Incidence, Mechanism, Predictors, and Long-Term Prognosis of Late Stent Malapposition After Bare-Metal Stent Implantation

Incidence and natural history of coronary artery aneurysm developing after drug-eluting stent implantation

AIMS

There is a growing concern about the occurrence of coronary artery aneurysms (CAAs) after drug-eluting stent (DES) implantation and their long-term course. We assessed the occurrence and the factors affecting the long-term outcome of DES-associated CAA.

METHODS AND RESULTS

We analyzed 3,612 consecutive patients (4,419 lesions) who underwent follow-up angiography after DES implantation. All 34 CAAs (0.76% per lesion) in 29 patients (0.8% per patient) were detected at follow-up, and the mean elapsed time from DES implantation to CAA diagnosis was 414 ± 213 days. Angiographically, CAAs developed almost exclusively in complex (type B2/C) de novo lesions (30 [88.2%] of 34 lesions), and lesion length was significantly greater in patients with CAA than without CAA (26.9 ± 9.03 vs 23.1 ± 7.14 mm; P = .004). Myocardial infarction with stent thrombosis occurred in 5 patients with CAA (17.2%), 4 of whom were on aspirin only without clopidogrel.

CONCLUSION

Although CAAs rarely develop after DES implantation and show mostly favorable clinical courses, long-term maintenance of clopidogrel therapy might be required to minimize occurrence of adverse clinical events resulting from stent thrombosis.

Incidence, Mechanisms, Predictors, and Clinical Impact of Acute and Late Stent Malapposition After Primary Intervention in Patients With Acute Myocardial Infarction

Background— The incidence and mechanisms of acute and late stent malapposition after primary stent implantation in ST-segment elevation myocardial infarction remain unclear.

Methods and Results— The Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial was a dual-arm, factorial, randomized trial comparing paclitaxel-eluting stents (PES) and otherwise equivalent bare metal stents (BMS) in ST-segment elevation myocardial infarction patients. The intravascular ultrasound substudy enrolled 241 patients with 263 native coronary lesions (201 PES, 62 BMS) with baseline and 13-month follow-up imaging. Postintervention acute stent malapposition (ASM) occurred in 34.3% PES- and 40.3% BMS-treated lesions. Of these, 39.1% PES- and 40.0% BMS-treated lesions resolved at follow-up, especially within the stent body (66.7%); complete resolution was accompanied by a reduction in external elastic membrane area. An ASM area >1.2 mm 2 best separated persistent from resolved ASM. At follow-up, a higher frequency of late stent malapposition was detected in PES-treated lesions (46.8%) mainly because of more late acquired stent malapposition (30.8%) compared with BMS-treated lesions. Late acquired stent malapposition area correlated to the decrease of peri-stent plaque in the subset of lesions without positive remodeling and only to change in external elastic membrane in the group with positive remodeling. Independent predictors of late acquired stent malapposition were plaque/thrombus protrusion (odds ratio, 5.60; 95% confidence interval [CI], 2.32 to 13.54) and PES use (odds ratio, 6.32; 95% CI, 2.15 to 18.62).

Conclusions— The incidence of ASM was similar in PES- and BMS-treated lesions, but late acquired stent malapposition was more common in PES-treated lesions. The reason for resolved ASM was negative remodeling, with larger ASM areas separating persistent from resolved ASM. Late acquired stent malapposition was due mainly to positive remodeling and plaque/thrombus resolution.

Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00433966.

Long-term impact of routinely detected early and late incomplete stent apposition: an integrated intravascular ultrasound analysis of the TAXUS IV, V, and VI and TAXUS ATLAS workhorse, long lesion, and direct stent studies

OBJECTIVES

We sought to determine the 2-year impact of early and late-acquired incomplete stent apposition (ISA) on clinical events.

BACKGROUND

The late clinical impact of early or late-acquired ISA in bare-metal stents (BMS) and TAXUS stents (Boston Scientific, Natick, Massachusetts) is debatable.

METHODS

We evaluated 1,580 patients enrolled in the intravascular ultrasound (IVUS) substudies of TAXUS IV, V, VI and TAXUS-ATLAS WH, LL, and DS trials.

RESULTS

There were 96 cases of early ISA in 26 (7.2%) BMS patients, 35 (9.7%) TAXUS Express patients (p = 0.28 vs. BMS), and 35 (7.3%) TAXUS Liberté patients (p = 0.21 vs. TAXUS Express, and p = 1.00 vs. BMS). Major adverse cardiovascular events were similar at 9 months in patients with early ISA versus control subjects with no ISA for BMS (3.8% vs. 15.2%, p = 0.13) and for TAXUS (11.6% vs. 8.8%, p = 0.45). There was no impact of early ISA on stent thrombosis. At 9-month follow-up, there were 36 cases of late-acquired ISA in 7 (2.7%) BMS patients, 17 (3.1%) patients with TAXUS slow-release (TAXUS Express or TAXUS Liberté), and 12 (15.4%) patients receiving TAXUS moderate-release. Over 2 ensuing years, major adverse cardiovascular events were similar in patients with late-acquired ISA versus control subjects with no ISA for BMS (14.3% vs. 7.9%, p = 0.54), TAXUS (overall, 8.3% vs. 8.1% p = 0.87), or TAXUS slow-release formulation (0% vs. 7.9%, p = 0.28). There was no impact of late-acquired ISA on stent thrombosis.

