Revisiting late loss and neointimal volumetric measurements in a drug-eluting stent trial: analysis from the SPIRIT FIRST trial

Experience with BioMatrix BES and other DES in all-comers setting: a retrospective overview

New generation DES are effectively used in all spectrum of coronary artery diseases (CAD) and are replacing earlier DES and BMS. Biolimus A9™-eluting stent is a new generation DES containing the anti-proliferative drug biolimus A9™ incorporating a biodegradable abluminal coating that leaves a polymer-free stent after drug release enhancing strut coverage while preventing neointimal hyperplasia. A retrospective data analysis was done in patients treated with DES, with a major share of Biolimus A9™ (BA9™) drug-eluting stents (DES) at Bombay Hospital, Mumbai. A total of 158 patients with 219 lesions were treated with DES, comprising Biolimus A9-eluting stent and others and the major adverse cardiac events (MACE) rate and stent thrombosis (ST) at 1, 6, 12 months and 24 months were analyzed. Mace rate was 3.16% for average follow-up of 19 months. There were 3 cases of ST (2 of acute and 1 of subacute onset) and one non-cardiac death reported during this time. This retrospective data demonstrates good one- and two-year clinical safety and efficacy of DES, especially of BioMatrix stents in real world setting.

One-year clinical outcomes of BioMatrix™-Biolimus A9™ eluting stent: the e-BioMatrix multicenter post marketing surveillance registry in India

OBJECTIVE

The e-BioMatrix is a post marketing multicenter registry with an objective to evaluate the 2 year clinical safety and efficacy outcomes in patients treated with BioMatrix™ - Biolimus A9™ (BA9™) drug eluting stents (DES).

BACKGROUND

Drug-eluting stents still have late-stage disadvantages that might be attributable to the permanent polymer. BioMatrix a new generation DES containing anti-proliferative drug Biolimus A9™ incorporating a biodegradable abluminal coating that leaves a polymer-free stent after drug release enhancing strut coverage while preventing neointimal hyperplasia.

METHODS

This interim analysis consists of a total of 1189 patients with 1418 lesions treated with BioMatrix stent who entered this multicenter registry in India. We analyzed the incidence of major adverse cardiac events (MACE) and stent thrombosis (ST) at 1, 6, and 12 months with an extended follow-up of 2 years. Recommended antiplatelet regimen included clopidogrel and aspirin for 12 months.

RESULTS

The mean age was 57.6 ± 10.9 years, 81.8% were males, comorbidity index was 1.20 ± 1.33, 68% presented with acute coronary syndrome, 49% had hypertension and 40.8% had diabetes mellitus. One-year clinical follow-up was completed in 987 patients at the time of interim analysis. The incidence of MACE is 0.45 for 1544 person-year follow-up. There were only 03 cases of ST (01 late ST) reported during this time.

CONCLUSION

This registry demonstrates excellent one-year clinical safety and efficacy of BioMatrix stents. The 1-year result shows that BioMatrix stent may be a suitable alternative as compared to contemporary DESs which are currently available in the market for simple as well complex disease.

Outcomes of patients treated with the everolimus-eluting stent versus the zotarolimus eluting stent in a consecutive cohort of patients at a tertiary medical center

Background

In this study we compared the outcomes of the everolimus-eluting stent (EES) versus the zotarolimus-eluting stent (ZES) in patients treated at a tertiary medical center, with up to one year of follow-up.

Methods

Unselected consecutive patients were retrospectively recruited following stenting with the ZES (n = 197) or EES (n = 190). The first 100 consecutive patients in each cohort underwent syntax scoring. The primary endpoint of the study was target vessel failure, defined as the combined endpoint of cardiac death, non-fatal myocardial infarction, or target vessel revascularization. Secondary endpoints included target lesion revascularization, target lesion failure, acute stent thrombosis, total death, cardiac death, and non-fatal myocardial infarction.

