Comparison of three coronary stents: clinical and angiographic outcome after elective placement in 134 consecutive patients

Comparison of a silicon carbide coated stent versus a noncoated stent in humans: the Tenax- versus Nir-Stent Study (TENISS)

PURPOSE

Stents coated with hypothrombogenic silicon carbide (a-SiC:H) exhibited low restenosis rates in the rabbit and in an observational study in humans. Thus, the clinical and angiographic outcome was assessed in a large multicenter study.

MATERIAL AND METHODS

Four hundred and ninety-seven patients (63.4 +/- 9.8 years) were randomized to either receive the a-SiC:H-coated Tenax stent or the stainless steel Nir stent. Lesions (diameter > or = 2.8 mm, length < 20 mm) were covered with one single stent.

RESULTS

Fifty-one of 497 (10.3%) patients were excluded for protocol violation. Three hundred and forty-two of 446 (76.7%) patients presented for scheduled angiographic follow-up after 4.7 +/- 1.2 months and 29 of 446 (6.5%) prematurely. In-hospital complications comprised two deaths (0.8%) (P > 0.99) and one (0.4%) (P > 0.99) CK-elevation in each group, target lesion revascularization in 5 of 250 (2%) of the Tenax and 4 of 244 (1.6%) of the Nir sample (P > 0.99), and subacute thrombosis in 2 of 250 (0.8%) of the Tenax patients (P = 0.5). In the Tenax/Nir patients mean percent diameter stenosis decreased from 82.3 +/- 9.1%/80.7 +/- 8.4% (P = 0.49) to 17.6 +/- 5.5%/17.6 +/- 5.5% (P = 0.99) postprocedure and increased to 34.5 +/- 21.5%/34.2 +/- 23.1% (P = 0.90) at follow-up.

CONCLUSIONS

Thus, there appears to be no advantage of the silicon carbide coated stent over a stainless steel stent after 4.7 +/- 1.2 months with regard to clinical and angiographic restenosis rates.

Randomized comparison of the coil-design Crossflex and the tubular NIR stent

The purpose of this study was to compare the angiographic outcome of implantation of the coil-design Crossflex stent with the tubular NIR stent for treatment of coronary artery stenoses. Two hundred twenty-three patients with one genuine coronary artery lesion were randomized to implantation with a 15 mm Crossflex stent (n = 112) or a 16 mm NIR stent (n = 111). The patients had angiographic follow-up after 6 months. Primary endpoint was minimal luminal diameter (MLD) after 6 months. There was a similar clinical outcome in the two groups. At 6-month follow-up, the MLD was significantly lower in the Crossflex group (1.94 +/- 0.79 mm) than in the NIR group (2.37 +/- 0.84 mm; P < 0.001). Early gain was the same in the two groups. Late loss and percent diameter stenoses were significantly higher in the Crossflex group. The binary restenoses rate was 26% and 17% in the Crossflex and the NIR groups, respectively (P = NS). The coil-design Crossflex stent was found to be inferior to the tubular NIR stent concerning late loss and MLD at 6-month follow-up.

Restenosis rates with flexible GFX stents (REFLEX): clinical and angiographic results

The objective of this prospective, multicenter, observational trial was to evaluate the procedural results and longterm outcomes of the flexible AVE GFX coronary stent in native coronary lesions. The trial included 137 consecutive patients (111 [81%] men, age 63.1 +/- 9.2 years) with one vessel disease (n = 76 [55.5%]), two vessel disease (n = 31 [22.6%]), and three vessel disease (n = 30 [21.9%]) with ischemia secondary to a significant denovo lesion (diameter > or = 3 mm, length < or = 18 mm) in a native coronary artery. Stent deployment was successful in 97.8% (134/137) of patients. Angiographic follow-up at 6.1 +/- 1.2 months was available in 111 (82.8%) of 134 patients. All angiographic images were analyzed by an independent core lab. The primary end point was the binary restenosis rate. In-hospital major cardiac events occurred in 3.7%. No postdischarge major adverse cardiac events occurred, except for one abrupt closure (0.7%). Angiographic restenosis was documented in 22 (19.8%) of 111 patients. The GFX stent is easy to handle with high success and low restenosis rates in patients with simple lesions in native coronary arteries and, thus, compares favorably with other sophisticated stents.

