Stent fracture and restenosis in the drug-eluting stent era

Stent fracture, an incidental finding or a significant marker of clinical in-stent restenosis?

BACKGROUND

The predictors and clinical significance for stent fracture (SF) in drug-eluting stents (DES) remain unknown. We identified procedural factors leading to SF and its clinical consequences in DES.

METHODS

Percutaneous coronary interventions were performed on 3,920 patients with DES over 12 months. In-stent restenosis (ISR) of DES was observed in 188 cases with 121 cases (64.4%) receiving a sirolimus-eluting stent (SES) and 67 (35.6%) a paclitaxol-eluting stent (PES).

RESULTS

SF was identified in 35 (18.6%) of the 188 cases. The 35 cases were then compared with 153 cases of ISR without angiographic evidence of SF. SF was identified in 29 (23.9%) SES compared with 6 (9.0%) in PES (P < 0.05). With univariate analysis, additional factors associated with SF included longer mean stented segment length, male gender, overlapping stents, vessel segment angulation >75 degrees , and more stents (all P < 0.05). With multivariate adjustment, three factors, i.e., stenting on a bend >75 degrees (OR = 13.8, 95%CI 3.7 to 51; P < 0.001), SES (OR = 4.1, 95%CI 1.3 to 13.4; P < 0.018) and overlapping stented segments (OR = 3.9, 95%CI 1.1 to 14.1; P < 0.041) were statistically significant independent predictors of SF while larger stent diameter was protective (OR = 0.14, 95%CI 0.04 to 0.70; P < 0.017).

CONCLUSION

SF proved to be associated with angiographically-documented clinical ISR. Although the exact mechanism is unknown, factors that appear to play a negative role in SF include vessel tortuosity, use of SES and overlapping stents. Larger stent diameter was protective. Further studies are needed to better define the factors important in the mechanism of SF.

Stent fracture following stenting of a myocardial bridge: report of two cases

Myocardial bridge is the most common congenital coronary anomaly. Patients with this anomaly are usually asymptomatic, but it may cause myocardial ischemia that may lead to myocardial infarction. Treatment for myocardial bridge remains controversial. Current recommendations include medical therapy, surgical treatment (unroofing myotomy), coronary artery bypass, and percutaneous coronary stenting. We report two cases of stent fracture following stenting of a myocardial bridge. The risk of stent fracture leading to restenosis and/or stent thrombosis should be considered when assessing the risks and benefits of coronary revascularization of a myocardial bridge.

Acute myocardial infarction as a consequence of stent fracture and plaque rupture after sirolimus-eluting stent implantation

Stent fracture (SF) is emerging as one of the leading causes of late cardiac events after sirolimus-eluting stent (SES) implantation. A 44-year old man was admitted with ST-segment elevated myocardial infarction 22 months after treatment with SES. SF was confirmed by fluoroscopy, intravascular ultrasound study (IVUS) and computerized tomographic study. IVUS demonstrated a soft, ruptured plaque at the site of the SF where the plaque was not covered by the stent strut. This case suggests that rupture of vulnerable plaque because of SF led to thrombosis and acute myocardial infarction.

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

BACKGROUND

Recently, stent fracture (SF) of sirolimus-eluting stents (SES) has been shown to be associated with an increased risk of in-stent restenosis. We sought to evaluate the incidence, predictors and clinical outcome of SF after SES implantation in comparable unselected lesions.

METHODS

A total of 430 lesions of 382 patients treated with SES were analyzed. SF was defined as single or multiple stent strut fracture as well as complete separation of stent segments.

RESULTS

At follow-up, SF was identified in 33 of 430 lesions (7.7%). In lesions with SF, the in-stent restenosis was observed more frequently than non-SF lesions (15.2% vs. 4.0%, P=0.004). At 450 days, however, the cumulative rate of major cardiac events was not significantly different between lesions with and without SF (9.1% vs. 7.1%, P=0.722). The risk of SF was independently associated with total stent length (OR 2.22; 95% CI, 1.25 to 3.95; P=0.007), the change in the angulation of the lesion after stenting (OR 1.55; 95% CI, 1.07 to 2.25; P=0.020), and the right coronary artery lesions (OR 3.26; 95% CI, 1.18 to 8.96; P=0.022).

CONCLUSIONS

The occurrence of SF after SES implantation, was found to be relatively common in the particular population, however, did not lead to an increased risk of adverse cardiac events at 450 days, despite a higher incidence of in-stent restenosis.

Dark side of drug-eluting stent: multiple stent fractures and sudden death

Recently reported stent fractures after sirolimus-eluting stent (SES) implantation were found several months later during the follow-up of coronary angiogram (CAG) and single fracture mostly. The study reports a case of sequential, continuous, multiple coronary stent fracture and sudden death.

