Impact of thiamin supplementation on thiamin pyrophosphate effect and cardiac function in pediatric heart disease patients on diuretics: A randomized controlled trial

Background and Aims: Thiamin is a water-soluble vitamin essential for energy metabolism. Patients on long-term diuretics, particularly those with heart disease, are at risk of thiamin deficiency (TD) due to increased urinary loss, which may impact cardiac function. We evaluated changes in thiamin pyrophosphate effect (TPPE) values after 4 weeks of thiamin supplementation compared to placebo in pediatric heart disease patients receiving diuretics. The secondary objectives included assessing changes in left ventricular ejection fraction (LVEF) and identifying factors associated with TPPE changes. Methods In this triple-blinded, randomized controlled trial, we recruited 45 children (aged 1 month to 15 years) with heart disease with increased pulmonary blood flow or congestive heart failure, all on diuretics for ≥ 1 month. Participants were randomly allocated to receive thiamin 25 mg/day, thiamin 50 mg/day, or placebo for 4 weeks. TD was defined as TPPE values ≥ 15%. Results At baseline, 9 of 45 participants (20%) had TD. After 4 weeks, no significant differences in changes in TPPE values or LVEF were observed among the three groups (all p > 0.05). Multiple linear regression showed that furosemide dosage was independently associated with TPPE changes (β: +0.36, p  = 0.015), indicating a dose-dependent association with thiamin status. Conclusions Thiamin supplementation at 25 mg/day or 50 mg/day did not significantly improve TPPE values or LVEF. However, furosemide dosage correlated with TPPE changes, indicating a need for tailored thiamin supplementation strategies in pediatric heart disease patients on diuretics. For those with TD, doses exceeding 50 mg/day may be necessary. Trial registration number: NCT03989700 (ClinicalTrials.gov). Date of registration: 18/06/2019.