[In hospital and mid-term outcome of patients with NIR stent implantation: multicenter ESPORT-NIR registry]

BACKGROUND AND OBJECTIVE

Despite improvements in the results and techniques of catheter-based revascularization, few studies have evaluated the clinical results of the application of new stent designs. We describe the in-hospital and mid-term outcome of patients undergoing a stent NIR implantation.

PATIENTS AND METHOD

At least 1 Stent NIR was implanted in 1.004 patients (1.136 lesions) recruited from 50 centers in an international, multicenter, prospective, registry (Spain and Portugal NIR stent registry). Inclusion criteria were objective coronary ischemia related to a severe de novo lesion or first restenosis in native vessels with a reference diameter >= 2.75 mm. The primary end-point was the incidence of major adverse cardiac events within the first 7 months of follow-up.

RESULTS

The mean age of the patients was 60 years and 82% were male. Angioplasty was indicated due to unstable angina in 61% of the cases. Stent implantation was successfully achieved in 99.6%. Clinical success (angiographic success without in-hospital major events) was achieved in 98.6% of patients. The rate of angiographic restenosis (> 50% stenosis narrowing) was 16% (CI 95%; 11.7-21.2). The accumulated major cardiac adverse event rate at seven months of follow-up was 8.7%: death (0.9%), acute myocardial infarction (1.2%) and target lesion revascularization (6.6%).

CONCLUSION

In the wide setting of the population included in the ESPORT-NIR registry, stent NIR implantation was a highly effective therapy with a good mid-term clinical and angiographic outcome.

Multilink Stent Promotes Less Platelet and Leukocyte Adhesion Than a Traditional Stainless Steel Stent

BACKGROUND

Platelet and leukocyte deposition onto metallic struts can be a crucial factor in the outcome of a coronary stenting procedure. By means of an in vitro, closed-loop circulation model, we aimed to assess blood-stent interaction patterns for a new stainless steel stent (MultiLink, Guidant Nederland BV, Nieuwegein, the Netherlands).

METHODS

The effect of MultiLink (n=20) on blood cells and blood activation was studied by biochemical assays. Platelet and leukocyte adhesion to MultiLink were studied by immunofluorocytometric assays (anti-GpIIIa [CD 61] and anti-CD11b labeled antibodies, respectively), and by scanning electron microscopy. MultiLink was compared with empty circuits (n=20) and to the Palmaz Schatz stent (n=20). Experiments were performed both in the presence and in the absence of an antiplatelet agent (15 microg/mL of indomethacin).

RESULTS

No significant effect on blood cells and blood activation was demonstrated for MultiLink. Antiplatelet treatment significantly reduced platelet adhesion to MultiLink (from 3.78+/-1.28 to 2.23+/-0.57 x 10(6) count per second [cps]/stent) but not to the Palmaz Schatz stent (from 4.11+/-0.31 to 5.02+/-1.29 x 10(6) cps/stent)(P=0.011). Leukocyte adhesion to MultiLink was significantly less than adhesion to the Palmaz Schatz stent (7.95+/-1.59 vs. 9.16+/-1.36 x 10(6) cps/stent, respectively; P=0.016), regardless of the presence of antiplatelet treatment.

CONCLUSIONS

When compared with a traditional stainless steel stent, MultiLink seems to have features of improved hemocompatibility, and single antiplatelet treatment is proposed as the treatment of choice to prevent platelet deposition.

