Late stent malapposition risk is higher after drug-eluting stent compared with bare-metal stent implantation and associates with late stent thrombosis

[Coronary stents: 30 years of medical progress]

The history of interventional cardiology has been marked by several technologic revolutions since the late 1970s. The first key step was the use of inflatable balloon angioplasty as an alternative to CABG surgery for coronary revascularization, followed by intracoronary delivery of bare metal stent (BMS) and drug eluting stents (DES) to drastically reduce intracoronary restenosis observed with BMS. Improved stents platforms and polymers (absorbable or biocompatible) led to a dramatic reduction in the rate of late stent thrombosis. Self-expanding stents are now available to improve stent a position especially in acute myocardial infarction. The emergence of new fully bioabsorbable stents that can be combined with antiproliferative drugs is the ongoing revolution. A new generation of stents is continuously improving and likely to become the ideal stent for coronary revascularization in the near future.

Everolimus- and sirolimus-eluting stents in patients with and without ST-segment elevation myocardial infarction

Aims

Everolimus-eluting stents (EES) were superior to sirolimus-eluting stents (SES) in a dedicated myocardial infarction trial, a finding that was not observed in trials with low percentages of ST-elevation myocardial infarction (STEMI). Therefore, this study sought to investigate the influence of clinical presentation on outcome after EES and SES implantation.

Methods

A pooled population of 1602 randomised patients was formed from XAMI (acute MI trial) and APPENDIX-AMI (all-comer trial). Primary outcome was cardiac mortality, MI and target vessel revascularisation at 2 years. Secondary endpoints included definite/probable stent thrombosis (ST). Adjustment was done using Cox regression.

Results

In total, 902 EES and 700 SES patients were included, of which 44 % STEMI patients (EES 455; SES 257) and 56 % without STEMI (EES 447; SES 443). In the pooled population, EES and SES showed similar outcomes during follow-up. Moreover, no differences in the endpoints were observed after stratification according to presentation. Although a trend toward reduced early definite/probable ST was observed in EES compared with SES in STEMI patients, long-term ST rates were low and comparable.

Conclusions

EES and SES showed a similar outcome during 2-year follow-up, regardless of clinical presentation. Long-term safety was excellent for both devices, despite wide inclusion criteria and a large sub-population of STEMI patients.

Worsening late-acquired incomplete stent apposition after sirolimus-eluting stent implantation for a chronic total occlusion lesion

A 70-year-old man underwent percutaneous coronary intervention (PCI) using sirolimus-eluting stent (SES) at the just proximal site of left anterior descending coronary artery. Six months after SES implantation, he suffered from late stent thrombosis. Intravascular ultrasound (IVUS) images demonstrated positive remodeling of the vessel, indicating late-acquired incomplete stent apposition (ISA). An angioplasty with a bigger balloon was performed to obtain sufficient stent struts apposition. Twenty-six months after the second PCI, he developed ST-elevation myocardial infarction and his CAG showed re-occlusion of the SES. Optical coherence tomography showed ISA and IVUS revealed further enlargement of the coronary artery around the SES.

Five-year outcomes for first generation drug-eluting stents versus bare-metal stents in patients with ST-segment elevation myocardial infarction: a meta-analysis of randomised controlled trials

BACKGROUND

Drug-eluting stent (DES) implantation has been proved more effective compared with bare-metal stent (BMS) implantation for ST-segment elevation myocardial infarction (STEMI) within medium follow up. However, limited information is available on the long-term safety and efficacy of DES.

METHODS

We performed a meta-analysis of randomised controlled trials (RCT) comparing DES with BMS in patients with STEMI at long-term follow up, defined as five years or more. The clinical end points were target vessel revascularisation (TVR), death, recurrent myocardial infarction (MI), stent thrombosis and very late stent thrombosis. We calculated the pooled estimate based on a fixed-effects model using odds ratio (OR) for rare events.

RESULTS

Four RCT were included, with a total of 1414 patients enrolled. Up to five years, DES showed a significant reduction in TVR (OR, 0.55; 95% confidence interval [CI], 0.55-0.77; P = 0.0005), but an increase in very late stent thrombosis (OR, 3.03; 95% CI, 1.28-7.18; P = 0.01), without increasing mortality (OR, 0.85; 95% CI, 0.59-1.20; P = 0.35), recurrent MI (OR, 1.05; 95% CI, 0.69-1.60; P = 0.80), and overall stent thrombosis (OR, 1.10; 95% CI, 0.66-1.82; P = 0.72).