Results

The two groups were similar, including for Syntax scores (19.6 ± 12.8 versus 20.6 ± 13.6), number of stents per patient (2.9 ± 1.9 versus 2.9 ± 2.1), and cardiovascular risk factors. By one year, the primary outcome occurred in 20.8% EES versus 26.7% ZES (P = 0.19) patients. The secondary endpoints were as follows: target lesion revascularization (8.9% versus 20.6%, P = 0.003), target vessel revascularization (18.9% versus 25.6%, P = 0.142), definite and probable stent thrombosis (0% versus 2.5%), non-fatal myocardial infarction (2.7% versus 3.6%), and mortality (3.2% versus 5.1%) for the EES versus the ZES, respectively.

Conclusion

EES had similar target vessel failure to ZES, but superior target lesion revascularization and target lesion failure at one year of follow-up in an unselected cohort of patients.

Low resolution limits and inaccurate algorithms decrease significantly the value of late loss in current drug-eluting stent trials

Quantitative coronary and vascular angiography (QCA resp., QVA) remains the current gold standard for evaluation of restenosis. Late loss as one of the most commonly accepted parameters to highlight efficacy of the various devices has shown high correlation to clinical parameters but, surprisingly, has no impact on the evaluation of the remaining amount of restenostic tissue. The current clinical practice leads to unrealistic late loss calculations. Smaller late loss differences are usually not greater than the inherited resolution limits of QCA, which is especially the case in small differences between the various stents in the drug-eluting stent era. Late loss include additional systematic and random errors, due to the fact that measurements were taken at two different time points including the inherited resolution and calibration limits of QCA on two occasions. Due to the limited value of late loss in discriminating the small differences between the one and other DES, late lumen area loss and clearly defined calculation algorithms (e.g., MLD-relocation) should be used in future DES studies also to fulfill the more stringent regulatory requirements.

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.

Quantitative multi-modality imaging analysis of a fully bioresorbable stent: a head-to-head comparison between QCA, IVUS and OCT

The bioresorbable vascular stent (BVS) is totally translucent and radiolucent, leading to challenges when using conventional invasive imaging modalities. Agreement between quantitative coronary angiography (QCA), intravascular ultrasound (IVUS) and optical coherence tomography (OCT) in the BVS is unknown. Forty five patients enrolled in the ABSORB cohort B1 study underwent coronary angiography, IVUS and OCT immediately post BVS implantation, and at 6 months. OCT estimated stent length accurately compared to nominal length (95% CI of the difference: -0.19; 0.37 and -0.15; 0.47 mm(2) for baseline and 6 months, respectively), whereas QCA incurred consistent underestimation of the same magnitude at both time points (Pearson correlation = 0.806). IVUS yielded low accuracy (95% CI of the difference: 0.77; 3.74 and -1.15; 3.27 mm(2) for baseline and 6 months, respectively), with several outliers and random variability test-retest. Minimal lumen area (MLA) decreased substantially between baseline and 6 months on QCA and OCT and only minimally on IVUS (95% CI: 0.11; 0.42). Agreement between the different imaging modalities is poor: worst agreement Videodensitometry-IVUS post-implantation (ICCa 0.289); best agreement IVUS-OCT at baseline (ICCa 0.767). All pairs deviated significantly from linearity (P < 0.01). Passing-Bablok non-parametric orthogonal regression showed constant and proportional bias between IVUS and OCT. OCT is the most accurate technique for measuring stent length, whilst QCA incurs systematic underestimation (foreshortening) and solid state IVUS incurs random error. Volumetric calculations using solid state IVUS are therefore not reliable. There is poor agreement for MLA estimation between all the imaging modalities studied, including IVUS-OCT, hence their values are not interchangeable.

Re-examining minimal luminal diameter relocation and quantitative coronary angiography--intravascular ultrasound correlations in stented saphenous vein grafts: methodological insights from the randomised RRISC trial

AIMS

Angiographic parameters (such as late luminal loss) are common endpoints in drug-eluting stent trials, but their correlation with the neointimal process and their reliability in predicting restenosis are debated.

