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.

Proximal to distal Y-stenting for coronary bifurcation lesions using radial access: A modern bifurcation technique.

Proximal to distal Y stenting technique is a modified bifurcation technique based on the original Y stenting technique described over 20 years ago. We use a bench top model to illustrate the steps of the technique, which can provide both provisional and full coverage options, using radial artery access. This technique may be applied in clinical settings on a wide range of bifurcation anatomies with a number of unique advantages.

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.

Coronary balloon angioplasty, stents, and scaffolds.

Since the first coronary angioplasty on Sept 16, 1977, the field of percutaneous coronary intervention has evolved rapidly. Now marking its 40th anniversary, percutaneous coronary intervention has become one of the most common medical procedures worldwide. Much of this progress has been due to the iteration and improvement of angioplasty technologies. Balloon angioplasty was limited by unpredictable procedural outcomes due to vessel dissection and recoil, and a high rate of restenosis. The introduction of stents resulted in more stable early results and lower rates of restenosis, although early stent thrombosis and neointimal hyperplasia causing vessel renarrowing were key limitations. Drug-eluting stents delivering antiproliferative agents significantly lowered the rates of restenosis, permitting widespread use of percutaneous coronary intervention in more advanced and complex disease. Although fully bioresorbable scaffolds have the potential to further improve long-term outcomes, they have not yet achieved results equivalent to those of conventional metallic drug-eluting stents in the early years after implantation. Progress in catheter technology did not occur in isolation, and the success of percutaneous coronary intervention is also due to important advances in intracoronary imaging, and adjunct pharmacotherapy-each of which is reviewed in other papers in this Series.

Rational and design of the European randomized Optical Coherence Tomography Optimized Bifurcation Event Reduction Trial (OCTOBER).

Background: Percutaneous coronary intervention in complex bifurcation lesions is prone to suboptimal implantation results and is associated with increased risk of subsequent clinical events. Angiographic ambiguity is high during bifurcation stenting, but it is unknown if procedural guidance by intravascular optical coherence tomography (OCT) improves clinical outcome. Methods and Design: OCTOBER is a randomized, investigator-initiated, multicenter trial aimed to show superiority of OCT-guided stent implantation compared to standard angiographic-guided implantation in bifurcation lesions. The primary outcome measure is a 2-year composite end point of cardiac death, target lesion myocardial infarction, and ischemia-driven target lesion revascularization. The calculated sample size is 1,200 patients in total, and allocation is 1:1. Eligible patients have stable or unstable angina pectoris or stabilized non­ST elevation myocardial infarction, and a coronary bifurcation lesion with significant main vessel stenosis and more than 50 % stenosis in a side branch with a reference diameter ≥2.5mm. Treatment is performed by the provisional side branch stenting technique or 2-stent techniques, and the systematic OCT guiding protocol is aimed to evaluate (1) plaque preparation, (2) lesion length, (3) segmental reference sizes, (4) lesion coverage, (5) stent expansion, (6) malapposition, (7) wire positions, and (8) ostial results. Implications: A positive outcome of the OCTOBER trial may establish OCT as a routine tool for optimization of complex percutaneous coronary intervention, whereas a negative result would indicate that OCT remains a tool for ad hoc evaluation in selected cases.

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.

Transcatheter Aortic Valve Implantation In Patients With a Large Aortic Annulus.

BACKGROUND: As the indications for transcatheter aortic valve implantation (TAVI) have expanded, so to have the demands on interventionists to allow as many patients to access this technology as possible. METHODS: We retrospectively reviewed our TAVI database for patients who had received a 29mm SAPIEN 3 valve despite having an annular area greater than the manufacturer-recommended upper limit of 683mm2, as determined by multi-detector computed tomography (MDCT). Procedural and inpatient outcome data were collected. RESULTS: The study population was 5 of 121 patients receiving a SAPIEN 3 valve since it became available in March 2015. Their annular area ranged from 691 to 800mm2. Valve deployment was successful in all patients. The deployment balloon volume was nominal, except for an additional 1ml in one patient. No patient had a new indication for permanent pacing, and no significant valvular or paravalvular regurgitation (PVR) was identified on post-procedure transthoracic echocardiography. All patients survived to hospital discharge. CONCLUSIONS: In this select group of patients we have demonstrated that it is safe and feasible to use the 29mm SAPIEN 3 in patients with annular dimensions greater than those recommended, with minimal balloon overfilling.