Limited balloon expansion through the struts of the Palmaz-Schatz and NIR stents compared with the Multi-Link stent

After placing a stent in the main vessel of a bifurcation lesion, it is sometimes necessary to perform further balloon inflation in order to treat an ostial lesion in a side branch. The stent struts may prevent full balloon expansion at the ostium of a side branch, resulting in residual ostial stenosis. The degree of completeness of balloon inflation may vary significantly depending on the stent design and structure. A model of a bifurcation lesion with an angle of 45 degrees was created from acrylic resin. The diameters of the main vessel and the side branch were both 3.5 mm. Deployment of the Palmaz-Schatz stent (n=5), NIR stent (n=5) or Multi-Link stent (n=5) was performed in the main vessel with a 3.5-mm balloon catheter inflated to 12 atm. A 3.5-mm balloon catheter was then inflated to 12 atm through the stent struts of the main vessel and into the ostium of the side branch. The degree of completeness of balloon inflation (% balloon expansion) was calculated as (smallest diameter of balloon catheter/reference diameter of balloon catheter) x 100%. The minimal lumen diameter (MLD) and cross-sectional area (CSA) at the ostium of the side branch created with the stent struts were also measured. Limited balloon expansion through the struts was observed with the Palmaz-Schatz stent and the NIR stent, but almost full balloon expansion was observed with the Multi-Link stent (% balloon expansion: Palmaz-Schatz stent 80%, NIR stent 60%, Multi-Link stent 94%, p<0.01). The MLD and CSA of the dilated struts, representing the ostium of the side branch, of the Palmaz-Schatz stent (2.2+/-0.1 mm, 4.5+/-0.3 mm2) and the NIR stent (1.8+/-0.1 mm, 3.1+/-0.3 mm2) were significantly smaller compared with those of the Multi-Link stent (3.0+/-0.2 mm, 8.4+/-0.6 mm2) (p<0.01). The struts of the Palmaz-Schatz stent and the NIR stent deployed in the main vessel of a bifurcation prevent full expansion of a balloon catheter inflated at the side branch ostium. In contrast, almost full balloon expansion through the struts of the Multi-Link stent is achieved.

Angiographic and clinical outcome of a new self-expanding intracoronary stent (RADIUS): results from multicenter experience in Japan

The RADIUS coronary stent featuring a multisegmented slotted tube design and self-expanding nitinol delivery system has a high radial force and flexibility, uniform expansion, and contours to the shape of the vessel. Successful stent deployment was achieved in 104 stable angina patients (106 lesions; 44% LAD, 19% circumflex, and 37% RCA). Mean minimal lumen diameter (MLD) increased from 0.77 +/- 0.46 mm to 2.88 +/- 0.61 mm and mean percent diameter stenosis (% DS) decreased from 73 +/- 14% to 6 +/- 13% immediately after the procedure. At 6-month follow-up, two patients (2%) underwent urgent target revascularization, and cerebral bleeding occurred in one patient (1%). Angiographic follow-up was performed in 94 lesions (89%) and mean MLD and mean % DS were 2.08 +/- 0.92 mm and 30% +/- 24%, respectively. Stent restenosis (>50% diameter stenosis at follow-up) was observed in 16 (17%) of all lesions. The high success rate for stent deployment, low incidence of major adverse cardiac event, and lower restenosis rate after stent implantation indicate that the RADIUS stent is useful for coronary intervention.

Difference in security of stent jail between Palmaz-Schatz, NIR, and Multi-Link stents: the effect of balloon inflation through stent struts