CONCLUSIONS

Neither routinely detected acute ISA nor routinely detected late-acquired ISA in BMS or TAXUS patients was associated with adverse clinical events over long-term follow-up.

Very late stent thrombosis occurring simultaneously in sirolimus-eluting stents and bare-metal stent in three different coronary vessels

A 36-year-old male was diagnosed with acute inferior myocardial infarction (MI). Emergent coronary angiography (CAG) revealed an occlusive lesion in the distal segment of the right coronary artery (RCA). The proximal and distal sites of the lesion were treated with a bare-metal stent (BMS) and a sirolimus-eluting stent (SES), respectively. Nine days later, he underwent elective percutaneous coronary intervention (PCI). Two SESs were implanted for the stenotic lesion in the left anterior descending artery (LAD), in addition to one SES for the mid-stenotic lesion in the left circumflex artery (LCX). Nine months after PCI, follow-up CAG revealed no restenosis at any stent-implanted site. Two years and 4 months after PCI, he was admitted to our hospital because of acute anterior MI. Emergent CAG revealed total thrombotic occlusion in the in-stent proximal site of LAD. Moreover, thrombotic lesions were also observed in in-stent sites: in both BMS of RCA and SES of LCX. He underwent intracoronary aspiration thrombectomy and plain old balloon angioplasty for LAD using intra-aortic balloon pumping. PCI for the thrombotic lesions in RCA and LCX was not performed. Seventeen days after the stent thrombosis, CAG revealed the complete disappearance of thrombi in LAD, LCX, and RCA.

Impact of thrombus aspiration use and direct stenting on final myocardial blush score in patients presenting with ST-elevation myocardial infarction

BACKGROUND

Many studies have reported that low final thrombolysis in myocardial infarction (TIMI) flow and/or myocardial blush grade (MBG) are independent predictors of mortality in patients with ST-elevation myocardial infarction (STEMI). In addition, distal coronary embolization is a major pitfall of conventional percutaneous coronary intervention (PCI) in such a context.

AIM

This study aimed to assess the impact of thrombus aspiration (TA) use before primary PCI on final myocardial reperfusion in patients presenting with STEMI.

METHODS

From January to December 2006, 100 patients presenting with STEMI in our catheterization laboratory were considered for the present study. During this time period, 50 patients underwent TA before primary PCI for treatment of STEMI and were then matched 1:1 to 50 controls who underwent conventional primary PCI for treatment of STEMI without TA. Patients of the control group were chosen after matching on age+/-3 years, sex, history of diabetes, and distribution of the infarct related coronary artery during the same period.

RESULTS

Baseline clinical characteristics, initial TIMI flow and initial MBG of both groups were similar. There was a trend for a better final TIMI flow in the group with TA and the final MBG was significantly improved in the group with TA compared to the group without TA: final MBG of two or three in 70% versus 30% of the cases (P=.001). In addition, direct stenting was significantly more often used in the TA group (92% versus 64%, P=.001). There were four patients with evident distal embolizations in the group without TA and none in the group with TA.

CONCLUSION

TA use before primary PCI for STEMI treatment resulted in improved final myocardial reperfusion. Of importance, TA use may have led to a better choice of the stent size and more frequent direct stenting. This benefit may directly improve patient outcomes.

Late and very late drug-eluting stent malapposition: serial 2-year quantitative IVUS analysis

BACKGROUND

The long-term natural history of acquired malapposition continues to be the subject of debate.

METHODS AND RESULTS

Using volumetric intravascular ultrasound analyses, we evaluated serial (poststenting, 6-month, and 2-year follow-up) changes in drug-eluting stent-treated vascular segments with acquired malapposition. External elastic membrane, stent, lumen, malapposition, and peristent plaque+media (P+M=external elastic membrane -stent- malapposition) areas were measured; and volumes were calculated and divided by stent length (normalized volume). Among 250 lesions in which complete serial intravascular ultrasound data were available, stent malapposition was identified in 19 lesions (7.6%) at 6 months, and an additional 13 malapposition lesions were newly detected at 2 years (5.2%). Because no malapposition sites resolved, the malapposition rate at 2 years was 12.8%. Malapposition areas and volumes were correlated to the increases in external elastic membrane (positive remodeling) throughout the study period, from immediately after stenting to 6 months and from 6 months to 2 years, both in the group that developed malapposition at 6 months and in the group that developed malapposition at 2 years. Clinical follow-up beyond the 2 year intravascular ultrasound study was done in all patients. Overall, there were 2 cardiac deaths and 1 noncardiac death. Two patients presented with acute myocardial infarction associated with very late stent thrombosis (1 definite stent thrombosis, 1 probable stent thrombosis). Three patients underwent repeat revascularization owing to in-stent restenosis developed after the 2-year follow-up.

CONCLUSIONS

Expansive vascular remodeling may play a role in the development and dynamic progression of acquired drug-eluting stent malapposition, not only during the first 6 months after implantation but thereafter.

