Abstract 1905: Triiodothyronine for Infants and Children Undergoing Cardiopulmonary Bypass (TRICC) Study: Age Analysis Reveals T3 Benefit in Youngest Patients
The Triiodothyronine for Infants and Children Undergoing Cardiopulmonary Bypass (TRICC) study is a six center, randomized, double-blinded, placebo-controlled clinical trial designed to determine safety and efficacy of triiodothyronine (T3) supplementation in children <2 years of age undergoing surgery for congenital heart disease. Preliminary data presented at AHA 2008 obtained from 193 patients, (TR) randomized to multiple T3 bolus over 12 hours or to placebo (PL), showed T3 was safe and improved cardiac function. T3 did not reduce time to extubation (TTE). We performed planned aged stratification analyses in two cohorts, I < 5 months (n= 98), and II, 5 months to 2 years(n = 95). For cohort I: PL median age was 1.30 mos (0.26, 3.78; 25%, 75%): TR, 0.99, 0.39, 3.09; and cohort II, PL, 7.99, 6.38, 12.63; TR 7.25, 6.22, 9.34. Using Cox Proportional Hazards, we found that grp I randomization to TR reduced the median TTE by 44 hours (p = .045 by COX and .024 by chi-square). The hazard ratio (chance of extubation) for TR was 1.72 (p= 0.023). PL Median TTE was 98.067 with 95% confidence intervals (CI): 70.667 and 142.250. TR Median TTE was 54.9 and CI: 43.617 and 92.450. Improvement in TTE corresponded to a reduction in Doppler myocardial performance index (p = .026, TEI, inversely proportional to contractile function) and a trend towards increased ejection fraction (p = .066). In contrast for Grp II, TR showed small but significant delays in TTE. The hazard ratio for Grp I TR was 0.54 (p-value 0.0055) and median times, PL 15.78 and TR 22.03. Although T3 levels were nearly identical in PL for Grps I and II, at hour 1, TR Grp II showed higher T3 than TR Grp I (medians 369 and 280, p = 0.0008). These results emphasize the importance of age-related analyses in Pediatric Cardiovascular Surgery. We identified an age related dichotomy in TR response with advantage in Grp I masked by evaluating the cohort as a whole. Disadvantage for TR in older cohort II may relate to higher T3 half life and resulting marked elevation in levels.