Proximal to Distal Y-Stent Deployment for Coronary Bifurcation Lesions: Procedure and Three-Year Clinical Outcomes.

AIMS: Percutaneous coronary intervention with Y-stenting of coronary bifurcation disease is not commonly undertaken. The procedural and medium-term clinical outcomes of coronary bifurcation lesions treated with the proximal to distal Y stent technique by a single experienced operator were reviewed. METHODS: A total of 167 consecutive procedures using either provisional Y strategies or full-coverage options performed at Auckland City Hospital, New Zealand, between January 2013 and July 2018 were included in this retrospective observational study. All medical records and coronary angiograms were reviewed. RESULTS: Three-year clinical follow-up data were available in 162 of 167 patients. The primary endpoint, defined as the composite of cardiovascular death, spontaneous myocardial infarction (MI), target-lesion revascularization (TLR), target-vessel nontarget-lesion revascularization (nontarget-lesion TVR), and stent thrombosis (ST) occurred in 25 patients (15%) at 3 years. Secondary endpoints were all-cause mortality (12%), including cardiovascular mortality (6%), noncardiovascular mortality (4%), undetermined death (2%), spontaneous MI (7%), TLR (1%), nontarget-lesion TVR (0%), and ST (0.6%). CONCLUSIONS: The proximal to distal Y-stent technique is a widely applicable approach to bifurcation lesions, with good medium-term clinical outcomes when used in a heterogeneous group of clinical and anatomical scenarios. Complications related to the stented site were infrequent. Randomized, controlled trials are needed to assess its efficacy compared with other bifurcation interventional techniques.

Real-time intravascular ultrasound guidance: A novel technique for accurate placement of ostial stents.

OBJECTIVES: To describe a novel technique for ostial stent placement using real-time IVUS guidance. BACKGROUND: Accurate placement of coronary stents at ostial locations is challenging with the true ostium frequently being missed increasing the risk of adverse events. We have developed a novel technique for ostial stent placement and report our benchtop testing and initial clinical experience. METHODS: Benchtop testing was performed to validate the appearance of the stent and delivery system on IVUS. Benchtop testing of real-time IVUS guided ostial stent positioning was carried out in a left main bifurcation phantom. Real-time IVUS guidance of stent placement in aorto-ostial, ostial left anterior descending (LAD), or ostial circumflex lesions was assessed in a prospective registry. RESULTS: Bench model IVUS demonstrated clear differences between the appearances of the stent and other components of the delivery system. Positioning of 10 consecutive stents into the ostial LAD using real-time IVUS guidance was assessed in a left main bifurcation model. Median distance from proximal stent edge to LAD ostium was 0.39 mm (interquartile range 0.31 to 0.73). Real-time IVUS guidance of ostial stent placement was performed in 50 patients (51 lesions). Angiographic success was 100%. IVUS post-stenting demonstrated median distance from the proximal stent edge to the ostium was 0.2 mm (interquartile range 0.1 to 0.5 mm). There was one periprocedural myocardial infarction but no other major adverse cardiac events at 30-days. CONCLUSIONS: We have developed a novel technique using real-time IVUS guidance allowing accurate ostial stent placement.

Critical aspects of balloon position during final proximal optimization technique (POT) in coronary bifurcation stenting.