Long-term vascular changes after drug-eluting stent implantation assessed by serial volumetric intravascular ultrasound analysis

Using serial volumetric intravascular ultrasonography, we evaluated the predictors of late intimal hyperplasia (IH) increases after drug-eluting stent implantation. All eligible patients who underwent 6-month angiography without visual restenosis were requested to undergo a 2-year follow-up examination. Complete serial (after stenting and early [6-month], and late [2-year] follow-up) angiographic and intravascular ultrasound data were available for 135 patients with 143 lesions: 99 sirolimus-eluting stents and 44 paclitaxel-eluting stents. The external elastic membrane, stent, lumen, and peri-stent plaque volumes (external elastic membrane minus stent) were normalized by stent length. The percentage of IH volume was calculated as IH volume/stent volume x 100. The early reduction in the minimum lumen area was greater than the late reduction in the minimum lumen area (-0.8 +/- 0.8 vs -0.2 +/- 0.5 mm(2), p <0.001). A progressive increase occurred in the percentage of IH volume: 8.1 +/- 7.1% from baseline to 6 months and 2.4 +/- 3.9% from 6 months to 2 years (p <0.001, between the early and late increases in the percentage of IH). The use of paclitaxel-eluting stents was the only independent predictor for the percentage of IH volume at 6 months (beta = 0.419, p <0.001). The use of paclitaxel-eluting stents (beta = 0.365, p <0.001, 95% confidence interval 3.7 to 9.7) and the post-stenting normalized plaque and media volume (beta = 0.195, p = 0.020, 95% confidence interval 0.1 to 1.6) were the only independent predictors for the percentage of IH volume at 2 years. However, when the percentage of IH at 6 months was forced into the model, the percentage of IH at 6 months and the post-stenting normalized plaque and media volume, not paclitaxel-eluting stent use, predicted the 2-year percentage of IH. In conclusion, although IH continued to increase beyond 6 months, the growth rate of intima and luminal loss attenuated with time.

Impact of intravascular ultrasound guidance in patients with acute myocardial infarction undergoing percutaneous coronary intervention

OBJECTIVES

The aim of this study was to examine the utility of routine intravascular ultrasound (IVUS) guidance in patients with acute myocardial infarction (MI) undergoing percutaneous coronary intervention (PCI) with stent implantation.

BACKGROUND

Stent thrombosis (ST) is a serious complication of PCI with stent implantation for patients presenting with acute MI. Mechanical factors such as incomplete stent expansion and smaller stent diameters are known to correlate with ST and restenosis. IVUS guidance for stent deployment is reported to reduce these events in stable patients.

METHODS

We analyzed a cohort of 905 consecutive patients who underwent primary PCI for acute MI and were discharged alive. The clinical outcomes of 382 patients who underwent IVUS-guided PCI were compared to those of 523 patients who did not. Patients who presented with cardiogenic shock and rescue PCI were excluded. The primary composite endpoint of death, MI, and target lesion revascularization at 1-year follow-up was systematically indexed and a propensity score was performed with regard to the use of IVUS-guided PCI.

RESULTS

Patients undergoing IVUS-guided PCI were older, more diabetic and hypertensive, but presented with less history of previous MI. The severity of coronary artery disease was balanced between both groups. The number of treated lesions and stents used was higher in the IVUS-guided group, with a longer procedural duration. The overall rates of the composite primary outcome were similar (14.5% vs. 14.3%, P = 0.94) as were the rates of definite and probable stent thrombosis at 1 year (2.1% vs. 2.1%, P = 0.99) in the IVUS-guided and no-IVUS groups, respectively. After multivariate and propensity score adjustment, IVUS guidance was not an independent predictor for the primary endpoint.

CONCLUSION

This study does not support the routine use of IVUS guidance for stent deployment in patients who present with acute MI and undergo primary PCI.

Comparison of carotid stents: an in-vitro experiment focusing on stent design

PURPOSE

To examine and compare different carotid stent designs with regard to flexibility, adaptability (adjustability), conformability (compliance) to the vessel, and scaffolding to reduce plaque prolapse and embolization.

METHODS

Six stents of different design were compared (Precise, Acculink, Protégé, Xact, Wallstent, and Cristallo Ideale). Optical microscopy was used to determine exact dimensions and scaffolding of each stent. Radial force was tested using a parallel plate setup, and flexibility (torsion and bending) was measured in water at body temperature. Particle penetration simulation was performed using plastic spheres from 1.5- to 6.0-mm outer diameter.

RESULTS

Stent dimensions met the manufacturers' data; none of the products showed any failure during the test program. Cell sizes in the middle part of the stents ranged from 1.36 mm(2) (Wallstent) to 15.10 mm(2) (Acculink). Bending forces at 20 degrees /30 degrees ranged from 0.063 N / 0.074 N (Cristallo Ideale) to 0.890 N / 0.616 N (Xact); forces to achieve torsion at 10 degrees /15 degrees ranged from 0.032 N / 0.043 N (Acculink) to 0.905 N / 1.071 N (Xact). According to the parallel plate method, mean lowest force was measured for Xact (0.765 N), while the Wallstent had the highest force (2.136 N). Mean radial force measurements were lowest for Cristallo Ideale (9.06 N at mid part) and highest for Protégé (24.09 N). The Cristallo Ideale stent at mid part resisted penetration by all but the smallest plastic spheres (1.5-mm spheres penetrated only at 0.65 N); the Precise and Protégé stent had the highest variation in sphere penetration (1.5- to 4.0-mm spheres). Only the Acculink let 6-mm spheres penetrate.

