Optimal dual antiplatelet therapy duration for bioresorbable scaffolds: an individual patient data pooled analysis of the ABSORB trials

BACKGROUND

Compared with everolimus-eluting metallic stents, the Absorb bioresorbable scaffold (BRS) results in increased rates of myocardial infarction (MI) and scaffold thrombosis (ST) during its three-year bioresorption phase. It is unknown whether prolonged dual antiplatelet therapy (DAPT) duration might decrease the risk of ischaemic events.

AIMS

We sought to evaluate the impact of DAPT duration on ischaemic and bleeding outcomes following BRS implantation.

METHODS

We conducted an individual patient data pooled analysis from four ABSORB randomised trials and one prospective ABSORB registry. Study endpoints were MI, ST, bleeding, and death up to three-year follow-up. Propensity score-adjusted Cox regression analysis was used to account for baseline differences related to DAPT duration.

RESULTS

The five ABSORB studies included 2,973 patients. DAPT use was 91.7%, 53.2%, and 48.0% at 1, 2, and 3 years, respectively. DAPT use within the first year after BRS implantation was associated with markedly lower risks of MI (adjusted hazard ratio [aHR] 0.17, 95% CI: 0.10-0.32; p<0.0001) and ST (aHR 0.08, 95% CI: 0.03-0.19; p<0.0001). Conversely, DAPT use between 1 and 3 years did not significantly affect the risk of MI (aHR 1.04, 95% CI: 0.70-1.55; p=0.84) or ST (aHR 0.86, 95% CI: 0.42-1.75; p=0.67). DAPT did not have major effects upon bleeding or death in either period.

CONCLUSIONS

DAPT use during the first year after BRS implantation was strongly associated with lower risks of ST and MI. However, a benefit of ongoing DAPT use between 1 and 3 years after BRS implantation was not apparent.

Bioresorbable Scaffolds: Contemporary Status and Future Directions

Percutaneous coronary intervention, which is safe, effective, and timely, has become an important treatment for coronary artery diseases and has been widely used in clinical practice. However, there are still some problems that urgently need to be solved. Permanent vessel caging through metallic implants not only prevents the process of positive vessel remodeling and the restoration of vascular physiology but also makes the future revascularization of target vessels more difficult. Bioresorbable scaffolds (BRSs) have been developed as a potential solution to avoid the above adverse reactions caused by permanent metallic devices. BRSs provide temporary support to the vessel wall in the short term and then gradually degrade over time to restore the natural state of coronary arteries. Nonetheless, long-term follow-up of large-scale trials has drawn considerable attention to the safety of BRSs, and the significantly increased risk of late scaffold thrombosis (ScT) limits its clinical application. In this review, we summarize the current status and clinical experiences of BRSs to understand the application prospects and limitations of these devices. In addition, we focus on ScT after implantation, as it is currently the primary drawback of BRS. We also analyze the causes of ScT and discuss improvements required to overcome this serious drawback and to move the field forward.

Intracoronary Imaging for Assessment of Vascular Healing and Stent Follow-up in Bioresorbable Vascular Scaffolds

Bioresorbable Vascular Scaffolds (BVS) are polymer-based materials implanted in the coronary arteries in order to treat atherosclerotic lesions, based on the concept that once the lesion has been treated, the material of the implanted stent will undergo a process of gradual resorption that will leave, in several years, the vessel wall smooth, free of any foreign material and with its vasomotion restored. However, after the first enthusiastic reports on the efficacy of BVSs, the recently published trials demonstrated disappointing results regarding long-term patency following BVS implantation, which were mainly attributed to technical deficiencies during the stenting procedure. Intracoronary imaging could play a crucial role for helping the operator to correctly implant a BVS into the coronary artery, as well as providing relevant information in the follow-up period. This review aims to summarize the role of intracoronary imaging in the follow-up of coronary stents, with a particular emphasis on the role of intravascular ultrasound and optical coherence tomography for procedural guidance during stent implantation and also for follow-up of bioabsorbable scaffolds.

