Clinical outcomes following "off-label" versus "established" indications of bioresorbable scaffolds for the treatment of coronary artery disease in a real-world population

AIMS

Our aim was to investigate one-year outcomes in patients treated with bioresorbable scaffolds (BRS) for "off-label" versus currently "established" indications.

METHODS AND RESULTS

Consecutive patients treated with BRS between May 2012 and September 2014 in two centres were retrospectively recruited. Patients who met inclusion criteria as defined by the ABSORB III study were allocated to the established indication group (ESTG; 21 patients with 35 lesions) and the remaining patients to the off-label group (OFLG; 168 patients with 225 lesions). Target vessel failure (TVF) and ischaemia-driven target lesion revascularisation (id-TLR) at one year were evaluated in both groups. Patients in the OFLG had a higher prevalence of diabetes mellitus and longer lesion length. Predilatation, post-dilatation and intracoronary imaging were conducted in the majority of patients. At one-year follow-up, TVF (0% vs. 7.8%, p=0.32) and id-TLR (0% vs. 4.5%, p=0.31) occurred only in the OFLG with no adverse events in the ESTG. Definite stent thrombosis occurred in two OFLG patients (1.3%).

CONCLUSIONS

In a real-world setting, the majority (88.9%) of patients were treated with BRS for off-label indications. Off-label use of BRS appears to be associated with an acceptable occurrence of outcomes considering the greater complexity of this patient group.

Procedural and one-year clinical outcomes of bioresorbable vascular scaffolds for the treatment of chronic total occlusions: a single-centre experience

Introduction

The bioresorbable vascular scaffold system (BVS) is the latest fully absorbable vascular therapy system that is used to treat coronary artery disease. The BVS has been used in different coronary lesion subsets, such as acute thrombotic lesions, bifurcation lesions, ostial lesions and lesions originating from bypass grafts. However, data about the use of BVS in chronic total occlusions (CTO) are limited. We report our BVS experience for the treatment of CTOs in terms of procedural features and one-year clinical follow-up results.

Methods

An analysis was made of 41 consecutive patients with CTO lesions who were referred to our clinic between January 2013 and December 2014. A total of 52 BVS were implanted. An analysis was made of patient characteristics, procedural features [target vessel, BVS diameter, BVS length, post-dilatation rate, type of post-dilatation balloon, procedure time, fluoroscopy time, contrast volume, postprocedure reference vessel diameter (RVD), post-procedure minimal lesion diameter (MLD), type of CTO technique and rate of microcatheter use] and one-year clinical follow-up results [death, myocardial infarction, angina, coronary artery bypass graft (CABG), target-lesion revascularisation (TLR) and target-vessel revascularisation (TVR)]. Descriptive and frequency statistics were used for statistical analysis.

Results

The mean age of the patient group was 61.9 ± 9.7 years, 85.4% were male, and 51.2 % had diabetes. Prior myocardial infarction incidence was 65.9%, 56.1% of the patients had percutaneous coronary intervention and 17.1% had a previous history of CABG. The procedure was performed via the radial route in 24.3% of the patients. The target vessel was the right coronary artery in 48.7% of the patients. Post-dilatation was performed on the implanted BVS in 97.5% of the patients, mainly by non-compliant balloon; 87.8% of the BVS were implanted by the antegrade CTO technique. Mean procedure time was 92 ± 35.6 minutes. Mean contrast volume was 146.6 ± 26.7 ml.

At one year, there were no deaths. One patient had lesionrelated myocardial infarction and needed revascularisation because of early cessation of dual anti-platelet therapy. Eleven patients had angina and five of them needed target-vessel revascularisation.

Conclusions

BVS implantation appeared to be effective and safe in CTO lesions but randomised studies with a larger number of patients and with longer follow-up times are needed

Bioresorbable Scaffold vs. Second Generation Drug Eluting Stent in Long Coronary Lesions requiring Overlap: A Propensity-Matched Comparison (the UNDERDOGS study)

BACKGROUND

Randomized clinical trials on bioresorbable scaffolds (BRS) enrolled patients with simple coronary lesions. The present study was sought to give preliminary findings about safety of BRS implantation in overlap in long coronary lesions.

METHODS

From June 2012 to January 2015, we prospectively collected data from 162 consecutive patients receiving overlapping BRS implantation in the 16 participating institutions. We applied a propensity-score to match BRS-treated patients with 162 patients receiving second generation drug eluting stents (DES) in overlap. The primary endpoint was a device-oriented endpoint (DOCE), including cardiac death, target vessel myocardial infarction, and target lesion revascularization.