CONCLUSIONS

At long-term follow-up, primary percutaneous coronary intervention with DES improved efficacy, without reducing overall safety. However, a trade-off must be made between the reduction of reintervention with DES and an increase in very late stent thrombosis.

Mechanisms, pathophysiology, and clinical aspects of incomplete stent apposition

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.

Incidences, Predictors, and Clinical Outcomes of Acute and Late Stent Malapposition Detected by Optical Coherence Tomography After Drug-Eluting Stent Implantation

Background—

We investigated the incidences, predictors, and clinical outcomes of acute and late stent malapposition detected by optical coherence tomography (OCT) after drug-eluting stent implantation.

Methods and Results—

We analyzed the OCT images from 351 patients with 356 lesions who received poststent and follow-up OCT examinations. Acute stent malapposition was observed in 62% of lesions. Approximately half of the acute stent malappositions were located within the edges of the stents. Severe diameter stenosis, calcified lesions, and long stents were independent predictors of acute stent malapposition. Follow-up OCT examinations were performed 175±60 days after drug-eluting stent implantation. Thirty-one percent of lesions with acute stent malapposition remained malapposed (late-persistent stent malapposition) and were typically (72%) located within the edges of the stent. The location within the stent edges and the volume of acute stent malapposition were independent predictors of late-persistent stent malapposition. Acute stent malapposition with a volume >2.56 mm 3 differentiated late-persistent stent malapposition from resolved acute stent malapposition. Late-acquired stent malapposition was detected in 15% of all lesions and was usually (61%) located within the stent body. Late-acquired stent malapposition was more frequently associated with plaque/thrombus prolapse on poststent OCT images (70% versus 42%; P <0.001). Clinical events, including cardiovascular death, nonfatal myocardial infarction, and stent thrombosis, did not occur in patients with late stent malapposition during the follow-up period of 28.6±10.3 months after drug-eluting stent implantation.

Conclusions—

Acute, late-persistent, and late-acquired stent malapposition had relatively high incidences but different predictors. The clinical outcome of stent malapposition was favorable.

Serial assessment by optical coherence tomography of early and late vascular responses after implantation of an absorbable-coating Sirolimus-Eluting stent (from the first-in-human DESSOLVE I trial)

The initial enthusiasm caused by the potent antirestenotic effect of early generation drug-eluting stents was recently plagued by concerns regarding their safety profile. Investigators worldwide were stimulated, therefore, to seek for improvement in drug-eluting stent technology, such as eliminating their permanent polymer blamed for vascular inflammation and delayed healing. Optical coherence tomography (OCT) assessments of stent-vessel interactions are used as a surrogate for vessel healing after DES implantation. Herewith, we report serial OCT assessments of vascular reactions to the implantation of a novel absorbable polymer sirolimus-eluting stent (MiStent). In total, 30 patients were included. At 4-, 6-, and 8-month follow-up, different groups of 10 patients underwent OCT imaging, whereas all the patients had OCT assessments scheduled at 18-month follow-up. A total of 13,569 stent struts were analyzed. Low rates of uncovered (14.34 ± 15.35%, 6.62 ± 10.93%, 3.51 ± 2.87%, and 0.84 ± 1.15%, respectively, p <0.05 for 8- vs 18-month follow-up) and malapposed (3.74 ± 7.35%, 3.15 ± 6.13%, 0.48 ± 0.56%, and 0.09 ± 0.28%, respectively, p = NS) stent struts coupled with thin and increasingly homogenous neointimal proliferation were demonstrated. Neointimal area increased from 4- to 8-month follow-up (0.46 ± 0.29 and 1.12 ± 0.73 mm(2), respectively, p <0.05), whereas no "late catch up" was demonstrated at 18-month follow-up (1.28 ± 0.66 mm(2), p = NS vs 8-month follow-up). Early tissue maturation and reduction of low signal intensity tissue covering stent struts (8.8%, 3.1%, 0.3%, and 0%, respectively, p <0.05 for 4- vs 8-month follow-up comparison) were revealed by optical density analysis. In addition, high rates of strut coverage overlying the ostia of side branches without proliferative pattern were demonstrated. In conclusion, this comprehensive OCT analysis depicted favorable absorbable polymer sirolimus-eluting stent-vessel interactions up to 18-month follow-up.

