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An independent bench comparison of two bioresorbable drug-eluting coronary scaffolds (Absorb and DESolve) with a durable metallic drug-eluting stent (ML8/Xpedition)

Selected in EuroIntervention by S. Brugaletta

References

Authors

Ormiston J, Webber B, Ubod B, Darremont O, Webster M

Reference

EuroIntervention 2015;10-online publish-ahead-of-print February 2015

Link

Access article

Aims

We compared the mechanical and physical properties and the safety from strut fracture of side branch and post-dilatation strategies for the Absorb and DESolve bioresorbable scaffolds with the durable metallic drug-eluting XIENCE Xpedition stent using largely independent bench testing.

Methods and results

The strut thickness and crossing profile of the polymeric scaffolds was greater than those of the metallic drug-eluting stent. While all three devices recoiled after deployment, the DESolve enlarged between 10 mins and one hour returning to the immediate post-deployment diameter (“self-correction”). In 3.0 mm stents/scaffolds, the main branch post-dilatation safe threshold without fracture for Absorb was 3.8 mm at 20 atm, for DESolve was 5.0 mm at 20 atm whereas the ML8 did not fracture. For side branch dilatation with a 3.0 mm non-compliant balloon, the threshold before the Absorb fractured was 10 atm whereas the DESolve and ML8 did not fracture at 22 atm. The safe threshold for mini-kissing balloon post-dilatation in 3.0 mm scaffolds/stents with 3.0 mm non-compliant balloons was 5 atm for the Absorb whereas the DESolve and ML8 did not fracture up to 20 atm.

Conclusions

The metallic stent has thinner struts, lower profile, and greater radial strength than the polymeric scaffolds. Different safe pressure thresholds exist for different scaffolds/stents. Unlike the others, the DESolve showed “self-correction” or enlargement after initial recoil.

My Comment

What is known 

As the physical properties of various polymers differ from each other and from those of metals, different polymeric bioresorbable scaffold (BRS) behave differently from each other and from metallic drug-eluting stent (DES). Polymeric struts may break more readily than metallic struts, and the crossing profile of polymeric BRS may be larger than that of metallic DES. The interventionalist needs to understand the different BRS performance characteristics in order to select appropriate coronary lesions for BRS, and to deliver, deploy and post-dilate BRS appropriately and safely. This study compares the mechanical and physical properties of the Absorb and DESolve (Elixir Medical Corp., Sunnyvale, CA, USA) BRS with the durable metallic DES, XIENCE Xpedition (bare metal version is MultiLink 8, ML8) (Abbott Vascular), largely using independent bench testing. In particular, it determines safe post-dilatation and side branch dilatation strategies.

Major findings

  • The strut thickness and crossing profile of the polymeric scaffolds was greater than those of the metallic drug-eluting stent.
  • While all three devices recoiled after deployment, the DESolve enlarged between 10 mins and one hour returning to the immediate post-deployment diameter (“self-correction”).
  • In 3.0 mm stents/scaffolds, the main branch post-dilatation safe threshold without fracture for Absorb was 3.8 mm at 20 atm, for DESolve was 5.0 mm at 20 atm whereas the ML8 did not fracture.
  • For side branch dilatation with a 3.0 mm non-compliant balloon, the threshold before the Absorb fractured was 10 atm whereas the DESolve and ML8 did not fracture at 22 atm.
  • The safe threshold for mini-kissing balloon post-dilatation in 3.0 mm scaffolds/stents with 3.0 mm non-compliant balloons was 5 atm for the Absorb whereas the DESolve and ML8 did not fracture up to 20 atm.

Comments  

This is a very interesting technical report on how to use safely BRS in daily clinical practice. After their introduction, it was clear that implantation technique was different as compared to DES, especially due to its thick crossing profile and to possible strut fracture when struts need to be dilated at the level of a side branch. For these reasons, the present report represents a useful guide on how to optimize their implantation. As physicians start to increase the use of BRS in daily practice, such independent testing is critical for a better understanding and use of these products in the most effective and safe manner. Post-dilatation, side branch dilatation and mini-kissing balloon post-dilatation can all be performed safely without strut fracture if safe pressures and balloon sizes are selected according to these testing results.

1 comment

  • mazen sudqi abuhusein 30 Aug 2015

    Thank you for this technical data ,which will help us when and how to use BRS