Frequency, predictors and outcome of stent fracture after sirolimus-eluting stent implantation

Numerical Simulation of Dynamic Degradation and Fatigue Damage of Degradable Zinc Alloy Stents

Current research on the fatigue properties of degradable zinc alloy stents has not yet considered the issue of the fatigue life changing with material properties during the dynamic degradation process. Therefore, in this paper, we established a fatigue damage algorithm to study the fatigue problem affected by the changing of material properties during the dynamic degradation process of the stent under the action of pulsating cyclic loading. Three models: the dynamic degradation model, the dynamic degradation model under pulsating cyclic loading, and the coupled model of fatigue damage and dynamic degradation, were developed to verify the effect of fatigue damage on stent life. The results show that fatigue damage leads to a deeper degree of inhomogeneous degradation of the stent, which affects the service life of the stent. Fatigue damage is a factor that cannot be ignored. Therefore, when studying the mechanical properties and lifetime of degradable stents, incorporating fatigue damage into the study can help more accurately assess the lifetime of the stents.

Stretched and fractured Neuroform Atlas® stent during a stent‑assisted coil embolization: A case report

The Neuroform Atlas^® stent is one of the most recently developed stents for coil embolization, with advancements in a lower-profile delivery system, enhanced trackability, smaller cell size, and increased wall conformability. Because of these advantages, the Neuroform Atlas^® stent shows high technical success with few procedure-related complications. However, the present study reported a rare complication of a stretched and partially fractured Neuroform Atlas^® stent due to unexpected partial withdrawal of microcatheter during deployment for coil embolization of an intracranial aneurysm. The measured length of the stent was ~30 mm, which was greater than the normal length (21 mm). An additional stent was inserted into the distal part of the deployed stent to stabilize the damaged stent and remodel the aneurysm neck. This complication was considered to potentially result from the combination of several factors, including: Curved vessel; open-cell stent; unexpected microcatheter withdrawal during stent deployment; and hooking of the aneurysm selecting microcatheter with stent strut. Understanding the stent design and careful manipulation while avoiding unexpected withdrawal of the microcatheter could prevent this complication.

Incidence of coronary drug-eluting stent fracture: A systematic review and meta-analysis

Background

Reported evidence of coronary stent fracture (CSF) has increased in recent years. The purpose of this study was to determine reliable estimates of the overall incidence of CSF.

Methods and results

The MEDLINE, Embase and Cochrane databases were searched until March 18, 2022. Pooled estimates were acquired using random effects models. Meta-regression and subgroup analysis were used to explore sources of heterogeneity, and publication bias was evaluated by visual assessment of funnel plots and Egger’s test. Overall, 46 articles were included in this study. Estimates of CSF incidence were 5.5% [95% confidence interval (CI): 3.7–7.7%] among 39,953 patients based on 36 studies, 4.8% (95% CI: 3.1–6.8%) among 39,945 lesions based on 29 studies and 4.9% (95% CI: 2.5–9.4%) among 19,252 stents based on 8 studies. There has been an obvious increase in the incidence of CSF over the past two decades, and it seems that the duration of stent placement after stent implantation has no impact on incidence estimation.

Conclusion

The incidence of CSF was 5.5% among patients, 4.8% for lesions and 4.9% for stents and increased over the past 20 years. The duration of stent placement after stent implantation was found to have no impact on the incidence of CSF, but drug-eluting stent (DES) types and right coronary artery (RCA) lesions influenced the pooled incidence.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022311995], identifier [CRD42022311995].

Is coronary artery tortuosity a predisposing factor for drug-eluting stent restenosis?

BACKGROUND

Coronary artery tortuosity (CAT) is a relatively common finding on coronary angiography and may be associated with impaired left ventricular relaxation and coronary ischemia However, the significance of CAT remains unknown. This study aimed to investigate whether the severity of tortuosity in the targeted coronary segment is a predictor of stent restenosis.

METHODS

The study included a total of 637 patients undergoing drug-eluting stent implantation due to stable or unstable angina and who had no native coronary artery stenosis on their last coronary angiogram. The patients were separated into two groups: 312 patients with in-stent restenosis and 325 patients without in-stent restenosis. All patients underwent computed tomography (CT) coronary angiography after invasive angiography and CAT was calculated using the computer software.

