Absorb everolimus-eluting bioresorbable scaffolds in coronary bifurcations: a bench study of deployment, side branch dilatation and post-dilatation strategies.

AIMS: To provide bench insights which may predict safety and efficacy of side branch dilatation (SB) and kissing balloon post-dilatation (KBPD) in Absorb everolimus-eluting bioresorbable scaffolds deployed in bifurcations. METHODS AND
RESULTS: Stages of deployment and post-dilatation of scaffolds (3.0 and 3.5 mm diameter) in bifurcation phantoms were imaged by fluoroscopy, light microscopy and micro-computed tomography. Dilatation through the scaffold side displaced struts from the side branch (SB) lumen, but caused main branch (MB) malapposition opposite the SB, MB scaffold narrowing beyond the SB, and protrusion of struts into the SB. Scaffold distortion was corrected by MB post-dilatation or by mini-kissing balloon post-dilatation (mini-KBPD). When 3.0 mm diameter balloons were used for SB dilatation or mini-KBPD in 3.0 mm Absorbs, strut fracture did not occur at or below inflation pressures of 10 and 5 atm, respectively. Above these thresholds, the likelihood of strut fracture increased with increasing pressure. Fractures were usually single without malapposition, but mini-KBPD or post-dilatation with high inflation pressures sometimes caused multiple strut fractures and lumen compromise.
CONCLUSIONS: SB dilatation of an Absorb caused MB distortion which was corrected by MB post-dilation or low-pressure mini-KBPD without scaffold damage below pressure thresholds. These benchtop insights may help guide the clinical deployment of Absorb scaffolds in bifurcations and might enhance clinical outcomes but need clinical confirmation.