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.

Bioabsorbable polymer-coated sirolimus-eluting stent implantation preserves coronary vasomotion: A DESSOLVE II trial sub-study.

OBJECTIVES: We studied coronary vasomotion in patients treated with the Mistent(®) absorbable polymer sirolimus-eluting stent (APSES) and in patients implanted with the Endeavor(®) zotarolimus-eluting stent (ZES). BACKGROUND: First generation (1st-gen) drug-eluting stents (DES) induce persistent vasomotor dysfunction in the treated coronary artery. It is unknown whether and to what extent the implantation of an absorbable polymer DES impairs coronary vasomotion. METHODS: This sub-study of the DESSOLVE II trial included 19 APSES Mistent(®) and 10 ZES Endeavor(®) patients. Incremental atrial pacing and quantitative coronary angiography were used to assess vasomotion proximal and distal to the stent and in a reference segment at 9 months after implantation. Percent changes in vessel diameter with pacing versus baseline were calculated and compared. Vasomotor response of the APSES group was also compared with changes observed in a historical group of 17 patients implanted with a 1st-gen sirolimus-eluting stent (SES). RESULTS: Normal vasomotion (vasodilatation) was preserved and of comparable magnitude in the APSES and in the ZES group both proximally (P = 0.34) and distally (P = 0.38) to the stent. This finding was not observed in the 1st-gen SES group showing marked pacing-induced vasoconstriction at both stent edges (P < 0.05 vs. APSES). The results were practically unchanged after excluding patients with absolute changes in vessel diameter <3% between baseline and maximal pacing. CONCLUSIONS: The implantation of an absorbable polymer sirolimus-eluting stent is associated with preserved coronary vasomotion, comparable to that observed after implantation of the Endeavor(®) ZES, and distinct from 1st-gen SES which induce coronary vasomotor dysfunction.

Bioresorbable scaffolds: rationale, current status, challenges, and future.

Current generation of drug-eluting stents has significantly improved the outcomes of percutaneous coronary intervention by substantially reducing in-stent restenosis and stent thrombosis. However, a potential limitation of these stents is the permanent presence of a metallic foreign body within the artery, which may cause vascular inflammation, restenosis, thrombosis, and neoatherosclerosis. The permanent stents also indefinitely impair the physiological vasomotor function of the vessel and future potential of grafting the stented segment. Bioresorbable scaffolds (BRSs) have the potential to overcome these limitations as they provide temporary scaffolding and then disappear, liberating the treated vessel from its cage and restoring pulsatility, cyclical strain, physiological shear stress, and mechanotransduction. While a number of BRSs are under development, two devices with substantial clinical data have already received a Conformité Européenne marking. This review article presents the current status of these devices and evaluates the challenges that need to be overcome before BRSs can become the workhorse device in coronary intervention.

Antiplatelet therapy duration following bare metal or drug-eluting coronary stents: the dual antiplatelet therapy randomized clinical trial.

