Polymer-Coated Stent Shows Promise in First Test


HOLLYWOOD, FLA. — A new type of polymer-coated coronary stent was safe and effective during 6 months of follow-up in the first 37 patients to receive the stent when tested at a single center in Italy.

Perhaps the most notable finding from this initial clinical study was that, after 6 months, binary restenosis occurred in three patients (8%) and there were no cases of stent thrombosis even though all patients received dual-antiplatelet therapy for only 1 month, Dr. Corrado Tamburino reported at ISET 2008, an international symposium on endovascular therapy. In addition, the initial patients included 20% with type C coronary lesions (70% had type B lesions and 10% had type A lesions), and a third of the patients had diabetes.

In contrast, most series with drug-eluting coronary stents have placed patients on longer treatment with dual-antiplatelet therapy (aspirin plus a thienopyridine, either clopidogrel or ticlopidine), and usually some patients who receive drug-eluting coronary stents develop stent thrombosis.

The new stent, called CATANIA, does not contain or release any drug. Instead, the cobalt-chromium alloy stent is coated with a very thin, 40-nm layer of a polymer, Polyzene-F, which is believed to have novel physiologic properties including a substantially reduced capacity to trigger blood clots, intimal hyperplasia, and restenosis, said Dr. Tamburino, professor and chairman of cardiology at the University of Catania (Italy).

“Neointimal hyperplasia is prevented by preventing inflammation,” commented Dr. Goetz M. Richter, a professor of radiology at the University of Heidelberg, Mannheim, Germany, who conducted several animal studies using the new, polymer-coated stent. Animal-study results also showed that the thin polymer coating is very stable following implantation.

The study enrolled 55 patients who underwent a percutaneous coronary intervention to treat myocardial ischemia. Their average age was 58 years, and 63% had unstable angina. The 55 patients underwent treatment on a total of 76 lesions using 89 stents. The average diameter of the treated arteries was 2.9 mm, and the average stent length used was 17 mm. The average number of stents placed in each patient was 1.4. Patients were placed on chronic aspirin treatment and received thienopyridine treatment for 1 month. The choice between treatment with clopidogrel or ticlopidine was based on the reimbursement rules of each patient's medical insurer.

One patient abruptly stopped aspirin treatment 1 day after hospital discharge, and another patient abruptly stopped aspirin and ticlopidine 2 weeks after stent placement.

At the time of Dr. Tamburino's report, 6-month follow-up data were available on 37 patients who were treated with 52 stents. This subgroup had no deaths, myocardial infarctions, or thrombotic events. The average late loss within treated coronary vessels was 0.5 mm, a rate comparable to what's been seen with various drug-eluting stents, he said. Neointimal hyperplasia occurred in 26%, and target lesion revascularization was needed for seven patients (19%), including the three patients with binary restenosis. Revascularization was done electively in four patients without binary restenosis based on the appearance of their treated artery after 6 months by quantitative coronary angiography. No binary restenosis occurred in coronary vessels wider than 2.5 mm, and five of the seven cases of lesion revascularization were in vessels less than 2.5 mm wide.

Further testing of the polymer-coated stent in patients is planned. The study was sponsored by CeloNova BioSciences Inc., which is developing the new stent. Dr. Tamburino has no financial relationship with CeloNova aside from receiving research support.

There were no cases of stent thrombosis even though all patients received dual-antiplatelet therapy for only 1 month. DR. TAMBURINO

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