CONCLUSION

Despite comparable stent sizes, these carotid stents showed differences in behavior due to stent design. The open-cell design displayed the greatest flexibility and adaptability to the vessel but easily allowed particle penetration due to the open structure. Closed-cell designs had low flexibility and thus low adaptability to the vessel but high resistance to particle penetration due to the closed-cell design and high scaffolding. The hybrid stent design (Cristallo Ideale) was able to combine both the flexibility of an open-cell structure and the resistance to particle penetration of closed-cell structures.

Major adverse cardiac events at follow-up after bare-metal stenting versus drug-eluting stenting in ST-elevated myocardial infarction

After thrombolytic therapy with tenecteplase for ST-segment elevation acute myocardial infarction, 376 patients were transferred from their hospital to Westchester Medical Center for percutaneous coronary intervention with stenting. Of 376 patients, 102 (27%) received bare-metal stents and 274 (73%) received drug-eluting stents with sirolimus-eluting or paclitaxel-eluting stents. At 43 months of follow-up, major adverse cardiac events occurred in 25 (25%) of 102 patients treated with bare-metal stents versus 40 (15%) of 274 patients treated with drug-eluting stents (p = 0.024). Cox regression analysis showed that significant independent prognostic factors for major adverse cardiac events were previous coronary artery bypass surgery (hazard ratio 2.2, p = 0.019), width of stent (hazard ratio 0.44, p = 0.006), and bare-metal stent (hazard ratio 1.8, p = 0.019). In conclusion, patients with bare-metal stents had a 1.8 times greater risk of developing major adverse cardiac events than did those using drug-eluting stents after controlling the confounding effects of previous coronary artery bypass surgery and stent width.

Combining sirolimus-eluting stents and external irradiation in cholesterol-fed rabbits increased incomplete stent apposition and decreased re-endothelialization

Restenosis after the implantation of a drug-eluting stent or after vascular irradiation therapy shares similar physiopathological mechanisms. No experimental data are currently available on vascular wall behavior after external irradiation on arteries stented with sirolimus-eluting stents (SES). Ten New Zealand white rabbits received a 0.5% cholesterol-enriched chow for 1 month. Bilateral iliac artery stent implantation was then performed with an SES (Cypher; Cordis Corp). The animals were randomized into either an irradiated group (I, 2 Gy external x-ray irradiation, n = 5) or a control group (C, n = 5). The cholesterol-enriched chow was continued for 1 additional month after stent implantation. The stented arteries were harvested for histological analyses. The number and the percentage of incompletely apposed stents struts (IASS) were significantly higher in irradiated versus control group (3.05 +/- 0.46 vs. 1.57 +/- 0.27 IASS, P < 0.01, and 28.44% +/- 3.97% vs. 15.2% +/- 2.46% of IASS, P < 0.01, respectively). The mean neointimal thickness behind the IASS was also higher in the irradiated group (I: 28.3 +/- 2.5 microm vs. C: 18.2 +/- 2.3 microm, P < 0.01). Re-endothelialization was lower in irradiated group (I: 44.6% +/- 17.5% vs. C: 75.2% +/- 5.7%, P < 0.01). The present study revealed that low-dose external irradiation increased incomplete stent apposition and reduced re-endothelialization of SES. These results underscore the potential deleterious cumulative side effects of these 2 procedures to prevent restenosis.

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

AIMS

Late stent malapposition (LSM) may be acquired (LASM) or persistent. LSM may play a role in patients who develop late stent thrombosis (ST). Our objective was to compare the risk of LASM in bare metal stents (BMS) with drug-eluting stents (DES) and to investigate the possible association of both acquired and persistent LSM with (very) late ST.

METHODS AND RESULTS

We searched PubMed and relevant sources from January 2002 to December 2007. Inclusion criteria were: (a) intra-vascular ultrasonography (IVUS) at both post-stent implantation and follow-up; (b) 6-9-month-follow-up IVUS; (c) implantation of either BMS or the following DES: sirolimus, paclitaxel, everolimus, or zotarolimus; and (d) follow-up for LSM. Of 33 articles retrieved for detailed evaluation, 17 met the inclusion criteria. The risk of LASM in patients with DES was four times higher compared with BMS (OR = 4.36, CI 95% 1.74-10.94) in randomized clinical trials. The risk of (very) late ST in patients with LSM (five studies) was higher compared with those without LSM (OR = 6.51, CI 95% 1.34-34.91).

CONCLUSION

In our meta-analysis, the risk of LASM is strongly increased after DES implantation compared with BMS. Furthermore, LSM seems to be associated with late and very late ST.

The influence of strut thickness and cell design on immediate apposition of drug-eluting stents assessed by optical coherence tomography

BACKGROUND

Stent strut malapposition correlates with poor intimal coverage and this may increase the risk of late stent thrombosis. At present, there is limited data on whether stent strut thickness and stent design impact on acute apposition. We aimed to investigate the influence of stent strut thickness and design on acute stent strut apposition (SSA) immediately following drug-eluting stent (DES) implantation using optical coherence tomography (OCT), a technique with higher resolution and fewer artefacts than intravascular ultrasound.