IMPORTANCE: Despite antirestenotic efficacy of coronary drug-eluting stents (DES) compared with bare metal stents (BMS), the relative risk of stent thrombosis and adverse cardiovascular events is unclear. Although dual antiplatelet therapy (DAPT) beyond 1 year provides ischemic event protection after DES, ischemic event risk is perceived to be less after BMS, and the appropriate duration of DAPT after BMS is unknown. OBJECTIVE: To compare (1) rates of stent thrombosis and major adverse cardiac and cerebrovascular events (MACCE; composite of death, myocardial infarction, or stroke) after 30 vs 12 months of thienopyridine in patients treated with BMS taking aspirin and (2) treatment duration effect within the combined cohorts of randomized patients treated with DES or BMS as prespecified secondary analyses. DESIGN, SETTING, AND PARTICIPANTS: International, multicenter, randomized, double-blinded, placebo-controlled trial comparing extended (30-months) thienopyridine vs placebo in patients taking aspirin who completed 12 months of DAPT without bleeding or ischemic events after receiving stents. The study was initiated in August 2009 with the last follow-up visit in May 2014. INTERVENTIONS: Continued thienopyridine or placebo at months 12 through 30 after stent placement, in 11,648 randomized patients treated with aspirin, of whom 1687 received BMS and 9961 DES. MAIN OUTCOMES AND MEASURES: Stent thrombosis, MACCE, and moderate or severe bleeding. RESULTS: Among 1687 patients treated with BMS who were randomized to continued thienopyridine vs placebo, rates of stent thrombosis were 0.5% vs 1.11% (n = 4 vs 9; hazard ratio [HR], 0.49; 95% CI, 0.15-1.64; P = .24), rates of MACCE were 4.04% vs 4.69% (n = 33 vs 38; HR, 0.92; 95% CI, 0.57-1.47; P = .72), and rates of moderate/severe bleeding were 2.03% vs 0.90% (n = 16 vs 7; P = .07), respectively. Among all 11,648 randomized patients (both BMS and DES), stent thrombosis rates were 0.41% vs 1.32% (n = 23 vs 74; HR, 0.31; 95% CI, 0.19-0.50; P < .001), rates of MACCE were 4.29% vs 5.74% (n = 244 vs 323; HR, 0.73; 95% CI, 0.62-0.87; P < .001), and rates of moderate/severe bleeding were 2.45% vs 1.47% (n = 135 vs 80; P < .001). CONCLUSIONS AND RELEVANCE: Among patients undergoing coronary stent placement with BMS and who tolerated 12 months of thienopyridine, continuing thienopyridine for an additional 18 months compared with placebo did not result in statistically significant differences in rates of stent thrombosis, MACCE, or moderate or severe bleeding. However, the BMS subset may have been underpowered to identify such differences, and further trials are suggested. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00977938.

Mid-term outcomes in patients following transcatheter aortic valve implantation in the CoreValve Australia and New Zealand Study.

BACKGROUND: Although numerous studies have reported the safety and effectiveness of transcatheter aortic valve implantation (TAVI), integration of this therapy into standard of care varies widely by region. We evaluated mid-term follow-up in 540 patients with severe symptomatic AS at high risk of surgical AV replacement, enrolled in the ongoing Medtronic CoreValve Australia-New Zealand Study. METHODS: Between August 2008 and July 2013, 10 centres in Australia/New Zealand enrolled 540 patients, which includes initial use of the CoreValve System for all investigators. Patients were deemed suitable for TAVI based on consensus of a multidisciplinary Heart Team. Primary endpoints were cardiovascular death and major adverse cardiovascular and cerebrovascular events (MACCE) at 30 days. Data were fully monitored, and an independent Clinical Events Committee employed. RESULTS: Baseline characteristics include; 45% female, mean age 84 years, EuroSCORE 17.3±10.7%, and 74.9% had New York Heart Association III/IV symptoms. At 30 days, all deaths were cardiovascular (4.1%); MACCE was 11.5%. At one and two years, all-cause mortality was 11.9% and 21.2%; cardiovascular mortality, 9.9% and 15.2%; and stroke, 8.2% and 10.1%, respectively. CONCLUSIONS: Early experience with the CoreValve System in a large cohort of fully-monitored patients was associated with good early- and mid-term safety outcomes.

A review of a regional primary percutaneous coronary intervention service, with a focus on door to reperfusion times: the 2012 Auckland/Northland experience.