Late giant coronary aneurysm associated with a fracture of sirolimus eluting stent: a case report

A 73-year-old female underwent percutaneous coronary intervention (PCI) because of stable angina. An elective PCI for the RCA lesion was first performed with deploying sirolimus eluting stents (SES). Three weeks later, PCI was also provided in the residual LAD lesion. Eight months later, she presented with new angina. CAG revealed an in-stent restenosis in the mid LAD and a large eccentric saccular coronary aneurysm (17 mm x 9 mm) at the proximal RCA. Intravascular ultrasound (IVUS) showed absence of stent struts around the orifice of aneurysm, which suggested a fracture of SES stent. The entry of coronary aneurysm was finally sealed with a polytetrafluoroethylene-covered stent. This report documented a rare case of late giant coronary artery aneurysm associated with a fracture of SES.

Acute coronary syndrome due to hinge movement of a bare-metal stent

Recently, attention has been given to stent fracture (SF) as a risk factor of in-stent restenosis. SF is sometimes revealed at the site of hinge movement (HM). HM synchronized to heart beats might cause chronic mechanical stress of the vessel wall, resulting in chronic inflammation and mobilization of inflammatory cells, and this might lead to formation of atheromatous plaque. A 59-year-old man in whom a bare metal stent (BMS) had been deployed to the right coronary artery 9 years ago visited our clinic due to acute coronary syndrome (ACS). Emergency coronary angiography revealed HM at the site of the BMS where thrombotic occlusion was revealed. ACS might be caused by chronic mechanical stress due to HM of the BMS.

Serial angiographic and intravascular ultrasound analysis of late stent strut fracture of sirolimus-eluting stents in native coronary arteries

BACKGROUND

Stent fracture in sirolimus-eluting stents (SES) has been reported to be associated with late adverse events. However, a suitable method to diagnose stent fracture is not fully elucidated.

METHODS

One hundred and two consecutive SES implantations were performed in 83 lesions in 56 patients and underwent serial angiography with intravascular ultrasound (IVUS) at baseline and at 6 months follow-up. Angiographic stent strut fracture was defined as stent bending with separation of stent struts. Angiographic hinge movement was defined as stent shaft deviation without separation of stent struts. IVUS stent strut dissociation was defined as the disappearance of stent struts in more than one cross-sectional image which were previously visualized at baseline.

RESULTS

By angiography, no cases of stent fracture were detected at 6 months. One case of angiographic hinge movement was found at 12 months. However, three instances of stent fracture were detected by IVUS at 6 months. One case of stent fracture showed a patent lumen area at 6 months but subsequently developed late stent restenosis at 12 months. The other two cases were associated with in-stent restenosis at 6 months.

CONCLUSION

Compared to angiography, IVUS can more reliably detect stent fracture during follow-up evaluation.

Features and parameters of drug-eluting stent deployment discoverable by intravascular ultrasound

The only routinely available tool for assessing many features of stent implantation, intravascular ultrasound (IVUS) has become indispensable in trials of drug-eluting stents (DESs) and is currently the best way to identify or exclude causes of DES failure. Although IVUS resolution is not sufficient for determining reendothelialization, serial (postprocedure and follow-up) IVUS can measure intimal hyperplasia (IH), assess acute and late incomplete stent apposition, detect the presence and persistence of edge dissections, assess vascular responses such as remodeling, study edge effects, compare overlapping with nonoverlapping segments, and look for causes of restenosis and thrombosis. Percentage IH volume is one IVUS measure of efficacy that has been routinely assessed and compared in studies of DESs; IH volume and external elastic membrane, luminal, and stent cross-sectional area are others. This review details and evaluates IVUS findings in the important clinical trials conducted with the first-generation DESs: a sirolimus-eluting stent, a polymeric paclitaxel-eluting stent, and a nonpolymeric paclitaxel-eluting stent. IVUS results apparent in DES failure (restenosis and thrombosis) are also examined.

Fracture of a Nitinol Carotid Artery Stent That Caused Restenosis

The placement of self-expanding nitinol stents in the carotid artery is rapidly emerging as a minimally invasive alternative in the treatment of cervical carotid artery occlusive disease. Fractures of balloon-expandable stents after placement in the carotid artery have been previously documented. The authors report on a single case of early stent fracture and complete mid-body disruption of a self-expanding stent associated with a significant restenosis necessitating repeat intervention after carotid artery stent placement for a de novo atherosclerotic lesion.