Cold drawn bioabsorbable ferrous and ferrous composite wires: an evaluation of in vitro vascular cytocompatibility

A systematic approach is applied to quantify the impact of bioabsorbable metals on human vascular endothelial cells (EC) and aortic smooth muscle cells (SMC) with the aim of optimizing bioabsorbable endovascular stent development. Composite wires comprising novel combinations of Fe, Mn, Mg, and Zn were produced and fabricated into tubular mesh stents. The stents were incubated with primary EC in order to assess attachment and cell proliferation. Migration of SMCs from the vessel medial wall to the target lesion site following recanalization of an atherosclerotic artery is important in the process of neointimal hyperplasia. Metal ion species were assayed for their impact on cell migration and survival at concentrations ranging from 0.037 to 10 mM. An MTT-based assay was used to assess cytotoxicity after insult with various metal ion concentrations. Fe(2+) and Fe(3+) ion species were found to repress the migration of SMCs across a porous polycarbonate track etch membrane at concentrations of 1 mM. Mn(2+) promoted SMC migration at a concentration of 1 mM, however, this effect was quenched when Fe(2+) was included. Mg(2+) was found to significantly increase SMC migration at concentrations above 1 mM. Cell survival was not reduced after 24 h insult with concentrations of Mg(2+) up to 10 mM. LD50 concentrations of greater than 1 mM were found for Mg(2+), Fe(2+), Fe(3+), and Fe(2+) with 35 wt.% Mn(2+). Significantly greater numbers of EC attached to bioabsorbable metal species compared with 316L stainless steel. Good EC coverage and proliferation were observed for all tested materials up to 120 h.

Long-term safety of drug-eluting stents

Stent implantation in coronary stenosis has revolutionized the treatment of coronary artery disease. The introduction of antirestenotic drug coatings further improved their efficacy in reducing target vessel revascularizations. With increasing use of drug-eluting stents (DES), stent thrombosis (ST) rose as potentially fatal major complication. Initially, the incidence of ST late after stent implantation seemed to be similar for DES and bare metal stents until several studies proved otherwise in first-generation DES. Since then, the design and components of DES have been changed and new polymers, drugs and different combinations of platelet inhibitors have been introduced to further improve the safety of DES. In this review, the authors focus on the relationship between DES, lesion anatomy, implantation technique and pharmacology to avoid the occurrence of ST. Furthermore, the relationship between dual antiplatelet therapy, bleeding rate and its significant impact on patient outcome is discussed. Finally, some promising future concepts are highlighted.

Stent malapposition, as a potential mechanism of very late stent thrombosis after bare-metal stent implantation: a case report

A 90-year-old man was admitted to our hospital with acute ST-segment elevation myocardial infarction. He had a history of post-infarction angina pectoris 79months ago and had a bare-metal stent (BMS) implanted in the proximal left anterior descending artery at our hospital. Emergent coronary angiography demonstrated thrombotic occlusion in the previously stented segment. After catheter thrombectomy, antegrade flow was restored, but 90% stenosis with haziness persisted in the proximal and distal portions of the previously stented segment. Intravascular ultrasound imaging showed interstrut cavities or stent malapposition at the proximal and distal sites of stented segment. In close proximity to the sites, residual thrombi were also observed. Optical coherence tomography (OCT) demonstrated neither lipid-laden neointimal tissue nor rupture but clearly demonstrated residual thrombus adjacent to the malapposed region in addition to the stent malapposition. PCI with balloon was successfully performed and stent apposition was confirmed by OCT. Stent malapposition is an unusual mechanism of very late stent thrombosis after BMS implantation. OCT can clearly reveal the etiology of stent thrombosis.

