Thiamine-responsive pulmonary arterial hypertension in early infancy - a three-year single-centre retrospective cohort
S ModaniAbstract
Background
Thiamine deficiency in exclusively or predominantly breast-fed infants can precipitate a rapidly reversible form of pulmonary arterial hypertension (PAH) characterised by respiratory distress, metabolic acidosis and raised pulmonary pressures on echocardiography. Evidence is heterogeneous and longitudinal severity transitions are seldom quantified.
Objectives
To characterize demographics, presentation and laboratories; to report baseline primary diagnosis at first echocardiography; to quantify severity trajectories across second and third/follow-up studies; to summarize therapies and in-hospital disposition; and to explore crude associations between therapies and improvement.
Methodology
Retrospective observational cohort (single tertiary children’s hospital), three-year window ending June 2025. Data abstracted from hospital records and electronic data sources. Echocardiography findings were documented at three timepoints (1st, 2nd, 3rd/follow-up). Longitudinal categories were harmonized as Severe/Moderate/Mild/Recovered. Improvement was any reduction on an ordinal scale (Severe=3, Moderate=2, Mild=1, Recovered=0). Categorical comparisons used χ²/Fisher’s exact tests; p<0.05 was considered evidence against the null.
Results
We analyzed 126 infants (median age 4.0 months; 66.7% male). At presentation, respiratory distress was noted in 110 infants (87.3%), fever in 37 (29.4%), cough/URTI in 47 (37.3%), gastrointestinal symptoms in 37 (29.4%), and feeding/cry/voice disturbances in 32 (25.4%). ABG revealed metabolic acidosis in 105 (83.3%) and was normal in 21 (16.7%). First echocardiography identified severe PAH in 89 (70.6%), moderate in 21 (16.7%), mild in 5 (4.0%), and other findings in 11 (8.7%). Thiamine deficiency was explicitly noted in 26 records, and thiamine levels were available for 71 infants (median 22.6; range 0.3–155.0, units per source lab). Therapies included sildenafil (n=105), milrinone (n=32), adrenaline (n=47), noradrenaline (n=16), IMV (n=53), and CPAP (n=16). Disposition: discharged 84 (66.7%), referred 16 (12.7%), LAMA 21 (16.7%), with no deaths. Serial echocardiography showed a significant improvement trend (1st→2nd→3rd): Severe 89→5→0; Moderate 21→26→5; Mild 5→32→11; Recovered 11→63→110 (χ² p<0.001). Comparative analyses did not demonstrate statistically significant differences in recovery based on individual therapies.
Conclusion
Infants presented with substantial initial disease burden but demonstrated progressive echocardiographic improvement to recovery by the last follow-up, with no inpatient deaths. These data support prompt consideration of thiamine assessment and repletion alongside supportive care for infants with PAH, respiratory distress and metabolic acidosis in settings where thiamine deficiency risk is non-trivial.