Biomarkers in care of congenital heart disease patients in the intensive care unit

Biomarker use in the care of intensive care unit (ICU) patients with congenital heart disease (CHD) is a promising field, currently centered around two classes of biomarkers: (1) cardiac function/failure markers, including natriuretic peptides (brain natriuretic peptide [BNP]), suppressor of tumorigenicity 2 (ST2), and galectin-3 (Gal3) and (2) cardiac injury markers, including troponins. As cardiac function/failure markers, postoperative BNP levels correlate with adverse outcome but may not indicate severity across all CHD subtypes or ages, especially neonates or patients with Fontan palliation. BNP trends are useful for risk stratification in pulmonary hypertension. Based on accruing adult evidence and new pediatric evidence, biomarkers of cardiac failure and fibrosis, soluble ST2 and Gal3, may soon be incorporated into CHD care. As cardiac injury markers, troponins have a limited role but remain useful in resolving the mechanism of postoperative dysfunction after coronary reimplantation and discriminating active myocarditis from dilated cardiomyopathy. Data on biomarkers of noncardiac organ system dysfunction, especially acute kidney injury and neurologic injury, also continue to accrue in pediatric CHD patients. There are no established pediatric guidelines at present for guiding any therapy solely based on biomarkers. We recommend incorporating pretest probability before ordering; establishing a baseline biomarker level; evaluating trends in individual patients; and accounting for interassay variability, developmental regulation of levels, and potential confounders such as renal failure. In the future, using biomarkers as surrogate end points in clinical trials, markers of therapeutic response, and/or a means of avoiding invasive procedures could revolutionize pediatric cardiac and ICU care.