Abstract Body (Do not enter title and authors here): Background: Tetralogy of Fallot with absent pulmonary valve (TOF/APV) is a rare congenital heart defect with a broad spectrum of outcomes. A multicenter study of prenatally diagnosed patients found left ventricular (LV) systolic dysfunction predicted fetal demise and prenatal right ventricular (RV) dysfunction predicted overall mortality and branch pulmonary artery (PA) diameter was not predictive of outcome.

Research Questions: To evaluate the relationship between prenatal and postnatal echocardiographic measures and whether postnatal echocardiographic findings were associated with morbidity and mortality.

Methods: We included liveborn patients from the prenatally diagnosed multicenter cohort. Differences between prenatal and postnatal measures were assessed using the paired t-test. Association between postnatal echocardiographic measures and outcomes were assessed using logistic regression. Outcomes included respiratory arrest, inotrope use, cardiac arrest, extracorporeal membrane oxygenation within 48 hours of birth, surgery during initial admission, death prior to and after discharge.

Results: Of 59 patients (42% male), mean gestational age at birth was 37.9 weeks and birthweight 2877 grams. Abnormal genetics were present in 23/53 (39%), with 20/53 (34%) with 22q11 deletion. Postnatal echo had larger branch PA diameters and RV size with increased pulmonary valve (PV) peak velocity and velocity time integral (VTI) and decreased LV function (Table 1). Univariate analysis revealed RV systolic dysfunction to be associated with respiratory and cardiac arrest. LV systolic dysfunction was associated with inotrope use and respiratory arrest (Table 2). Higher PV peak velocity and PV VTI were associated with lower likelihood of inotrope use, respiratory arrest, and surgery during initial admission. RV dilation, RV and LV systolic dysfunction were associated with death prior to discharge. Increased branch PA diameter correlated with respiratory arrest, inotrope use, early surgery, and death prior to discharge (Table 2,3).

Conclusions: Signs of poor cardiac output including increased RV dilation and RV or LV dysfunction were associated with poor outcome. Newborns with increased PV peak velocity and VTI after birth had better outcomes, possibly due to better RV systolic function or decreased pulmonary vascular resistance (anatomical or functional). In contrast to prenatal findings, larger branch PA diameter was associated with poor outcome.