RESULTS

Patients with in-stent restenosis had higher CAT than those without restenosis (1.25 ± 0.11 vs. 1.11 + 0.07, p < 0.001). Multivariate Cox regression analysis showed that the tortuosity index (hazard ratio [HR]: 1.246 95% confidence interval [CI]: 1.127-1.376 p < 0.001) and the circumflex lesion (HR: 1.437 95% CI: 1.062-1.942 p = 0.019) were independently associated with in-stent restenosis. With the threshold value of severe tortuosity set at 1.15, the prediction of could be made with 81% sensitivity and 80% specificity.

CONCLUSION

The severity of tortuosity is proportional to coronary in-stent stenosis in patients with stable and unstable angina pectoris undergoing drug-eluting stent implantation for a severe single coronary artery.

Coronary Stent Strut Fractures: Classification, Prevalence and Clinical Associations

Introduction. The frequency, characteristics and clinical implications of Strut fractures (SFs) remain incompletely understood. Methods and results. A total of 185 (160 patients) newer-generation drug-eluting stents (DES) were imaged. SFs were found in 21 DES (11.4%) and were classified in four patterns: one single stacked strut (41%); two or more stacked struts (23%); deformation without gap (27%); transection (9%). In multivariable analysis, calcific and bifurcation lesions were associated with SF in DES (OR: 3.5 [1.1–11] and 4.0 [2.2–7.2], p < 0.05). Device eccentricity and asymmetry as well as optical coherence tomography (OCT) features of impaired strut healing were also associated with SF. The prevalence of fractures was similar in a set of 289 bioresorbable scaffolds (BRS). In a separate series of 20 device thromboses and 36 device restenoses, the prevalence of SF was higher (61.2% of DES and 66.7% of BRS, p < 0.001 for both), with a higher frequency of complex SF patterns (p < 0.0001). In logistic regression analysis, fractures were a correlate of device complications (p < 0.0001, OR = 24.9 [5.6–111] for DES and OR = 6.0 [1.8–20] for BRS). Discussion. The prevalence of OCT-diagnosed SF was unexpectedly high in the setting of elective controls and it increased by about three-fold in the setting of device failure. Fractures were associated with increased lesion complexity and device asymmetry/eccentricity and were more frequent in the setting of device failure such as restenosis and thrombosis.

Validating Fatigue Safety Factor Calculation Methods for Cardiovascular Stents

Evaluating risk of fatigue fractures in cardiovascular implants via nonclinical testing is essential to provide an indication of their durability. This is generally accomplished by experimental accelerated durability testing and often complemented with computational simulations to calculate fatigue safety factors (FSFs). While many methods exist to calculate FSFs, none have been validated against experimental data. The current study presents three methods for calculating FSFs and compares them to experimental fracture outcomes under axial fatigue loading, using cobalt-chromium test specimens designed to represent cardiovascular stents. FSFs were generated by calculating mean and alternating stresses using a simple scalar method, a tensor method which determines principal values based on averages and differences of the stress tensors, and a modified tensor method which accounts for stress rotations. The results indicate that the tensor method and the modified tensor method consistently predicted fracture or survival to 107 cycles for specimens subjected to experimental axial fatigue. In contrast, for one axial deformation condition, the scalar method incorrectly predicted survival even though fractures were observed in experiments. These results demonstrate limitations of the scalar method and potential inaccuracies. A separate computational analysis of torsional fatigue was also completed to illustrate differences between the tensor method and the modified tensor method. Because of its ability to account for changes in principal directions across the fatigue cycle, the modified tensor method offers a general computational method that can be applied for improved predictions for fatigue safety regardless of loading conditions.

Stent Fracture and Peri-Stent Contrast Staining After Everolimus-Eluting Stent Implantation - 5-Year Outcomes

BACKGROUND

Stent fracture (SF) and peri-stent contrast staining (PSS) after sirolimus-eluting stent implantation are reported to be risk factors of adverse events. However, the effect of these after everolimus-eluting stent (EES) implantation on long-term outcomes remains unclear.Methods and Results:The study sample comprised 636 patients (1,081 lesions) undergoing EES implantation in 2010 and follow-up angiography within 1 year. The 5-year cumulative rates of target lesion revascularization (TLR) and major adverse cardiac events (MACE: a combination of all-cause death, myocardial infarction, and TLR) were compared between patients with and without SF or PSS. SF was observed in 2.7%, and PSS in 3.0%. The cumulative rates of MACE and TLR were significantly higher in the SF group than in the non-SF group (51.7% vs. 27.5% and 48.3% vs. 13.4%, respectively), but showed no significant differences between the PSS and non-PSS groups. In a landmark analysis, the rate of TLR within 1 year was significantly higher in the SF group than in the non-SF group (44.8% vs. 7.2%), but beyond 1 year showed no significant difference (6.3% vs 6.7%).