Snare extraction of a fractured coronary stent in a saphenous vein graft

Retrieval of intravascular objects can be accomplished through snare retrieval. We report a case in which a patient presented with symptomatic in-stent restenosis caused by a fractured aorto-ostial sirolimus-eluting stent in a saphenous vein graft. Because of the inability to selectively engage the stent ostium with the guide catheter, the fractured stent was removed with an endovascular snare in order to permit successful revascularization. With the proximal portion of the stent retrieved by the snare, a new stent was implanted without complication.

Transition from bare metal to drug eluting stenting in contemporary US practice: effect on incidence and predictors of clinically driven target lesion revascularization

BACKGROUND

The performance of drug eluting stents (DES) and impact on every day practice in the USA, where complex, nonselective cases are the rule, remain unknown.

METHODS

The Brigham and Women's Hospital interventional experience in the bare metal stents (BMS) (6/2002 to 2/2003) and after abrupt and near universal adoption of DES (4/2003 to 9/2004) were compared. Demographic, procedural and in-hospital outcomes for all consecutive cases where investigated. Predictors and angiographic characteristics of patients returning for clinically driven target lesion revascularization (TLR) in both eras were analyzed.

RESULTS

Of 2,555 DES cases (3,061 lesions, 87.9% Cypher, 12.1% Taxus), 47 underwent TLR during follow-up (68 lesions, 2.2%). Of the 1,731 BMS cases (1,798 lesions), 162 underwent clinically indicated TLR (209 lesions, 11.6%), representing an 81% DES era TLR risk reduction. Multivariate predictors of TLR in the DES era: left main lesion (LM) (odds ratio (OR) 7.65, 95% confidence interval (CI) 3.33-17.53, P<0.01, treatment of restenosis (OR 5.96, CI 3.21-11.08, P<0.01), and diabetes (OR 1.68, CI 0.92-3.04, P=0.07). Predictors of restenosis in the BMS era included additional clinical, lesion, and stent characteristics, while LM lesion was absent. Angiographic patterns of stent restenosis differed in the DES (focal) and BMS (diffuse) era.

CONCLUSIONS

The transition from BMS to DES in the setting of a large USA hospital practice is safe and associated with significant reduction in clinically driven TLR. Treatment of specific lesions types (repeat restenosis, distal LM) and diabetic patients remain suboptimal and warrant further investigation.

Intravascular ultrasound parameters associated with stent thrombosis after drug-eluting stent deployment

Drug-eluting stent (DES) thrombosis (ST) can be devastating. The study aim was to evaluate intravascular ultrasound (IVUS) predictors for DES thrombosis by comparing IVUS studies after implantation in 13 patients with 14 DES thrombosis lesions with a group of controls (30 lesions in 27 patients) matched for history of chronic renal failure and type of DES. Five patients (38%) discontinued dual antiplatelet therapy at the time of ST. There were 3 in-stent restenosis lesions (21%) treated using DESs in the ST group compared with 0 in the control group (p <0.05). Compared with the control group, IVUS studies in the ST group showed a smaller minimum stent area (4.6 +/- 1.1 vs 5.6 +/- 1.7 mm(2), p = 0.0489). In the ST group, 11 of 14 stents had a minimum stent area < or =5.0 mm(2) compared with 12 of 30 in the control group (p = 0.0392). Minimum stent area in patients who stopped clopidogrel therapy and developed ST (5.30 +/- 1.15 mm(2)) tended to be larger compared with that in patients who developed ST while using clopidogrel (4.24 +/- 0.96 mm(2), p = 0.091). Within the 5-mm-long proximal and distal reference segments analyzed, the ST group had larger proximal reference maximum plaque burdens and smaller minimum lumen areas, along with a tendency toward similar findings in the distal reference segments. In conclusion, IVUS findings at the time of DES implantation in patients who subsequently developed ST showed a smaller minimum stent area (especially in patients who developed ST while using clopidogrel) and more residual disease at the stent edges.

Incidence and clinical impact of coronary stent fracture after sirolimus-eluting stent implantation

BACKGROUND

Stent fracture is one of the possible causes of restenosis after sirolimus-eluting stents (SES) implantation. The aim of our study was to evaluate the prevalence and clinical impact of coronary stent fracture after SES implantation.

METHODS

From our prospective institutional database, 280 patients were treated solely with SES from August 2004 to June 2005. Among the 280 patients, 256 patients with a total of 307 lesions underwent follow-up angiography on an average of 240 days after the procedure.

