fibrillation Out-of-Hospital Cardiac Arrest: The Influence Of Electrocardiogram Waveform Measures

Abstract

Background: Studies of sex-based outcome in out-of-hospital cardiac arrest (OHCA) have produced mixed results that may depend on age. Menopause produces a range of effects that may influence resuscitation. We used quantitative measures of the presenting OHCA ventricular fibrillation (VF) waveform - a surrogate of the myocardium’s acute physiology - to assess whether outcome differences according to sex and age group may be mediated via a biologic mechanism. Methods: We conducted a retrospective cohort study of adults with non-traumatic VF-OHCA in a metropolitan Emergency Medical Services system between 2008-2020. We used multivariable logistic regression to assess the association of outcome (survival to hospital discharge, favorable neurological outcome (Cerebral Performance Category (CPC) 1 or 2), with sex and age group (<55, > 55 yrs). We then determined the proportion of the outcome difference mediated by the waveform measure by incorporating previously described quantitative VF waveform measures - an estimated probability of survival (P Survival ) and amplitude spectrum area (AMSA - into the model individually. Results: Of 1526 VF-OHCA patients, average age was 62 years, and 29% were female. Overall, younger women were more likely to survive than younger men (survival 67% vs 54%, p=0.02 with CPC 1-2 61% vs 51%, p=0.07), while older women and older men had similar worse outcomes. After adjusting for Utstein characteristics, women <55 compared to men <55 was associated with greater odds of survival to hospital discharge (OR 1.93, 95% CI 1.23-3.09, p=0.005) and CPC 1-2 survival (OR 1.72, 95% CI 1.10-2.71, p=0.02), whereas no associated sex-based differences in these outcomes were observed between the older groups. Each waveform measure mediated some of the beneficial association between sex and age group with survival: 47% for P Survival and 25% AMSA. Conclusions: Women <55 years were more likely to survive to hospital discharge and with favorable neurological status compared to men <55 years, a sex-associated outcome difference not observed in the older age group. The biologic mechanism represented by VF waveform measures mediated some (47% at most), though not all, of the outcome differences.