O0006: The Value of Novel and Conventional Echocardiography Parameters in Predicting Clinical Outcomes of Persistent Pulmonary Hypertension of the Newborn

Background: Persistent Pulmonary Hypertension of the Newborn (PPHN) is associated with adverse clinical outcomes including the requirement of ECMO (Extracorporeal membrane Oxygenation) or mortality. Echocardiography remains the most feasible imaging modality to diagnose and assess the severity of PPHN. The Pulmonary Perfusion Index (PPI) has been recently used to assess flow in the branched pulmonary arteries as a surrogate marker for pulmonary perfusion but has not yet been studied in neonates with PPHN. The objective of this study was to evaluate the association of individual echocardiography markers, including the PPI with clinical outcomes.

Methods: This is a single center retrospective study. We included all neonates admitted to the neonatal intensive care unit between January 2017 and December 2021 with gestational age (GA) ≥ 28 weeks, and the diagnosis of PPHN by clinical and echocardiographic findings within the first 7 days of life. Patients with congenital heart disease except for Patent Foramen Ovale (PFO) and patent ductus arteriosus (PDA) were excluded. Our primary composite outcome was use of ECMO and/or mortality. Clinical parameters included the heart rate, blood pressure, Oxygenation Index (OI), need for inhaled Nitric Oxide (iNO), Sildenafil, inotropic support, and duration of mechanical ventilation. Data from the initial diagnostic echocardiogram was reviewed. Conventional 2-D and Doppler measurements were used to derive markers of Right ventricular pressure and function including Tricuspid annular plane systolic excursion (TAPSE), left ventricular end-systolic eccentricity index (EI), RV fractional area change (FAC), Tricuspid regurgitation velocity (TRV), PFO and PDA shunt direction and gradient in addition to the PPI.

Results: Eighty-five patients met inclusion criteria. 28 (33%) patients were in the ECMO/mortality group. The mean GA of the cohort was 38.1 weeks and mean birth weight was 3150 gm with no statistical difference between groups. The ECMO/mortality group had higher heart rate (135.76 ± 21 vs 117.61 ± 25, p=0.01) and higher OI (22.79 ± 14.53 vs 6.31 ± 8.35, p < 0.001). The prevalence of receiving iNO, Sildenafil, Milrinone, and inotropic support was also higher in the ECMO/mortality group (all with p< 0.001). Significant echocardiography parameters included lower TAPSE (0.67 ± 0.22 vs 0.85 ± 0.27, p=0.002), higher LV eccentricity index (2.37 ± 1.05 vs 1.67 ± 0.70, p=0.005), higher prevalence of right to left shunt across PFO and PDA (p=0.001), and a lower PPI (1.89±0.96 vs 3.43±1.28, p= < 0.001). There was no statistically significant difference in TRV or FAC. On multivariate regression, PPI was the only echocardiographic parameter to independently predict freedom from ECMO/mortality with an adjusted OR of 0.39 (95% C.I: 0.178-0.846, p=0.017).

Conclusion: The Pulmonary Perfusion Index (PPI) is a novel echocardiographic parameter that independently predicts ECMO/mortality in PPHN. It can be used as a surrogate marker for assessing disease severity and early prognosis in PPHN.