METHODS

Thirty-six DES in 23 patients (25 lesions) were studied by OCT. SSA was defined as embedded when a strut was buried in the intima for more than half its thickness, protruding when apposed to the intima but not embedded and malapposed when there was no intimal contact.

RESULTS

Cypher Select stents were implanted in 52%, Taxus Liberte in 32%, Costar in 12% and Endeavour in 4%. A total of 6402 struts were evaluated. Despite stent optimisation using balloons with a final balloon/artery ratio of 1.26+/-0.19 at a maximum inflation pressure of 17.5+/-3.0 atm, only 57.1+/-20.7% of struts were embedded, whereas 33.8+/-18.4% were protruding and 9.1+/-7.4% were malapposed. Stent type was a strong predictor of malapposition on logistic multilevel analysis (OR 3.95, 95%CI: 1.27-12.23, p=0.017). At 12 months follow-up, there were no adverse clinical events.

CONCLUSION

Despite angiographic optimisation with high pressures and adequately sized balloons, malapposed stent struts are frequently found in complex coronary lesions and more often following the implantation of Cypher Select stents which have a thicker stent strut and closed cell design. With no adverse clinical events at 12 months follow-up, this likely represents a benign phenomenon at least as long as combined anti-platelet therapy is maintained.

Cardiac death and reinfarction after 1 year in the Thrombus Aspiration during Percutaneous coronary intervention in Acute myocardial infarction Study (TAPAS): a 1-year follow-up study

BACKGROUND

Percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction can be complicated by spontaneous or angioplasty-induced embolisation of atherothrombotic material. Distal blockage induces microvascular obstruction and can result in less than optimum reperfusion of viable myocardium. The Thrombus Aspiration during Percutaneous coronary intervention in Acute myocardial infarction Study (TAPAS) found that thrombus aspiration resulted in improved myocardial reperfusion compared with conventional PCI, but whether this benefit improves clinical outcome is unknown. We aimed to investigate whether the early efficacy of thrombus aspiration seen in TAPAS translated into clinical benefit after 1 year.

METHODS

Patients with ST-elevation myocardial infarction enrolled at the University Medical Centre Groningen were randomly assigned in a 1:1 ratio to either thrombus aspiration or conventional treatment, before undergoing initial coronary angiography. Exclusion criteria were rescue PCI after thrombolysis and known existence of a concomitant disease with life expectancy less than 6 months. Of the 1071 patients enrolled between January, 2005, and December, 2006, vital status at or beyond 1 year after randomisation was available for 1060 (99%). The primary endpoint was cardiac death or non-fatal reinfarction after 1 year, and analysis was by intention to treat. The TAPAS trial is registered with Current Controlled Trials number ISRCTN16716833.

FINDINGS

Cardiac death at 1 year was 3.6% (19 of 535 patients) in the thrombus aspiration group and 6.7% (36 of 536) in the conventional PCI group (hazard ratio [HR] 1.93; 95% CI 1.11-3.37; p=0.020). 1-year cardiac death or non-fatal reinfarction occurred in 5.6% (30 of 535) of patients in the thrombus aspiration group and 9.9% (53 of 536) of patients in the conventional PCI group (HR 1.81; 95% CI 1.16-2.84; p=0.009).

INTERPRETATION

Compared with conventional PCI, thrombus aspiration before stenting of the infarcted artery seems to improve the 1-year clinical outcome after PCI for ST-elevation myocardial infarction.

Sirolimus-eluting stents versus bare-metal stents in patients with ST-segment elevation myocardial infarction: 9-month angiographic and intravascular ultrasound results and 12-month clinical outcome results from the MISSION! Intervention Study

OBJECTIVES

Our purpose was to evaluate the efficacy and safety of drug-eluting stents in the setting of primary percutaneous coronary intervention for ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

There is inconsistent and limited evidence about the efficacy and safety of drug-eluting stents in STEMI patients.

METHODS

A single-blind, single-center, randomized study was performed to compare bare-metal stents (BMS) with sirolimus-eluting stents (SES) in 310 STEMI patients. The primary end point was in-segment late luminal loss (LLL) at 9 months. Secondary end points included late stent malapposition (LSM) at 9 months as determined by intravascular ultrasound imaging and clinical events at 12 months.

RESULTS

In-segment LLL was 0.68 +/- 0.57 mm in the BMS group and 0.12 +/- 0.43 mm in the SES group with a mean difference of 0.56 mm, 95% confidence interval 0.43 to 0.68 mm (p < 0.001). Late stent malapposition at 9 months was present in 12.5% BMS patients and in 37.5% SES patients (p < 0.001). Event-free survival at 12 months was 73.6% in BMS patients and 86.0% in SES patients (p = 0.01). The target-vessel-failure-free survival was 84.7% in the BMS group and 93.0% in the SES group (p = 0.02), mainly because of a higher target lesion revascularization rate in BMS patients (11.3% vs. 3.2%; p = 0.006). Rates of death, myocardial infarction, and stent thrombosis were not different.

