High resolution ECG differences between hospital survivors and non-survivors of out-of-hospital cardiac arrest during mild therapeutic hypothermia

Our aim was to evaluate electrocardiographic (ECG) diferences between survivors and non-survivors of out of hospital cardiac arrest (OHCA). The study included 76 patients that suffered from OHCA. In all patients, serum arterial lactate was obtained on admission to the intensive care unit was obtained as an index of ischemia during cardiac arrest and resuscitation. A 5-minute 12-lead high fidelity ECG recording was recorded during mild therapeutic hypothermia (MTH) (defined as core body temperature of 32-34°C). Custom software programs were used to calculate conventional and advanced spatial, repolarisation and interval variability ECG parameters. Survival versus non survival to hospital discharge was considered as the outcome variable. There were 38 survivors of OHCA among our patients. Survivors displayed significantly lower serum arterial lactate levels and lower values of beat-to-beat QT interval variability parameters. We conclude that a relatively greater degree of anoxic injury in patients that fail to survive OHCA results in altered electrophysiological properties of the heart muscle leading to increased ventricular repolarisation variability.