OBJECTIVES: In a coronary bifurcation bench model, to determine the effects of side branch (SB) wire crossing position and balloon position on the stent scaffolding after the final proximal optimization technique (POT). BACKGROUND: POT performed as a final step after SB dilatation or kissing balloon inflation (KBI) has been widely advocated despite limited evidence. METHODS: Thirty-one stent implantations in bifurcation phantoms were performed using a one-stent provisional technique with (KBI) (n = 13), with POT-side-POT technique (n = 12) or with the two-stent culotte technique (n = 6). SB wiring was performed through either a proximal or a distal stent cell and confirmed by optical coherence tomography. Final POT was performed with the balloon positioned either across or proximal to the SB takeoff. The area of the opened stent cell in front of the SB was assessed by 3D reconstructed microcomputation tomography scans performed before and after Final POT. RESULTS: In cases with metallic carina, final POT across the SB takeoff caused SB rejailing. Regardless of stent technique and wire position, a Final POT across the SB takeoff reduced the SB cell opening area by 43% [32%;58%] (n = 15). The largest reduction (54-70%) was found after the POT-side-POT technique in procedures with a proximal wiring. Final POT performed proximal to the SB takeoff caused limited or no SB cell opening area reduction (4% [0.6%;6%] [n = 16]). CONCLUSION: Final POT with balloon positioned across the SB takeoff in a narrow angle bifurcation reduces largest stent cell area in front of the SB ostium and may cause SB rejailing in cases with metallic carina.

Mechanical properties of the drug-eluting bioresorbable magnesium scaffold compared with polymeric scaffolds and a permanent metallic drug-eluting stent.

OBJECTIVES: To compare on the bench the physical and mechanical properties of Magmaris, a magnesium bioresorbable scaffold (BRS), with Absorb and DESolve polymeric BRS and a permanent metallic stent. BACKGROUND: Understanding the mechanical and physical properties of BRS is crucial for appropriate implantation and postdilatation. METHODS: Testing was performed in fluid at 37°C and in silicone bifurcation phantoms with a 30° angle between main branch (MB) and side branch. RESULTS: The 3.0-mm Magmaris BRS did not fracture after MB postdilatation up to 4.4 mm in contrast to the Absorb where the safe postdilatation diameter was 3.7 mm. For dilatation through stent cells, there were no Magmaris fractures with 3.0-mm noncompliant (NC) balloons inflated to nominal pressure. Mini-kissing balloon postdilatation with two 3.0-mm NC balloons up to 17 atm was without fracture except for an outlier. Longitudinal and radial strengths were similar for Magmaris and Absorb BRS. The crossing profile for the Magmaris was larger than other devices. Recoil 120 min after deployment was the greatest for Magmaris but 120 min after 3.5 mm postdilatation all devices had similar diameters. CONCLUSIONS: The Magmaris BRS was more resistant to strut fracture than Absorb. It had a larger crossing profile than other devices and similar radial and longitudinal strengths to Absorb. While recoil after deployment was greater with Magmaris, 120 min after 3.5 mm postdilatation all devices had similar diameters.

Relation between bioresorbable scaffold sizing using QCA-Dmax and long-term clinical outcomes in 1,232 patients from three study cohorts (ABSORB Cohort B, ABSORB EXTEND, and ABSORB II).

AIMS: This study sought to investigate the long-term clinical outcomes related to scaffold sizing based on quantitative coronary angiography. METHODS AND RESULTS: A total of 1,248 patients who received Absorb bioresorbable scaffolds in the ABSORB Cohort B, ABSORB EXTEND, and ABSORB II trials were included in the analysis. The incidence of MACE (a composite of cardiac death, any myocardial infarction [MI], and ischaemia-driven target lesion revascularisation [ID-TLR]) was analysed according to the Dmax subclassification of oversized scaffold group versus non-oversized (any undersize) scaffold group. At three years, event rates were similar in both groups in MACE (9.4% vs. 9.8%, p=0.847), target vessel MI (5.2% vs. 4.8%, p=0.795), and ID-TLR (4.8% vs. 5.8%, p=0.445). Landmark analysis after one year showed that the non-oversized scaffold group had higher rates of MACE (3.2% vs. 6.9%, log-rank p=0.004), target vessel MI (0.7% vs. 2.7%, log-rank p=0.007), and ID-TLR (2.5% vs. 4.7%, log-rank p=0.041). CONCLUSIONS: Implantation of an undersized scaffold was associated with a higher risk of MACE between one and three years, while in the previous report an oversized scaffold was associated with a higher risk of MACE up to one year. This implies different mechanisms for early and late events after scaffold implantation.