METHODS AND RESULTS

Using quantitative coronary angiography (QCA) data (49 bare metal stent and 44 sirolimus-eluting stent lesions) and intravascular ultrasound (IVUS) data (39 bare metal stent and 34 sirolimus-eluting stent lesions) from the randomised Reduction of Restenosis In Saphenous vein grafts with Cypher stent (RRISC) trial, we analysed the "relocation phenomenon" of QCA-based in-stent minimal luminal diameter (MLD) between post-procedure and follow-up and we correlated QCA-based and IVUS-based restenotic parameters in stented saphenous vein grafts. We expected the presence of MLD relocation for low late loss values, as MLD can "migrate" along the stent if minimal re-narrowing occurs, while we anticipated follow-up MLD to be located close to post-procedural MLD position for higher late loss. QCA-based MLD relocation occurred frequently: the site of MLD shifted from post-procedure to follow-up an "absolute" distance of 5.8 mm [2.5-10.2] and a "relative" value of 29% [10-46]. MLD relocation failed to correlate with in-stent late loss (rho = 0.14 for "absolute" MLD relocation [p = 0.17], and rho=0.03 for "relative" relocation [p = 0.811). Follow-up QCA-based and IVUS-based MLD values well correlated in the overall population (rho = 0.76, p < 0.001), but QCA underestimated MLD on average 0.55 +/- 0.49 mm, and this was mainly evident for lower MLD values. Conversely, the location of QCA-based MLD failed to correlate with the location of IVUS-based MLD (rho = 0.01 for "absolute" values--in mm [p = 0.911, rho = 0.19 for "relative" values--in % [p = 0.111). Overall, the ability of late loss to "predict" IVUS parameters of restenosis (maximum neointimal hyperplasia diameter, neointimal hyperplasia index and maximum neointimal hyperplasia area) was moderate (rho between 0.46 and 0.54 for the 3 IVUS parameters).

CONCLUSIONS

These findings suggest the need for a critical re-evaluation of angiographic parameters (such as late loss) as endpoints for drug-eluting stent trials and the use of more precise techniques to describe accurately and properly the restenotic process.

Next-generation drug-eluting stents in coronary artery disease: focus on everolimus-eluting stent (Xience V)

Percutaneous coronary revascularization has been a mainstay in the management of coronary artery disease since its introduction in the late 1970s. Bare-metal stents and, more recently, first-generation drug-eluting stents (DES), such as sirolimus-eluting (Cypher^®) and paclitaxel-eluting stents (Taxus^®), have further improved results of percutaneous coronary intervention (PCI) by improving early results and reducing the risk of restenosis. There is currently debate on the safety of these first-generation DES, given the potential for late stent thrombosis, especially after discontinuation of dual antiplatelet therapy. There are well known caveats on the performance of their respective metallic stent platforms, delivery, and dilation systems, and polymer coatings. Second-generation DES, such as zotarolimus-eluting (Endeavor^®) and everolimus-eluting stents (Xience V^®), have recently become available in the USA and/or Europe. The Xience V stent holds the promise of superior anti-restenotic efficacy as well as long-term safety. In addition, this stent is based on the Multi-link platform and delivery system. Recently available data already suggest the superiority of the Xience V stent in comparison to the Taxus stent in terms of prevention of restenosis, without significant untoward events. Nonetheless, the number of patients studied and the follow-up duration are still too limited to enable definitive conclusions. Only indirect meta-analyses can be used to date to compare the Xience V with the Cypher. This systematic review tries to provide a concise and critical appraisal of the data in support of the Xience V everolimus-eluting stent.

Head-to-head comparison of sirolimus- and paclitaxel-eluting stent in the same diabetic patient with multiple coronary artery lesions: a prospective, randomized, multicenter study

OBJECTIVE

It is still controversial whether sirolimus-eluting stent (SES) and paclitaxel-eluting stent (PES) are equally effective in patients with diabetes. In these patients, multiple individual variables may be responsible for neointimal hyperplasia, thus making difficult the comparison of the two drug-eluting stents (DES).

RESEARCH DESIGN AND METHODS

We designed a prospective, randomized study to compare the efficacy in prevention of restenosis of SES and PES, both implanted in the same diabetic patient with multiple de novo coronary artery lesions undergoing elective percutaneous coronary intervention. We enrolled 60 patients with diabetes with at least two significant de novo angiographic stenoses in different coronary segments. The primary end point was in-stent late luminal loss (LLL) at 8-month angiographic follow-up.

