Device specificity of vascular healing following implantation of bioresorbable vascular scaffolds and bioabsorbable polymer metallic drug-eluting stents in human coronary arteries: the ESTROFA OCT BVS vs. BP-DES study

Coronary microevaginations characterize culprit plaques and their inflammatory microenvironment in a subtype of acute coronary syndrome with intact fibrous cap: results from the prospective translational OPTICO-ACS study

AIMS

Coronary microevaginations (CMEs) represent an outward bulge of coronary plaques and have been introduced as a sign of adverse vascular remodelling following coronary device implantation. However, their role in atherosclerosis and plaque destabilization in the absence of coronary intervention is unknown. This study aimed to investigate CME as a novel feature of plaque vulnerability and to characterize its associated inflammatory cell-vessel-wall interactions.

METHODS AND RESULTS

A total of 557 patients from the translational OPTICO-ACS study programme underwent optical coherence tomography imaging of the culprit vessel and simultaneous immunophenotyping of the culprit lesion (CL). Two hundred and fifty-eight CLs had a ruptured fibrous cap (RFC) and one hundred had intact fibrous cap (IFC) acute coronary syndrome (ACS) as an underlying pathophysiology. CMEs were significantly more frequent in CL when compared with non-CL (25 vs. 4%, P < 0.001) and were more frequently observed in lesions with IFC-ACS when compared with RFC-ACS (55.0 vs. 12.7%, P < 0.001). CMEs were particularly prevalent in IFC-ACS-causing CLs independent of a coronary bifurcation (IFC-ICB) when compared with IFC-ACS with an association to a coronary bifurcation (IFC-ACB, 65.4 vs. 43.7%, P = 0.030). CME emerged as the strongest independent predictor of IFC-ICB (relative risk 3.36, 95% confidence interval 1.67-6.76, P = 0.001) by multivariable regression analysis. IFC-ICB demonstrated an enrichment of monocytes in both culprit blood analysis (culprit ratio: 1.1 ± 0.2 vs. 0.9 ± 0.2, P = 0.048) and aspirated culprit thrombi (326 ± 162 vs. 96 ± 87 cells/mm2, P = 0.017), while IFC-ACB confirmed the accumulation of CD4+ T cells, as recently described.

CONCLUSION

This study provides novel evidence for a pathophysiological involvement of CME in the development of IFC-ACS and provides first evidence for a distinct pathophysiological pathway for IFC-ICB, driven by CME-derived flow disturbances and inflammatory activation involving the innate immune system.

TRIAL REGISTRATION

Registration of the study at clinicalTrials.gov (NCT03129503).

Structural and Functional Evaluation of Coronary Arteries Treated With ABSORB Bioresorbable Vascular Scaffold at 5-Year Follow-Up

Although complete bioresorbable vascular scaffold (BVS) resorption has been demonstrated at 5-year follow-up, whether corresponding vasomotor function restoration occurs remains unknown. The objective was to simultaneously assess the structural healing response along with vasomotor responses at 5-year follow-up of BVS implantation. We studied consecutive patients treated with ABSORB-BVS at 5-year follow-up (n = 31), who were recruited from a multicenter registry and were contacted to undergo a research protocol-driven repeat coronary angiogram involving intracoronary optical coherence tomography (OCT) and invasive coronary endothelial function testing. Epicardial endothelium-dependent vasomotion was defined as any vasodilatation after intracoronary acetylcholine (ACh), whereas endothelium-independent vasomotion was defined as any vasodilatation after intracoronary nitroglycerine (NTG), using quantitative coronary angiography. The mean implantation time point was 60.5 ± 4.6 months. OCT imaging demonstrated complete scaffold resorption in all patients. New coronary lesions (stenosis >50%) were found in 5 patients (16.1%), 3 of them underwent ad hoc percutaneous revascularization (9.7%). Intracoronary ACh (27 patients) and NTG testing (30 patients) was performed. Quantitative coronary angiography analysis demonstrated vasoconstriction after ACh administration and lack of response to NTG in BVS segments (mean lumen diameter = 2.00 ± 0.61 mm at baseline vs 1.74 ± 0.70 mm post-ACh, p <0.001; 2.05 ± 0.54 mm at baseline vs 2.03 ± 0.50 mm post-NTG, p = 0.69). OCT lumen analysis demonstrated similar vasoconstrictive responses to ACh (mean lumen area = 5.31 ± 2.26 mm² at baseline vs 5.12 ± 2.55 mm² post-ACh, p = 0.007) but had a vasodilatory response to NTG (5.96 ± 2.35 mm² at baseline vs 6.17 ± 2.55 mm² post-NTG, p<0.001). In conclusion, complete ABSORB-BVS resorption was demonstrated at 5-year follow-up. However, this healing response was associated with endothelium-dependent vasomotor dysfunction within the BVS segment.