Evaluation neointimal coverage in patients with coronary artery aneurysm formation after drug-eluting stent implantation by optical coherence tomography

The neointimal coverage in patients with coronary artery aneurysms (CAA) formation after drug eluting stent (DES) implantation is not clear. Total of 175 patients who had been implanted DES were identified. Patients were divided into the CAA group (n = 31) and non-CAA group (n = 144) based on the results of the coronary angiography. The cardiac events including angina and acute myocardial infarction were noted, in addition, the neointimal thickness and the frequence of strut malapposition and strut uncoverage were noted. A greater proportion of incomplete neointimal coverage (17.17 vs. 1.9 %, P < 0.001) and malapposition struts (18.2 vs. 1.38%, P < 0.001) were observed in the CAA group. 8 patients in CAA group underwent OCT examination twice in the period of follow-up. The proportion of incomplete neointimal coverage increased significantly as compared the second OCT results with the first examination (18.45 vs. 2.66 %, P < 0.001). Hyperplasia neointimal desquamated from struts and acquired struts incomplete neointimal coverage were detected. Patients with CAA had a higher frequency of cardiac events including angina pectoris (25.81 vs. 6.25 %, P = 0.001) and acute myocardial infarction (9.68 vs. 0.13 %, P = 0.002) and thrombosis (16.13 vs. 0.69 %, P < 0.001). The longitudinal length of CAA in cardiac event group was significantly longer than no cardiac event group (20.0 ± 9.07 vs. 12.05 ± 5.38 mm, P = 0.005). CAA formation after DES implantation frequently associated with cardiac events as a result of stent malapposition and incomplete neointimal coverage. Acquired incomplete neointimal coverage associated with CAA formation.

Optical coherence tomography versus intravascular ultrasound to evaluate coronary artery disease and percutaneous coronary intervention

OBJECTIVES

We compared intravascular ultrasound (IVUS) and 2 different generations of optical coherence tomography (OCT)-time-domain OCT (TD-OCT) and frequency-domain OCT (FD-OCT)-for the assessment of coronary disease and percutaneous coronary intervention (PCI) using stents.

BACKGROUND

OCT is a promising light-based intravascular imaging modality with higher resolution than IVUS. However, the paucity of data on OCT image quantification has limited its application in clinical practice.

METHODS

A total of 227 matched OCT and IVUS pull backs were studied. One hundred FD-OCT and IVUS pull backs in nonstented (n = 56) and stented (n = 44) vessels were compared. Additionally, 127 matched TD-OCT and IVUS images were compared in stented vessels.

RESULTS

FD-OCT depicted more severe native coronary disease than IVUS; minimal lumen area (MLA) was 2.33 ± 1.56 mm(2) versus 3.32 ± 1.92 mm(2), respectively (p < 0.001). Reference vessel dimensions were equivalent between FD-OCT and IVUS in both native and stented coronaries, but TD-OCT detected smaller reference lumen size compared with IVUS. Immediately post-PCI, in-stent MLAs were similar between FD-OCT and IVUS, but at follow-up, both FD-OCT and TD-OCT detected smaller MLAs than did IVUS, likely due to better detection of neointimal hyperplasia (NIH). Post-PCI malapposition and tissue prolapse were more frequently identified by FD-OCT.

CONCLUSIONS

FD-OCT generates similar reference lumen dimensions but higher degrees of disease severity and NIH, as well as better detection of malapposition and tissue prolapse compared with IVUS. First-generation TD-OCT was associated with smaller reference vessel dimensions compared with IVUS.

New coronary aneurysm formation and malapposition after zotarolimus-eluting stent implantation in Kawasaki disease

Coronary artery involvement is the most important complication of Kawasaki disease. Coronary artery bypass surgery has been performed for ischemic heart disease caused by Kawasaki disease, however, long-term coronary graft patency is not satisfactory. Therefore, percutaneous coronary intervention (PCI) has its role in Kawasaki disease-related coronary artery disease. The incidence of new aneurysm is lower following stent implantation than balloon dilatation alone, even if a higher balloon pressure is applied. However, there are few reports about the efficacy of drug-eluting stent implantation for Kawasaki disease with coronary artery disease. Here, we describe a case of new coronary aneurysm formation and malapposition after zotarolimus-eluting stent implantation in Kawasaki disease. <Learning objective: New aneurysm formation after balloon angioplasty for coronary artery lesions in Kawasaki disease is a relatively well-known phenomenon, however there have been no reports about the influence of drug-eluting stents for coronary artery disease with Kawasaki disease. This report is useful when we consider strategies of revascularization for coronary artery disease with Kawasaki disease.>.