CONCLUSIONS

Sirolimus-eluting stent implantation in STEMI patients is associated with a favorable midterm clinical and angiographic outcome compared with treatment with BMS. However, LSM raises concern about the long-term safety of SES in STEMI patients.

Impact of postprocedure minimum stent area on long-term results following abciximab-coated stent implantation: an intravascular ultrasound analysis

BACKGROUND

Smaller postprocedural minimum stent areas (MSA) measured by intravascular ultrasound (IVUS) have been associated with higher restenosis rates.

METHODS

This was a single-center, prospective, randomized trial and we assessed the predictive value of MSA for long-term patency and the incidence and extent of incomplete stent apposition (ISA) following abciximab-coated stent (n=69) compared to bare metal stent (BMS) implantation (n=69). All patients underwent IVUS follow-up at 6 months.

RESULTS

At follow-up coronary angiogram, the restenosis rate and late loss were 12%, 0.30+/-0.24 mm in abciximab-coated stent group and 29%, 0.68+/-0.36 mm in BMS group (p=0.011, 0.010, respectively). At follow-up IVUS, intrastent lumen area was significantly larger and intrastent neointimal hyperplasia area was significantly smaller in abciximab-coated stent group than those in BMS group (5.9+/-1.6 mm(2) vs. 4.5+/-1.7 mm(2), p=0.001, and 1.9+/-1.5 mm(2) vs. 3.3+/-1.9 mm(2), p<0.001, respectively). Target lesion revascularization occurred in 9%, 0%, and 0% in abciximab-coated stent group and 19%, 4%, and 1% in BMS group in lesions with a MSA <6.0 mm(2), from 6 to 7.5 mm(2), and >7.5 mm(2), respectively. Late-acquired ISA at follow-up was observed in 7 patients and there was no difference in the incidence of ISA between both groups [abciximab-coated stent: n=3 (4%) vs. BMS: n=4 (6%), p=0.698].

CONCLUSION

Abciximab-coated stent reduced restenosis and had a considerably lower optimal MSA threshold compared to BMS and showed lower incidence of late-acquired ISA.

Drug-eluting stent safety

Drug-eluting stents (DESs) held the promise of mitigating, if not abolishing, in-stent restenosis. This led to early adoption and high penetration of DES use in percutaneous coronary intervention (PCI). Outcomes have not demonstrated an improvement in the hard end points of death and myocardial infarction with these devices, but repeat procedures for in-stent restenosis have decreased. The problem of stent thrombosis, a major obstacle that arose early in coronary stent development, has raised new contemporary concerns about the safety of DESs. The risk for stent thrombosis after bare metal stent placement appears to diminish with time, while very late stent thrombosis (>1 year after index PCI) occurs in small but measurable numbers after DES placement at a rate that continues to increase. Late-acquired incomplete stent apposition and abnormal endothelial function have also been reported. Restenosis, although significantly lessened, does occur after DES PCI. This report reviews DES safety issues that have been described.

Comparison of intravascular ultrasonic imaging with versus without incomplete stent apposition at follow-up after drug-eluting stent implantation

BACKGROUND

Incomplete stent apposition (ISA) at follow-up has been reported to be more common after drug-eluting stent (DES) implantation than after bare-metal stent (BMS) implantation. The aim of this study was to use intravascular ultrasound (IVUS) to evaluate the coronary characteristics after drug-eluting stent implantation in patients with ISA at follow-up.

METHODS

From the IVUS database of our institute, a total of 89 patients with 125 native lesions who underwent DES implantation into de novo lesions with IVUS imaging at 6-month follow-up were identified, and 15 (16.9%) patients had documented ISA at follow-up by IVUS. The ISA group was compared with a matched control group of patients (n = 30) who had no evidence of ISA at follow-up.

RESULTS

Of the 15 documented ISA at follow-up after DES implantation, two located at the edge (within 5 mm from stent margin) while 13 in the body of the stent. The maximum area and arc of ISA measured 5.3 +/- 2.2 mm(2) and 163 +/- 67 degrees , respectively. In patients with ISA, the maximum EEM area of stent segment with ISA was significantly larger than the adjacent stent segment without ISA (24.1 +/- 3.3 vs. 20.1 +/- 3.1 mm(2), P = 0.002), while stent area, plaque plus media (P&M) area and intrastent lumen area were comparable (P > 0.05). Compared to the matched control cohort without ISA at follow-up, the maximum EEM area was also significantly larger (24.1 +/- 3.3 vs. 18.8 +/- 4.2 mm(2), P < 0.001), while the areas of reference EEM and lumen, stent, P&M behind the stent, intimal hyperplasia and intrastent lumen were all comparable between the two groups (P > 0.05).

CONCLUSION

ISA at follow-up after DES implantation for de novo coronary lesions was associated with a larger EEM area.

Angiographic stent thrombosis after routine use of drug-eluting stents in ST-segment elevation myocardial infarction: the importance of thrombus burden

OBJECTIVES

This study sought to investigate the impact of thrombus burden on the clinical outcome and angiographic infarct-related artery stent thrombosis (IRA-ST) in patients routinely treated with drug-eluting stent (DES) implantation for ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

There are limited data for the safety and effectiveness of DES in STEMI.