CONCLUSIONS

The 5-year clinical outcomes suggested that SF after EES implantation is related to increased risk of MACE and TLR, especially within 1 year after the procedure, but PSS after EES implantation is unrelated.

Diagnosis and management challenges of in-stent restenosis in coronary arteries

Over the course of the 3 decades, percutaneous coronary intervention (PCI) with stent implantation transformed the practice of cardiology. PCI with stenting is currently the most widely performed procedure for the treatment of symptomatic coronary disease. In large trials, drug-eluting stents (DES) have led to a significant reduction in in-stent restenosis (ISR) rates, one of the major limitations of bare-metal stents. Due to these favorable findings, DES was rapidly and widely adopted enabling more complex coronary interventions. Nevertheless, ISR remains a serious concern as late stent complications. ISR mainly results from aggressive neointimal proliferation and neoatherosclerosis. DES-ISR treatment continues to be challenging complications for interventional cardiologists.

Coronary Stent Failure: Fracture, Compression, Recoil, and Prolapse

Current-generation coronary drug-eluting stents are associated with low rates of restenosis and target lesion revascularization. However, several mechanisms of stent failure remain clinically important. Stent fracture may occur in areas of excessive torsion or angulation. Longitudinal stent deformation is related to axial stent compression owing to extrinsic forces or secondary devices that disrupt stent architecture. Stent recoil occurs when a stent does not deploy at its optimal cross-sectional area. Tissue prolapse between stent struts may also predispose patients to adverse outcomes. Prevention, recognition, and treatment of these stent failures are necessary to optimize patient outcomes after percutaneous coronary interventions.

The role of angiographic follow-up after percutaneous coronary intervention

In the early days of coronary angioplasty, follow-up coronary angiography was often performed to assess restenosis. Angiographic restenosis has been shown to be associated with worse clinical outcomes, though the exact causality has yet to be determined. Numerous studies have repeatedly demonstrated that routine follow-up coronary angiography increases the incidence of target lesion revascularization without a clear reduction in mortality or myocardial infarction. Despite the lack of proven benefit of angiographic follow-up, routine follow-up coronary angiography is still being performed in certain countries and facilities. There are several factors that might explain the lack of benefit of angiographic follow-up: 1) lower incidence of stent failure in the current drug-eluting stent era has attenuated the net clinical benefit of follow-up angiography. 2) Angiographic restenosis might not lead to myocardial ischemia. 3) Patients that do have functionally significant restenosis are often referred for coronary angiography due to clinical indications such as intractable angina. 4) Absence of restenosis at the time of follow-up angiography does not exclude future restenosis. The absence of proven benefit in unselected populations does not necessarily preclude the presence of benefit in selected population, and there may be a subgroup of patients who can benefit from angiographic follow-up such as those with a large myocardial ischemic territory or those at very high risk of restenosis. Until there is more clinical evidence with respect to follow-up angiography, the decision of whether or not to perform it routinely in selected high-risk population should entail an in-depth discussion with the patient.

In-stent Restenosis

In-stent restenosis (ISR) is the narrowing of a stented coronary artery lesion. The mean time from percutaneous coronary intervention (PCI) to ISR was 12 months with drug-eluting stents (DES) and 6 months with bare metal stents (BMS). ISR typically presents as recurrent angina. The use of DES has significantly reduced the rate of ISR compared with BMS. Predictors of ISR include patient, lesion, and procedural characteristics. Intravascular ultrasound, optical coherence tomography, and fractional flow reserve are important tools for the anatomic and hemodynamic assessment of ISR. Treatment options for ISR include percutaneous coronary intervention with DES.

Incidence, predictive factors, and clinical impact of stent recoil in stent fracture lesion after drug-eluting stent implantation

BACKGROUND

Stent fracture (SF) after drug-eluting stent (DES) implantation was reported to be associated with target lesion revascularization (TLR). We have noted abnormal late acquired stent axial deformation in lesions after DES implantation, especially in SF lesions, and defined it as stent recoil (SR). We evaluated the incidence, predictive factors, and clinical impact of SR in SF lesions.

METHODS

Between 2003 and 2012, 5456 patients (11,712 lesions) underwent DES implantations and follow-up angiography within one year after the index procedure. SR was defined as an axial recoil deformation less than 80% of the stent diameter and SF was defined as the separation of stent segments or stent struts. SF and SR were confirmed by follow-up angiography. The primary endpoint was defined as clinically driven TLR.