Enlarged coronary artery pseudoaneurysm after drug-eluting stent implantation

A 73-year-old man with 2-vessel coronary artery disease underwent a staged percutaneous coronary intervention that resulted in rupture of the right coronary artery and pseudoaneurysm formation. Although the pseudoaneurysm regressed over a week, it reexpanded after a year. Resection of the pseudoaneurysm and coronary artery bypass grafting were performed. The drug-eluting stent at the coronary artery injury site may have delayed healing and remodeling of the artery, thus contributing to reexpansion of the pseudoaneurysm.

Frequency, mechanisms, and implications of late peri-stent contrast staining: analysis (from the HORIZONS-AMI Trial)

Previous studies have suggested that angiographically detected persistent contrast staining (PSS) at follow-up may predict subsequent very late stent thrombosis. The Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial was a dual-arm, factorial, randomized trial in patients with ST-segment elevation myocardial infarctions. All follow-up angiograms (1,330 lesions in 1,115 patients, median time 13.3 months) without major cardiovascular events before follow-up angiography were analyzed at a core laboratory blinded to clinical events for the presence of PSS (defined as contrast staining outside the stent contour extending to ≥20% of the stent diameter). Corresponding follow-up intravascular ultrasound (IVUS) data (275 lesions in 248 patients) were also evaluated to assess the mechanisms of PSS. PSS was present in 23 patients (2.1%) at follow-up and was not more common with paclitaxel-eluting than with bare-metal stents. All 6 PSS patients with follow-up IVUS had stent malapposition (vs 41.2% malapposition in the follow-up IVUS cohort). Comparing poststent and follow-up IVUS, 2 patients had late acquired and 4 had persistent malapposition; all 6 showed positive vessel remodeling from baseline to follow-up (mean vessel area 22.0 ± 8.0 to 32.4 ± 11.7 mm(2), p = 0.07). During 3-year follow-up, stent thrombosis developed in no patient with PSS compared with 8 PSS-negative patients (0% vs 0.8%, p = 0.68). The rates of revascularization and major adverse cardiovascular events were also not increased in PSS patients. In conclusion, in the large-scale HORIZONS-AMI trial, PSS at angiographic follow-up was infrequent and was associated with late stent malapposition and positive remodeling but was independent of stent type. Identification of PSS was not associated with subsequent stent thrombosis.

OCT analysis in patients with very late stent thrombosis

OBJECTIVES

We report optical coherence tomography (OCT) findings in 33 patients who presented with very late stent thrombosis (VLST) after either drug-eluting stent (DES) or bare-metal stent (BMS) implantation.

BACKGROUND

VLST is a potentially life-threatening complication, but the underlying mechanisms remain unclear.

METHODS

In 33 patients (27 DES- and 6 BMS-treated lesions) with definite VLST, OCT images were acquired before either thrombus aspiration or intravascular ultrasonography (IVUS) imaging.

RESULTS

The median duration from implantation was 61.5 months in the DES group and 109.1 months in the BMS group. In the overall cohort, combining DES and BMS, 94% showed intraluminal thrombi. VLST was associated with in-stent neointimal rupture in 23 patients (70%); 22 had thrombi near the site of neointimal rupture. Stent malapposition was observed in 14 (42%) lesions, but only 9 of them showed thrombi at the site of stent malapposition; moreover, 6 (18%) stented segments with malapposition also had neointimal rupture. Only 2 (6%) lesions had no evidence of neointimal rupture or malapposition. Stent fracture was detected in 3 DES-treated lesions, all with concomitant neointimal rupture. Compared with lesions without neointimal rupture, lesions with neointimal rupture showed a higher frequency of ST-segment elevation myocardial infarction (65% vs. 20%, respectively, p = 0.040) as well as a higher peak creatine kinase-myocardial band level (163.1 ng/ml vs. 15.7 ng/ml, respectively, p = 0.017).

CONCLUSIONS

OCT imaging indicated that advanced neoatherosclerosis with neointimal rupture and thrombosis was the most common mechanism of definite VLST and was associated with a high frequency of ST-segment elevation myocardial infarction.

Triple, simultaneous, very late coronary stent thrombosis

Coronary artery stent thrombosis is an uncommon but potentially catastrophic complication. The risk of very late stent thrombosis (VLST) raises important safety issues regarding the first generation of drug-eluting stents (DES). Although several complex mechanisms for VLST have been suggested and various predictors have been described, its pathophysiology is not completely understood and it is not known whether longer-term dual antiplatelet therapy reduces the risk. We present a rare case of simultaneous very late DES thrombosis in the three vascular territories, following discontinuation of antiplatelet therapy seven years after stent placement, presenting as cardiogenic shock.

