Recipient Twin Circular Shunt Physiology Before Fetal Laser Surgery: Survival and Risks for Postnatal Right Ventricular Outflow Tract Obstruction.

Objectives: To evaluate risk for congenital heart disease (CHD) in recipient twins with circular shunt physiology (CSP).

Methods: This prospective study enrolled twin-twin transfusion syndrome (TTTS) cases from 2006 to 2015. Fetal echocardiography (FE) was performed before laser surgery when cardiac involvement was suspected. Diagnosis of recipient twin CSP required tricuspid and pulmonary regurgitation, right ventricular dysfunction, and flow reversal in the ductus arteriosus. Outcomes were assessed at 30 days after birth.

Results: Of the 496 TTTS pregnancies, 20 (4%) met the criteria for CSP. Among those born alive, who had documented cardiac outcomes (n = 457), patients with CSP were more likely to have CHD, specifically right ventricular outflow tract obstruction (5 of 18 [27.8%] versus 22 of 439 [5.0%], odd ratio [OR] 7.29, 95% confidence interval [CI] 2.05-24.72, P = .0025). Of the recipient twins with preoperative FE (n = 259, 52%) who were born alive and had documented cardiac outcomes (n = 242), those with CSP were still more likely to have right ventricular outflow tract obstruction (5 of 18 [27.8%] versus 14 of 224 [6.3%], OR 5.77, CI 1.54-20.92, P = .0077). With both analyses, twins with CSP had higher Quintero stage, but similar patient characteristics and 30-day mortality compared with those without CSP. Subgroup analyses of the CSP cohort identified no differences in preoperative characteristics or FE findings predictive of CHD.

Conclusions: Recipient twins with preoperative CSP were at increased risk for postnatal right ventricular outflow tract obstruction, but appeared to have comparable survival after fetal laser surgery despite these dramatic pathophysiological prenatal findings. Preoperative FE in TTTS remains important for prediction of postnatal CHD.