RESULTS

Stent fractures were observed in eight (2.6%) lesions. Of the eight lesions with stent fracture, five were located in the right coronary artery (RCA), two in the saphenous vein (SV) graft, and one in the left anterior descending coronary artery. The stent fractures were all in the locations that served as hinges during vessel movement in the cardiac contraction cycle. Seven of the eight stent fractures were adjacent to the edge of previously implanted or overlapped stent. Significant multivariate predictors of stent fracture were SV graft location (Odds ratio 35.88; 95% confidence interval 2.73-471.6, P = 0.006), implanted stent length (Odds ratio 1.04; 95% confidence interval 1.01-1.07, P = 0.02), and RCA location (Odds ratio 10.00; 95% confidence interval 1.11-89.67, P = 0.04). In-stent binary restenosis rate was 37.5% and target lesion repeat revascularization rate was 50.0% in patients with stent fracture.

CONCLUSIONS

Stent fracture was likely to be affected by mechanical stress provoked by rigid structures and hinge points. Stent fracture might be associated with the high incidence of target lesion revascularization.

Stent fracture associated with drug-eluting stents: clinical characteristics and implications

OBJECTIVE

To evaluate the clinical characteristics and implications of stent fracture in drug-eluting stents.

BACKGROUND

Approximately 2.5 million drug-eluting stents are implanted every year worldwide. In 10 randomized controlled trials involving 2,602 patients, no incidence of stent fracture was recognized or reported.

METHODS

From April 2003 to December 2005, 2,728 patients underwent drug-eluting stenting. The angiograms of all 530 patients who underwent repeat angiography were analyzed to identify the presence of stent fracture. We then documented the incidence of adverse events associated with drug-eluting stent fracture and systematically analyzed the clinical, procedural, and structural factors, which might predispose to stent fracture.

RESULTS

Stent fracture was identified in 10 patients. None of these fractures were detectable at the time of stent placement. The median time interval from stent implantation to detection of fracture at repeat angiography was 226 days (range, 7-620 days). Adverse clinical outcomes associated with stent fracture occurred in 7 patients (6 patients had binary restenosis and 1 patient had stent thrombosis), all necessitating repeat intervention. Analysis of potential predisposing clinical, procedural, and structural factors revealed that 4 patients had excessive tortuosity in the proximal segment, and overlapping stents were used in 5 cases. All fractures occurred in sirolimus-eluting stents.

CONCLUSIONS

Stent fracture may represent a new potential mechanism of restenosis and stent thrombosis in drug-eluting stents. Predisposing clinical and procedural factors may be vessel tortuosity and use of overlapping stents. The most important predisposing factor, however, may be stent structure, since all fractures occurred in sirolimus-eluting stents.

Modeling of Size Dependent Failure in Cardiovascular Stent Struts under Tension and Bending

Cardiovascular stents are cylindrical mesh-like metallic structures that are used to treat atherosclerosis. The thickness of stent struts are typically in the range of 50-150 microm. At this microscopic size scale, the tensile failure strain has been shown to be size dependent. Micromechanically representative computational models have captured this size effect in tension. In this paper polycrystalline models incorporating material fracture are used to investigate size effects for realistic stent strut geometries and loading modes. The specific loading a stent undergoes during deployment is uniquely captured and the implications for stent design are considered. Fracture analysis is also performed, identifying trends in terms of strut thickness and loading type. The results show, in addition to the size effect in tension, further size effects in different loading conditions. The results of the loading analyses are combined to produce a tension and bending failure graph. This design safety diagram is presented as a tool to predict failure of stent struts. This study is particularly significant given the current interest in producing smaller stents.

Stent fracture and restenosis after placement of a drug-eluting device in the vertebral artery origin and treatment with the stent-in-stent technique

✓ The authors report two cases of stent fracture and restenosis after placement of a drug-eluting device in the vertebral artery (VA) origin, and describe management of restenosis with the stent-in-stent technique. Two women, one 62 and the other 67 years of age, underwent stent placement in the VA origin to treat symptomatic and angiographically significant stenosis in this vessel. Sirolimus-eluting coronary stents (Cypher) were used in both cases. Four months after placement of the devices, the symptoms recurred. Follow-up angiography performed 5 months after insertion of the devices revealed a transverse stent fracture with separation of the fragments and severe in-stent restenosis in both cases. The restenoses were treated with reinsertion of coronary stents (Cypher and Jostent FlexMaster) by using the stent-in-stent technique. After stent reinsertion, the patients exhibited relief of symptoms.

This paper is the first report of fracture in a drug-eluting stent and restenosis after stent placement in the VA origin. Restenosis caused by such a fracture can be managed successfully by performing the stent-in-stent maneuver. The physical properties of metallic devices, stent strut geometry, and anatomical peculiarities of the subclavian artery may be associated with stent fractures. Earlier follow-up angiography studies (within 6 months) are warranted.