Natural consequence of post-intervention stent malapposition, thrombus, tissue prolapse, and dissection assessed by optical coherence tomography at mid-term follow-up

Aims

We performed this study to clarify natural consequences of abnormal structures (stent malapposition, thrombus, tissue prolapse, and stent edge dissection) after percutaneous coronary intervention (PCI).

Methods and results

Thirty-five patients treated with 40 drug-eluting stents underwent serial optical coherence tomography (OCT) imaging immediately after PCI and at the 8-month follow-up. Among a total of 73 929 struts in every frame, 431 struts (26 stents) showed malapposition immediately after PCI. Among these, 49 remained malapposed at the follow-up examination. The mean distance between the strut and vessel wall (S–V distance) of persistent malapposed struts on post-stenting OCT images was significantly longer than that of resolved malapposed struts (342 ± 99 vs. 210 ± 49 μm; P <0.01). Based on receiver-operating characteristic curve analysis, an S–V distance ≤260 µm on post-stenting OCT images was the corresponding cut-off point for resolved malapposed struts (sensitivity: 89.3%, specificity: 83.7%, area under the curve = 0.884). Additionally, 108 newly appearing malapposed struts were observed on follow-up OCT, probably due to thrombus dissolution or plaque regression. Thrombus was observed in 15 stents post-PCI. Serial OCT analysis revealed persistent thrombus in 1 stent, resolved thrombus in 14 stents, and late-acquired thrombus in 8 stents. Tissue prolapse observed in 38 stents had disappeared at the follow-up. All eight stent edge dissections were repaired at the follow-up.

Conclusion

Most cases of stent malapposition with a short S–V distance, thrombus, tissue prolapse, or minor stent edge dissection improved during the follow-up. These OCT-detected minor abnormalities may not require additional treatment.

Angiographically confirmed stent thrombosis in contemporary practice: insights from intravascular ultrasound

OBJECTIVE

We hypothesized that patients presenting with stent thrombosis (ST) have a high prevalence of stent underexpansion and malapposition when assessed by intravascular ultrasound (IVUS).

BACKGROUND

IVUS can provide mechanistic insight into mechanical factors, including stent underexpansion, malapposition, and fracture that may predispose to ST.

METHODS

All consecutive cases of angiographically confirmed ST from a multicenter registry (from 2005 to 2010) were reviewed. All IVUS images were reviewed off-line for the presence of stent underexpansion, malapposition, and fracture. Kaplan-Meier analysis was used to determine whether use of IVUS at the time of ST was associated with long-term mortality and major adverse cardiovascular events.

RESULTS

IVUS was performed in 32 of 173 subjects with ST (18%). Stent underexpansion was present in 82% of cases and in all cases of early ST, with a mean stent expansion of 0.7 ± 0.23 by MUSIC criteria. Stent malapposition was most frequently observed in very late ST (40%). In-hospital mortality was similar between subjects who had IVUS performed at the time of ST when compared with the non-IVUS group (3.2% vs. 4.3%, P = 0.8). Subjects who had IVUS performed at the time of ST had lower rates of mortality (HR 0.4, 95% CI 0.1-1.6, P =0.2) and major adverse cardiovascular events (HR 0.5, 95% CI 0.2-1.4, P =0.2) at follow-up, but these values were not statistically significant.

CONCLUSIONS

There is a high prevalence of stent underexpansion in early ST, while the prevalence of malapposition is higher in very late ST. Use of IVUS during treatment for ST may identify mechanisms underlying the development of ST.

[Cardiovascular diseases in the focus of health economics. The example of drug-eluting vascular stents in coronary heart disease]

Coronary heart disease is an important disorder in Western industrialized societies, with regard to both the epidemiologic and economic burden of illness. A modern therapeutic strategy consists of coronary interventions and the implantation of drug-eluting vascular stents. The cost-effectiveness of such drug-eluting stents has been an important subject of health-economic evaluation research in recent years. This article presents two examples of such studies and deals with the question whether existing study projects are able to provide sufficient evidence for allocation decisions in health care. On this basis we discuss important challenges for future health economic analysis. A key conclusion is the need for long-term and cross-sectoral evaluation strategies that could be based on routinely collected health care data. Supplemented by health economic results from clinical trials, the use of such data would lead to a broader data basis for allocation decisions in health care.

