Impact of pre-stage II hemodynamics and pulmonary artery anatomy on 12-month outcomes in the Pediatric Heart Network Single Ventricle Reconstruction trial

Objective: To compare the interstage cardiac catheterization hemodynamic and angiographic findings between shunt types for the Pediatric Heart Network Single Ventricle Reconstruction trial. The trial, which randomized subjects to a modified Blalock-Taussig shunt (MBTS) or right ventricle-to-pulmonary artery shunt (RVPAS) for the Norwood procedure, demonstrated the RVPAS was associated with a smaller pulmonary artery diameter but superior 12-month transplant-free survival.

Methods: We analyzed the pre-stage II catheterization data for the trial subjects. The hemodynamic variables and shunt and pulmonary angiographic data were compared between shunt types; their association with 12-month transplant-free survival was also evaluated.

Results: Of 549 randomized subjects, 389 underwent pre-stage II catheterization. A smaller size, lower aortic and superior vena cava saturation, and higher ventricular end-diastolic pressure were associated with worse 12- month transplant-free survival. The MBTS group had a lower coronary perfusion pressure (27 vs 32 mm Hg; P.001) and greater pulmonary blood flow/systemic blood flow ratio (1.1 vs 1.0, P = .009). A greater pulmonary blood flow/systemic blood flow ratio increased the risk of death or transplantation only in the RVPAS group (P=.01). The MBTS group had fewer shunt (14%vs 28%, P=.004) and severe left pulmonary artery (0.7%vs 9.2%, P = .003) stenoses, larger mid-main branch pulmonary artery diameters, and greater Nakata indexes (164 vs 134, P < .001).

Conclusions: Compared with the RVPAS subjects, the MBTS subjects had more hemodynamic abnormalities related to shunt physiology, and the RVPAS subjects had more shunt or pulmonary obstruction of a severe degree and inferior pulmonary artery growth at pre-stage II catheterization. A lower body surface area, greater ventricular end-diastolic pressure, and lower superior vena cava saturation were associated with worse 12-month transplant-free survival.