Three-year clinical outcomes of patients treated with everolimus-eluting bioresorbable vascular scaffolds: Final results of the ABSORB EXTEND trial

BACKGROUND

There is still limited data on the very long term clinical outcomes after ABSORB BRS in daily practice. We sought to evaluate the 3 year-performance of the Absorb bioresorbable vascular scaffolds for the treatment of low/moderate complexity patients enrolled in the ABSORB EXTEND trial.

METHODS

ABSORB EXTEND is a prospective, single-arm, open-label clinical study in which 812 patients were enrolled at 56 sites. This study allowed the treatment of lesions ≤28 mm in length and reference vessel diameter of 2.0-3.8 mm (as assessed by on-line QCA). To determine the independent predictors of MACE, a multivariable logistic regression model was built using a stepwise (forward/backward) procedure.

RESULTS

Average population age was 61 years and 26.5% had diabetes. Most patients had single target lesion (92.4%). Adequate scaffold deployment (PSP) was achieved in 14.2% of the cases. At three years, the composite endpoints of MACE and ischemia-driven target vessel failure were 9.2% and 10.6%, respectively. The cumulative rate of ARC definite/probable thrombosis was 2.2%, with 1.2% of the cases occurring after the 1st year. Independent predictors of MACE were hypertension and the need for "bail out" stent.

CONCLUSION

At three-year follow-up, the use of ABSORB in low/moderate complex PCI was associated with low and acceptable rates of major adverse clinical events, despite the infrequent use of the recommended contemporary scaffold deployment technique. However, scaffold thrombosis rate was higher than reported with current generation of metallic DES. The study is registered on clinicaltrials.gov (unique identifier NCT01023789).

One-year clinical outcomes after unrestricted implantation of the Absorb bioresorbable scaffold (RAI registry)

AIMS

The aim of this study was to assess outcomes following Absorb bioresorbable scaffold (BVS) implantation in an unrestricted clinical practice according to an "on-label" versus "off-label" indication.

METHODS AND RESULTS

RAI is a prospective registry, investigating BVS performance in different lesion subsets. No specific exclusion criteria were applied. Co-primary endpoints were target lesion revascularisation (TLR) and definite/probable scaffold thrombosis (ScT) at one year. A total of 1,505 patients (1,969 lesions) were enrolled. In 58% of patients, BVS was implanted in at least one off-label subset according to the manufacturer's instructions for use. Predilatation was performed in 98.5% of the cases, and post-dilatation in 96.8%. At one-year follow-up, TLR and ScT rates were 3.3% and 1.3%, respectively. TLR was significantly higher in the off-label group (4.0% vs. 2.2%, HR 1.8, 95% CI: 1.0-3.4; p=0.05) while a trend towards a higher ScT rate was observed in the off-label group (1.7% vs. 0.6%, HR 2.7, 95% CI: 0.9-8.2; p=0.06). At multivariate analysis, treatment of in-stent restenosis, chronic total occlusion and BVS diameter were independent predictors of TLR.

CONCLUSIONS

Our data from a real-world population suggest that BVS could be associated with acceptable one-year clinical outcomes when meticulously implanted. However, a higher rate of adverse events was observed when this device was used in off-label lesions.

The State of the Absorb Bioresorbable Scaffold: Consensus From an Expert Panel

Significant progress has been made in the percutaneous coronary intervention technique from the days of balloon angioplasty to modern-day metallic drug-eluting stents (DES). Although metallic stents solve a temporary problem of acute recoil following balloon angioplasty, they leave behind a permanent problem implicated in very late events (in addition to neoatherosclerosis). BRS were developed as a potential solution to this permanent problem, but the promise of these devices has been tempered by clinical trials showing increased risk of safety outcomes, both early and late. This is not too dissimilar to the challenges seen with first-generation DES in which refinement of deployment technique, prolongation of dual antiplatelet therapy, and technical iteration mitigated excess risk of very late stent thrombosis, making DES the treatment of choice for coronary artery disease. This white paper discusses the factors potentially implicated in the excess risks, including the scaffold consideration and deployment technique, and outlines patient and lesion selection, implantation technique, and dual antiplatelet therapy considerations to potentially mitigate this excess risk with the first-generation thick strut Absorb scaffold (Abbott Vascular, Abbott Park, Illinois). It remains to be seen whether these considerations together with technical iterations will ultimately close the gap between scaffolds and metal stents for short-term events while at the same time preserving options for future revascularization once the scaffold bioresorbs.