Role of endothelial shear stress in stent restenosis and thrombosis: pathophysiologic mechanisms and implications for clinical translation

Restenosis and thrombosis are potentially fatal complications of coronary stenting with a recognized multifactorial etiology. The effect of documented risk factors, however, cannot explain the preponderance of certain lesion types, stent designs, and implantation configurations for the development of these complications. Local hemodynamic factors, low endothelial shear stress (ESS) in particular, are long known to critically affect the natural history of atherosclerosis. Increasing evidence now suggests that ESS may also contribute to the development of restenosis and thrombosis upon stenting of atherosclerotic plaques, in conjunction with well-appreciated risk factors. In this review, we present in vivo and mechanistic evidence associating ESS with the localization and progression of neointimal hyperplasia and in-stent clotting. Clinical studies have associated stent design features with the risk of restenosis. Importantly, computational simulations extend these observations by directly linking specific stent geometry and positioning characteristics with the post-stenting hemodynamic milieu and with the stent's thrombogenicity and pro-restenotic potential, thereby indicating ways to clinical translation. An enhanced understanding of the pathophysiologic role of ESS in restenosis and thrombosis might dictate hemodynamically favorable stent designs and deployment configurations to reduce the potential for late lumen loss and thrombotic obstruction. Recent methodologies for in vivo ESS profiling at a clinical level might allow for early identification of patients at high risk for the development of restenosis or thrombosis and might thereby guide individualized, risk-tailored treatment strategies to prevent devastating complications of endovascular interventions.

Automatic stent strut detection in intravascular optical coherence tomographic pullback runs

We developed and evaluated an automatic stent strut detection method in intravascular optical coherence tomography (IVOCT) pullback runs. Providing very high resolution images, IVOCT has been rapidly accepted as a coronary imaging modality for the optimization of the stenting procedure and its follow-up evaluation based on stent strut analysis. However, given the large number of struts visible in a pullback run, quantitative three-dimensional analysis is only feasible when the strut detection is performed automatically. The presented method first detects the candidate pixels using both a global intensity histogram and the intensity profile of each A-line. Gaussian smoothing is applied followed by specified Prewitt compass filters to detect the trailing shadow of each strut. Next, the candidate pixels are clustered using the shadow information. In the final step, several filters are applied to remove the false positives such as the guide wire. Our new method requires neither a priori knowledge of the strut status nor the lumen/vessel contours. In total, 10 IVOCT pullback runs from a 1-year follow-up study were used for validation purposes. 18,311 struts were divided into three strut status categories (malapposition, apposition or covered) and classified based on the image quality (high, medium or low). The inter-observer agreement is 95%. The sensitivity was defined as the ratio of the number of true positives and the total number of struts in the expert defined result. The proposed approach demonstrated an average sensitivity of 94%. For malapposed, apposed and covered stent struts, the sensitivity of the method is respectively 91, 93 and 94%, which shows the robustness towards different situations. The presented method can detect struts automatically regardless of the strut status or the image quality, and thus can be used for quantitative measurement, 3D reconstruction and visualization of the stents in IVOCT pullback runs.

Long-term clinical outcomes following sirolimus-eluting stent implantation in patients with acute myocardial infarction. A meta-analysis of randomized trials

OBJECTIVES

The aim of this study was to perform a meta-analysis of randomized trials, evaluating the long-term outcomes of sirolimus-eluting stents (SES) versus bare-metal stents (BMS) in patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

Despite short-term outcomes of patients with STEMI undergoing primary percutaneous coronary intervention indicate a benefit of SES in terms of reintervention, several concerns remain on the long-term safety and efficacy of SES.

METHODS

A systematic literature search of electronic resources, through October 2011, was performed using specific search terms. Included trials were randomized studies comparing SES to BMS in STEMI patients, with a follow-up ≥3 years.