Strut fracture of DES: An increasing problem?

Drug-eluting stents (DES) have greatly reduced the possibility of in-stent restenosis by inhibiting neointimal growth. But recently stent fracture has emerged as a complication. Stent fracture may cause restenosis, even occlusion. Here we report a case of stent fracture after percutaneous coronary intervention with DES without restenosis.

Coronary stent fracture in a saphenous vein graft to right coronary artery--successful treatment by the novel use of the Jomed coronary stent graft: case report and review of the literature

Coronary stents ultimately owe their success to the mechanical scaffolding effect that they provide. The mechanical properties of these metallic stents were designed not only to provide radial strength so as to prevent vessel recoil, but also to be able to resist the mechanical stress of vessel movement over millions of cardiac cycles. We present a case whereby the latter mechanical stresses may have contributed to the fracture of a stent implanted in the saphenous vein graft to the right coronary artery. We demonstrated that the point at which the stent fracture occurred coincided with an area of maximal graft movement. Our patient presented with acute myocardial infarction due to graft occlusion 3 months after stent implantation. We re-intervened by deploying a Jomed coronary stent graft, consisting of 2 layers of stent, to cover the stent fracture, thereby providing optimal support to this area of high mechanical stress, resulting in a good long-term clinical outcome. The novel use of a Jomed coronary stent graft for this indication has not been previously described. Review of the literature indicates that factors that may predispose to stent fracture include location in the right coronary vein graft, long stents, overlapping stents and stent over-expansion.

The incidence and clinical impact of stent strut fractures developed after drug-eluting stent implantation

BACKGROUND

Cases of stent strut fractures (SSFs) after DES implantation have been reported, but the clinical significance is uncertain. Then we sought to define the incidence and clinical implications of SSFs developed after drug-eluting stent (DES) implantation.

METHODS

We gathered SSF cases from 13 centers in Korea retrospectively. SSF was defined as angiographically visible interrupted connection of stent struts or fewer visible stent struts at the suspected site than normally looking stented area on intravascular ultrasound (IVUS). Furthermore, we classified the SSFs cases into three patterns (disruption, avulsion, and displacement) according to the interruption site and absence or presence of displacement.

RESULTS

Thirty-seven SSFs (2 disruption, 7 avulsion, 28 displacement) were detected in 35 lesions in 35 patients. All fractured stents were sirolimus-eluting stents (SESs). The incidence of SSFs was 0.84% and the proportion of restenosis related with SSF was 6.3% after SES implantation driven from the data of 8 centers. The average length of stent used was 49 mm, overlapping stenting was performed in 19 lesions (54%), and the average maximal angulation in the initial coronary angiography was 67 degrees . Twenty-four fractures (65%) were associated with focal in stent restenosis and 11 fractures (30%) with target lesion revascularization. No acute coronary syndrome developed.

CONCLUSIONS

SSF after DES implantation might be a considerable complication after DES implantation especially after SES implantation.

Contemporary treatment of in-stent restenosis and the incidence of recurrent in-stent restenosis in the era of drug-eluting stents

BACKGROUND

Optimal treatment of in-stent restenosis (ISR) remains uncertain in the era of drug-eluting stents (DES). This study aims to determine contemporary treatment of ISR and to assess recurrent ISR rates in the era of DES.

METHODS

We examined 60 patients presenting for treatment of ISR (one lesion per patient) who were enrolled in the Melbourne Interventional Group Registry (4% of total population of 1423 patients) between April 2004 and January 2005. Twelve-month follow-up is complete for all patients.

RESULTS

The majority of ISR treated occurred in bare metal stents [BMS (n=52, 87%)] and had a focal (<10 mm) pattern of ISR (53%). In-stent restenosis of DES occurred in eight (13%) patients. The majority of ISR were treated with additional stenting with a preference for DES over BMS in almost all cases. At 12 months, one patient died of non-cardiac cause and four patients (7%) presented with recurrent ISR. The incidence of recurrent ISR in DES was 5% (n=3). No late thrombosis was reported despite only 50% of patients having >or=12 months of clopidogrel therapy.

CONCLUSIONS

Our study suggests drug-eluting stents are safe, effective and the preferred therapy for in-stent restenosis. The incidence of recurrent drug-eluting stent restenosis at 12 months is low.

A pooled analysis of data comparing sirolimus-eluting stents with bare-metal stents

BACKGROUND

Although randomized studies have shown a beneficial effect of drug-eluting stents in reducing the risk of repeated revascularization, these trials were underpowered to compare rates of death and myocardial infarction. The long-term safety of drug-eluting stents has been questioned recently.