Longer Inflation Duration and Predilation-Sizing-Postdilation Improve Bioresorbable Scaffold Outcomes in a Long-term All-Comers Canadian Registry

BACKGROUND

Real-world long-term safety and efficacy of the ABSORB (Abbott Vascular, Santa Clara, CA) bioresorbable vascular scaffold has not been well characterized in the literature, particularly in the setting of acute coronary syndromes (ACS). Herein, we report outcomes up to 4 years in such a high-risk cohort, with identification of parameters associated with better outcomes.

METHODS

ReABSORB is a Canadian dual-centre, prospective, nonrandomized, all-comers registry consisting of 125 consecutively enrolled nontrial patients between October 2012 and December 2016. Angiographic and clinical follow-up is now available up to 4 years.

RESULTS

Average age was 59 ± 11 years and 69% were male. Most (70.4%) presented with ACS and the median available follow-up was 1330 days (interquartile range, 1035-1483). Treated lesions (n = 163) were type A in 23%, type B (1 or 2) in 64%, and type C in 13%. Procedural success and device success were 98.2% and 98.8%, respectively. Using Kaplan-Meier methods, major adverse cardiac event-free survival (EFS) up to 4 years of clinical follow-up was 90.7% overall. However, use of a predilation-sizing-postdilation (PSP) technique was associated with an EFS rate of 95.8% vs 74.0% without PSP (P = 0.001). No significant differences in major adverse cardiac EFS rates were found between patients with or without ACS (92.7% vs 86.0%, respectively, P = 0.239). Use of PSP as well as inflation time ≥ 60 seconds were independent predictors of EFS at 2 years.

CONCLUSIONS

In this prospective, real-world registry with mostly ACS patients, use of the recommended PSP implantation technique and longer inflations times were associated with significantly higher EFS.

In-stent Flow Hemodynamics and the Risk of STent Failure Following Bioresorbable Vascular ScAFFolds Implantation – the STAFF Study

Background: Myocardial revascularization procedures have undergone important developments over the last decades, which led to a major shift in current clinical practice and therapeutic guidelines across the world. Bare metal and drug-eluting stents present several limitations, all centered on the concept of disturbed coronary hemodynamics after implantation, which can be surpassed by bioresorbable vascular scaffolds (BVS). BVSs are fourth-generation stents used in coronary revascularization procedures, but despite all the promising initial results published on their efficiency, several clinical trials have reported unsatisfactory results, and the main explanation was accredited to improper implantation method. Shear stress is a central element of intravascular homeostasis; it controls vascular remodeling, as well as the development, progression, and destabilization of atheromatous plaques. This study aims to assess the role of in-stent flow hemodynamics (evaluated by computational determination of shear stress via coronary CT imaging) in predicting the clinical evolution following BVS implantation.

Material and methods: This case-control observational study will include patients with BVSs implanted at least 12 months prior to randomization. Each patient will undergo a complete evaluation of the demographic and clinical characteristics, cardiovascular risk factors, and imaging acquisitions via coronary CT angiography, based on which the endothelial shear stress will be calculated before and after BVS implantation. Post-processing of CT imaging data will evaluate the shear stress and the composition of the coronary plaques along the entire coronary tree. The primary endpoint will be the major adverse cardiovascular events (MACE) in patients with altered vs. non-altered BVS-related shear stress, and the secondary endpoints will comprise evaluating the rate of progression of stent resorption and progression of shear stress alteration.

Conclusions: The findings of the STAFF study can be extremely useful in clinical practice for providing an answer to a key question that is still under debate: why do BVSs fail and how can we prevent this?.

