Bioabsorbable everolimus-eluting stent experience in newborns and infants with congenital heart disease – clinical application and pharmacokinetics

Background
There remains an important role for small diameter stents in the management of blood vessels associated with congenital heart disease. Shortcomings of current stents have been the limited future expansion capabilities and in-stent stenosis. The Absorb stent (Abbott Vascular, Santa Clara, CA) is a bioresorbable everolimus-eluting coronary stent which disappears over 2-3 years with potential to restore the regular functions of the blood vessel wall. Furthermore, even prior to complete disappearance, these stents may be amenable to circumferential fracture and earlier intervention.

Methods
This is a retrospective review of infants and children who underwent implantation of the bioabsorbable everolimus-eluting stents (Absorb) and everolimus pharmacokinetics.

Results
During the period between September 2016 and October 2017, 17 Absorb stents were implanted into 15 blood vessels of 13 patients. The median patient age and weight were 180 (17, 511) days and 6.0 (2.9, 12.2) kg respectively. Stented blood vessels were left pulmonary artery (n=7), lower left pulmonary artery (n=3), right pulmonary artery (n=1) and pulmonary vein (n=6). All stents were 3.5 mm nominal diameter inflated to 4.0 mm. Six (40%) of the blood vessels had ineffective balloon dilations prior to stent implantation. There were no procedural complications. Peak serum everolimus level was 21.2 ng/mL at 1 hour. All patients were within or below therapeutic range at 24 hours and were all below therapeutic level by 5 days (n=11). No patient experienced adverse events related to the everolimus drug. Thirteen (87%) stented vessels were amenable to further intervention – balloon dilation alone (n=10), balloon dilation with additional stent implantation (n=1), additional stent (n=2) at a median interval of 96 (9, 356) days. Indications for intervention were progressive vessel narrowing in n=20 (80%) and need for further vessel enlargement in 5 vessels.

Conclusions
Bioabsorbable everolimus-eluting stents provided effective and safe improvement of severely stenotic blood vessels. The re-intervention rate was high but anticipated. Stented blood vessels were amenable to re-intervention prior to complete resorption.