METHODS

We performed a pooled analysis of 1748 patients in four randomized trials evaluating the safety of sirolimus-eluting stents as compared with bare-metal stents. Patient-level data were obtained and analyzed by independent statisticians at two academic institutions. The primary safety end point was survival at 4 years. We tested for heterogeneities in treatment effect in patient subgroups.

RESULTS

The survival rate at 4 years was 93.3% in the sirolimus-stent group, as compared with 94.6% in the bare-metal-stent group (hazard ratio for death, 1.24; 95% confidence interval [CI], 0.84 to 1.83; P=0.28). In the 428 patients with diabetes, a significant difference in the survival rate was observed in favor of the bare-metal-stent group over the sirolimus-stent group (95.6% vs. 87.8%; hazard ratio for death in the sirolimus-stent group, 2.9; 95% CI, 1.38 to 6.10; P=0.008). The lower survival rate among patients with diabetes who were treated with sirolimus-eluting stents was due to increased numbers of deaths from both cardiovascular and noncardiovascular causes. No difference in survival rate was detected among the patients without diabetes. Rates of myocardial infarction and stent thrombosis were similar in the two groups.

CONCLUSIONS

In a pooled analysis of data from four trials comparing sirolimus-eluting stents and bare-metal stents, no significant differences were found between the two treatments in rates of death, myocardial infarction, or stent thrombosis. (ClinicalTrials.gov numbers, NCT00233805 [ClinicalTrials.gov] , NCT00381420 [ClinicalTrials.gov] , NCT00232765 [ClinicalTrials.gov] , and NCT00235144 [ClinicalTrials.gov].)

Predictors of Target Lesion Revascularization and Documented Stent Thrombosis Beyond 30 Days After Sirolimus-Eluting Stent Implantation Retrospective Analysis in Consecutive 1,070 Angiographic Follow-up Lesions

BACKGROUND

Outcomes after sirolimus-eluting stent (SES: Cypher) implantation remained to be elucidated in Japan.

METHODS AND RESULTS

Among 1,070 consecutive angiographic follow-up lesions, 99 lesions underwent target lesion revascularization (TLR) with in-stent restenosis (ISR). Retrospective estimation by multivariate analysis including 50 variables showed that the ostiums of right coronary and left circumflex arteries, hemodialysis, calcification, non-direct stenting, ISR of SES, and non-eccentric lesion were the predictors of TLR. There was no documented late stent thrombosis (LST) among 2,166 lesions and very LST (VLST) among 1,423 lesions.

CONCLUSION

Further revises are needed to implant SES to these predictive lesions. LST and VLST were very rare.

Stent fracture: An unusual cause of late restenosis after sirolimus-eluting stent placement

Stent fracture is uncommon but may have consequences including restenosis. To date, stent fractures reported have been related to aggressive post dilation. We describe a case that involves fracture of a stent deployed to nominal pressure. Unlike most stent fractures reported that involve stent struts only our case demonstrated circumferential disruption with complete separation of the stent segments.

Volumetric intravascular ultrasound assessment of neointimal hyperplasia and nonuniform stent strut distribution in sirolimus-eluting stent restenosis

The neointimal hyperplasia (IH) distribution pattern of in-stent restenotic lesions after sirolimus-eluting stent (SES) implantation has not been well described. We identified 48 in-stent restenotic lesions (41 patients) after SES implantation and performed volumetric intravascular ultrasound analyses. Lumen area, stent area, and IH area at the minimal lumen area site were 2.7 +/- 1.0, 5.4 +/- 1.9, and 2.7 +/- 1.4 mm(2), respectively. IH area at the minimal lumen site was larger in the group with a stent area > or =5.0 mm(2) than the group with a stent area <5.0 mm(2) (3.7 +/- 1.3 vs 1.9 +/- 0.8 mm(2), p <0.001). There were fewer visualized stent struts in lesions with a minimum stent area > or =5.0 mm(2) at the minimum lumen site compared with those with a stent area <5.0 mm(2) (0.69 +/- 0.25 vs 0.83 +/- 0.16, p = 0.04). When we compared lesions in patients with diabetes mellitus with patients without diabetes, minimum lumen areas, percent IH at minimal lumen area, percent IH, and neointima-free stent length were identical. In conclusion, (1) lesions without SES underexpansion at the minimum lumen site had more IH and greater nonuniform stent strut distribution compared with restenotic SESs that were underexpanded, and (2) the IH response did not appear to be more aggressive in patients with diabetes mellitus than in those without diabetes mellitus.

