Does troponin-I measurement predict low cardiac output syndrome following cardiac surgery in children?

OBJECTIVE: To determine whether serum troponin I (TnI), measured 4 hours after surgery for congenital heart disease, is a predictor of myocardial dysfunction and low cardiac output syndrome (LCOS). DESIGN: Prospective, observational study. SETTING: Paediatric intensive care unit in a tertiary care academic children's hospital, 1 June 2003 to 12 May 2004. PATIENTS: 99 consecutive eligible children who underwent a variety of surgical procedures for congenital heart disease, using cardiopulmonary bypass. All patients were cared for by a consistent perioperative care team. INTERVENTIONS: Measurement of TnI preoperatively, and at 0, 4, 8, 12, 24 and 36 hours after ICU admission. RESULTS: Patient demographics and outcome (as median and 25th-75th percentile) were as follows: age, 23.9 (4.6- 65.9) months; cardiopulmonary bypass time, 135 (98-178) minutes; aortic cross-clamp time, 65 (28-85) minutes; preoperative TnI level, 0.02 (0.01-0.03) ng/mL; 4h TnI, 10.6 (3.0-23.4) ng/mL; highest 24 h TnI, 11.7 (3.9-29.5) ng/mL; time to discontinuation of inotropes, 43.9 (18.7-92.9) hours; maximal inotrope score, 10.0 (5.0-16.3); time to extubation, 42.4 (19.8-137.5) hours; and time to ICU discharge 91.8 (45.7-169.7) hours. Twenty-three patients developed LCOS. A 4h TnI level > 13 ng/mL predicted LCOS with a sensitivity of 0.78 (95% CI, 0.56-0.93), and a specificity of 0.72 (95% CI, 0.61-0.82). The area under the receiver operating characteristic curve for TnI as a predictor of LCOS was 0.75 (95% CI, 0.63-0.88). TnI was the only predictive variable associated with LCOS in multivariate logistic regression analysis, with an odds ratio of 1.45 (95% CI, 1.05-2.01) for developing LCOS with each 10 ng/mL increase in 4h TnI. Linear regression analysis showed TnI to be significantly correlated with increased time to discontinuation of inotropes, maximal inotrope administration, time to extubation, and time to ICU discharge. CONCLUSIONS: Measurement of early postoperative levels of TnI may aid in the early identification of children who will develop LCOS.