In vitro performance investigation of bioresorbable scaffolds - Standard tests for vascular stents and beyond

BACKGROUND/PURPOSE

Biodegradable polymers are the main materials for coronary scaffolds. Magnesium has been investigated as a potential alternative and was successfully tested in human clinical trials. However, it is still challenging to achieve mechanical parameters comparative to permanent bare metal (BMS) and drug-eluting stents (DES). As such, in vitro tests are required to assess mechanical parameters correlated to the safety and efficacy of the device.

METHODS/MATERIALS

In vitro bench tests evaluate scaffold profiles, length, deliverability, expansion behavior including acute elastic and time-dependent recoil, bending stiffness and radial strength. The Absorb GT1 (Abbott Vascular, Temecula, CA), DESolve (Elixir Medical Corporation, Sunnyvale, CA) and the Magmaris (BIOTRONIK AG, Bülach, Switzerland) that was previously tested in the BIOSOLVE II study, were tested.

RESULTS

Crimped profiles were 1.38±0.01mm (Absorb GT1), 1.39±0.01mm (DESolve) and 1.44±0.00mm (Magmaris) enabling 6F compatibility. Trackability was measured depending on stiffness and force transmission (pushability). Acute elastic recoil was measured at free expansion and within a mock vessel, respectively, yielding results of 5.86±0.76 and 5.22±0.38% (Absorb), 7.85±3.45 and 9.42±0.21% (DESolve) and 5.57±0.72 and 4.94±0.31% (Magmaris). Time-dependent recoil (after 1h) was observed for the Absorb and DESolve scaffolds but not for the Magmaris. The self-correcting wall apposition behavior of the DESolve did not prevent time-dependent recoil under vessel loading.

CONCLUSIONS

The results of the suggested test methods allow assessment of technical feasibility based on objective mechanical data and highlight the main differences between polymeric and metallic bioresorbable scaffolds.

One-Year Clinical and Computed Tomography Angiographic Outcomes After Bioresorbable Vascular Scaffold Implantation During Primary Percutaneous Coronary Intervention for ST-Segment-Elevation Myocardial Infarction: The PRAGUE-19 Study

BACKGROUND

Bioresorbable vascular scaffolds (BVS) represent promising new technology, but data on their long-term outcomes in ST-segment-elevation myocardial infarction (STEMI) setting are missing. The aim was to analyze 1-year clinical and computed tomographic angiographic outcomes after BVS implantation in STEMI.

METHODS AND RESULTS

PRAGUE-19 is a prospective multicenter single-arm study enrolling consecutive STEMI patients undergoing primary percutaneous coronary intervention (pPCI) with intention-to-implant BVS. A total of 343 STEMI patients were screened during 15 months enrollment period, and 70 patients (mean age 58.6±10.3 and 74% males) fulfilled entry criteria and BVS was successfully implanted in 96% of them. All patients were invited for clinical and computed tomographic angiographic control 1 year after BVS implantation. Restenosis was defined as ≥75% area stenosis within the scaffolded segment. Three events were potentially related to BVS: 1 in-stent restenosis (treated 7 months after pPCI with drug-eluting balloon), 1 stent thrombosis (treated 2 weeks after pPCI by balloon dilatation-this patient stopped all medications after pPCI), and 1 sudden death at home 9 months after pPCI. Four other patients had events definitely unrelated to BVS. Overall, 1-year mortality was 2.9%. Computed tomographic angiography after 1 year was performed in 59 patients. All BVS were widely patent, and binary restenosis rate was 2% (the only restenosis mentioned above). Mean in-scaffold minimal luminal area was 7.8±2.6 mm(2), area stenosis was 20.1±16.3%, minimal luminal diameter was 3.0±0.6 mm, and diameter stenosis was 12.8±11.1%.

CONCLUSIONS

BVS implantation in STEMI is feasible and safe and offers excellent 1-year clinical and angiographic outcomes.