Predictive Value of Plasma and Urinary Metabolomic Profile in Newborns with Congenital Heart Disease

The incidence of adverse outcomes for infants undergoing complex congenital heart dis- ease (CHD) surgery with cardiopulmonary bypass (CPB) is still high. Early identification and treatment of high-risk patients remain challenging, especially because clinical risk factors often fail to explain the different outcomes of this vulnerable population. Metabolomics offers insight into the phenotype of the patient and the complex interplay between the genetic substrate and the environmental influences at the time of sampling. For these reasons, it may be helpful to identify the mechanisms of physio-pathological disruptions experienced in neonates undergoing congenital heart surgery and to identify potential therapeutic targets. We conducted a pilot prospective, observational, single-center study at the Neonatal In- tensive Care Unit (NICU) of Padua University Hospital Between May 2024 and May 2025. The study includes full-term newborns (gestational age >37 weeks) diagnosed with com- plex congenital heart disease (CHD) requiring either corrective or palliative cardiac sur- gery, or hemodynamic catheterization. Plasma and urine samples were collected at birth (within 72 hours), pre-cardiac surgery (within 24 hours), and post-cardiac surgery (within 3 days). A total of 30 neonates with CHD were enrolled. Results of a preliminary analysis on urine samples are shown. Two predefined and clinically significant subgroups of CHD were recognized for the pur- pose of the analysis: Left Ventricular Outflow Tract Obstruction (LVOTO, n=11) and Transposition of the Great Arteries (TGA, n=8). Baseline characteristics were overall comparable between the two groups, with no signi- ficant differences in gestational age, birth weight, sex distribution, or mode of delivery. The mean gestational age was 38.9 weeks and the mean birth weight was 3.13 kg across the cohort. The median age at surgery was 10 days (IQR: 7.5–11.5), with similar timing in both subgroups. The only variable showing a significant difference was pre-operative oxygen saturation, which was markedly lower in the TGA group (median 84.5%, IQR: 73.8–92.0) compared to the LVOTO group (median 98%, IQR: 97–98; P < 0.001), consi- stent with the expected pathophysiological profile of these two CHD subtypes. Urinary metabolomic profiling at TP0 (Time point 0) distinguished LVOTO from TGA, with steroid conjugates such as 17α-hydroxypregnanolone glucuronide and DHEA glucuro- nide emerging as discriminant metabolites. Longitudinal comparisons revealed periope- rative alterations involving catecholamine metabolism (vanillylmandelic acid), purine turnover (adenine), bile acid conjugation, and amino acid acetylation, with some featu- res shared across subgroups (e.g., N-acetyl-tryptophan). Exploratory analyses of early urinary profiles in relation to adverse outcomes (ECMO, mortality) suggested that af- fected neonates appeared as statistical outliers within the overall distribution, although these findings lacked statistical robustness due to the limited sample size. In summary, this interim analysis supports the feasibility of urinary metabolomics in neo- natal CHD and highlights biologically plausible pathways related to adrenal function, energy metabolism, and amino acid catabolism. These results are preliminary and hy- pothesis-generating, underscoring the need for larger, integrated studies to validate whether early urinary metabolic signatures can contribute to risk stratification in this high-risk population.