AIMS: Primary percutaneous coronary intervention (PCI) is the optimal management for ST segment elevation myocardial infarction (STEMI) patients. We reviewed the largest primary PCI regional service in New Zealand: the Auckland/Northland service based at Auckland City Hospital, to assess patient management, in particular the door to reperfusion times (DTRTs), and predictors of death in hospital. METHODS: We obtained patient details from a comprehensive prospective database of all primary PCI patients admitted with STEMI from 1/1/12 to 31/12/12 to the Auckland City Hospital cardiac catheterisation laboratory. Of four District Health Boards (DHBs) within the region, two accessed this regional service at all times, and two accessed the Auckland City Hospital cardiac catheterisation laboratory 'after hours': all times except for 08:00 to 16:00 hours on Monday to Friday. RESULTS: A total of 401 adult patients underwent a primary PCI at the Auckland City Hospital Regional centre for a STEMI presentation, over the 12 months period. The median patient age was 61 years, 77% were male. Overall 183 (46%) (95% CI 41, 51) patients achieved a DTRT of < 90 mins, and 266 (66%) (95% CI 61, 71) a DTRT of < 120 mins, with a clear geographical influence to these times. Of 27 patients with direct transfer to the catheter laboratory from the community, the DTRT was < 120 mins in 24 (92%) (95% CI 72, 96) patients. In-hospital mortality was 24 (6%) patients (95% CI 4, 9). CONCLUSIONS: The 2012 Auckland/Northland primary PCI service delivers good outcomes consistent with current Australasian standards. Although geographical isolation complicates door to reperfusion times, these may potentially be improved by more focus on direct transfer to the cardiac catheterisation laboratory, especially directly from the community.

A randomized, controlled, multicenter trial to evaluate the safety and efficacy of Zotarolimus- vs. Paclitaxel-eluting stents in de novo occlusive lesions in coronary arteries: five-year results from the ZOMAXX I trial.

BACKGROUND: The ZOMAXX I trial tested the noninferiority of a zotarolimus-eluting coronary stent (ZoMaxx(™) ) when compared with a paclitaxel-eluting coronary stent (Taxus(™) Express(2™) ) in a randomized trial of percutaneous intervention for de novo coronary artery stenosis. Angiographic analysis at the primary endpoint of 9 months has been reported previously. The purpose of this follow-on analysis was to describe the clinical results of the ZoMaxx and Taxus cohorts of the ZOMAXX I trial after 5 years. METHODS AND RESULTS: In the ZOMAXX I trial, 199 patients received a ZoMaxx stent and 197 patients received a Taxus stent at 29 investigative sites in Europe, Australia, and New Zealand. The two groups were generally well matched with respect to both clinical and lesional characteristics, including the incidence of diabetes (ZoMaxx 22% vs. Taxus 26%; P = 0.29), reference vessel diameter (ZoMaxx 2.79 ± 0.43 mm vs. Taxus 2.81 ± 0.46 mm; P = 0.65), and lesion length (ZoMaxx 14.9 ± 5.7 mm vs. Taxus 14.6 ± 5.5; P = 0.61). Through 5 years of follow-up, a total of 21 patients had died, six patients had withdrawn, nine had been lost to follow-up, and 13 missed their 5-year visit, leaving a total of 347 patients for analysis (169 ZoMaxx and 178 Taxus). At the 5-year time point, there were no significant differences in any clinical metric including ischemia-driven target lesion revascularization (TLR; ZoMaxx 10.6% vs. Taxus 7.1%; P = 0.29), Q-wave myocardial infarction (ZoMaxx 1.5% vs. Taxus 1.0%; P = 0.99), definite/probable stent thrombosis (ZoMaxx 1.5% vs. Taxus 3.0%; P = 0.34), and cardiac death (ZoMaxx 3.0% vs. Taxus 1.0%; P = 0.28). CONCLUSIONS: After 5 years, the differences in clinical outcome between patients treated with ZoMaxx vs. Taxus stents did not reach statistical significance. However, the nominally higher rate of ischemia-driven TLR (10.6 vs. 7.1%) and the previously reported higher rate of restenosis after 9 months suggest that the ZoMaxx stent afforded less neointimal inhibition when compared with Taxus. © 2013 Wiley Periodicals, Inc.

