Background: The bioresorbable scaffold (BRS) is a novel approach for the treatment of coronary artery disease. Outcome after everolimus-eluting BRS implantation seen in registries and meta-analyses continue to show a higher rate of scaffold thrombosis than those reported with DES. The available BRS are poly-lactid acid based. Lately, a resorbable magnesium scaffold gained permission for clinical use (Biotronik Magmaris, Biotronik AG, Bülach, Switzerland).

Objectives: To evaluate the acute performance of resorbable magnesium scaffold using optical coherence tomography (OCT) in terms of appropriate scaffold deployment and to compare acute post-implantation behaviour with novolimus-eluting BRS.

Design: Consecutive patients undergoing PCI with OCT-guided scaffold implantation from January 2014 to July 2017 were reviewed. Using the very final pullback, the following indexes were calculated: mean and minimal area, residual area stenosis (RAS), incomplete strut apposition (ISA), tissue prolapse, eccentricity index, symmetry index, strut fracture and edge dissection. Longitudinal cross-sections were analysed at 1-mm intervals within the stented lesion. Statistical analysis was carried out using IBM SPSS Statistics (SPSS Statistics 23, IBM Deutschland GmbH, Ehningen, Germany).

Results: A total of 98 patients were included. While 79 patients were treated with an DESolve BRS, 19 patients received a Magmaris BRS. Significantly more female patients were enrolled in the Magmaris BRS group (68.4 vs. 36.7%, p=0.01). The patients did not differ significantly with respect to their age (62.0±8.1 vs. 61.7±8.9, p=0.81) and baseline characteristics. Clinical indication was stable angina in most of the cases (66.7 vs. 57.0%, p=0.36). Lesions were of de novo type in all cases. They were typically located in the RCA (47.4 vs. 41.8%, p=0.78). Average BRS diameter (3.1±0.2 vs. 3.1±0.4mm, p=0.91) and length (18.9±4.0 vs. 19.7±5.7mm, p=0.68) were similar in both groups. Post-dilatation was performed in 100% of the cases; pre-dilatation - on the other hand - in only 94.9% of DESolve patients versus 100% in Magmaris BRS group (p=0.33). Maximum post-dilatation balloon inflation pressure (15.4±3,9 vs. 16.6±3.5atm, p=0.29) was akin while similar balloons were used (diameter 3.5±0.3 vs 3.6±0.6mm, p=0.41). Though, in the Magmaris group pre-dilatation (16.5±2.3 vs. 13.7±3.1atm, p<0.001) and BRS deployment pressure were higher (15.1±1.9 vs. 13.4±2.4atm, p<0.001).

OCT analysis did not show a difference in mean scaffold area (7.9±1.5 vs. 7.7±2.3mm², p=0.54) and lumen area (3.4±0.3 vs. 3.4±0.5mm², p=0.30). Minimum scaffold diameter, however, varied significantly (2.9±0.2 vs. 2.7±0.4mm, p=0.01). Assessment of geometrical parameters revealed a mean eccentricity index of 0.89±0.20 vs. 0.70±0.10, p<0.001 and a symmetry index of 0.31±0.08 vs. 0.42±0.09, p<0.001. Mean residual area stenosis was 13.5 and 16.6% respectively. More patients in the DESolve group showed a RAS > 20% (p=0.01). OCT showed dissections predominantly in the DESolve group and strut fractures solely. The percentage of malapposed struts was 0.03 vs. 2.3%, p<0.001.