METHODS

We retrospectively analyzed 812 consecutive patients treated with DES implantation for STEMI. Intracoronary thrombus burden was angiographically estimated and categorized as large thrombus burden (LTB), defined as thrombus burden > or =2 vessel diameters, and small thrombus burden (STB) to predict clinical outcomes. Major adverse cardiac events (MACE) were defined as death, repeat myocardial infarction, and IRA reintervention.

RESULTS

Mean duration of follow-up was 18.2 +/- 7.8 months. Large thrombus burden was an independent predictor of mortality (hazard ratio [HR] 1.76, p = 0.023) and MACE (HR 1.88, p = 0.001). The cumulative angiographic IRA-ST was 1.1% at 30 days and 3.2% at 2 years, and continued to augment beyond 2 years. It was significantly higher in the LTB compared with the STB group (8.2% vs. 1.3% at 2 years, respectively, p < 0.001). Significant independent predictors for IRA-ST were LTB (HR 8.73, p < 0.001), stent thrombosis at presentation (HR 6.24, p = 0.001), bifurcation stenting (HR 4.06, p = 0.002), age (HR 0.55, p = 0.003), and rheolytic thrombectomy (HR 0.11, p = 0.03).

CONCLUSIONS

Large thrombus burden is an independent predictor of MACE and IRA-ST in patients treated with DES for STEMI.

Coronary dilatation 10 weeks after paclitaxel-eluting stent implantation. No role of shear stress in lumen enlargement?

We report a patient with coronary dilatation 10 weeks after paclitaxel-eluting stent implantation in the right coronary artery (RCA). Coronary angiography demonstrated a double-locular lumen dilatation in the body of the stented segment of the RCA, and intravascular ultrasound interrogation revealed the corresponding region with evidence of tissue regression behind the stent struts, incomplete stent apposition, and lumen enlargement. After three-dimensionally (3D) reconstructing the RCA, we applied computational fluid dynamics to the 3D RCA model, representing the lumen of the artery at the moment of stent implantation, and investigated the correlation of both neointimal thickness and tissue regression depth with shear stress in the stent. Neointimal thickness was found to be inversely related to shear stress, but there was no significant association of tissue regression depth with shear stress. Post-procedural stent malapposition, thrombus dissolution, and less possibly, a localized hypersensitivity reaction are potential mechanisms for the lumen enlargement in this case.

Incomplete Stent Apposition and Very Late Stent Thrombosis After Drug-Eluting Stent Implantation

Background— Stent thrombosis may occur late after drug-eluting stent (DES) implantation, and its cause remains unknown. The present study investigated differences of the stented segment between patients with and without very late stent thrombosis with the use of intravascular ultrasound.

Methods and Results— Since January 2004, patients presenting with very late stent thrombosis (>1 year) after DES implantation underwent intravascular ultrasound. Findings in patients with very late stent thrombosis were compared with intravascular ultrasound routinely obtained 8 months after DES implantation in 144 control patients, who did not experience stent thrombosis for ≥2 years. Very late stent thrombosis was encountered in 13 patients at a mean of 630±166 days after DES implantation. Compared with DES controls, patients with very late stent thrombosis had longer lesions (23.9±16.0 versus 13.3±7.9 mm; P <0.001) and stents (34.6±22.4 versus 18.6±9.5 mm; P <0.001), more stents per lesion (1.6±0.9 versus 1.1±0.4; P <0.001), and stent overlap (39% versus 8%; P <0.001). Vessel cross-sectional area was similar for the reference segment (cross-sectional area of the external elastic membrane: 18.9±6.9 versus 20.4±7.2 mm 2 ; P =0.46) but significantly larger for the in-stent segment (28.6±11.9 versus 20.1±6.7 mm 2 ; P =0.03) in very late stent thrombosis patients compared with DES controls. Incomplete stent apposition was more frequent (77% versus 12%; P <0.001) and maximal incomplete stent apposition area was larger (8.3±7.5 versus 4.0±3.8 mm 2 ; P =0.03) in patients with very late stent thrombosis compared with controls.

Conclusions— Incomplete stent apposition is highly prevalent in patients with very late stent thrombosis after DES implantation, suggesting a role in the pathogenesis of this adverse event.

Does Free Cell Area Influence the Outcome in Carotid Artery Stenting?

OBJECTIVES

To identify if carotid stent design, especially free cell area, impacts on the 30-day rates for stroke, death and TIA after carotid artery stenting (CAS).

MATERIAL AND METHODS

A CAS database of 3179 consecutive CAS patients was retrospectively assessed. The distribution of neurological complications were analysed for association with the different stent types and designs. Events where subdivided into procedural and postprocedural events.

RESULTS

The overall combined rate of TIA, stroke and death was 2.8% at 30 days (late events 1.9%). The post-procedural event rate analyzed for differences stents varied from 1.2% using BSCI Carotid Wallstent to 5.9% using Medtronic Exponent. The late event rates varied from 1.2% to 3.4% for free cell areas <2.5mm(2) and >7.5mm(2) respectively (p<0.05). Post-procedural event rate was 1.3% for closed cells and 3.4% for open cells. All these differences were highly pronounced among symptomatic patients (p<0.0001).

