Coronary stenting (Cordis) without anticoagulation

Zotarolimus (ABT-578) eluting stents

Drug-eluting stents have revolutionized the field of interventional cardiology and have provided a significant innovation for preventing coronary artery restenosis. Polymer coatings that deliver anti-proliferative drugs to the vessel wall are key components of these revolutionary medical devices. This article focuses on the development of stents which elute the potent anti-proliferative agent, zotarolimus, from a synthetic phosphorylcholine-based polymer known for its biocompatible profile. Zotarolimus is the first drug developed specifically for local delivery from stents for the prevention of restenosis and has been tested extensively to support this indication. Clinical experience with the PC polymer is also extensive, since more than 120,000 patients have been implanted to date with stents containing this non-thrombogenic coating. This review provides background on pre-clinical studies with zotarolimus, on the development of the biocompatible PC polymer and on the clinical trials conducted using two stent platforms which deliver this drug to patients with coronary artery disease.

Material-specific thrombin generation following contact between metal surfaces and whole blood

Little is known about the blood compatibility of metals used in various medical devices. We have previously shown that titanium and derivatives thereof are among the most thrombogenic materials which may explain its outstanding osteointegrating properties. The aim of the present study was to characterize the thrombogenic and complement-activating properties of various metals used today in medical applications. Polyester chips were coated with 50- to 100-nm thick layers of aluminium, iridium, indium, nickel, tantalum, tin, titanium, or zirconium using magnetron sputtering. The metal-coated chips were then incubated in direct contact with whole blood in an in vitro chamber model, and the blood was then analyzed for platelet counts, thrombin-antithrombin (AT), fXIIa-AT, fXIa-AT and fXIIa-C1INH complexes and the complement parameters C3a and sC5b-9. Titanium, tantalum and indium were found to exhibit pronounced thrombogenic properties, whereas aluminium, nickel and, in particular, iridium were essentially non-thrombogenic. Tin and zirconium were intermediate activators. All metals activated complement to a similar degree, with the exception of aluminium, which had more pronounced activating properties. This study clearly indicates that metals indeed have varying thrombogenic and complement activating properties. These studies have implications for the selection of metals intended for medical applications.

Ticlopidine versus oral anticoagulation for coronary stenting

BACKGROUND

A 2-4 week course of ticlopidine plus aspirin following coronary stenting is considered effective in preventing thrombotic occlusion of the stented vessel and safe in regards to bleeding and peripheral vascular complications. However, rare, although potentially life-threatening haematological complications have been reported with this drug regimen.

OBJECTIVES

To evaluate the efficacy and safety of ticlopidine plus aspirin versus oral anticoagulants after coronary stenting

SEARCH STRATEGY

Electronic search of the Cochrane Library, Medline, Embase from 1991 to June 1999; references from trials and experts.

SELECTION CRITERIA

Randomised controlled trials comparing ticlopidine plus aspirin versus oral anticoagulants (either with or without aspirin) after elective or bail out coronary stenting.

DATA COLLECTION AND ANALYSIS

Three reviewers assessed trial quality and compiled data on outcomes including: total mortality, non fatal myocardial infarction and revascularization occurring within the first 30 days after hospitalization, stent thrombosis on angiography, major and minor bleeding, neutropenia, thrombocytopenia, thrombotic thrombocytopenic purpura.

MAIN RESULTS

Four trials (n=2436 patients) were included. Ticlopidine plus aspirin compared to oral anticoagulants significantly reduced the risk of non-fatal acute myocardial infarction and revascularization at 30 days, combined negative events (mortality, myocardial infarction, revascularization at 30 days) (RR: 0.41; 95% CI: 0.25-0.69; NNT for 30 days: 22; 95% CI: 14-45), and major bleeding (RR in high quality studies: 0.24; 95% CI: 0.07-0.79). Ticlopidine plus aspirin compared to oral anticoagulants significantly increased the risk of eutropenia, thrombocytopenia and neutropenia (RR 5; 95% CI: 1.08-13.07; NNT for 30 days: 142; 95% CI: 76-1000). Ticlopidine plus aspirin vs oral anticoagulation did not affect all cause mortality. Ticlopidine plus aspirin significantly reduced the risk of stent thrombosis (angiography) which was seen only on studies with blinded outcome assessment (RR: 0.14; 95% CI: 0.03-0.60; NNT for 30 days: 33; 95% CI:16-166). Minor bleeding was reported only in one study and no studies recorded thrombotic thrombocytopenic purpura (TTP).