Stent fracture in revascularization for symptomatic ostial vertebral artery stenosis

INTRODUCTION

We assessed the long-term follow-up examinations and complications of percutaneous transluminal angioplasty and stenting (PTAS) for symptomatic ostial vertebral artery (VA) stenosis.

METHODS

A retrospective study was done to evaluate 12 patients with symptomatic ostial VA stenosis who underwent PTAS. Six patients were treated with the Palmaz stent and six with a balloon-expandable coronary stent. Initial angiographic follow-up examination was conducted about 12 months after PTAS in all patients. Simple radiographic, ultrasonographic and clinical follow-up examinations were scheduled every 6 months.

RESULTS

Excellent dilatation was achieved in all patients without any procedural complications. Initial angiographic follow-up obtained at a mean of 13 months after PTAS detected no restenosis. However, an asymptomatic severe restenosis was detected at 24 months after PTAS in one patient (8%). During a mean follow-up of 31.5 months, three stent fractures were detected in deployed coronary stents (50%). None of the stent fractures was associated with either recurrent stroke or restenosis. No patients developed recurrent symptoms during the follow-up period.

CONCLUSION

PTAS for symptomatic ostial VA stenosis is effective in preventing recurrent stroke. As the open-cell single-joint type of stent is associated with the risk of fracture, long-term follow-up examinations including simple radiography are needed.

In vivo MR angiographic quantification of axial and twisting deformations of the superficial femoral artery resulting from maximum hip and knee flexion

PURPOSE

The goal of this study was to quantify in vivo deformations of the superficial femoral artery (SFA) during maximum knee and hip flexion with use of magnetic resonance (MR) angiography to improve description of the complex, dynamic SFA environment.

MATERIALS AND METHODS

Contrast medium-enhanced MR angiography was performed on the leg vasculature of eight healthy adults in the supine and fetal positions. The SFA was defined as the centerline path of the iliofemoral segment from the profunda femoris to the descending genicular artery. Deformations that resulted from flexion from the supine position to the fetal position were quantified with the SFA path and its branches.

RESULTS

Fourteen SFAs shortened from the supine position to fetal position, whereas two lengthened. Six of eight left SFAs twisted counterclockwise, and seven of eight right SFAs twisted clockwise. Straightness percentages for supine and fetal SFAs were 99.1%+/-0.4% and 98.7%+/-0.6%, respectively. From the supine position to the fetal position, the SFA shortened 13%+/-11% (P<.001) and twisted 60 degrees+/-34 degrees (P<.001). SFA arc length and percent shortening were strongly correlated (r>.8) between left and right limbs; however, no significant correlation existed for SFA twist angle.

CONCLUSIONS

Complex and varying vascular and muscular anatomy among study participants made SFA lengths and deformations from the supine position to the fetal position unpredictable a priori; however, there were strong symmetries between left and right SFAs in terms of arc length, length change, and direction of twist. The data show that, from the supine position to the fetal position, the SFA tended to shorten and twist substantially, suggesting these as possible fracture mechanisms and also providing important parameters for stent design.

Early- and medium-term outcomes after paclitaxel-eluting stent implantation for sirolimus-eluting stent failure

The optimal treatment for sirolimus-eluting stent (SES) restenosis is not known. This study evaluated the safety and clinical outcome of paclitaxel-eluting stent (PES) implantation for SES restenosis. From March 2004 to July 2005, PESs were implanted in 125 patients with 140 lesions with SES restenosis. Acute and 6-month clinical outcomes were determined through review of the medical record and/or telephone interview. In-hospital major adverse cardiac events (death, nonfatal myocardial infarction, or repeat revascularization) occurred in 14 patients (11.2%), driven entirely by postprocedure non-Q-wave myocardial infarction. At a mean clinical follow-up of 7.2 +/- 1.8 months, the incidence of target lesion revascularization (TLR) was 14.0%, and the rate of major adverse cardiac events was 17.2%. Subacute thrombosis occurred in 2 patients (1.6%). Length of PES implanted, postprocedure diameter stenosis, and total occlusion of the target lesion were independent predictors of TLR. In patients with de novo SES restenosis, TLR was only 8.7%. In conclusion, at medium-term follow-up, PES implantation for SES failure appears to be safe and effective, although efficacy is decreased in the setting of total occlusions, greater residual diameter stenosis, and longer PESs.

Drug-eluting stent fracture occurred within 2 days after stent implantation

Recently the cases of stent fracture after sirolimus-eluting stent (SES) implantation have been reported in the real world. All of them were found several months later during the follow-up of coronary angiogram (CAG), and some were related to in-stent restenosis (ISR). We report a case of stent fracture after percutaneous coronary intervention (PCI) with SES within 2 days after stent implantation. Further investigation is required to elucidate the mechanism and clinical significance of stent fracture of SES.

