Heart rate variability predicts short-term outcome for successfully resuscitated patients with out-of-hospital cardiac arrest

Objective: To assess the possibility of heart rate variability (HRV) measures as predictors of 24-h mortality in successfully resuscitated patients with out-of-hospital cardiac arrest (OHCA). Methods: This prospective cohort study was conducted at a 40-bed emergency department (ED) of a university-affiliated medical centre. Adult patients with OHCA who were successfully resuscitated were consecutively enrolled over an 18-month period. A 10-min electrocardiogram was recorded for retrospective off-line HRV analysis 30-60 min after the return of spontaneous circulation and further correlated with 24-h mortality of the patients. Results: Sixty-nine patients aged 31-82 years who met the inclusion criteria were enrolled. According to the 24-h mortality, the patients were categorised into non-survivors (n = 28) and survivors (n = 41) groups. The HRV measures were compared between these two groups. The low-frequency power (UP), normalized UP (nLFP) and low-/high-frequency power ratio in the non-survivors were significantly lower than those of the Survivors, whereas root mean square Successive difference, high-frequency power (HFP), HFP/tidal volume, normalized HFP (nHFP), and nHFP/tidal volume in the non-survivors were significantly higher than those of the survivors. Multiple logistic regression model identified nLFP as the independent variable to predict 24-h mortality (odds ratio, 1.354; 95% confidence interval [CI], 1.124-1.632; p = 0.001). Receiver operating characteristic area for nLFP in the prediction of 24-h mortality was 0.946 (95% Cl, 0.897-0.995; p < 0.001). Conclusions: HRV measures, especially the nLFP, may be used as predictors of 24-h mortality for successfully resuscitated patients with OHCA in the ED. (C) 2009 Elsevier Ireland Ltd. All rights reserved.