RESULTS

SF was observed in 494 lesions (4.2%) and SR in 138 of SF lesions (27.9%). According to multinomial logistic regression analyses, severe calcification and ostial lesion in the right coronary artery were stronger predictive factors of SF with SR lesions. The cumulative incidences of any and clinically driven TLR at 5years were both significantly higher in the SF with SR group than in the SF without SR group (51.7% versus 35.0%, P<0.001; 22.2% versus 12.8%, P=0.019; respectively).

CONCLUSIONS

SR in SF lesions after DES implantation could be related to the lesion characteristics. SF with SR was highly associated with subsequent TLR compared with SF without SR.

Serial Intravascular Ultrasound Findings After Treatment of Chronic Total Occlusions Using Drug-Eluting Stents

Morphologic changes after chronic total occlusion (CTO) treatment with drug-eluting stents (DESs) have not been assessed in detail. Our aim was to use both baseline and follow-up intravascular ultrasound studies to evaluate the morphologic changes and, especially, the changes in distal vessel size and the effect of subintimal stenting after treatment of CTOs with DES. We analyzed serial follow-up intravascular ultrasound (baseline and follow-up at 9 ± 2 months) after DES implantation into 40 CTOs. Overall, 33 CTOs were treated by the anterograde approach; and 7 were treated by the retrograde approach. Minimum lumen cross-sectional area (CSA) trended toward a decrease from baseline to follow-up (4.8 ± 1.7 vs 4.5 ± 1.7 mm(2), p = 0.10), although the minimum stent CSA (4.8 ± 1.7 vs 4.9 ± 1.7 mm(2), p = 0.26) did not change. The distal reference, but not the proximal reference lumen CSA, increased significantly at follow-up (3.8 ± 2.0 to 5.1 ± 2.3 mm(2), p = 0.0004). Late-acquired stent malapposition was seen in 17 patients (42.5%). In 8 CTOs (20%), a part of the stent was implanted into a subintimal space; in these 8 patients, maximum percent neointimal hyperplasia and minimum lumen area was similar in the subintimal segment compared with the adjacent intraplaque segment. The frequency of late-acquired stent malapposition was similar. In conclusion, after CTO treatment with DES, distal vessel enlargement was detected. Subintimal stenting after recanalization of CTO was not inferior compared with stenting within the plaque in terms of long-term morphologic impact.

Mechanical response of cardiovascular stents under vascular dynamic bending

Backround

Currently, the effect of vascular dynamic bending (VDB) has not been fully considered when studying cardiovascular stents’ long-term mechanical properties, as the previous studies about stent’s mechanical properties mostly focus on the effect of vascular pulsation (VP). More and more clinical reports suggested that the effect of VDB have a significant impact on stent.

Methods

In this paper, an explicit-implicit coupling simulation method was applied to analyze the mechanical responses of cardiovascular stents considering the effect of VDB. The effect of VP on stent mechanical properties was also studied and compared to the effect of VDB.

Results

The results showed that the dynamic bending deformation occurred in stents due to the effect of VDB. The effects of VDB and VP resulted in alternating stress states of the stent, while the VDB alternate stresses effective on the stent were almost three times larger than that of the VP. The stress concentration under VDB mainly occurred in bridge struts and the maximal stress was located in the middle loops of the stent. However, the stress distributed uniformly in the stents under the effect of VP. Stent fracture occurred more frequently as a result of VDB with the predicted fracture position located in the bridging struts of the stent. These results are consistent with the reported data in clinical literatures. The stress of the vessel under VDB was higher, than that caused by VP.

Conclusions

The results showed that the effect of VDB has a significant impact on the stent’s stress distribution, fatigue performance and overall stress on the vessel, thus it is necessary to be considered when analyzing stent’s long-term mechanical properties. Meanwhile, the results showed that the explicit-implicit coupling simulation can be applied to analyze stent mechanical properties.

Complete stent fracture 1 year after LIMA PCI due to LIMA and subclavian artery dissection

Stent platforms are prone to fracture while incidental data are demonstrating a potential unfavorable outcome. Predisposing factors usually involve long lesions and tortuous vessels requiring more than one stent. This issue is magnified when it involves a periprocedural iatrogenic left internal mammary artery (LIMA) and subclavian artery dissection. In such complex clinical scenarios, the risk of potential complications including stent fractures is thought to be higher, though there is no data to determine the prognosis or to outline the outcomes of any management option. We present a case of complete stent fracture 1 year after LIMA percutaneous coronary intervention due to LIMA and subclavian artery dissection highlighting the circumstantial evidence in the literature that guided our management decisions.