RESULTS

A total of 120 lesions were successfully treated with the randomly assigned DES (SES, n = 60; PES, n = 60). In-stent LLL was lower in the SES than in the PES group (0.26 +/- 0.4 vs. 0.50 +/- 0.6 mm; P = 0.01). Coronary lesions treated with SES presented a reduced in-stent LLL in 40 (68%) patients, while PES resulted in a lower in-stent LLL in 19 (32%) patients (P = 0.0002). At multivariable analysis, the type of DES implanted was the only independent predictor of in-stent LLL (odds ratio 2.3 [95% CI 1.1-5.0]; P = 0.03).

CONCLUSIONS

SES directly compared with PES in the same diabetic patient is associated with a decrease in the extent of in-stent LLL at 8 months, suggesting a reduced risk of restenosis.

Two-year serial coronary angiographic and intravascular ultrasound analysis of in-stent angiographic late lumen loss and ultrasonic neointimal volume from the TAXUS II trial

Late loss has been used as a reliable surrogate end point for evaluation and differentiation of short-term performance of drug-eluting stents. This study investigated the consistency between angiographic and intravascular ultrasound (IVUS) outcomes of late lumen loss (late loss) and neointimal growth to measure restenotic plaque load in TAXUS and bare metal stents. The randomized TAXUS II trial evaluates the polymer-based paclitaxel-eluting TAXUS stent in slow- and moderate-release formulations. Serial angiographic and IVUS analyses were available in 155 event-free patients (bare metal stent, 74; TAXUS stent, 81) after the procedure, at 6 months, and at 2 years. For this subanalysis, quantitative coronary angiographic (QCA) and IVUS measurements were used to derive late loss and neointimal volume. From after the procedure to 6 months, quantitative coronary angiography and IVUS showed matching results for the 2 groups with significant decreases in late loss and neointimal volume in the TAXUS versus the control group. From 6 months to 2 years, QCA and IVUS measurements also showed results similar to those in the control group, demonstrating neointimal compaction over time. However, in the TAXUS group, QCA late loss showed a nonsignificant decrease from 6 months to 2 years, whereas IVUS neointimal volume increased. In conclusion, although QCA and IVUS results were similar over the first 6 months, long-term assessment of changes in restenotic plaque load showed discrepant findings for the TAXUS. These findings suggest the need for critical reevaluation of current end points and the use of more precise techniques to detect lumen and stent boundaries.

Relocation of minimal luminal diameter after bare metal and drug-eluting stent implantation: Incidence and impact on angiographic late loss

Late loss (LL) has been a fundamental angiographic end-point in drug-eluting stents (DES) clinical trials. However, calculation of LL may be affected by a mismatch between post-procedure (PO) and follow-up (FU) sites of the minimal lumen diameter (MLD). Our aims were to investigate the incidence and methodological implications of the relocation of MLD after bare metal (BMS), sirolimus-eluting (SES), and paclitaxel-eluting (PES) stent implantation. Data from DIABETES I and II trials, which involved diabetic patients treated with BMS, SES, and PES, were analyzed. Angiographic data with matched projections between PO and 9-month angiographic FU were included. In-stent, in-lesion, and in-segment analyses included conventional and customized sub-segmental (5-mm/subsegment) methodology. MLD relocation was considered when the sites of MLD shifted a distance >> the intrinsic variability of the method. Conventional LL, site matched LL, maximal LL (MaxLL), and average LL (AvgLL) were calculated. Relationships between various LL and 1-year target lesion revascularization (TLR) were investigated. Post MLD was located distally, outside the stent, in > or =65% of the analyses. At FU, MLD relocation occurred in 70.5% (BMS), 40% (SES), and 35% (PES). MLD shifted > or =11 mm on average, mainly towards the stented segment. MLD relocation still occurred in 42.8% (BMS), 33.7% (SES), and 36.4% (PES), when analysis was restricted to in-stent segment. Among LL measurements, MaxLL showed the best association with TLR rates. Relocation of the MLD is a frequent phenomenon after both BMS and DES, and should be taken into account when calculating LL. Comprehensive LL analyses, including MaxLL and AvgLL, provides a better appraisal of the biological and clinical effectiveness of DES.