Long-term clinical outcomes of a crystalline sirolimus-eluting coronary stent with a fully bioabsorbable polymer coating: five-year outcomes from the DESSOLVE I and II trials.

AIMS: The aim of this study was to evaluate the five-year clinical results of a sirolimus-eluting stent (MiStent SES) with a bioabsorbable coating designed for sustained drug delivery during and after rapid polymer dissolution. METHODS AND RESULTS: The five-year results from the DESSOLVE I and II trials including major adverse cardiac events (MACE), target lesion failure (TLF), target vessel failure (TVF), and stent thrombosis (ST) at five-year follow-up are reported. In DESSOLVE I, 10.3% of patients receiving the MiStent SES (3/29) had a MACE event up to five years without TLF. In DESSOLVE II, 15.1% of patients in the MiStent group (18/119) had a five-year MACE event compared to 22.0% of patients in the Endeavor group (p=0.295). TLF was 9.2% in the MiStent group and 8.5% in the Endeavor group (p=1.00). TVF was 10.1% for MiStent versus 15.3% for Endeavor (p=0.331). Up to five-year follow-up, the MiStent SES has continued to demonstrate low rates of TLR across DESSOLVE I (0.0%) and DESSOLVE II (3.4%). No ST was reported with the MiStent up to five years in the DESSOLVE I trial. In DESSOLVE II, definite or probable ST was 0.0% with MiStent and 1.7% with Endeavor up to five years. CONCLUSIONS: The MiStent SES demonstrated long-term safety and effectiveness with low rates of five-year MACE, TLF, and TVF across these two clinical trials.

Coronary balloon catheter tip damage. A bench study of a clinical problem.

OBJECTIVES: To confirm clinically that coronary balloon catheter tips may be damaged during bifurcation treatment with side-branch access through the side of a stent. On the bench, we aimed to assess the susceptibility of different balloon designs to damage. We compared catheter tip widths. We tested whether balloon tip flaring can cause stent distortion. BACKGROUND: We had observed that balloon catheters that failed to cross to a side-branch frequently exhibited tip damage. METHODS AND RESULTS: We examined microscopically for damage 82 balloon tips after clinical side-branch access. In a bench study, the forces required to compress catheter tips 0.5 mm were compared to assess susceptibility to damage. We compared tip widths of balloons of different nominal inflation diameters. We examined stents after side-branch access for distortion. In 42 of 48 (88%) of balloon tips from patients with resistance to or failure to cross through the side of a stent there was tip damage. Even when the balloon crossed without perceptible resistance, tip damage occurred in over half of balloons 18/34 (53%). Some balloon designs were more resistant to damage than others. Tips from balloons of different nominal diameters from the same manufacturer had the same width. Stent distortion caused by damaged balloon tips is improved by kissing balloon post-dilatation. CONCLUSIONS: Balloon tip damage is common with crossing between stent struts. This is one cause of failure of a balloon to access a side-branch and a new balloon should be used. If stent distortion is suspected, it should be corrected with kissing balloon post-dilatation.

Bench testing and coronary artery bifurcations: a consensus document from the European Bifurcation Club.

This is a consensus document from the European Bifurcation Club concerning bench testing in coronary artery bifurcations. It is intended to provide guidelines for bench assessment of stents and other strategies in coronary bifurcation treatment where the United States Food and Drug Administration (FDA) or International Organization for Standardization (ISO) guidelines are limited or absent. These recommendations provide guidelines rather than a step-by-step manual. We provide data on the anatomy of bifurcations and elastic response of coronary arteries to aid model construction. We discuss testing apparatus, bench testing endpoints and bifurcation nomenclature.

Long and short of optimal stent design.

