In-Vivo Vascular Healing Following Bifurcation Interventions with the Absorb Bioresorbable Vascular Scaffold.

BACKGROUND

Long-term vascular healing, evaluated by optical coherence tomography (OCT) and histology, following complex bifurcation interventions with polymeric Absorb Bioresorbable Vascular Scaffold (BVS, Abbott Vascular, Santa Clara, CA) has not been previously described.

METHODS

Fifteen New-Zealand-White rabbits (4.0 ± 0.3 kg) underwent stenting of non-diseased aorto-iliac bifurcations with BVS using provisional stenting (PS, n = 2), culotte stenting (n = 7) and modified-T (n = 6) stenting techniques. At 18 months angiography, optical coherence tomography (OCT) and histology were performed.

RESULTS

The acute angiographic results were excellent. Three rabbits succumbed acutely due to anaesthetic and renal complications, whilst one was euthanized electively at 4 months for a skin infection. At 18 months, 11 rabbits (PS (2), modified-T (4) and culotte (5)) underwent angiography, revealing excellent results, followed by OCT and histological evaluation. No acute scaffold thrombosis occurred. All non-bifurcation segments revealed complete endothelialisation with excellent healing characteristics on OCT and histology. Following one PS and all 2-stent techniques, uncovered, deformed and malapposed struts were present at the neocarina with adherent fibrin and chronic thrombus in 10/11 cases, extending as long fibrin strands (mean length 11.0 ± 8.3 mm) in 3 culotte and 1 modified-T cases. Late intraluminal scaffold discontinuity was present following five 2-stent cases.

CONCLUSIONS

Pathological vascular healing with uncovered, distorted and malapposed neocarinal struts with adherent strands of chronic thrombus, suggest that exposed polymeric breakdown products may be thrombogenic and caution against the use of polymeric BVS in interventions when there is a chance of suboptimal results with strut malapposition or compromise of scaffold integrity.