Racial differences in long-term outcomes after percutaneous coronary intervention with paclitaxel-eluting coronary stents.

OBJECTIVES: To assess the influence of race on long-term outcomes following percutaneous coronary intervention (PCI) with paclitaxel-eluting stents (PES). BACKGROUND: Data on the influence of race on long-term outcomes following PCI with drug-eluting stents are limited because of severe underrepresentation of minority populations in randomized trials. METHODS: We compared 5-year outcomes of 2,301 whites, 127 blacks, and 169 Asians treated with PES in the TAXUS IV, V, and ATLAS trials. Outcomes were adjusted using a propensity score logistic regression model with 1:4 matching. RESULTS: Blacks were more likely than whites to be female, have a history of hypertension, diabetes mellitus, congestive heart failure, and stroke, but were less likely to have prior coronary artery disease. Compared with whites, Asians were younger, more likely to be male, have stable angina, and left anterior descending disease, and less likely to have silent ischemia, previous coronary artery bypass surgery, prior coronary artery disease, diabetes mellitus, peripheral vascular disease, and to receive glycoprotein IIb/IIIa inhibitors. Despite higher antiplatelet compliance, the adjusted 5-year rates of myocardial infarction (15.4% vs. 5.4%, P < 0.001) and stent thrombosis (5.6% vs. 1.1%, P = 0.002) were higher in blacks than whites. Despite lower antiplatelet compliance, Asians had no differences in myocardial infarction and stent thrombosis compared with whites. Mortality and revascularization rates were similar between the three groups. CONCLUSIONS: The long-term risk of major thrombotic events after PCI with PES was higher in blacks, but not Asians, compared with whites. The mechanisms underlying these racial differences warrant further investigation.

Endothelial-dependent vasomotion in a coronary segment treated by ABSORB everolimus-eluting bioresorbable vascular scaffold system is related to plaque composition at the time of bioresorption of the polymer: indirect finding of vascular reparative therapy?

AIMS: To analyse the vasoreactivity of a coronary segment, previously scaffolded by the ABSORB bioresorbable vascular scaffold (BVS) device, in relationship to its intravascular ultrasound-virtual histology (IVUS-VH) composition and reduction in greyscale echogenicity of the struts. Coronary segments, transiently scaffolded by a polymeric device, may in the long-term recover a normal vasomotor tone. Recovery of a normal endothelial-dependent vasomotion may be enabled by scaffold bioresorption, composition of the underlying tissue, or a combination of both mechanisms. METHODS AND RESULTS: All patients from the ABSORB Cohort A and B trials, who underwent a vasomotion test and IVUS-VH investigation at 12 and 24 months, were included. Acetylcholine (Ach) and nitroglycerin were used to test either the endothelial-dependent or -independent vasomotion of the treated segment. Changes in polymeric strut echogenicity-a surrogate for bioresorption-IVUS-VH composition of the tissue underneath the scaffold and their relationship with the pharmacologically induced vasomotion were all evaluated. Overall, 26 patients underwent the vasomotion test (18 at 12 and 8 at 24 months). Vasodilatory response to Ach was quantitatively associated with larger reductions over time in polymeric strut echogenicity (y= -0.159x- 6.85; r= -0.781, P< 0.001). Scaffolded segments with vasoconstriction to Ach had larger vessel areas (14.37 ± 2.50 vs. 11.85 ± 2.54 mm(2), P= 0.030), larger plaque burden (57.31 ± 5.96 vs. 49.09 ± 9.10%, P= 0.018), and larger necrotic core (NC) areas [1.39 (+1.14, +1.74) vs. 0.78 mm(2) (+0.20, +0.98), P= 0.006] compared with those with vasodilation. CONCLUSION: Vasodilatory response to Ach, in coronary segments scaffolded by the ABSORB BVS device, is associated with a reduction in echogenicity of the scaffold over time, and a low amount of NC. In particular, the latter finding resembles the behaviour of a native coronary artery not caged by an intracoronary device.