Stent Fracture After Sirolimus-Eluting Stent Implantation

Background—

Stent fracture (SF) after sirolimus-eluting stent implantation is reported to be associated with target lesion revascularization (TLR) and stent thrombosis. We aimed to assess the clinical impact of SF at 8 years.

Methods and Results—

Between 2002 and 2005, 972 patients (1795 lesions) underwent sirolimus-eluting stent implantation and follow-up angiography within 1 year after index procedure. SF, defined as the complete separation of stent segments or stent struts at follow-up angiography, was observed in 105 lesions (5.8%). The study sample comprised 954 patients (1630 lesions), excluding 147 lesions undergoing TLR and 18 patients (18 lesions) who died or in whom stent thrombosis developed within 1 year after sirolimus-eluting stent implantation. The median follow-up duration was 9.1 years (the first and third quarters, 8.7 and 9.4 years). The primary end point was defined as any TLR. The 8-year cumulative rates of adverse events were estimated by Kaplan–Meier methods with P values from log-rank tests. Between patients with and without SF, there were no significant differences in the cumulative rates of all-cause death (23.5% versus 27.6%, P =0.35) and cardiac death (4.7% versus 9.1%, P =0.14), whereas patients with SF had significantly higher cumulative rates in myocardial infarction (10.1% versus 3.3%, P =0.001), very late stent thrombosis (6.8% versus 0.7%, P <0.001), any TLR (38.1% versus 10.8%, P <0.001), and clinically driven TLR (26.2% versus 6.6%, P <0.001).

Conclusions—

SF after sirolimus-eluting stent implantation was consistently associated with higher rates of adverse cardiac events during the 8-year follow-up.

Incidence and Clinical Impact of Stent Fracture After PROMUS Element Platinum Chromium Everolimus-Eluting Stent Implantation

OBJECTIVES

This study sought to assess the incidence and clinical impact of stent fracture (SF) after the PROMUS Element platinum-chromium everolimus-eluting stent (PtCr-EES).

BACKGROUND

SF remains an unresolved, clinically relevant issue, even in the newer-generation drug-eluting stent era.

METHODS

From March 2012 to August 2013, 816 patients with 1,094 lesions were treated only with PtCr-EES and 700 patients (85.7%) with 898 lesions undergoing follow-up angiography within 9 months after the index procedure were analyzed. SF was defined as complete or partial separation of the stent, as assessed by plain fluoroscopy, intravascular ultrasound, or optical coherence tomography during the follow-up. We assessed the rate of SF and the cumulative incidence of clinically driven target lesion revascularization and definite stent thrombosis within 9 months after the index procedure.

RESULTS

SF was observed in 16 of 898 lesions (1.7%) and 16 of 700 patients (2.2%). Lesions with in-stent restenosis at baseline (odds ratio [OR]: 14.2, 95% confidence intervals [CI]: 5.09 to 39.7; p < 0.001) or hinge motion (OR: 4.31, 95% CI: 1.12 to 16.5; p = 0.03), and total stent length (per 10-mm increase; OR: 1.32, 95% CI: 1.12 to 1.57; p = 0.001) were predictors of SF. Cumulative incidence of clinically driven target lesion revascularization within 9-months was numerically higher in the SF group than that in the non-SF group (18.7% vs. 2.3%). Cumulative incidence of definite stent thrombosis within 9 months after the index procedure was similar between the SF and non-SF groups (0.0% vs. 0.23%).

CONCLUSIONS

SF after PtCr-EES occurs in 1.7% of lesions and appears to be associated with clinically driven target lesion revascularization.

Mechanical complications of everolimus-eluting stents associated with adverse events: an intravascular ultrasound study

AIMS

Mechanical complications contribute to bare metal and first-generation drug-eluting stent (DES) failure. However, the importance of the mechanical complications of second-generation DES remains unclear. We report mechanical complications associated with everolimus-eluting stent (EES) failures.