The ideal stent must fulfil a broad range of technical requirements. Stents must be securely crimped onto the delivery balloon and, in this form, must have a low profile and be sufficiently flexible to facilitate deliverability to the lesion site without distortion or displacement. Following expansion, stents must exert sufficient radial force on the vessel wall to overcome lesion resistance and elastic recoil. To achieve an optimal lumen diameter, the lesion must be uniformly and adequately scaffolded, with minimal tissue prolapse between struts but without compromising side-branch access. Furthermore, the deployed stent must conform to the vessel curvature to minimise vessel distortion, particularly at the stent edges. Radio-opacity is also important to guide safe positioning, adequate deployment and postdilataion and to permit assessment of optimal stent expansion. Equally though, the stent lumen must also be sufficiently visible to allow radiographic assessment of flow dynamics and restenosis. Efforts to optimise one characteristic of stent design may have detrimental effects on another. Thus, currently available stents all reflect a compromise between competing desirable features and have subtle differences in their performance characteristics. Striving to achieve stents with optimal deliverability, conformability and radial strength led to a reduction in longitudinal strength. The importance of this parameter was highlighted by complications occurring in the real-world setting where percutaneous coronary intervention is often undertaken in challenging anatomy. This review focuses on aspects of stent design relevant to longitudinal strength.

Serial 5-Year Evaluation of Side Branches Jailed by Bioresorbable Vascular Scaffolds Using 3-Dimensional Optical Coherence Tomography: Insights From the ABSORB Cohort B Trial (A Clinical Evaluation of the Bioabsorbable Everolimus Eluting Coronary Stent System in the Treatment of Patients With De Novo Native Coronary Artery Lesions).

BACKGROUND: The long-term fate of Absorb bioresorbable vascular scaffold (Abbott Vascular, Santa Clara, CA) struts jailing side branch ostia has not been clarified. We therefore evaluate serially (post-procedure and at 6 months, 1, 2, 3, and 5 years) the appearance and fate of jailed Absorb bioresorbable vascular scaffold struts. METHODS AND RESULTS: We performed 3-dimensional optical coherence tomographic analysis of the ABSORB Cohort B trial (A Clinical Evaluation of the Bioabsorbable Everolimus Eluting Coronary Stent System in the Treatment of Patients With De Novo Native Coronary Artery Lesions) up to 5 years using a novel, validated cut-plane analysis method. We included 29 patients with a total of 85 side branch ostia. From the 12 ostia which could be assessed in true serial fashion, 7 showed a pattern of initial decrease in the ostial area free from struts, followed by an increase in strut-free ostial area toward the end of the 5 years of follow-up. In a repeated-measures analysis with time as fixed variable and ostial area free from struts as dependent variable, we showed a numeric decrease in the estimated ostial area free from struts from 0.75 mm2 (baseline) to 0.68 mm2 (first follow-up visit at 6 months or 1 year) and 0.63 mm2 (second follow-up visit at 2 or 3 years). However, from the second visit to the 5-year follow-up visit, there was a statistically significant increase from 0.63 to 0.89 mm2 (P=0.001). Struts overlying an ostium divided the ostium into compartments, and the number of these compartments decreased over time. CONCLUSIONS: This study showed that in most cases, the side branch ostial area free from struts initially decreased. However, with full scaffold bioresorption, the ostial area free from scaffold increased between 2 to 3 years and 5 years in the vast majority of patients. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00856856.

Change in lumen eccentricity and asymmetry after treatment with Absorb bioresorbable vascular scaffolds in the ABSORB cohort B trial: a five-year serial optical coherence tomography imaging study.