After placing a stent in the main vessel of a bifurcation lesion, it is often necessary to perform further balloon inflation or stent placement through the stent struts in order to treat a lesion of the secondary vessel or side branch. This balloon inflation with dilatation through the cells of the stent in the main vessel results in stent strut disfigurement. This disfigurement causes various degrees of stenosis within the main vessel secondary to stent strut deformity. The degree of strut deformity, and therefore stenosis, may vary significantly depending on stent design and structure. A model of a bifurcation lesion with an angle of 45 degrees was created from acrylic resin. The diameters of the main vessel and the secondary vessel were both 3.5 mm. Deployment of the Palmaz-Schatz stent (PS, n = 5), NIR stent (n = 5), or Multi-Link stent (n = 5) was performed in the main vessel with a 3.5-mm balloon catheter inflated to 6 atm. A second 3.5-mm balloon catheter was then inflated to 6 atm through the stent struts of the main vessel and into the ostium of the secondary vessel. The minimal lumen diameter (MLD) and cross-sectional area (CSA) at the ostium of the side branch and the stenosis within the main vessel were then measured, taking into account the stent deformity that occurred. Kissing balloon dilatation with two 3.5-mm balloon catheters was then performed and the stenosis secondary to stent deformity in the main vessel was remeasured. The MLD of the Multi-Link stent at the side-branch ostium was greater compared with those of the Palmaz-Schatz stent or the NIR stent (2.4 +/- 0.1, 1.6 +/- 0.1, 1.7 +/- 0.1 mm, P < 0.01) and CSA (4.9 +/- 0.5, 2.7 +/- 0.3, 2.5 +/- 0.3 mm(2), P < 0.01). Balloon inflation through the stent struts caused stent deformity that resulted in some degree of stenosis within the stent of the main vessel in all three stent types. Kissing balloon inflation reduced, but never eliminated, this stenosis. The percent stenosis in the main vessel secondary to stent deformity (PS 34% +/- 9%, NIR 25% +/- 8%, Multi-Link 34% +/- 7%, NS) and residual stenosis postkissing balloon inflation (PS 12% +/- 1%, NIR 10% +/- 3%, Multi-Link 14% +/- 3%, NS) were not significantly different among these three stents. At the side-branch ostium, the MLD and CSA were significantly greater for the Multi-Link stent compared with those of the Palmaz-Schatz or NIR stent. Balloon inflation through the stent struts caused stent deformity that resulted in stenosis within the stent in the main vessel. Kissing balloon inflation reduced this stenosis, but some residual stenosis always remained. The stenoses within the main vessel did not differ among the three stent types. Cathet. Cardiovasc. Intervent. 48:230-234, 1999.

Effect of stent design on reduction of elastic recoil: a comparison via quantitative intravascular ultrasound

The increase in minimum lumen diameter achieved by coronary stent placement can be further enhanced by reducing the immediate recoil that occurs after stent deployment. The effect of various stent designs-flexible coils, slotted tubes, and a locking stent-on minimization of postdilation stent recoil was evaluated using an in vitro model of circumferential compression. The stents were expanded to 7 atm (3.82 +/- 0.02 mm); as pressure was reduced, lumen diameter and cross-sectional area (CSA) were determined by on-line intravascular ultrasound imaging (30 MHz) positioned inside the dilating balloon (n = 10-15 inflation-deflation cycles). Stent recoil was assessed by calculation of percent change in CSA from 7 atm to negative balloon pressure: -33.1 +/- 5.6% (GR-II) and -22.4 +/- 3.8% (Wiktor) in the coil stents; -20.0 +/- 4.2% (JJIS coronary), -8.4 +/- 2.6% (JJIS biliary), and -6.9 +/- 1.5% (Multilink) in the slotted tube stents; and -1.9 +/- 3.2% in the Navius ZR1 locking stent (P < 0.05 vs. Multilink, P < 0.0001 vs. others). A range of resistances to recoil is demonstrated by this model, with coil stent designs undergoing greater elastic recoil than slotted tube stent designs. The locking stent design demonstrated the greatest radial strength and the most reduction in elastic recoil.

Coronary artery stenting in unstable angina pectoris: a comparison with stable angina pectoris

OBJECTIVE

To compare early complication rates in unselected cases of coronary artery stenting in patients with stable v unstable angina.

SETTING

Tertiary referral centre.

PATIENTS

390 patients with stable angina pectoris (SAP) and 306 with unstable angina (UAP). Patients treated for acute myocardial infarction (primary angioplasty) or cardiogenic shock were excluded.

INTERVENTIONS

268 coronary stents were attempted in 211 patients (30.3%). Stents used included AVE (63%), Freedom (14%), NIR (7%), Palmaz-Schatz (5%), JO (5%), and Multilink (4%). Intravascular ultrasound was not used in any of the cases. All stented patients were treated with ticlopidine and aspirin together with periprocedural unfractionated heparin.

