Hypothermia after cardiac arrest: impact on myocardial injury

Introduction

The Hypothermia after Cardiac Arrest (HACA) trial assessed whether mild therapeutic hypothermia improved the rate of good neurological recovery in patients successfully resuscitated from ventricular fibrillation cardiac arrest of presumed cardiac origin. Animal data suggest protection of ischemic myocardium with reduced temperature. We evaluated for a subset of patients of the HACA trial the impact of mild therapeutic hypothermia on myocardial injury.

Methods

Post-hoc analysis of data of the HACA multicenter trial for patients included at our study center. Patients after ventricular fibrillation cardiac arrest were randomly assigned to mild therapeutic hypothermia of 32–34°C over 24 hours or to conventional treatment. For the present analysis we analysed the effect on plasma levels of CK and CKMB as a measure of infarct size.

Results

Fifty-five patients underwent cooling and 56 patients received standard treatment after successful resuscitation. The analysis was performed according to the intention-to-treat principle. The areas under the curve (AUC) within 24 hours for CK were 28,786 U/l × 24 hours (IQR 5646-44,998) in the cooling group and 20,373 U/l × 24 hours (IQR 8211–30,801) for controls (P = 0.40). For CK-MB the AUC was 1690 U/l × 24 hours (IQR 724–3330) in the cooling group and 1187 U/l × 24 hours (IQR 490–2469) for controls (P = 0.18).

Conclusion

In our sample cooling after successful resuscitation for ventricular fibrillation cardiac arrest did not influence infarct size as estimated by CK and CK-MB levels.