AIMS: The aim of the study was to investigate long-term changes in lumen eccentricity and asymmetry at five years after implantation of the Absorb bioresorbable vascular scaffold (BVS). METHODS AND RESULTS: Out of 101 patients from the ABSORB cohort B trial, 28 patients (29 lesions) with serial optical coherence tomography (OCT) examination at four different time points (cohort B1: post-procedure, six months, two, and five years [n=13]; cohort B2: post-procedure, one, three, and five years [n=16]) were evaluated. The longitudinal variance in lumen diameter was assessed by asymmetry index (AI). An asymmetric lesion was defined as AI >0.3. The circularity of the lumen or scaffold was evaluated by the eccentricity index calculated as minimal divided by maximal luminal or scaffold diameter per cross-section. The lowest lumen eccentricity index within a scaffold segment (EIL) <0.7 was defined as an eccentric lesion. Post procedure, an eccentric lesion was observed in 72.4% and became concentric in 93.1% at five years (post EIL 0.67±0.05 vs. five-year EIL 0.80±0.10, p=0.03) with a modest reduction of the lumen area from baseline to five years by 0.75±0.32 mm2. Asymmetric lumen morphology was observed in 93.1% (n=27) post implantation and persisted until five-year follow-up. On serial OCT analyses, there was a substantial increase in the scaffold EI during the first two years (post 0.70±0.06, six months 0.76±0.08, two years 0.85±0.07); then, it remained stable whereas the lumen circularity improved further. There were no significant differences in major adverse cardiac events regarding the lumen morphology over the five-year follow-up. CONCLUSIONS: In patients treated with the Absorb BVS, the cross-sectional circularity improved over five years while the variance in longitudinal diameters remained. Regaining of lumen circularity is mainly caused by reshaping of the scaffold during the first two years.

Review: Stent fracture in the drug-eluting stent era.

Stent fracture has been recognized as one cause of stent failure and has been associated with in-stent restenosis and stent thrombosis, even in 2nd-generation drug-eluting stents. Given the wide use of drug-eluting stents and paucity of contemporary data available concerning stent fracture, we reviewed clinical studies and the Food and Drug Administration's Manufacturer and User Device Experience (MAUDE) database to analyze the current trends, mechanisms, predictors, outcomes and treatment for stent fracture.

The Impact of Post-Procedural Asymmetry, Expansion, and Eccentricity of Bioresorbable Everolimus-Eluting Scaffold and Metallic Everolimus-Eluting Stent on Clinical Outcomes in the ABSORB II Trial.

OBJECTIVES: The study sought to investigate the relationship between post-procedural asymmetry, expansion, and eccentricity indices of metallic everolimus-eluting stent (EES) and bioresorbable vascular scaffold (BVS) and their respective impact on clinical events at 1-year follow-up. BACKGROUND: Mechanical properties of a fully BVS are inherently different from those of permanent metallic stent. METHODS: The ABSORB II (A bioresorbable everolimus-eluting scaffold versus a metallic everolimus-eluting stent for ischaemic heart disease caused by de-novo native coronary artery lesions) trial compared the BVS and metallic EES in the treatment of a de novo coronary artery stenosis. Protocol-mandated intravascular ultrasound imaging was performed pre- and post-procedure in 470 patients (162 metallic EES and 308 BVS). Asymmetry index (AI) was calculated per lesion as: (1 - minimum scaffold/stent diameter/maximum scaffold/stent diameter). Expansion index and optimal scaffold/stent expansion followed the definition of the MUSIC (Multicenter Ultrasound Stenting in Coronaries) study. Eccentricity index (EI) was calculated as the ratio of minimum and maximum scaffold/stent diameter per cross section. The incidence of device-oriented composite endpoint (DoCE) was collected. RESULTS: Post-procedure, the metallic EES group was more symmetric and concentric than the BVS group. Only 8.0% of the BVS arm and 20.0% of the metallic EES arm achieved optimal scaffold/stent expansion (p < 0.001). At 1 year, there was no difference in the DoCE between both devices (BVS 5.2% vs. EES 3.1%; p = 0.29). Post-procedural devices asymmetry and eccentricity were related to higher event rates while there was no relevance to the expansion status. Subsequent multivariate analysis identified that post-procedural AI >0.30 is an independent predictor of DoCE (hazard ratio: 3.43; 95% confidence interval: 1.08 to 10.92; p = 0.037). CONCLUSIONS: BVS implantation is more frequently associated with post-procedural asymmetric and eccentric morphology compared to metallic EES. Post-procedural devices asymmetry were independently associated with DoCE following percutaneous coronary intervention. However, this approach should be viewed as hypothesis generating due to low event rates. (ABSORB II Randomized Controlled Trial [ABSORB II]; NCT01425281).