REVIEWER'S CONCLUSIONS

Ticlopidine plus aspirin after coronary stenting is effective in reducing the risk of the revascularization, non fatal myocardial infarction and bleeding complications when compared with oral anticoagulants. No effect is observed on total mortality. However, the haematological side effects of ticlopidine are still a matter of concern, and strict monitoring of blood-cell counts is recommended. Physicians should also be aware of the possibility of rare although potentially life-threatening complications such as TTP

Multivessel coronary stenting versus bypass surgery in patients with multivessel coronary artery disease and normal left ventricular function: immediate and 2-year long-term follow-up

BACKGROUND

Compared with coronary artery bypass surgery (CABG), the clinical benefits of intracoronary stenting have not been established in patients with multivessel coronary lesions.

METHODS AND RESULTS

To compare the clinical outcomes of intracoronary stenting with that of CABG, we reviewed the outcomes of patients with multivessel coronary artery disease from an observational database. Two hundred consecutive patients with multivessel coronary artery disease and normal left ventricular function were evaluated. In 200 patients, multivessel stenting was performed in 100 and CABG was performed in 100. Complete revascularization was achieved in 95% in the CABG group and in 69% in the stent group (P <.05). The duration of total hospital stay and coronary care unit admission was significantly shorter in the stent group (P <.05). The long-term survival was similar between the 2 groups. There were no significant differences of cardiac events between the 2 groups except for the recurrence of angina (19% in stenting vs 8% in CABG, P =.03) and target lesion revascularization (19% vs 2%, P <.01) in the patients with stents.

CONCLUSIONS

In selected patients with multivessel coronary artery disease and normal left ventricular function, intracoronary stenting may offer an effective alternative to coronary bypass surgery.

Comparison of the efficacy and safety of aspirin alone with coumadin plus aspirin after provisional coronary stenting: final and follow-up results of a randomized study

BACKGROUND

The antithrombotic benefit of the conventional treatment with coumadin after coronary stenting is limited by bleeding complications. However, the superiority of an antiplatelet therapy with aspirin alone compared with coumadin plus aspirin has not been proven by randomized studies. The efficacy and safety of treatment with aspirin alone in comparison to coumadin plus aspirin were evaluated in this randomized study.

METHODS

Out of 164 patients aged 59.7 +/- 9.2 years, 79 patients were randomly assigned to receive 100 mg aspirin daily (group A) and 85 patients randomly assigned to coumadin plus aspirin (group CA) after provisional coronary stenting with a high-pressure technique. The primary end point was defined as the absence of death, subacute closure of the target vessel, myocardial infarction, urgent coronary bypass surgery, repeated coronary angioplasty, and peripheral vascular complications requiring transfusion or surgery. High-pressure inflation technique was used, but ultrasound guidance was not.

RESULTS

During hospitalization (median 8 days), 135 patients (82. 3%) were free of events (A, 84.8%; CA, 80.8%; P =.42). Eleven (6.7%) subacute closures occurred (A, 10.1%; CA, 3.5%; P =.09); 2 of them were lethal in the aspirin group. Emergency bypass surgery was performed in 1 patient in each group. Peripheral vascular complications were observed in 13 patients (7.9%) (A, 1.3%; CA, 14. 1%; P <.01). At 3-month follow-up, 15 (9.1%) elective revascularization procedures (A, 7.6%; CA, 10.6%; P =.51) were performed.

CONCLUSION

Aspirin alone at the low dose of 100 mg administered or the combination of coumadin and aspirin after high-pressure coronary stenting does not prevent adverse clinical events when ultrasound guidance is not used.