METHODS AND RESULTS

We retrospectively analysed 177 consecutive EES-treated lesions in 136 patients who underwent intravascular ultrasound (IVUS) at follow-up. Mechanical complications were identified in 17 patients (five stable angina, 10 unstable angina, two non-ST-elevation myocardial infarction [NSTEMI] without angiographic thrombus). Fifteen (88.2%) were treated with repeat revascularisation. By IVUS, there were 16 focal (94.1%) and one diffuse (5.9%) in-stent restenoses. Complete stent fracture with separation was seen in only one, partial stent fracture with separation was seen in three, and in 13 there was longitudinal deformation (n=2) or stent strut fracture (n=11) with overlapping of the proximal and distal stent fragments. In 13 EES with evidence of overlapping in the setting of either fracture or deformation, there was a 35.5±12.2% smaller stent area compared to the adjacent proximal and distal stent fragments, and >50% neointimal hyperplasia in 12 (92.3%).

CONCLUSIONS

We found EES mechanical complications, often followed by longitudinal deformation or fracture leading to excessive neointimal hyperplasia, in-stent restenosis, and repeat revascularisation.

Association of localized hypersensitivity and in-stent neoatherosclerosis with the very late drug-eluting stent thrombosis

BACKGROUND

Localized hypersensitivity reaction, delayed arterial healing, and neoatherosclerosis inside the stent have been suggested as the underlying pathologic mechanisms of very late stent thrombosis (VLST) of drug-eluting stent (DES). The present study sought to explore the prevalence of inflammatory cell infiltrates and evidence for fragments of atherosclerotic plaques in the aspirated thrombi in patients with DES VLST.

METHODS AND RESULTS

From April 2004 to September 2012, 48 patients with stent thrombosis (ST) of DES underwent thrombus aspiration with retrieved material sufficient for the histopathologic analysis; early ST (EST, within 30 days): N = 17, late ST (LST, between 31 and 365 days): N = 7, and very late ST (VLST, >1 year): N = 24. Eosinophil fraction in the aspirated thrombi was significantly higher in patients with VLST (8.2±5.7%) as compared with those with EST (4.3±3.0%) and LST (5.5±3.8%) (P = 0.03). Eosinophil fraction in the aspirated thrombi was significantly higher in 12 VLST patients with angiographic peri-stent contrast staining (PSS) and/or incomplete stent apposition (ISA) by intravascular ultrasound than in 12 VLST patients without PSS or ISA (10.6±6.1% versus 5.8±4.1%, P = 0.03). Evidences for fragments of atherosclerotic plaques in the aspirated thrombi were observed only in 3 (13%) out of 24 patients with DES VLST.

CONCLUSIONS

Eosinophil fraction in the aspirated thrombi was significantly higher in patients with DES VLST as compared with those with EST and LST. Evidences for fragments of atherosclerotic plaques were relatively uncommon in patients with DES VLST.

Incidence and clinical impact of stent fracture after the Nobori biolimus-eluting stent implantation

Background

Stent fracture (SF) after drug‐eluting stent implantation has become an important concern. The aim of this study was to assess the incidence, predictors, and clinical impact of SF after biolimus‐eluting stent.

Methods and Results

A total of 1026 patients with 1407 lesions undergoing the Nobori biolimus‐eluting stent implantation and follow‐up angiography within 9 months after index procedure were analyzed. SF was defined as complete or partial separation of the stent, as assessed by using plain fluoroscopy, intravascular ultrasound, or optical coherence tomography during the follow‐up. We assessed the rate of SF and the cumulative incidence of clinically driven target lesion revascularization and definite stent thrombosis within 9 months. SF was observed in 58 (4.1%) of 1407 lesions and 57 (5.5%) of 1026 patients. Lesions with hinge motion (OR 8.90, 95% CI 3.84 to 20.6, P<0.001), tortuosity (OR 4.16, 95% CI 1.75 to 9.88, P=0.001), and overlapping stents (OR 2.41, 95% CI 0.95 to 6.10, P=0.06) were predictors of SF. Cumulative incidence of clinically driven target lesion revascularization within 9 months was numerically higher in the SF group than that in the non‐SF group (12.0% versus 1.0%). Cumulative incidence of definite stent thrombosis within 9 months tended to be higher in the SF group than that in the non‐SF group (1.7% versus 0.5%).

Conclusions

SF after biolimus‐eluting stent occurs in 4.1% of lesions and appears to be associated with clinically driven target lesion revascularization.

Pathology of second-generation everolimus-eluting stents versus first-generation sirolimus- and paclitaxel-eluting stents in humans

BACKGROUND

Clinical trials have demonstrated that the second-generation cobalt-chromium everolimus-eluting stent (CoCr-EES) is superior to the first-generation paclitaxel-eluting stent (PES) and is noninferior or superior to the sirolimus-eluting stent (SES) in terms of safety and efficacy. It remains unclear whether vascular responses to CoCr-EES are different from those to SES and PES because the pathology of CoCr-EES has not been described in humans.

