451 - Trajectory of PDA Phenotypes in Extremely Preterm Infants: Insights from Early Hemodynamic Screening

Publication Number: 3436.451

Tiffany Lau, University of Iowa Stead Family Children's Hospital, Coralville, IA, United States; Paula Dias Maia, University of Iowa Stead Family Children's Hospital, Iowa City, IA, United States; Amy HC. Stanford, University of Iowa Stead Family Children's Hospital, Iowa City, IA, United States; Adrianne R. Bischoff, University of Iowa Stead Family Children's Hospital, Iowa City, IA, United States; Patrick McNamara, University of Iowa, Iowa city, IA, United States

Background: Patent ductus arteriosus (PDA) is associated with increased morbidity and mortality. Although clinical trials of PDA treatment at 72 hours show no benefit, early ( < 24 hours) targeted treatment of infants with a moderate-high volume shunt reduces the risk of intraventricular hemorrhage and necrotizing enterocolitis. Imprecision in physiologic adjudication may explain the lack of benefit and harm seen in RCTs.

Objective: To characterize trajectory of PDA phenotypes in extremely preterm infants undergoing early hemodynamic screening (HS) and investigate the relationship of PDA diameter.

Design/Methods: Retrospective cohort study (January 2019-June 2025) of infants ≤ 26 6/7 weeks' gestation who underwent HS using targeted neonatal echocardiography (TNE) at the University of Iowa. PDA size and associated physiology was determined at different timepoints (baseline, 7 days, overall NICU stay) as follows: i) no transductal shunt, ii) low volume (PDA score < 6) shunt and no medical therapy, iii) moderate-high volume (PDA score ≥6) shunt for which medical therapy was given, iv) Ductal dependent physiology e.g. pulmonary hypertension or ventricular dysfunction. Sankey plots illustrated transitions between physiologic categories across time and initial ductal size. Analyses were descriptive.

Results: Among 356 infants included, a wide range of PDA physiologic states on initial HS were noted: no shunt (5%), low-volume (49%), moderate-high volume (26%), and ductal dependent physiology (20%). Phenotypes evolved during the first week and throughout NICU stay (Figure 1). PDA size ≥ 1.5mm was significantly associated with moderate-high volume shunt or PDA supportive physiology on initial HS (p < 0.001 for both), yet 12.4% of these infants had spontaneous ductal closure. In contrast, PDA < 1.5mm was associated with low-volume shunt (p < 0.001), but 21% ultimately required definitive closure (Table 1). Notably, some infants with no shunt or with PDA size < 1.5mm on initial HS later developed moderate-high volume shunts requiring definitive closure (Figure 2). PDA size ≥ 1.5mm on initial HS was associated with higher rates of IVH at day 7 (p < 0.041), respiratory support at 36 weeks PMA (p < 0.037), and death (p < 0.037).

Conclusion(s): Size of PDA does not predict shunt physiology or need for PDA treatment. These findings highlight the importance of serial physiologic targeted assessments over static size-based treatment strategies at a single time point.

Table 1: Comparison based on PDA size on the initial hemodynamic screening at <24 hours postnatal.
Legend: IUGR: Intrauterine growth restriction, IVH: Intraventricular hemorrhage, NEC: Necrotizing enterocolitis.

Figure 1: Trajectory of infants ≤26 6/7 weeks' gestation undergoing hemodynamic screening.
The first column shows Iowa PDA severity classification at 12-24 hours, the second reclassification over the first 7 days, the third the overall trajectory during the NICU stay, and the fourth infants who underwent definitive PDA closure. Flow widths indicate the number of infants transitioning between categories, with colors reflecting baseline physiology: blue (no PDA), orange (low volume), green (moderate-high volume receiving therapy), and red (supportive physiology). The category "Others" includes infants with early death, absent repeat targeted neonatal echo, or variable physiologies.

Figure 2: Trajectory of infants ≤26 6/7 weeks' gestation undergoing hemodynamic screening.
The first column shows patients categorized by size (no transductal shunt, PDA <1.5mm, PDA ≥1.5mm); the second column shows Iowa PDA severity classification at 12-24 hours, the third column shows the overall trajectory during the NICU stay, and the fourth column shows infants who underwent definitive PDA closure. Flow widths indicate the number of infants transitioning between categories, with colors reflecting initial PDA size: orange (no PDA), green ( <1.5mm), red (≥1.5mm). The category "Others" includes infants with early death, absent repeat targeted neonatal echo, or variable physiologies.