Tissue coverage of a hydrophilic polymer-coated zotarolimus-eluting stent vs. a fluoropolymer-coated everolimus-eluting stent at 13-month follow-up: an optical coherence tomography substudy from the RESOLUTE All Comers trial

Comparison of resolute zotarolimus-eluting stents and sirolimus-eluting stents in patients with de novo long coronary artery lesions: a randomized LONG-DES IV trial

BACKGROUND

Procedural and clinical outcomes still remain unfavorable for patients with long coronary lesions who undergo stent-based coronary interventions. Therefore, we compared the relative efficacy and safety of resolute zotarolimus-eluting stents (R-ZES) and sirolimus-eluting stents (SES) for patients with de novo long coronary lesions.

METHODS AND RESULTS

This randomized, multicenter, prospective trial, called the Percutaneous Treatment of LONG Native Coronary Lesions With Drug-Eluting Stent-IV (LONG-DES IV) trial, compared long R-ZES and SES in 500 patients with long (≥25 mm) native coronary lesions. The primary end point of the trial was in-segment late luminal loss at 9-month angiographic follow-up. The baseline characteristics were not different between R-ZES and SES groups, including lesion lengths (32.4±13.5 mm versus 31.0±13.5 mm, P=0.27). At 9-month angiographic follow-up, the R-ZES was noninferior to the SES with respect to in-segment late luminal loss, the primary study end point (0.14±0.38 mm versus 0.12±0.43 mm, P for noninferiority=0.03, P for superiority=0.68). In addition, in-stent late luminal loss (0.26±0.36 mm versus 0.24±0.42 mm, P=0.78) and the rates of in-segment (5.2% versus 7.2%, P=0.44) and in-stent (4.0% versus 6.0%, P=0.41) binary restenosis were not significantly different between the 2 groups. There were no significant between-group differences in the rate of adverse clinical events (death, myocardial infarction, stent thrombosis, target-lesion revascularization, and composite outcomes).

CONCLUSIONS

For patients with de novo long coronary artery disease, R-ZES implantation showed noninferior angiographic outcomes as compared with SES implantation.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01186094.

Optical Coherence Tomography: Potential Clinical Applications

Optical coherence tomography (OCT) is a novel intravascular imaging modality using near-infrared light. By OCT it is possible to obtain high-resolution cross-sectional images of the vascular wall structure and assess the acute and long-term effects of percutaneous coronary intervention. For the time being OCT has been mainly used in research providing new insights into the pathophysiology of the atheromatic plaque and of the vascular response to stenting, however, it seems that there is potential for clinical application of OCT in various fields, such as pre-interventional evaluation of coronary arteries, procedural guidance in coronary interventions, and follow-up assessment of vascular healing after stent implantation. This review will focus on the potential and advantages of OCT in the clinical practice of a catheterization laboratory.

Optical Coherence Tomography Imaging: Novel Insights into the Vascular Response After Coronary Stent Implantation

Optical coherence tomography (OCT) is a high-resolution imaging technique that is increasingly used for intracoronary imaging to characterize coronary atherosclerotic plaques and vascular responses after coronary stent implantation. Introduction of optical frequency-domain imaging (OFDI; second generation OCT) has simplified practical use of this novel imaging modality resulting in a more widespread availability in interventional cardiology. Here we highlight recent insights into the acute and chronic vascular response after coronary stent implantation by OCT imaging. OCT provides cross-sectional images with approximately 10-fold higher resolution as compared to intravascular-ultrasound (IVUS), allowing for precise evaluation of tissue coverage and malapposition of coronary stent struts. More than 30 studies using OCT to compare vascular responses to different stents have now been reported. Recent studies have examined the relation between OCT-image characteristics and tissue composition around stent struts. OCT is used for evaluation of novel stent concepts, such as bioengineered stents and bioabsorbable stents, where it provides more accurate information than IVUS. While intracoronary OCT imaging is further developed, including faster 3D-OCT-image-reconstruction, larger OCT studies/registries with standardized analysis will provide more insights into clinical implications of observations from OCT-imaging after coronary stent implantation.

ComparisOn of neointimal coVerage betwEen zotaRolimus-eluting stent and everolimus-eluting stent using Optical Coherence Tomography (COVER OCT)

BACKGROUND

Data on strut surface coverage of second-generation drug-eluting stents (DES) are limited. We investigated stent strut coverage of resolute zotarolimus-eluting stent (ZES-R) or everolimus-eluting stent (EES) at 9 months after implantation using optical coherence tomography (OCT).

METHODS

ComparisOn of neointimal coVerage betwEen zotaRolimus-eluting stent and everolimus-eluting stent using Optical Coherence Tomography (COVER OCT) is a prospective, randomized, multicenter trial comparing ZES-R to EES using OCT at 9 months after stent implantation. The primary end point was the rate of stent strut coverage at 9 months.

RESULTS

A total of 51 patients were randomized to receive either ZES-R (ZES-R group) or EES (EES group), and 47 stents (24 ZES-R and 23 EES) in 44 of 51 patients were evaluated by OCT both immediately after stent implantation and at 9 months. The neointimal thickness was not significantly different between the 2 groups at 9 months (ZES-R vs EES: 139 ± 58 vs 124 ± 42 μm, P = .31). The mean percentages of uncovered stent struts were 3.3% for ZES-R versus 3.4% for EES at 9 months (P = .51). The proportions of malapposed struts immediately after stent implantation (P = .89) and at 9-month follow-up (P = .34) were 0.8% and 0.7% for ZES-R versus 1.0% and 0.1% for EES, respectively. Thrombi were documented in 1 stent (1 [4.2%] in ZES-R vs 0 [0%] in EES).