Coronary stent fracture and restenosis in the drug-eluting stent era: do we have clues of management?

Despite the fact that the drug-eluting stents (DES) have markedly reduced neointimal proliferation, restenosis is still an open subject. Although DES fracture is very rare, it has been considered as one of the reasons for DES restenosis, however, the mechanism and proper management are not clearly elucidated yet. We describe two cases of sirolimus-eluting stent fracture combined with significant restenosis and suggest the possible revascularization strategies for successful management.

Three-year clinical follow-up of the unrestricted use of sirolimus-eluting stents as part of the Rapamycin-Eluting Stent Evaluated at Rotterdam Cardiology Hospital (RESEARCH) registry

Sirolimus-eluting stents (SESs) have been shown to decrease restenosis compared with bare metal stents (BMSs). Currently, there are limited data on the long-term efficacy of these devices in a real-world patient population. Furthermore, the potential of a late restenotic phenomenon has not yet been excluded. From April to October 2002, 508 consecutive patients with de novo lesions exclusively treated with SESs were enrolled and compared with 450 patients treated with BMSs in the preceding 6 months (control group). Patients in the SES group more frequently had multivessel disease and type C lesions, received more stents, and had more bifurcation stenting. After 3 years, the cumulative incidence of major adverse cardiac events (comprising death, myocardial infarction, and target vessel revascularization) was significantly lower in the SES group compared with the pre-SES group (18.9% vs 24.7%, hazards ratio 0.73, 95% confidence interval 0.56 to 0.96, p = 0.026). The 3-year risk of target lesion revascularization was 7.5% in the SES group versus 12.6% in the pre-SES group (hazards ratio 0.57, 95% confidence interval 0.38 to 0.87, p = 0.01). In conclusion, the unrestricted use of SESs is safe and superior to the use of BMSs. The beneficial effects, reported after 1 and 2 years in reducing major adverse cardiac events, persisted with no evidence of a clinical late restenotic "catch-up" phenomenon.

Coronary artery stent fracture

Coronary stent fracture is a rare but potentially serious complication of coronary artery stenting. In light of the non-specific presentation of stent fracture, it is also an easily missed complication. In order to ensure rapid recognition and treatment of this entity, physicians must be aware of its existence and its possibility under the right circumstances. We present the case of a 61-year-old Guyanese male who presented with unstable angina secondary to a stent fracture within two weeks of elective percutaneous coronary intervention (PCI) for in-stent restenosis.

A case of popliteal stent fracture with pseudoaneurysm formation

We describe a case of angiographically documented stent fracture and pseudoaneurysm formation in a patient with femoropopliteal disease, which was successfully treated with deployment of an endovascular stent graft. Technical aspects of the procedure are discussed and the experience with stent fractures previously reported in the literature is reviewed.

The influence of grain size on the ductility of micro-scale stainless steel stent struts

Vascular stents are used to restore blood flow in stenotic arteries, and at present the implantation of a stent is the preferred revascularisation method for treating coronary artery disease, as the introduction of drug eluting stents (DESs) has lead to a significant improvement in the clinical outcome of coronary stenting. However the mechanical limits of stents are being tested when they are deployed in severe cases. In this study we aimed to show (by a combination of experimental tests and crystal plasticity finite element models) that the ductility of stainless steel stent struts can be increased by optimising the grain structure within micro-scale stainless steel stent struts. The results of the study show that within the specimen size range 55 to 190 microm ductility was not dependent on the size of the stent strut when the grain size maximised. For values of the ratio of cross sectional area to characteristic grain length less than 1,000, ductility was at a minimum irrespective of specimen size. However, when the ratio of cross sectional area to characteristic grain length becomes greater than 1,000 an improvement in ductility occurs, reaching a plateau when the ratio approaches a value characteristic of bulk material properties. In conclusion the ductility of micro-scale stainless steel stent struts is sensitive to microstructure and can be improved by reducing the grain size.

Stent Strut Fracture-Induced Restenosis in a Bifurcation Lesion Treated With the Crush Stenting Technique

Percutaneous treatment of a bifurcation lesion still shows a significant complication rate, mainly because of restenosis at the ostial site of the side branch vessel. Different techniques, such as V-stenting, culottes-stenting or crush stenting, allow full ostial coverage and may therefore achieve uniform drug distribution within the lesion. The crush technique results in a strong mechanical constraint on the side branch stent. A case of stent strut fracture-induced restenosis in a bifurcation lesion treated with the crush stenting technique is described.