Optical coherence tomography guidance during bioresorbable vascular scaffold implantation

Long-Term Outcomes After Implantation of Magnesium-Based Bioresorbable Scaffolds—Insights From an All-Comer Registry

Background

The magnesium-based sirolimus-eluting bioresorbable scaffold (Mg-BRS) Magmaris™ showed promising clinical outcomes, including low rates of both the target lesion failure (TLF) and scaffold thrombosis (ScT), in selected study patients. However, insights regarding long-term outcomes (>2 years) in all-comer populations remain scarce.

Methods

We analyzed data from a single-center registry, including patients with acute coronary syndrome (ACS) and chronic coronary syndrome (CCS), who had undergone percutaneous coronary intervention (PCI) using the Mg-BRS. The primary outcome comprised the device-oriented composite endpoint (DoCE) representing a hierarchical composite of cardiac death, ScT, target vessel myocardial infarction (TV-MI), and clinically driven target lesion revascularization (TLR) up to 5 years.

Results

In total, 84 patients [mean age 62 ± 11 years and 63 (75%) men] were treated with the Mg-BRS devices between June 2016 and March 2017. Overall, 101 lesions had successfully been treated with the Mg-BRS devices using 1.2 ± 0.4 devices per lesion. Pre- and postdilatation using dedicated devices had been performed in 101 (100%) and 98 (97%) of all the cases, respectively. After a median follow-up time of 62 (61–64) months, 14 (18%) patients had experienced DoCEs, whereas ScT was encountered in 4 (4.9%) patients [early ScTs (<30 days) in three cases and two fatal cases]. In 4 (29%) of DoCE cases, optical coherence tomography confirmed the Mg-BRS collapse and uncontrolled dismantling.

Conclusion

In contradiction to earlier studies, we encountered a relatively high rate of DoCEs in an all-comer cohort treated with the Mg-BRS. We even observed scaffold collapse and uncontrolled dismantling. This implicates that this metal-based BRS requires further investigation and may only be used in highly selected cases.

Impact of bioresorbable scaffold design characteristics on local haemodynamic forces: an ex vivo assessment with computational fluid dynamics simulations

AIMS

Bioresorbable scaffold (BRS) regions exposed to flow recirculation, low time-averaged wall shear stress (TAWSS) and high oscillatory shear index (OSI) develop increased neointima tissue. We investigated haemodynamic features in four different BRSs.

METHODS AND RESULTS

Fantom (strut height [SH] = 125 µm), Fantom Encore (SH = 98 µm), Absorb (SH = 157 µm) and Magmaris (SH = 150 µm) BRSs were deployed in phantom tubes and imaged with microCT. Both 2D and 3D geometrical scaffold models were reconstructed. Computational fluid dynamics (CFD) simulation was performed to compute TAWSS and OSI. Thicker struts had larger recirculation zones and lower TAWSS in 2D. Absorb had the largest recirculation zone and the lowest TAWSS (240 µm and -0.18 Pa), followed by Magmaris (170 µm and -0.15 Pa), Fantom (140 µm and -0.14 Pa) and Fantom Encore (100 µm and -0.13 Pa). Besides strut size, stent design played a dominant role in 3D. The highest percentage area adverse TAWSS (<0.5 Pa) and OSI (>0.2) were found for Fantom (56% and 30%) and Absorb (53% and 33%), followed by Fantom Encore (30% and 25%) and Magmaris (25% and 20%). Magmaris had the smallest areas due to a small footprint and rounded struts.

CONCLUSIONS

Due to stent design, both Fantom Encore and Magmaris showed smaller TAWSS and OSI than Fantom and Absorb. This study quantifies which scaffold features are most important to reduce long-term restenosis.

Three-year outcomes of bioresorbable vascular scaffolds versus second-generation drug-eluting stents: Meta-analysis of randomized trials

BACKGROUND

Bioresorbable vascular scaffolds (BVS) completely resorb within 3 years after placement into the coronary artery. The safety and effectiveness of bioabsorbable scaffolds are of critical importance during this 3-year period.

OBJECTIVE

We performed a meta-analysis to compare the safety and efficacy of BVS and second-generation drug-eluting stents (DES) at 3 years after implantation.

METHODS

Published randomized trials comparing BVS to second-generation DES for the treatment of coronary artery disease were identified within PubMed, EMBASE, Cochrane Library, Web of Science, and relevant Web sites with publication dates through June 2019. The primary efficacy endpoint was target lesion failure. The primary safety endpoint was definite/probable stent/scaffold thrombosis. Secondary outcomes were cardiac death, target vessel myocardial infarction, ischemia-driven target lesion revascularization, and a patient-oriented composite end point.

RESULTS

Six randomized controlled trials, with a total of 5,412 patients (BVS n = 3,177; DES n = 2,235), were included. At 3 years, BVS was associated with higher rates of target lesion failure (OR = 1.33, 95%CI: 1.10-1.60, P = 0.003) and definite/probable stent/scaffold thrombosis (OR = 3.75, 95% CI: 2.22-6.35, P < .00001)compared with DES. The incidence of target vessel myocardial infarction (OR = 1.68, 95% CI: 1.30-2.17, P < .0001), ischemia-driven target lesion revascularization (OR = 1.46, 95% CI: 1.14-1.86, P = .003), and the patient-oriented composite end point(OR = 1.20, 95% CI: 1.04-1.39, P = .01) were higher for those treated with BVS compared with DES. However, there was no significant difference in risk of cardiac death (OR = 0.94, 95%CI: 0.61-1.45, P = .79) between treatment groups.

CONCLUSIONS

At the 3-year follow-up, BVS was inferior to second-generation DES in both safety and efficacy.

Imaging during percutaneous coronary intervention for optimizing outcomes

Angiography is the current gold standard for imaging during percutaneous coronary interventions but has significant limitations. Catheter-based intravascular imaging techniques such as intravascular ultrasound and the more recent optical coherence tomography have the potential to overcome these limitations and thus optimize clinical outcomes. In this update, we discussed the current applications of the available imaging techniques, existing evidence, continuing unmet needs, and potential areas for further research.