CONCLUSION

According to the sequential OCT evaluation, ZES-R and EES showed comparable neointimal thickness and the rate of uncovered stent strut at 9 months after stent implantation.

The role of optical coherence tomography in coronary intervention

Optical coherence tomography (OCT) is an optical analog of intravascular ultrasound (IVUS) that can be used to examine the coronary arteries and has 10-fold higher resolution than IVUS. Based on polarization properties, OCT can differentiate tissue characteristics (fibrous, calcified, or lipid-rich plaque) and identify thin-cap fibroatheroma. Because of the strong attenuation of light by blood, OCT systems required the removal of blood during OCT examinations. A recently developed frequency-domain OCT system has a faster frame rate and pullback speed, making the OCT procedure more user-friendly and not requiring proximal balloon occlusion. During percutaneous coronary intervention (PCI), OCT can provide detailed information (dissection, tissue prolapse, thrombi, and incomplete stent apposition [ISA]). At follow-up examinations after stent implantation, stent strut coverage and ISA can be assessed. Several OCT studies have demonstrated delayed neointimal coverage following drug-eluting stent (DES) implantation vs. bare metal stent (BMS) placement. While newer DESs promote more favorable vascular healing, the clinical implications remain unknown. Recent OCT studies have provided insights into restenotic tissue characteristics; DES restenotic morphologies differ from those with BMSs. OCT is a novel, promising imaging modality; with more in-depth assessments of its use, it may impact clinical outcomes in patients with symptomatic coronary artery disease.

Optical coherence tomography: from research to practice

Optical coherence tomography (OCT) is a high-resolution imaging technique with great versatility of applications. In cardiology, OCT has remained hitherto as a research tool for characterization of vulnerable plaques and evaluation of neointimal healing after stenting. However, OCT is now successfully applied in different clinical scenarios, and the introduction of frequency domain analysis simplified its application to the point it can be considered a potential alternative to intravascular ultrasound for clinical decision-making in some cases. This article reviews the use of OCT for assessment of lesion severity, characterization of acute coronary syndromes, guidance of intracoronary stenting, and evaluation of long-term results.

Optical coherence tomography: on the way to decipher the 'Rosetta stone'

Optical coherence tomography is an exciting light-based imaging modality with a much higher axial resolution as compared with intravascular ultrasound. The diagnostic value of optical coherence tomography resides in its ability to provide information on the stent interaction with the vessel wall at the level of individual struts. Chief clinical implications include evaluating strut neointimal coverage and strut malapposition following coronary stenting. This Editorial covers the basics of optical coherence tomography, its established and potential clinical implications, probable caveats and downsides, in addition to a future perspective, all in view of the late-breaking peer-reviewed literature.

Spatial distribution and temporal evolution of scattering centers by optical coherence tomography in the poly(L-lactide) backbone of a bioresorbable vascular scaffold

BACKGROUND

Scattering centers (SC) are often observed with optical coherence tomography (OCT) in some struts of bioresorbable vascular scaffolds (BVS). These SC might be caused by crazes in the polymer during crimp-deployment (more frequent at inflection points) or by other processes, such as physiological loading or hydrolysis (eventually increasing with time). The spatial distribution and temporal evolution of SC in BVS might help to understand their meaning.

METHODS AND RESULTS

Three patients were randomly selected from 12 imaged with Fourier-domain OCT at both baseline and 6 months in the ABSORB cohort B study (NCT00856856). Frame-by-frame analysis of the SC distribution was performed using spread-out vessel charts, and the results from baseline and 6 months were compared. A total of 4,328 struts were analyzed. At baseline and follow-up all SC appeared at inflection points. No significant difference was observed between baseline and 6 months in the number of SC struts (14.9 vs. 14.5%, P=0.754) or in the distribution of SC. The proportion and distribution of SC did not vary substantially among the patients analyzed.

CONCLUSIONS

The SC observed in OCT imaging of the BVS are located exclusively at inflection points and do not increase with time. These findings strongly suggest that SC are caused by crazes in the polymer during crimp-deployment, ruling out any major role of hydrolysis or other time-dependent processes.

Long-term tissue coverage of a biodegradable polylactide polymer-coated biolimus-eluting stent: comparative sequential assessment with optical coherence tomography until complete resorption of the polymer

BACKGROUND

Biolimus-eluting stents (BESs) with a biodegradable polymer in abluminal coating achieve more complete coverage at 9 months compared with sirolimus-eluting stents (SESs) with a durable polymer, as assessed by optical coherence tomography (OCT). Whether this advantage persists or augments after complete resorption of the polymer (>12 months) is unknown.

METHODS

The LEADERS trial compared the performance of BES with that of SES. Patients were randomly allocated to a sequential angiographic follow-up, including OCT in selected sites, at 9 and 24 months. Struts coverage was compared using Bayesian hierarchical models as the primary outcome for the OCT substudy.

RESULTS

Fifty-six patients (26 BES, 30 SES) were enrolled in the OCT substudy. Twenty-one patients (10 BES, 11 SES) agreed to perform a second OCT follow-up at 24 months. Eleven lesions and 12 stents were analyzed sequentially in the BES group (2,455 struts at 9 months, 2,131 struts at 24 months) and 11 lesions and 18 stents in the SES group (3,421 struts at 9 months, 4,170 struts at 24 months). The previously reported advantage of BES over SES in terms of better strut coverage at 9 months was followed by improvement in coverage of the SES, resulting in identical coverage in both BES and SES at 24 months: 1.5% versus 1.8% uncovered struts, difference -0.2%, 95% credibility interval, -3.2% to 2.6%, P = .84.

CONCLUSIONS

More complete strut coverage of BES as compared with SES at 9 months was followed by improvement of coverage in SES between 9 and 24 months and a similar long-term coverage in both stent types at 24 months.