Immediate results and late clinical outcomes after new CrossFlex coronary stent implantation

This study evaluates the safety and efficacy of the new CrossFlex stent in the treatment of native coronary artery disease. The CrossFlex stent is a flexible, balloon-expandable new device with an excellent flexibility, radial strength, conformability, and radio-opacity. Little data are available concerning the clinical and angiographic outcomes of this device. The CrossFlex stent was implanted in 209 consecutive patients with 226 lesions. Follow-up angiography was performed at 6 months, and clinical evaluation was undertaken at regular intervals after stent implantation. Procedural success was achieved in all lesions without in-hospital complications. Angiographic follow-up data were available in 153 of the 187 eligible lesions (follow-up rate, 82%), and the overall angiographic restenosis rate was 16.3%. Minimal lumen diameter immediately after stent placement was the only predictor of angiographic restenosis. Clinical follow-up was obtained in all patients at 10.5 +/- 5.2 months. There were 4 deaths (1 cardiac in origin, the others noncardiac in origin), and 1 nonfatal myocardial infarction (nonstented artery) during follow-up. Target lesion revascularization was required in 15 patients (7%), and the overall event-free survival rate (death, myocardial infarction, and repeat revascularization) was 87% at the end of the follow-up period. The CrossFlex stent is a safe and effective device with a high procedural success rate, and a favorable late clinical outcome for treatment of native coronary artery disease. Further randomized trials are needed to compare the CrossFlex stent with standard slotted-tube stents.

Wiktor stent for treatment of chronic total coronary artery occlusions: short- and long-term clinical and angiographic results from a large multicenter experience

OBJECTIVES

This study reports the first multicenter experience with the Wiktor coil stent for treatment of chronic total coronary artery occlusions (CTOs).

BACKGROUND

Percutaneous transluminal coronary angioplasty (PTCA) of CTO is associated with very high restenosis and reocclusion rates. Coronary stenting has been proposed as a means of improving outcome. However, the Wiktor device for CTOs has never been tested in a large patient sample.

METHODS

From January 1993 to December 1996, 89 patients with 91 CTOs underwent Wiktor stent implantation after successful PTCA. The post-stenting regimen consisted of warfarin (Coumadin) plus aspirin in the initial 49 patients (55%) and aspirin plus ticlopidine in 40 patients (45%).

RESULTS

Stenting was successful in 87 patients (98%). At 1 month, 6% of patients had subacute stent thrombosis, 3% had a major bleeding event, and 1% had access-site complications. Subacute stent thrombosis showed univariate association with warfarin therapy (p = 0.009). Angiographic follow-up was obtained in 76 (93%) of 82 eligible patients. The restenosis rate was 32%, including 4% reocclusions. By multiple logistic regression analysis, restenosis was independently associated with multiple stents (adjusted odds ratio [OR] 27.67, 95% confidence interval [CI] 4.25 to 79.95, p = 0.0008) and increasing values of occlusion length (adjusted OR 1.23, 95% CI 1.09 to 1.39, p = 0.001). Freedom from death, myocardial infarction or stented vessel revascularization was 87% and 72% at 1 and 3 years, respectively.

CONCLUSIONS

Short- and long-term clinical and angiographic outcomes are favorable in patients undergoing Wiktor stent implantation in CTO. Further technical improvement is needed to reduce the restenosis rate in patients with long lesions and multiple stents.

Late clinical outcomes of cordis tantalum coronary stenting without anticoagulation

This study was performed to evaluate clinical and angiographic restenosis rates after successful Cordis coronary stent implantation and intravascular ultrasound images were acquired to compare results with quantitative angiographic findings in a subgroup of patients. We conclude that (1) the angiographic restenosis rate of Cordis stent was 19%, which was comparable to that of other slotted-tube stents, and (2) the quantitative coronary angiographic calliper method is reliable for assessing Cordis in-stent restenosis, especially diffuse in-stent restenosis.