RESULTS

DOCE rate did not significantly differ between the two groups (5.6% in BRS group vs. 7.4% in DES group, HR 0.79, 95%CI 0.37-3.55, p=0.6). Also stent/scaffold thrombosis did not differ between groups (1.2% in BRS group vs. 1.9% in DES group, p=0.6). Occurrence of procedural-related myocardial injury was significantly higher in the BRS group (25% vs. 12%, p=0.001), although it was not related to DOCE (HR 1.1, 95%CI 0.97-1.2, p=0.2). Imaging techniques and enhanced stent visualization systems were significantly more employed in the BRS group (p=0.0001 for both). Procedure length, fluoroscopy time and contrast dye amount were significantly higher in the BRS group (p=0.001, p=0.001 and p=0.01, respectively).

CONCLUSIONS

Overlapping BRS utilization in long coronary lesions showed a comparable DOCE rate at 1year if compared to second generation DES. Further and larger studies are on demand to confirm our findings.

Everolimus-eluting bioresorbable stent vs. durable polymer everolimus-eluting metallic stent in patients with ST-segment elevation myocardial infarction: results of the randomized ABSORB ST-segment elevation myocardial infarction-TROFI II trial

AIMS

Patients with ST-segment elevation myocardial infarction (STEMI) feature thrombus-rich lesions with large necrotic core, which are usually associated with delayed arterial healing and impaired stent-related outcomes. The use of bioresorbable vascular scaffolds (Absorb) has the potential to overcome these limitations owing to restoration of native vessel lumen and physiology at long term. The purpose of this randomized trial was to compare the arterial healing response at short term, as a surrogate for safety and efficacy, between the Absorb and the metallic everolimus-eluting stent (EES) in patients with STEMI.

METHODS AND RESULTS

ABSORB-STEMI TROFI II was a multicentre, single-blind, non-inferiority, randomized controlled trial. Patients with STEMI who underwent primary percutaneous coronary intervention were randomly allocated 1:1 to treatment with the Absorb or EES. The primary endpoint was the 6-month optical frequency domain imaging healing score (HS) based on the presence of uncovered and/or malapposed stent struts and intraluminal filling defects. Main secondary endpoint included the device-oriented composite endpoint (DOCE) according to the Academic Research Consortium definition. Between 06 January 2014 and 21 September 2014, 191 patients (Absorb [n = 95] or EES [n = 96]; mean age 58.6 years old; 17.8% females) were enrolled at eight centres. At 6 months, HS was lower in the Absorb arm when compared with EES arm [1.74 (2.39) vs. 2.80 (4.44); difference (90% CI) -1.06 (-1.96, -0.16); Pnon-inferiority < 0.001]. Device-oriented composite endpoint was also comparably low between groups (1.1% Absorb vs. 0% EES). One case of definite subacute stent thrombosis occurred in the Absorb arm (1.1% vs. 0% EES; P = ns).

CONCLUSION

Stenting of culprit lesions with Absorb in the setting of STEMI resulted in a nearly complete arterial healing which was comparable with that of metallic EES at 6 months. These findings provide the basis for further exploration in clinically oriented outcome trials.

The duration of balloon inflation affects the luminal diameter of coronary segments after bioresorbable vascular scaffolds deployment

BACKGROUND

Adequate expansion is critical to achieve optimal Bioresorbable Vascular Scaffolds (BVS) apposition to the vessel wall. However, compared to metallic stents, BVS present different mechanical properties. Hence, slow deployment and maintenance of balloon inflation for at least 30" is recommended for BVS implantation. However, since no evidences are available demonstrating the superiority of a longer balloon dilatation time, the implantation technique is highly variable among different centers.

METHODS

A total of 24 BVS-treated lesions were included in the present analysis. After BVS deployment at 12 atmosphere (ATM) the balloon was rapidly deflated and scaffold expansion was documented with an angiogram. The same balloon was then inflated again and kept at 12 ATM for 30". Finally, a further angiogram was obtained to evaluate BVS expansion. Quantitative coronary angiography (QCA) was performed at each step.

RESULTS

A significant increase of minimal luminal diameter (MLD)-to-reference scaffold diameter (RSD) ratio (MLD to RSD Ration, MR-Ratio) from 0.70 ± 0.10 after initial stent deployment to 0.79 ± 0.10 after the 30"-long balloon dilation was observed (p < 0.001). Of note, this result was consistent across all sub-segments, as well as across almost all lesion subgroups. A substantial reduction in the prevalence of residual stenosis from 29 % to 17 % was registered after the 30"-long dilation.

CONCLUSIONS

Our results strongly support the maintenance of balloon inflation for at least 30" during BVS deployment to achieve optimal scaffold expansion and minimize the occurrence of residual stenosis.

