Abstract 17810: Spectral Analysis-Based Risk Score to Early Predict Mortality and Cerebral Performance in Patients Undergoing Therapeutic Hypothermia for Ventricular Fibrillation and Comatose Status

Abstract

Introduction: Early reliable prognostication in comatose survivors after cardiac arrest due to ventricular fibrillation (VF) is very limited, especially in patients undergoing mild hypothermia. Hypothesis: Spectral analysis of VF before a DC shock will reflect the degree of acute cerebral injury as a consequence of time in VF and concomitant myocardial ischemia. Methods: We included consecutive patients undergoing mild hypothermia after cardiac arrest due to VF, eventually with return of spontaneous circulation (ROSC), and a comatose status on admission. Background clinical variables, VF time and frequency domain fundamental variables were considered in the analysis. The primary and secondary outcomes were a favorable neurological performance (FNP) during hospitalization and survival to hospital discharge, respectively. The predictive model was developed in a retrospective cohort (September 2006 to September 2011) and further validated in a prospective cohort (October 2011 to July 2013). The model was also tested at follow-up. Results: Sixty-one patients out of 239 who underwent mild hypothermia fulfilled the inclusion criteria. FNP was present in 16 (50.0%) and 21 patients (72.4%) in the retrospective and prospective cohorts, respectively. Seventeen (53.1%) and 21 patients (72.4%), respectively, survived to hospital discharge. Both outcomes were significantly associated (p<0.001). Multivariate analysis on the retrospective cohort provided a prediction model (sensitivity=0.94, specificity=1) including dominant frequency, ratio between number of peaks in high and low frequency bands, power spectral density ratio between high and low frequency bands and the number of shocks delivered before ROSC. Validation on the prospective cohort showed sensitivity=0.88 and specificity=0.91 for both primary and secondary outcomes. A model-derived risk score properly predicted 93% of FNP. The model showed cstatistic ≥0.89 after a median follow-up of 48.5±10.5 and 5±1.8 months in the retrospective and prospective cohorts, respectively. Conclusions: A spectral analysis-based model reliably correlates time-dependent VF spectral changes with acute cerebral injury in comatose survivors after cardiac arrest undergoing mild hypothermia.