CONCLUSIONS

After carotid stenting, complication rates vary according to stent type, free cell area and cell design. In the symptomatic population (and also in the total population), post-procedural complication rates are highest for the open cell types and increase with larger free cell area.

Comparison of the incidence of acute coronary event after balloon angioplasty vs. stenting in native coronary arteries

OBJECTIVES

We sought to determine the incidence of acute coronary events after coronary stenting in comparison to that after plain old balloon angioplasty (POBA).

BACKGROUND

Although coronary stenting is proven to be effective in reducing the incidence of restenosis, the long-term outcome in terms of acute coronary events has not been clarified.

METHODS

Study subjects were 1,507 patients with 2,780 native coronary artery lesions treated by POBA (n=1,400) or stenting (n=1,380). Lesion stabilization, which was defined as freedom from restenosis confirmed by follow-up angiography 3 months after POBA and 6 months after stenting, was achieved in all subjects. All patients were clinically monitored for symptoms for at least 1 year after angioplasty, and the incidence of angiographically confirmed acute coronary event was compared between groups.

RESULTS

The clinical follow-up period was significantly longer in the POBA group than in the stent group (8.4 +/- 5.0 years vs. 5.9 +/- 3.0 years, p<0.0001). Acute coronary events occurred in association with 32 lesions (1.2% overall); the incidence was 1.1% (15 of 1,400) after POBA and 1.2% (17 of 1,380) after stenting. Freedom from acute coronary events related to the treated lesions was similar between the two groups. (p=0.0518 by log-rank test).

CONCLUSION

In terms of acute coronary events, the long-term clinical outcome of stenting is equivalent to that of POBA.

Do device characteristics impact outcome in carotid artery stenting?

OBJECTIVES

The study was conducted to identify patient and procedural parameters that negatively impact the 30-day rates for stroke, death and transient ischemic attack (TIA) after carotid artery stenting (CAS) and that might be modified or further studied in future efforts to improve CAS.

METHODS

This was a retrospective investigation of a dual-center CAS database of 701 consecutive CAS patients (414 men; mean age, 72.4 +/- 8.4). A subset of patient-related, lesion-related, or procedure-related variables (age >or=80, left sided lesion, symptomatic, nicotine abuse, hypertension, diabetes mellitus, other peripheral vascular disease, hypercholesterolemia, embolic protection devices usage, predilation, ulcerated lesion, echolucent plaque, restenosis after surgery) were analyzed for association with occurrence of stroke, death, or TIA <or=30 days after CAS. The odds ratio (OR) and 95% confidence interval (CI) and P value were calculated for each variable to predict adverse outcome.

RESULTS

The overall combined rate of stroke, death, and TIA within this database was 3.7% at 30 days. In the total population of 701 patients, only the OR of 2.7 for hypercholesterolemia (95% CI, 1.0 to 7.3; P = .041) was found to be significant. Subgroup analysis of the 304 symptomatic patients (43%) showed that open-cell stent designs and concentric EPD designs yielded an OR of 4.1 (95% CI, 1.4 to 12, P = .0136) and 3.3 (95% CI, 1.016 to 10, P = .0525), respectively, for 30-day stroke/death/TIA within this database. Analysis of open-cell stent designs and concentric EPD designs in patients with echolucent lesions yielded an OR of 3.1 (95% CI,1.2 to 8.2, P = .0343) and 3.7 (95% CI, 1.3 to 10, P = .0174), respectively, for 30-day stroke/death/TIA.

CONCLUSIONS

We conclude that increased analysis of device design variables may be necessary. Particularly in symptomatic patients or with echolucent lesions, closed-cell design and eccentric filters seem superior. Prospective investigation comparing open-cell vs closed-cell stents and eccentric vs concentric filter devices may be warranted.

Outcome after acute incomplete sirolimus-eluting stent apposition as assessed by serial intravascular ultrasound

We investigated the fate of postprocedural incomplete stent apposition (ISA) after sirolimus-eluting stent (SES) implantation by evaluating long-term intravascular ultrasound findings in 168 consecutive patients (182 de novo lesions). Postprocedural ISA was defined as > or = 1 stent strut that was clearly separated from the vessel wall with evidence of blood speckle behind the strut without overlapping a side branch. After SES implantation, there were 61 ISA sites in 46 stents in 31 patients (23 at the proximal edge, 7 at the distal edge, and 31 within the stent body). There were no clinical, procedural, or intravascular ultrasound measurement differences between patients and lesions with versus without ISA. At follow-up, 15 acute ISA sites (25%) in 11 patients completely resolved and 40 sites (75%) in 20 patients persisted, although 32 of 46 persisting ISA sites (70%) decreased. There was a greater decrease in effective lumen area and a greater increase in peristent plaque area in the complete-resolution group than in the persistent-ISA group. No lesion developed stent thrombosis or in-stent restenosis (angiographic diameter stenosis > 50%). Six acute ISA sites were also associated with new, late acquired ISA, only 1 of which resulted in aneurysm formation. Although most ISAs after SES implantation do not resolve completely, the incidence of restenosis or thrombosis is not affected.