Bench top evaluation and clinical experience with the Szabo technique: new questions for a complex lesion.

BACKGROUND: The Szabo technique has been described as a method to ensure accurate ostial stent placement. We sought to investigate this novel technique in detail both in vitro and in vivo. METHODS AND RESULTS: The technique was subjected to bench testing and also undertaken in 26 patients. Each step was recorded with cine angiography and the stents imaged by microcomputed tomography. The ostial LAD was treated in 81% and a DES was implanted in 92%. Angiographic success was 88.5% (one case of stent dislodgement). Repeat angiography was performed in 78% and restenosis observed in two patients. MACE rate at 15.5 ± 5.1 months was 13% (1 TLR, 1 MI, 1 cardiac death). Despite a seemingly excellent immediate angiographic result, we report one case of restenosis at follow up and one case of IVUS examination (performed in four patients) in which significant stent protrusion, into the proximal main vessel, was observed. In vitro bench testing confirmed a significant and asymmetric (carina side) stent protrusion into the main branch, with the last cell of the stent undergoing significant deformation. CONCLUSIONS: The Szabo technique is not a precise technique to implant a stent at the level of the ostium. The proximal end of the stent undergoes significant and asymmetric deformation, protruding into main branch. Additional concerns with this complex technique include the potential for stent damage or contamination before implantation and the risk of stent dislodgement. We conclude that there are more disadvantages than benefits to this technique which only partially addresses the difficulties encountered in the treating ostial lesions.

Comparison of in vivo eccentricity and symmetry indices between metallic stents and bioresorbable vascular scaffolds: insights from the ABSORB and SPIRIT trials.

OBJECTIVE: To compare the geometrical parameters of a bioresorbable vascular scaffold (BVS) with a standard metallic stent. BACKGROUND: The introduction of polymeric bioresorbable materials in the design of novel coronary scaffolds may affect some geometrical parameters, such as eccentricity and symmetry indices, previously introduced as IVUS criteria for optimal metallic stent deployment. METHODS: From ABSORB Cohort A, ABSORB Cohort B, SPIRIT I, and SPIRIT II, all patients implanted with BVS 1.0, BVS 1.1, or XIENCE V, respectively and intravascular ultrasound analyses post-implantation were selected. The eccentricity index was calculated frame by frame and expressed as an average per device (minimum diameter/maximum diameter). The symmetry index of the device was reported as ([maximum diameter - minimum diameter]/maximum diameter). Six months major adverse cardiac events (MACE) were analyzed. RESULTS: A total of 242 patients were selected (BVS 1.0: n = 28, BVS 1.1: n = 94, XIENCE V: n = 120). The BVS exhibited a significantly lower eccentricity index (BVS 1.0: 0.83 ± 0.09; BVS 1.1: 0.85 ± 0.08; XIENCE V: 0.90 ± 0.06; P < 0.01) and a significantly higher symmetry index (BVS 1.0: 0.30 ± 0.07; BVS 1.1: 0.31 ± 0.06, XIENCE V 0.26 ± 0.07; P < 0.01) as compared to the XIENCE V. An inverse correlation was found between the symmetry and eccentricity indices for both (BVS r = -0.69, P < 0.01; XIENCE V r = -0.61, P < 0.01). No differences in MACE were detected between the groups according to their geometrical parameters. CONCLUSIONS: The introduction of a new polymeric material in the design of BVS resulted in a lower eccentricity index and a higher symmetry index as compared to metallic stents, without detectable impact in MACE, at 6 months.