Technical overview on the MiStent coronary stent.

Drug-eluting stents (DES) have dramatically improved the long-term efficacy of percutaneous coronary intervention (PCI). Over the last decade there have been numerous advances in DES platforms, however, all but one currently approved DES in the United States and many of the approved DES worldwide still have 3 common features: a metal stent platform, an anti-proliferative drug, and a permanent polymer. In this context, the polymer is critical to control drug release, but the polymer serves no purpose after the drug is eluted. While designed to be completely biocompatible, synthetic polymers have the potential to illicit an inflammatory response within the vessel including but not limited to delayed healing and hypersensitivity. Adverse vascular reactions to these polymers have been implicated as a cause of very late stent thrombosis, ongoing intimal hyperplasia and late "catch-up" in addition to neoatherosclerosis. To avoid the long-term risks associated with prolonged polymer exposure, DES with bioabsorbable polymers have been developed. The MiStent® Sirolimus-Eluting Absorbable Polymer Coronary Stent System (MiStent SES) (MiCell Technologies, Durham, NC, USA) combines crystalline sirolimus, a rapidly absorbing polylactide-co-glycolic acid (PLGA) coating and a thin-strut cobalt chromium alloy stent platform (Genius MAGIC® Stent System, EuroCor GmbH, Germany). MiCell's supercritical fluid technology allows a rigorously controlled, solvent-free drug and polymer coating to be applied to a bare-metal stent. This solvent-free application of drug uniquely allows a crystalline form of sirolimus to be used on the MiStent SES potentially providing improved clinical benefits. It avoids the uncontrolled burst of drug seen with other DES, provides uniform drug delivery around and between the stent struts, and allows the anti-inflammatory and anti-restenotic drug (sirolimus) to be present in the tissue through the entire polymer absorption period and for months after the polymer has been absorbed. On the MiStent SES, the PLGA/crystalline sirolimus combination is cleared from the stent within 45-60 days and PLGA is fully absorbed within 90 days. The crystalline form of sirolimus uniquely remains in the tissue and continues to expose the surrounding tissue to therapeutic levels of drug for up to 9 months which is long after the polymer is resorbed.

Dynamically scaled phantom phase contrast MRI compared to true-scale computational modeling of coronary artery flow.

PURPOSE: To examine the feasibility of combining computational fluid dynamics (CFD) and dynamically scaled phantom phase-contrast magnetic resonance imaging (PC-MRI) for coronary flow assessment. MATERIALS AND METHODS: Left main coronary bifurcations segmented from computed tomography with bifurcation angles of 33°, 68°, and 117° were scaled-up ∼7× and 3D printed. Steady coronary flow was reproduced in these phantoms using the principle of dynamic similarity to preserve the true-scale Reynolds number, using blood analog fluid and a pump circuit in a 3T MRI scanner. After PC-MRI acquisition, the data were segmented and coregistered to CFD simulations of identical, but true-scale geometries. Velocities at the inlet region were extracted from the PC-MRI to define the CFD inlet boundary condition. RESULTS: The PC-MRI and CFD flow data agreed well, and comparison showed: 1) small velocity magnitude discrepancies (2-8%); 2) with a Spearman's rank correlation ≥0.72; and 3) a velocity vector correlation (including direction) of r(2) ≥ 0.82. The highest agreement was achieved for high velocity regions with discrepancies being located in slow or recirculating zones with low MRI signal-to-noise ratio (SNRv ) in tortuous segments and large bifurcating vessels. CONCLUSION: Characterization of coronary flow using a dynamically scaled PC-MRI phantom flow is feasible and provides higher resolution than current in vivo or true-scale in vitro methods, and may be used to provide boundary conditions for true-scale CFD simulations. J. MAGN. RESON. IMAGING 2016;44:983-992.