RESULTS

123 stents were successfully deployed in 99 SAP patients v 132 stents in 103 UAP patients. Failed deployment occurred with nine stents in SAP patients, v four in UAP patients (NS). Stent thrombosis occurred in four SAP patients and 11 UAP patients. Multivariate analysis showed no relation between stent thrombosis and clinical presentation (SAP v UAP), age, sex, target vessel, stent length, or make of stent. Stent thrombosis was associated with small vessel size (p < 0.001) and bailout stenting (p = 0.01) compared with elective stenting and stenting for suboptimal PTCA, with strong trends toward smaller stent diameter (p = 0.052) and number of stents deployed (p = 0.06). Most stent thromboses occurred in vessels < 3 mm diameter.

CONCLUSIONS

Coronary artery stenting in unstable angina is safe in vessels >/= 3 mm diameter, with comparable initial success and stent thrombosis rates to stenting in stable angina.

Failed coronary stent deployment

BACKGROUND

Coronary stent deployment failure may be more common in clinical practice than generally appreciated. The incidence of failed deployment in routine clinical practice and the clinical sequelae have not been described. This study sought to determine the incidence and consequences of failed coronary stent deployment and to identify clinical and angiographic characteristics associated with deployment failure.

METHODS AND RESULTS

A series of 1303 consecutive procedures involving attempted coronary stenting were reviewed retrospectively. Failed stent deployment was defined as failure of the stent to be either delivered to or adequately deployed at the target lesion site. Clinical records and angiograms were reviewed and qualitative coronary angiography was performed for all cases of failed deployment. Deployment was unsuccessful in 108 (8.3%) cases involving 134 stents. Stenting was attempted as a primary procedure in 40%, as bailout in 18%, and for suboptimal angioplasty in 43% of cases. In 87% of cases, attempts were made to withdraw the stent from the coronary artery. Stent retrieval was successful in 45%, peripheral embolization occurred in 38% of patients, and in 4% the stent dislodged in the left main artery. In 35% of cases, additional stent(s) were successfully deployed. Deployment failure was associated with an overall in-hospital adverse outcome in 19% of patients, including 16% urgent coronary artery bypass grafting, 5% nonfatal myocardial infarction, and 3 in-hospital deaths. At 6-month follow-up, 39% of patients had had at least 1 adverse clinical outcome of death, myocardial infarction, or repeat target lesion revascularization.

CONCLUSIONS

Failure to deploy stents is a serious and relatively common problem that is associated with significant morbidity and mortality rates. Improved deployment strategies, including new stent designs, are required to improve procedural outcomes.

Diagnosing coronary arterial stent thrombosis and arterial closure

This single-center review of a consecutive series of patients requiring reexamination by angiography within 1 week of a coronary stent placement due to chest pain reveals that patients treated with a poststent anticoagulation regimen of warfarin and aspirin, and those with lower poststent deployment dilation pressures, have an increased risk of subacute stent thrombosis. Repeat cardiac catheterization within the first week after coronary artery stent implantation should be reserved for patients with significant electrocardiographic changes.

Micro stent implantation in patients with acute myocardial infarction without anticoagulation: clinical experience with two different antithrombotic protocols

The 4-week outcome following Micro stent implantation for acute myocardial infarction was assessed with the use of two different antithrombotic regimens. The patients were postprocedurally treated with acetyl salicylic acid (ASA) and heparin for 24-48 h (Group I; n = 52), or ASA and ticlopidine plus abciximab if indicated (Group II; n = 52). Stent implantation was successful in 49 patients (94%) of group I and in 46 patients (89%) of group II (NS). Subacute stent thrombosis occurred in nine patients (17%) of group I and in 1 patient (2%) of group II (P < 0.05). There were no significant differences in the rates of mortality, coronary bypass operation, or vascular complications. Micro stent implantation in acute myocardial infarction is highly effective and associated with a low risk for subacute stent thrombosis if the patients are postprocedurally treated with ASA and ticlopidine plus abciximab if indicated.

