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Background: Persistent or late acquired incomplete stent apposition (ISA) may be associated with late or very late stent thrombosis following drug-eluting stent implantation. Presence of calcium at the target lesion may increase the risk of ISA even after rotational atherectomy (RA) followed by stenting with high pressure balloon inflation. The aim of this study is to examine the incidence and characteristics of ISA in heavily calcified lesions.Methods: A total of 52 heavily calcified coronary artery lesions requiring RA plus stenting were selected and studied. After successful ablation followed by stent implantation, optical coherence tomography (OCT) was performed to assess stent expansion and apposition. Presence or absence of ISA was examined and maximal stent strut to vessel wall distance (max SV distance) was measured. In lesions with repeated OCT at follow-up, serial changes in ISA were investigated.Results: ISA was documented in 51 of 52 (98%) lesions. Mean max SV distance was 713 ± 371 μm. In lesions with serial OCT images (n = 11), max SV distance decreased significantly (692.1 ± 420.2 to 462.5 ± 387.0 μm, P < 0.01) but persisted in all but 2 lesions (82%).Conclusions: ISA is frequently documented in heavily calcified lesions requiring RA. Significant ISA still persisted with minimal improvement in SV distance at follow-up. Prognostic impact of the persistent ISA in such calcified lesions needs further investigations. [ABSTRACT FROM AUTHOR]

Key Clinical Message If we had a case with angiographic peri-stent contrast staining( PSS)s after the first-generation sirolimus-eluting stent, we need a further observation using coronary imaging modalities to evaluate the risk of very late stent thrombosis due to PSSs and to continue or to resume the dual antiplatelet therapy if necessary. [ABSTRACT FROM AUTHOR]

Background: Incomplete stent apposition (ISA) is related to stent thrombosis, which is a serious adverse event. We aim to assess the time-course of ISA after 2nd generation everolimus-eluting stent (EES) implantation.Methods: In HEAL-EES study, we enrolled 36 patients who underwent percutaneous coronary intervention (PCI) with EES. OCT imaging was performed at baseline and follow-up. Patients were randomized 1:1:1 into 3 groups according to the time in which follow-up was performed: group A (6-month), group B (9-month), and group C (12-month). In this subanalysis, patients who had ISA segments at baseline and/or follow-up OCT were analyzed.Result: At baseline, among 41 lesions in 36 patients, 20 lesions in 18 patients had ISA segments and were analyzed. At baseline, there were 3.0% ISA struts in group A (n=8), 2.8% in group B (n=4), and 4.5% in group C (n=8). At follow-up, ISA struts were present in 0.09%, 0.16% and 0.64%; respectively in groups A, B, and C. At follow-up, there was a significant decrease in the frequency of ISA: group A 3.0% vs. 0.09% (p<0.001), group B 2.8% vs. 0.16% (p<0.001), and group C 4.5% vs. 0.64% (p<0.001). In group A, there was one late acquired ISA at follow-up.Conclusions: In patients undergoing 2nd generation EES implantation, area of acute ISA assessed by OCT, was almost resolved at 6-month follow-up. [ABSTRACT FROM AUTHOR]

A 60-year-old man with a previous history of sirolimus-eluting stent implantation was admitted because of chest pain. Coronary angiography revealed nonsignificant in-stent luminal narrowing at the previously stented segment with an unusual linear peri-stent strut contrast staining. Frequency-domain optical coherence tomography showed a cavity at the segment connecting to the coronary lumen at the distal part of the stent. This unusual 'ant-colony'-like appearance of the stented segment may be a subtype of the incomplete stent apposition and/or interstrut hollows. [ABSTRACT FROM AUTHOR]

Incomplete stent apposition (ISA) is characterized by the lack of contact of at least 1 stent strut with the vessel wall in a segment not overlying a side branch; it is more commonly found in drug-eluting stents than bare-metal stents. The accurate diagnosis of ISA, initially only possible with intravascular ultrasound, can currently be performed with higher accuracy by optical coherence tomography, which also enables strut-level assessment due to its higher axial resolution. Different circumstances related both to the index procedure and to vascular healing might influence ISA occurrence. Although several histopathology and clinical studies linked ISA to stent thrombosis, potential selection bias precluded definitive conclusions. Initial studies usually performed single time point assessments comparing overall ISA percentage and magnitude in different groups (i.e., stent type), thus hampering a comprehensive understanding of its relationship with vascular healing. Serial intravascular imaging studies that evaluated vascular response heterogeneity recently helped fill this gap. Some particular clinical scenarios such as acute coronary syndromes, bifurcations, tapered vessels, overlapping stents, and chronic total occlusions might predispose to ISA. Interventional cardiologists should be committed to optimal stent choices and techniques of implantation and use intravascular imaging guidance when appropriate to aim at minimizing acute ISA. In addition, the active search for new stent platforms that could accommodate vessel remodeling over time (i.e., self-expandable stents) and for new polymers and/or eluting drugs that could induce less inflammation (hence, less positive remodeling) could ultimately reduce the occurrence of ISA and its potentially harmful consequences. [ABSTRACT FROM AUTHOR]

The primary aim of this work was to investigate the performance of self-expanding Nitinol stents in a curved artery through finite element analysis. The interaction between a PROTÉGE™ GPS™ self-expanding Nitinol stent and a stenosed artery, as well as a sheath, was characterized in terms of acute lumen gain, stent underexpansion, incomplete stent apposition, and tissue prolapse. The clinical implications of these parameters were discussed. The impact of stent deployment orientation and the stent length on the arterial wall stress distribution were evaluated. It was found that the maximum principal stress increased by 17.46%, when the deployment orientation of stent was varied at a 5 deg angle. A longer stent led to an increased contact pressure between stent and underlying tissue, which might alleviate the stent migration. However, it also caused a severe hinge effect and arterial stress concentration correspondingly, which might aggravate neointimal hyperplasia. The fundamental understanding of the behavior of a self-expanding stent and its clinical implications will facilitate a better device design. [ABSTRACT FROM AUTHOR]

Abstract: Background: Dedicated IVUS analyses of the second CObalt chromium STent with Antiproliferative for Restenosis (COSTAR II) trial have not been documented. We aim to compare IVUS findings between CoStar paclitaxel-eluting stent (PES) and Taxus PES in patients enrolled in the COSTAR II trial. We also attempted to examine the possible regional impact of multiple stenting. Methods and materials: Among the 1700 patients enrolled, 238 were assigned to an IVUS cohort including 168 patients treated by provisional multiple stenting. At 9 months, qualitative and quantitative IVUS observations including incomplete stent apposition (ISA) and neointimal proliferation (neointimal obstruction: neointimal volume/stent volume ×100) were compared between CoStar and Taxus PESs. Results: In qualitative analysis, late-acquired ISA was observed in 1 patient treated by Taxus PES. Impaired strut continuity suggestive of stent fracture was observed in 2 out of 33 patients treated by multiple CoStar, and 4 out of 21 patients treated by multiple Taxus (P=.14). No such findings were found in single-stented patients in either stent subset. Quantitative analysis showed greater neointimal obstruction in CoStar (19.7%±13.4%, n=52) than in Taxus (10.7%±9.9%, n=38), whereas no significant difference in neointimal obstruction was found between single and multiple stenting in either CoStar or Taxus PES. Conclusions: The CoStar PES exhibits greater neointimal proliferation compared with Taxus PES at 9 months but with similar qualitative outcomes including late-acquired ISA. IVUS findings suggestive of stent fracture were found only in multiple-stenting cases irrespective of the stent used. [Copyright &y& Elsevier]