Effect of cooling after human cardiac arrest on myocardial infarct size

SummaryAimsThe Hypothermia after Cardiac Arrest (HACA) trial assessed whether mild therapeutic hypothermia improved the rate of good neurological recovery in patients after ventricular fibrillation cardiac arrest of presumed cardiac origin. We evaluated the impact of hypothermia on myocardial injury.MethodsRe-analysis of a HACA trial subset for our department (cooling, n = 55; controls, n = 56). Plasma levels of CK, CKMB and ST-scores were used as a measure of infarct size.ResultsArea under the curve (AUC) for CK was 28,786 U/l × 24 h (IQR 5646-44,998) in the cooling group and 20,373 U/l × 24 h (IQR 8211-30,801) for controls (p = 0.40), for CKMB AUC was 1691 U/l × 24 h (IQR 724-3330) and 1187 U/l × 24 h (IQR 490-2469), respectively (p = 0.18). The ST score was −40% (IQR [−55] − [+16]) in the cooling group (n = 23) and −22% (IQR [−84] − [+33]) for controls (n = 24) (p = 0.76). When the cooling group was stratified into early (≤8 h) and longer (>8 h) time to target temperature, the early group displayed a significantly lower CK 7340 U/l × 24 h (IQR 3921-33,753) vs. 38,986 U/l × 24 h (IQR 23,945-57,514, p = 0.007) and a lower CKMB.ConclusionCooling after successful resuscitation for ventricular fibrillation cardiac arrest did not influence infarct size. Cautious interpretation of the subgroup analysis may indicate a favourable trend for early cooling.