METHODS AND RESULTS

A total of 204 lesions (SES=73; PES=85; CoCr-EES=46) from 149 autopsy cases with duration of implantation >30 days and ≤3 years were pathologically analyzed, and comparison of vascular responses was corrected for duration of implantation. The observed frequency of late and very late stent thrombosis was less in CoCr-EES (4%) versus SES (21%; P=0.029) and PES (26%; P=0.008). Neointimal thickness was comparable among the groups, whereas the percentage of uncovered struts was strikingly lower in CoCr-EES (median=2.6%) versus SES (18.0%; P<0.0005) and PES (18.7%; P<0.0005). CoCr-EES showed a lower inflammation score (with no hypersensitivity) and less fibrin deposition versus SES and PES. The observed frequency of neoatherosclerosis, however, did not differ significantly among the groups (CoCr-EES=29%; SES=35%; PES=19%). CoCr-EES had the least frequency of stent fracture (CoCr-EES=13%; SES=40%; PES=19%; P=0.007 for CoCr-EES versus SES), whereas fracture-related restenosis or thrombosis was comparable among the groups (CoCr-EES=6.5%; SES=5.5%; PES=1.2%).

CONCLUSIONS

CoCr-EES demonstrated greater strut coverage with less inflammation, less fibrin deposition, and less late and very late stent thrombosis compared with SES and PES in human autopsy analysis. Nevertheless, the observed frequencies of neoatherosclerosis and fracture-related adverse pathological events were comparable in these devices, indicating that careful long-term follow-up remains important even after CoCr-EES placement.

Stent fracture: how frequently is it recognized?

In spite of there being several case reports, coronary stent fracture is not a well-recognized entity and incidence rates are likely to be underestimated. In this article, we review different aspects of stent fracture, including incidence, classification, predictors, outcome, diagnosis, and management.

Application of a new three-dimensional method for the measurement of coronary stent angulation and comparison with conventional methods

The precision of the measurement of the angulation of coronary stents or lesions using coronary angiography (CA) and computed tomographic angiography (CTA) has not been established, and obtaining a rotating artery tree to measure angulation based on CTA is time-consuming. The aim of this study was to evaluate the utility of a new three-dimensional centerline method that we have developed for the measurement of coronary stent angulation based on CTA and to compare it with other conventional methods. We used the centerline method compacted by means of our new software, the conventional artery rotation method based on CTA and the simple CA method to measure the angulations of phantoms in vitro and stents implanted in patients. The precision and repetition of this new method was compared with those of the other two methods. The angulation values obtained from both the centerline and artery rotation methods based on CTA had high correlation and agreement with the true angulation values measured using a phantom; the 95 % confidence intervals (CIs) for the differences were -0.67° to 0.91° and -0.59° to 2.93°, respectively, while the difference between the value determined using the CA method and the true angulation of the phantoms ranged from 3° to 21.8° (median 8.1°). In clinical coronary stent measurement, the difference between artery rotation and centerline measurement was small (95 % CI -9.0° to 7.6°), and both methods had good repeatability. The time required to complete the measurement was considerably shorter (p < 0.001) using the centerline method than artery rotation method (12.5 ± 1.86 vs. 71.8 ± 13.6 s), while the CA method had poor precision and repeatability in the measurement of clinical stent angulation relative to the methods based on CTA (95 % CI -14.7° to 21.7°). Our three-dimensional centerline method based on CTA for the measurement of angulation was reliable and easy to implement in both clinical and basic research image analysis, and the centerline and conventional artery rotation methods can be used interchangeably. In addition, the value obtained for the coronary stent angulation using the CA method had a large bias.

Incidence and clinical impact of stent fracture after everolimus-eluting stent implantation

BACKGROUND

Stent fracture (SF) after drug-eluting stent implantation has recently become an important concern because of its potential association with in-stent restenosis and stent thrombosis. However, the incidence and clinical impact of SF after everolimus-eluting stent implantation remain unclear.