Fracture of Bioresorbable Vascular Scaffold After Side-Branch Balloon Dilation in Bifurcation Coronary Narrowings

The possibility of strut fractures after bioresorbable vascular scaffold (BVS) treatment is a new problem associated with the use of this novel technology. There is little in vivo information regarding the effects of lateral dilation on BVS. The present study aimed to evaluate the effects of lateral balloon dilation after bioresorbable vascular scaffold implantation in the treatment of bifurcation lesions. From January 2012 to February 2015, 49 patients with bifurcation lesions who had been treated with BVS required balloon dilation of the side branch (SB). Optical coherence tomographic studies were performed in each of these patients. In 3 patients (6%), the optical coherence tomographic results met the criteria for rupture. Prolonged inflation using a noncompliant balloon with a diameter within the expansion limits of the device resolved the complication in all patients. The clinical course was favorable in all patients, and there were no inhospital deaths or myocardial infarctions. At 14 ± 8 months of follow-up, 2 patients with integrity of the BVS presented target lesion revascularization (4%). Another patient (2%) suffered a probable stent thrombosis 11 months after the procedure (myocardial infarction and death at home). The patients with the BVS rupture at the index procedure had a favorable clinical outcome, and the 6-month computed tomographic scan revealed maintenance of the initial good results. In conclusion, minor BVS rupture after 2.5-mm lateral balloon dilation may occur but is infrequent (6%). Prolonged balloon inflation of the main vessel may partially restore the geometry of the BVS.

Bioresorbable vascular scaffold implantation in acute coronary syndromes: clinical evidence, tips and tricks

Percutaneous coronary intervention (PCI) with a drug-eluting stent (DES) is routine treatment for patients with acute coronary syndromes (ACS). However, permanent metallic caging of the vessel has several shortcomings, such as side branch jailing and impossibility of late lumen enlargement. Moreover, DES PCI is affected by vasomotion impairment. In ACS a high thrombus burden and vasospasm lead to a higher risk of acute and late acquired stent malapposition than in stable patients. This increases the risk of acute, late and very late stent thrombosis. In this challenging clinical setting, the implantation of bioresorbable vascular scaffolds (BVS) could represent an appealing therapeutic option. Temporary vessel scaffolding has proved to have several advantages over metallic stent delivery, such as framework reabsorption, late lumen enlargement, side branch patency, and recovery of physiological reactivity to vasoactive stimuli. In the thrombotic environment of ACS, BVS implantation has the benefit of capping the thrombus and the vulnerable plaque. Bioresorbable vascular scaffolds also seems to reduce the incidence of angina during follow-up. Acute coronary syndromes patients may therefore benefit more from temporary polymeric caging than from permanent stent platform implantation. The aim of this review is to update the available knowledge concerning the use of BVS in ACS patients, by analyzing the potential pitfalls in this challenging clinical setting and presenting tricks to overcome these limitations.

Bioresorbable vascular scaffold overlap evaluation with optical coherence tomography after implantation with or without enhanced stent visualization system (WOLFIE study): a two-centre prospective comparison

To assess if enhanced stent visualization (ESV)-guided implantation of overlapping bioresorbable vascular scaffold (BVS) is superior to angiography alone-guided implantation in the reduction of overlap length. WOLFIE is a two-centre prospective open study enrolling 30 patients treated with implantation of at least two overlapping BVS. In the first centre (London), BVS implantation was guided by conventional angiography, while in the second centre (Ferrara), an ESV system was systematically employed. The primary endpoint of the study was overlap length. Secondary endpoints were: stacked struts number, area, thickness, and amount of clusters. In the ESV-guided group, overlap length was significantly lower compared to angiography-guided group [0.9 (0.6-1.8) vs. 2.2 (1.3-3.2) mm, p = 0.02]. Similarly, all secondary endpoints were significantly reduced. ESV-guided implantation of overlapping BVS is safe and effective in minimizing both overlap length and number of stacked struts.

Clinical utility of platinum chromium bare-metal stents in coronary heart disease

Coronary stents represent a key development for the treatment of obstructive coronary artery disease since the introduction of percutaneous coronary intervention. While drug-eluting stents gained wide acceptance in contemporary percutaneous coronary intervention practice, further developments in bare-metal stents remain crucial for patients who are not candidates for drug-eluting stents, or to improve metallic platforms for drug elution. Initially, stent platforms used biologically inert stainless steel, restricting stent performance due to limitations in flexibility and strut thickness. Later, cobalt chromium stent alloys outperformed steel as the material of choice for stents, allowing latest generation stents to be designed with significantly thinner struts, while maintaining corrosion resistance and radial strength. Most recently, the introduction of the platinum chromium alloy refined stent architecture with thin struts, high radial strength, conformability, and improved radiopacity. This review will provide an overview of the novel platinum chromium bare-metal stent platforms available for coronary intervention. Mechanical properties, clinical utility, and device limitations will be summarized and put into perspective.