RESULTS

Seven trials were included, with a total of 2,364 patients. At a median follow-up of 3 years, SES significantly reduced the risk of target-vessel revascularization when compared with BMS [odds ratio (OR), 0.44; 95 % confidence interval (CI), 0.34-0.57; p < 0.0001], without increasing the risk of mortality (OR 0.78; 95 % CI, 0.57-1.08; p = 0.14), reinfarction (OR 0.91; 95 % CI, 0.61-1.35, p = 0.64) and early to late stent thrombosis (OR 0.77; 95 % CI, 0.49-1.20; p = 0.25). However after the first year, SES did not further reduce target-vessel revascularization (OR 1.06; 95 % CI, 0.64-1.74; p = 0.83) and increased the risk of very late stent thrombosis (OR 2.81; 95 % CI, 1.33-5.92; p = 0.007).

CONCLUSIONS

At long-term follow-up, SES compared to BMS use in STEMI patients reduces the risk of target-vessel revascularization, without increasing the risk of death and reinfarction. However, the strong SES efficacy is counterbalanced by a significant risk of very late stent thrombosis.

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 optical coherence tomographic assessment between first- and second-generation drug-eluting stents

PURPOSE

There is a lack of sufficient data in comparison of optical coherence tomographic (OCT) findings between first- and second-generation drug-eluting stents (DES). Compared to first-generation (i.e., sirolimus- or paclitaxel-eluting stents), second-generation DESs (i.e., everolimus- or biolinx-based zotarolimus-eluting stents) might have more favorable neointimal coverage.

MATERIALS AND METHODS

Follow-up OCT findings of 103 patients (119 lesions) treated with second- generation DESs were compared with those of 139 patients (149 lesions) treated with first-generation DESs. The percentage of uncovered or malapposed struts, calculated as the ratio of uncovered or malapposed struts to total struts in all OCT cross-sections, respectively, was compared between the two groups.

RESULTS

Both DES groups showed similar suppression of neointimal hyperplasia (NIH) on OCT (mean NIH cross-sectional area; second- vs. first-generation=1.1±0.5 versus 1.2±1.0 mm², respectively, p=0.547). However, the percentage of uncovered struts of second-generation DESs was significantly smaller than that of first-generation DESs (3.8±4.8% vs.7.5±11.1%, respectively, p<0.001). The percentage of malapposed struts was also significantly smaller in second-generation DESs than in first-generation DESs (0.4±1.6% vs.1.4±3.7%, respectively, p=0.005). In addition, intra- stent thrombi were less frequently detected in second-generations DESs than in first-generation DESs (8% vs. 20%, respectively, p=0.004).

CONCLUSION

This follow-up OCT study showed that second-generation DESs characteristically had greater neointimal coverage than first-generation DESs.

Long-term outcomes with use of intravascular ultrasound for the treatment of coronary bifurcation lesions

Percutaneous coronary intervention (PCI) of bifurcation lesions remains challenging with a higher risk of adverse outcomes. Whether adjunctive intravascular ultrasound (IVUS) imaging improves outcomes of PCI of bifurcation lesions remains unclear. This study sought to determine the long-term clinical outcomes associated with using IVUS for percutaneous treatment of coronary bifurcation lesions. From April 2003 through August 2010, 449 patients with 471 bifurcation lesions underwent PCI with (n = 247) and without (n = 202) the use of IVUS. Clinical outcomes (death, myocardial infarction [MI], periprocedural MI, stent thrombosis, target vessel revascularization [TVR], and target lesion revascularization [TLR]) were compared between patients undergoing PCI with and without IVUS using univariate and propensity score-adjusted analyses. Most patients (61%) presented with acute coronary syndrome and 89% of bifurcations lesions were Medina class 1,1,1. After propensity score adjustment, use of IVUS was associated with significantly lower rates of death or MI (odds ratio 0.38, 95% confidence interval 0.20 to 0.74, p = 0.005), death (odds ratio 0.40, 95% confidence interval 0.18 to 0.88, p = 0.02), MI (odds ratio 0.37, 95% confidence interval 0.14 to 0.98, p = 0.04), periprocedural MI (odds ratio 0.45, 95% confidence interval 0.20 to 0.97, p = 0.04), TVR (odds ratio 0.28, 95% confidence interval 0.14 to 0.53, p <0.0001), and TLR (odds ratio 0.27, 95% confidence interval 0.14 to 0.53, p = 0.0003) compared to no IVUS. In conclusion, IVUS-guided treatment of complex bifurcation lesions was associated with significantly lower rates of adverse cardiac events at late follow-up. Further study is warranted to evaluate the role of IVUS guidance in improving long-term outcomes after PCI of bifurcation lesions.