Can an ultrathin strut stent design and a polymer free, proendothelializing probucol matrix coating improve early strut healing? The FRIENDLY-OCT trial. An intra-patient randomized study with OCT, evaluating early strut coverage of a novel probucol coated polymer-free and ultra-thin strut sirolimus-eluting stent compared to a biodegradable polymer sirolimus-eluting stent

BACKGROUND

incomplete strut coverage determines the risk of stent thrombosis in the first months after stent implantation.

AIMS

To evaluate the potential better early healing of a novel probucol coated polymer free ultra-thin strut sirolimus eluting stent (PF-SES). [Clinical trial unique identifier: NCT02785237].

METHODS

Patients with two (angiographically similar) lesions with clinical indication for PCI were enrolled. The investigated stent was compared to a thin strut, bioresorbable polymer, sirolimus eluting stent (BP-SES). Every patient received both stents, one in each lesion, assigned in a randomized sequence. OCT was systematically performed at 3 months. Primary end point was the difference in the proportion of covered struts at 3 months (defined as ≥20 μm of tissue coverage). Secondary end points included differences in percentage of uncovered struts (0 μm coverage), mean strut coverage thickness, and malapposed struts' coverage proportion. Major adverse cardiac events (cardiac death, myocardial infarction, target lesion revascularization, and definite or probable stent thrombosis) at 12 months were also evaluated.

RESULTS

70 patients were included. At 3 months, a consistent and significantly higher strut coverage rate (≥20 μm) was observed in PF-SES as compared to BP-SES, both for well apposed (87.3% versus 79.1%, p < 0.001) and malapposed struts (50.4% vs 37.8%, p 0.00). Uncoverage rate (0 μm) was also significantly lower for the PF-SES (3.1% vs 5.3%, p < 0.001). There were no differences in clinical endpoints.

CONCLUSION

The probucol coated non-polymeric ultra-thin strut sirolimus eluting stent showed a significantly better early strut coverage at 3 months.

Modern Stents: Where Are We Going?

Coronary artery stenting is the treatment of choice for patients requiring coronary angioplasty. We describe the major advancements with this technology. There have been significant developments in the design of stents and adjunctive medical therapies. Newer-generation drug-eluting stents (DES) have almost negligible restenosis rates and, when combined with proper anti-platelet treatment and optimal deployment, a low risk of stent thrombosis. The introduction of newer-generation DES with thinner stent struts, novel durable or biodegradable polymer coatings, and new antiproliferative agents has further improved the safety profile of early-generation DES. In parallel the effectiveness has been kept, with a significant reduction in the risk of target lesion revascularization compared with the early-generation DES. However, to date, the development of completely bioresorbable vascular scaffolds has failed to achieve further clinical benefits and has been associated with increased thrombosis. Newer-generation DES-including both durable polymer as well as biodegradable polymer-have become the standard of care in all patient and lesion subsets, with excellent long-term results.

Bioresorbable Vascular Scaffolds-Dead End or Still a Rough Diamond?

Percutaneous coronary interventions with stent-based restorations of vessel patency have become the gold standard in the treatment of acute coronary states. Bioresorbable vascular scaffolds (BVS) have been designed to combine the efficiency of drug-eluting stents (DES) at the time of implantation and the advantages of a lack of foreign body afterwards. Complete resolution of the scaffold was intended to enable the restoration of vasomotor function and reduce the risk of device thrombosis. While early reports demonstrated superiority of BVS over DES, larger-scale application and longer observation exposed major concerns about their use, including lower radial strength and higher risk of thrombosis resulting in higher rate of major adverse cardiac events. Further focus on procedural details and research on the second generation of BVS with novel properties did not allow to unequivocally challenge position of DES. Nevertheless, BVS still have a chance to present superiority in distinctive indications. This review presents an outlook on the available first and second generation BVS and a summary of results of clinical trials on their use. It discusses explanations for unfavorable outcomes, proposed enhancement techniques and a potential niche for the use of BVS.