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The Decline and Fall of the Cardiac Biomarker: A Good Indicator of Resolution of Cardiac Dysfunction following Perinatal Asphyxia

perinatal asphyxia using the cardiac biomarkers cTnI and brain natriuretic peptide (BNP). Troponin T and I are sensitive markers of myocardial injury following a perinatal hypoxic-ischaemia insult. BNP is a marker of ventricular wall stress secondary to myocardial dysfunction [8] . cTnI and BNP were collected before the start of hypothermia, at 24 and 48 h after birth, and after rewarming. BNP was significantly lower in the infants who underwent hypothermia compared with historical controls with perinatal asphyxia but not treated with hypothermia. The authors did not see a difference in troponin levels in the 2 groups which normalised in both groups by 84 h of age. This study differed from other studies of neonatal cardiac dysfunction following perinatal asphyxia and hypothermia as comparison was made with historical controls with perinatal asphyxia rather than normal healthy controls. This may explain why the authors found decreased BNP and no difference in troponin in infants treated with hypothermia. This study is interesting as it shows that although following perinatal asphyxia troponin levels are very elevated they decline to normal levels in both groups by day 4 of life, which may indicate complete resolution of cardiac dysfunction. Cardiac troponin T, cTnI and BNP are well-described markers of myocardial ischaemia and cardiac failure in adults, children and neonates [9] . BNP is released in reNeonatal asphyxia induces global hypoxia-ischaemia resulting in multi-organ injury [1] . Cardiac, renal, hepatic and haematological dysfunction are well-described. Martin-Ancel et al. [2] found that 29% of neonates with perinatal asphyxia had cardiac dysfunction consistent with myocardial ischaemia. Hypothermia is the latest treatment for neonatal brain injury following perinatal asphyxia to come into widespread use [3] . Infants with perinatal asphyxia treated with hypothermia have decreased biventricular function and coronary artery flow and significantly elevated troponin compared with normal term control infants [4] . In addition the cardiac biomarker cardiac troponin I (cTnI) and pathological cardiac lesions are significantly reduced after hypothermia treatment in hypoxic-ischaemic newborn pigs [5] . Hypothermia has a direct cardioprotective role and reduces cardiomyocyte injury after oxidative stress in animal models [6] . However, the effect of hypothermia on cardiac biomarkers has not been extensively investigated in human newborns. The paper ‘Cardiac biomarkers as indicators of hemodynamic adaptation during postasphyxial hypothermia treatment’ by Vijlbrief et al. [7] reports an observational cohort study of infants treated with mild hypothermia following perinatal asphyxia. They investigated whether hypothermia exerts a beneficial effect on the heart after Received: July 15, 2012 Accepted: July 16, 2012 Published online: August 15, 2012