Impact of PSP Technique on Clinical Outcomes Following Bioresorbable Scaffolds Implantation

Bioresorbable scaffolds (BRS) were introduced in clinical practice to overcome the long-term limitations of newer-generation drug-eluting stents. Despite some initial promising results of the Absorb BRS, safety concerns have led to the discontinuation of the commercialization of this device. Several retrospective studies have assessed the impact of the so-called Pre-dilation, Sizing and Post-dilation (PSP) technique concluding that an optimal PSP technique can improve clinical outcomes following BRS implantation. In this article, the definition of the PSP technique, and the current evidence of its impact on clinical outcomes are put in perspective. Additionality, the relationship between the PSP technique and the dual-antiplatelet therapy to prevent scaffold thrombosis is addressed. Finally, the future perspectives of BRS technology in clinical practice are commented.

Impact of calcium on procedural and clinical outcomes in lesions treated with bioresorbable vascular scaffolds - A prospective BRS registry study

BACKGROUND

There is limited data on the impact of calcium (Ca) on acute procedural and clinical outcomes in patients with lesions treated with bioresorbable vascular scaffolds (BRS). We sought to evaluate the effect of calcium on procedural and clinical outcomes in a 'real world' population.

METHODS

Clinical outcomes were compared between patients with at least 1 moderately or heavily calcified lesion (Ca) and patients with no/mild calcified lesions (non-Ca) enrolled in our institutional BRS registry.

RESULTS

455 patients (N) with 548 lesions (L) treated with 735 BRS were studied. Patients in the Ca group (N=160, L=200) had more complex (AHA B2/C lesion: 69.0% in Ca vs 14.9% in non-Ca, p<0.001) and significantly longer lesions (27.80±15.27 vs 19.48±9.92mm, p<0.001). Overall device success rate was 99.1% with no significant differences between the groups. Despite more aggressive lesion preparation and postdilation compared to non Ca, acute lumen gain was significantly less in Ca lesions (1.50±0.66 vs 1.62±0.69mm, p=0.040) with lower final MLD (2.28±0.41 vs 2.36±0.43, p=0.046). There were no significant differences in all-cause mortality, total definite scaffold thrombosis (ST), target lesion revascularization and myocardial infarction between the 2 groups. Late ST was more frequent in the Ca group compared to non Ca group (late ST: 2.1 vs 0%, p=0.02).

CONCLUSIONS

Clinical outcomes after BRS implantation in calcified and non-calcified lesions were similar. A remarkable difference in timing of thrombosis was observed, with an increased rate of late thrombosis in calcified lesions.

Evaluation of potential substrates for restenosis and thrombosis in overlapped versus edge-to-edge juxtaposed bioabsorbable scaffolds: Insights from a computed fluid dynamic study

BACKGROUND/PURPOSE

Multiple BRSs and specifically the Absorb scaffold (BVS) (Abbott Vascular, Santa Clara, CA USA) have been often used to treat long diffuse coronary artery lesions. We evaluate by a computational fluid dynamic(CFD) study the impact on the intravascular fluid rheology on multiple bioabsorbable scaffolds (BRS) by standard overlapping versus edge-to-edge technique.

METHODS/MATERIALS

We simulated the treatment of a real long significant coronary lesion (>70% luminal narrowing) involving the left anterior descending artery (LAD) treated with a standard or edge-to-edge technique, respectively. Simulations were performed after BVS implantations in two different conditions: 1) Edge-to-edge technique, where the scaffolds are kissed but not overlapped resulting in a luminal encroachment of 0.015cm (150μm); 2) Standard overlapping, where the scaffolds are overlapped resulting in a luminal encroachment of 0.030cm (300μm). After positioning the BVS across the long lesion, the implantation procedure was performed in-silico following all the usual procedural steps.

RESULTS

Analysis of the wall shear stress (WSS) suggested that at the vessel wall level the WSS were lower in the overlapping zones overlapping compared to the edge-to-edge zone (∆=0.061Pa, p=0.01). At the struts level the difference between the two WSS was more striking (∆=1.065e-004 p=0.01) favouring the edge-to-edge zone.

CONCLUSIONS

Our study suggested that at both vessel wall and scaffold struts levels, there was lowering WSS when multiple BVS were implanted with the standard overlapping technique compared to the "edge-to-edge" technique. This lower WSS might represent a substrate for restenosis, early and late BVS thrombosis, potentially explaining at least in part the recent evidences of devices poor performance.