Results of the multicenter early feasibility study (EFS) of the Renata Minima stent as treatment for branch pulmonary artery stenosis and coarctation of aorta in infants.

Results of the multicenter early feasibility study (EFS) of the Renata Minima stent as treatment for branch pulmonary artery stenosis and coarctation of aorta in infants.

Berman DP, Morray B, Sullivan P, Shahanavaz S, Zahn EM.Catheter Cardiovasc Interv. 2024 Jul;104(1):61-70. doi: 10.1002/ccd.31074. Epub 2024 May 12.PMID: 38736246

Take Home Points

  • The Minima Stent is a symmetrical, closed cell cobalt-chromium stent premounted on either a 6 or 8 mm balloon with in-vitro dilation up to 24 mm in diameter
  • The stent is delivered by the Minima Delivery System which has an outer diameter equivalent to a 4 Fr sheath.
  • In this early feasibility study all 10 patients had successful stent implantation without serious adverse events

Commentary from Dr. Jonathon Hagel (C.S. Mott Children’s Hospital, University of Michigan)

Endovascular stent implantation for the treatment of branch pulmonary artery stenosis and coarctation of the aorta has become the mainstay of treatment for older children and young adults with stents that can be implanted with a final diameter that can reach adult size. Unfortunately, there remains a gap in the availability of a stent which can be implanted at a size appropriate for infants but that can also be dilated to adult size. Further, current stent technology requires delivery through large delivery sheaths leading to increased risk of vascular injury. The authors of this early feasibility study sought to address the safety and feasibility of the newly developed Renata Minima Stent and delivery system that were specifically designed to meet these needs. 

The Minima Stent is a symmetrical, closed cell cobalt-chromium stent which is delivered by the Minima Delivery System which has an outer diameter equivalent to a 4 Fr sheath and can be advanced through a 6 Fr sheath if desired. The stent is premounted on either a 6 or 8 mm balloon with in-vitro dilation up to 24 mm in diameter while maintaining radial strength. The stent has a predictable shortening profile starting at 17mm fully crimped that shortens down to 5mm when dilated to 22mm. 

The median age at implant was 9 months with a median weight of 7.6 Kg. The stent was successfully deployed in 10/10 patients and all patients met the predefined primary efficacy endpoint of successful relief of stenosis with >50% increase in vessel diameter and all were free of stent explant at 6 months post-implantation. Two patients treated for coarctation of the aorta developed pulse loss requiring low molecular weight heparin initiation and one patient had malposition of stent placement requiring a second stent to treat the lesion. Five patients have had elective stent re-dilation at a mean of 7 months post-implantation.

In this early feasibility study, the Renata Minima Stent is safe and effective at treating infants and young children with native and recurrent branch pulmonary artery stenosis and coarctation of the aorta. This study, by nature of it design, was not able to describe in-human stent characteristics when dilated to adult diameters, though significant stent shortening and long-term radial strength without frame fracture remain uncertain. A multi-center pivotal trial is ongoing targeting the enrollment of 42 patients across 7 centers which will provide a larger cohort with longer follow-up to address some of these ongoing concerns.