Intracoronary stent implantation in native coronary arteries and saphenous vein grafts: a consecutive experience with six types of stents without prolonged anticoagulation

OBJECTIVE

To analyze the results of implantation of six different intracoronary stents without the use of prolonged anticoagulation.

MATERIAL AND METHODS

Between Mar. 30, 1993, and Jun. 30, 1995, 889 patients with 1,194 coronary or vein graft lesions underwent implantation of one of six types of stents-Palmaz-Schatz, Gianturco-Roubin, Wiktor, Micro, Cordis, or Wallstent. The patients were classified into seven groups on the basis of the type of stent that was implanted, including one group with combined use of two or more types of stents. Among the 851 patients with successful stent delivery and without major complications, 801 received only antiplatelet therapy, and 50 received a standard anticoagulation regimen. One-month clinical followup data were obtained in all patients, and clinical events were investigated.

RESULTS

The mean number of stents was 1.8 per lesion and 2.4 per patient. Procedural success was achieved in 93% of the lesions. The clinical success rate at 1 month was 90%. Intravascular ultrasound assessment was performed in 90% of the lesions. The final minimal luminal cross-sectional area of the stent increased from 6.8 to 7.8 mm2 after intravascular ultrasound-guided optimization. Within 1 month, 16 stent thrombosis events (1.9%) occurred. No significant differences were noted in stent thrombosis rates among the various stent cohorts. Multivariate logistic regression analysis revealed that the final stent minimal luminal diameter measured by intravascular ultrasonography was the only variable associated with stent thrombosis.

CONCLUSION

This study showed that six different stents could possibly be inserted without subsequent anticoagulation if optimal stent expansion and total lesion coverage were achieved.

Contemporary stent designs: technical considerations, complications, role of intravascular ultrasound, and anticoagulation therapy

A number of studies have shown the benefits of stent placement over balloon angioplasty for the treatment of focal, native coronary artery, and saphenous vein graft disease. Although the number of stent designs available for clinical use has increased dramatically, the late clinical benefit of stenting over balloon angioplasty has yet to be shown in diffuse disease, complex bifurcation stenoses, or smaller (2.5-mm) vessels, each of which may require unique stent designs and adjunct therapies not currently available or extensively studied. The purposes of this review are to discuss the various stent designs currently available for clinical use, outline the known complications associated with these stents, assess the contribution of intravascular ultrasound, and describe current antiplatelet and antithrombotic therapy used after stent use.

Subacute stent thrombosis: evolving issues and current concepts

During percutaneous coronary revascularization, intracoronary stents are effective in the treatment of abrupt vessel closure and improvement of suboptimal angioplasty results, and compared to balloon angioplasty, they reduce stenosis recurrence. Opposing these benefits, subacute thrombosis of stents is associated with a substantial increase in periprocedural morbidity and mortality. To review factors associated with stent thrombosis and to study the impact of evolving procedural techniques on the incidence of stent thrombosis, we reviewed all English articles from MEDLINE (1988 to 1995) with key words "stent" and "thrombosis." Stent registry data and recent abstracts from scientific meetings were also reviewed. Factors related to the clinical setting, the lesion, the stent and the procedural technique that affect the risk of stent thrombosis were identified. Sixty clinical studies were reviewed and include 7,914 patients receiving intracoronary stents. Studies were separated into those reporting stents placed emergently or electively without adjunct high-pressure balloon inflations, stents placed in saphenous vein graft conduits, and stents placed with high-pressure balloon inflations but without subsequent oral anticoagulants. Overall, subacute thrombosis was substantially higher in stents placed emergently (10.1%) compared to those placed electively (4.3%). Among contemporary trials employing high-pressure balloon inflations, the rate of stent thrombosis appears markedly lower (1.3%) despite reduced postprocedural anticoagulation. Taken together, these studies suggest factors associated with a heightened risk of stent thrombosis, many of which can be avoided with proper case selection and contemporary techniques.