METHODS AND RESULTS

A total of 1035 patients with 1339 lesions undergoing everolimus-eluting stent implantation and follow-up angiography 6 to 9 months after index procedure were analyzed. SF was defined as complete or partial separation of the stent, as assessed by plain fluoroscopy or intravascular ultrasound during follow-up. We assessed the rates of SF and major adverse cardiac events, defined as cardiac death, myocardial infarction, stent thrombosis, and clinically driven target lesion revascularization within 9 months. SF was observed in 39 of 1339 lesions (2.9%) and in 39 of 1035 patients (3.8%). Ostial stent location and lesions with hinge motion, tortuosity, or calcification were independent predictors of SF. The rate of myocardial infarction and target lesion revascularization were significantly higher in the SF group than in the non-SF group (5.1% versus 0.4%; P=0.018 and 25.6% versus 2.0%; P<0.001, respectively). Stent thrombosis was more frequently observed in the SF group than in the non-SF group (5.1% versus 0.4%; P=0.018). Major adverse cardiac events within 9 months were significantly higher in the SF group than in the non-SF group (25.6% versus 2.3%; P<0.001).

CONCLUSIONS

SF after everolimus-eluting stent implantation occurs in 2.9% of lesions and is associated with higher rate of major adverse cardiac events, driven by higher target lesion revascularization and stent thrombosis.

Flat panel digital detector cinefluoroscopy late following SES or BMS implantation for detection of coronary stent fracture in asymptomatic patients

BACKGROUND

Coronary stent fracture (SF), is rare and confined mainly in patients treated with sirolimus eluting stents (SES). The role of flat panel digital detector (FPDD) fluoroscopy in detecting SF has not been investigated.

METHODS

Assessment with FPDD fluoroscopy of asymptomatic patients, with 200 SES (Cypher, Cordis, J&J, Miami, Florida, US), and 200 bare metal stents (BMS), at 45.5 ± 15.7 and 38.4 ± 3.9 months post-stenting respectively. SF was defined as discontinuity of stent struts on fluoroscopy. Coronary angiography was reserved for patients with documented SF.

RESULTS

Effective radiation dose was 0.26 ± 0.14 mSv. SF was depicted in 6 (3%) SES, and 1 BMS (0.5%). Stent length was an independent predictor of SF (OR 1.19, 95% CI 1.03-1.4, p=0.024). RCA location and vessel angulation were marginally significant (OR 7.7, 95% CI 0.8-74.2, p=0.077 and OR 5.1, 95% CI 0.8-34, p=0.089). Significant angiographic restenosis was detected in 4 SES (66.6%), and 1 BMS (0.5%). Re-intervention was needed in 3 (42.8%) cases, (2 SES and 1 BMS).

CONCLUSION

Detection of SF with FPDD cinefluoroscopy late following coronary stenting is feasible, involves low radiation and is confined mainly to SES compared to BMS. Application of cinefluoroscopy as part of a routine stent surveillance programme in asymptomatic patients may be more appropriate in "high risk" settings (SES, long stents and adverse angiographic characteristics). The role of invasive imaging and subsequent management of such patients need further studying.

Impact of Sirolimus-Eluting Stent Fracture on 4-Year Clinical Outcomes

Background—

Although stent fracture (SF) after sirolimus-eluting stent (SES) implantation has been recognized as one of the predisposing factors of in-stent restenosis, it remains uncertain whether SF can increase the risk of major adverse cardiac events (MACE), especially beyond 1 year after SES implantation. The aim of this study was to assess the impact of SF relative to non-SF on 4-year clinical outcomes after treatment with SES of comparable unselected lesions.

Methods and Results—

A total of 874 lesions in 793 patients undergoing SES implantation and subsequent angiography 6 to 9 months after index procedure were analyzed. At 6- to 9-month angiographic follow-up, SF was identified in 70 of 874 lesions (8.0%). In-stent late loss was significantly higher in SF lesions versus non-SF lesions (0.42±0.59 mm versus 0.13±0.49 mm, P <0.001), resulting in a significantly higher in-stent restenosis rate (21.4% versus 4.1%, P <0.001). At 4 years, SF versus non-SF was associated with a significantly higher MACE rate (23.2% versus 12.6%, P =0.014), mainly driven by significantly higher target-lesion revascularization (18.8% versus 10.2%, P =0.029) rate. Adverse effects of SF on clinical outcomes occurred mostly within the first year (17.4% versus 6.6%, P =0.001), with similar MACE rate between 1 and 4 years (5.8% versus 5.9%, P =0.611). No significant differences between SF versus non-SF patients were observed in the cumulative frequency of very late stent thrombosis (2.9% versus 1.4%, P =0.281), death (0% versus 2.1%, P =0.252), or myocardial infarction (5.8% versus 2.9%, P =0.165).

Conclusions—

SF of SES was associated with higher MACE rate up to 1 year, mainly driven by higher target-lesion revascularization, whereas no significant association was evident between years 1 and 4.