Effect of non-compliant balloon postdilatation on magnesium-based bioresorbable vascular scaffolds.

Background: Optimal implantation results of bioresorbable scaffolds (BRS) are typically assumed to require postdilatation with non-compliant (NC) balloons to achieve full scaffold apposition and minimize event rates. We systematically evaluated the mechanical effect of NC balloon postdilatation on magnesium-based BRS (Magmaris (R), Biotronik AG, Bulach, Switzerland) in vivo. Methods: In 35 patients, 40 Magmaris (R) BRS were implanted to treat 37 de novo coronary artery stenoses. A systematic implantation protocol was followed. After appropriately sized NC balloon predilatation (1:1:1 vessel: balloon: scaffold ratio), Magmaris (R) BRS were implanted with a pressure of 10 atm, followed by NC balloon postdilatation at nominal BRS size (standardized at 16 atm). OCT was performed before and after postdilatation and OCT images were analyzed at a spacing of 0.2 mm to measure BRS dimensions and determine apposition as well as to detect strut fractures. Results: PCI with Magmaris (R) BRS (mean diameter: 3.21 +/- 0.32 mm; mean length: 20 +/- 4 mm) was successful in all cases, in one case a non-flow-limiting distal edge dissection occurred after implantation and before postdilatation. NC balloon postdilatation led to significantly larger mean scaffold diameter (3.21 +/- 0.32 mm vs. 2.80 +/- 0.39 mm, P < 0.001), abluminal scaffold area (7.92 +/- 1.43 mm(2) vs. 6.72 +/- 1.28 mm(2), P < 0.001) and lumen area (7.58 +/- 1.1 mm(2) vs. 6.83 +/- 1.12 mm(2), P < 0.001). Incomplete scaffold apposition area was significantly lower if postdilatation was performed (0.01 +/- 0.04 mm(2) vs. 0.17 +/- 0.11 mm(2), P < 0.001). Strut fractures could neither be observed before nor after postdilatation. Conclusion: NC balloon postdilatation of Magmaris (R) BRS is required to achieve optimal expansion. It significantly reduces malapposition and can safely be performed without relevant rates of strut fracture.