<b><i>Introduction:</i></b> Monochorionic twins are at increased risk of congenital heart defects (CHDs). Up to 26% have a birth weight <1,500 g, a CHD requiring neonatal surgery, therefore, poses particular challenges. <b><i>Objective:</i></b> The aim of the study was to describe pregnancy characteristics, perinatal management, and outcome of monochorionic twins diagnosed with critical coarctation of the aorta (CoA). <b><i>Methods:</i></b> We included monochorionic twins diagnosed with critical CoA (2010–2019) at 2 tertiary referral centers, and we systematically reviewed the literature regarding CoA in monochorionic twins. <b><i>Results:</i></b> Seven neonates were included. All were the smaller twin of pregnancies complicated by selective fetal growth restriction. The median gestational age at birth was 32 weeks (28–34). Birth weight of affected twins ranged as 670–1,800 g. One neonate underwent coarctectomy at the age of 1 month (2,330 g). Six underwent stent implantation, performed between day 8 and 40, followed by definitive coarctectomy between 4 and 9 months in 4. All 7 developed normally, except for 1 child with neurodevelopmental delay. Three co-twins had pulmonary stenosis, of whom 1 required balloon valvuloplasty. The literature review revealed 10 cases of CoA, all in the smaller twin. Six cases detected in the first weeks after birth were treated with prostaglandins alone, by repeated transcatheter angioplasty or by surgical repair, with good outcome in 2 out of 6. <b><i>Conclusions:</i></b> CoA specifically affects the smaller twin of growth discordant monochorionic twin pairs. Stent implantation is a feasible bridging therapy to surgery in these low birth weight neonates.
The Delphi definition for selective fetal growth restriction may not improve detection of pathologic growth discordance in monochorionic twins.
