CLINICAL TRIALS PRESENTED FOR DRUG-ELUTING STENTS
Discussed by Dr. Hans H. Bauer, MD, FACC
Late-breaking clinical trials presented at the Scientific Session of the 54th Annual Convocation of the American College of Cardiology provided continued evidence of the superiority of drug-eluting stents over bare metal stents, according to Dr. Hans H. Bauer, who attended the convocation in Orlando, Fla.
Several studies presented at the Scientific Session also provided for the first time head-to-head comparisons of two drug-eluting stents, the sirolimus-eluting Cypher stent and the paclitaxel-eluting Taxus stent.
Dr. Bauer also commented on the findings of CLARITY-TIMI 28, a study in which Associated Cardiovascular Consultants participated, which showed the benefits of giving patients with acute myocardial infarction Plavix along with thrombolytic therapy.
Drug-eluting vs. bare metal stents
ARTS II , part two of the Arterial Revascularization Therapies Study, involved a registry of consecutive patients with multi-vessel coronary disease. The patients had implanted an average of 3.7 Cypher stents. The study showed a MACE rate (Major Adverse Cardiac Events) at one year of 10.4 percent. The historical comparison group, patients with bypass surgery in the previous ARTS I study, conducted in 1997 and 1998, had a roughly comparable MACE rate of 11.6 percent.
Dr. Bauer noted, however, that in the earlier study, comparing bare metal stents to coronary artery bypass grafting, stent patients required a higher incidence of repeat procedures. "Now repeat procedures have been reduced from 26.5 percent for bare metal stents to 10.4 percent for drug-eluting stents," he said.
The TAXUS V trial, comparing the outcomes of the use of the drug-eluting Taxus stent versus bare metal stents in patients with complex coronary artery disease, showed a 75-percent decrease in restenosis in the drug-eluting stent group.
Another study, comparing the use of the Cypher stent to bare metal in saphenous vein bypass grafts showed a restenosis rate of 5 percent in the Cypher stent group versus 37 percent in the bare metal group.
Cypher vs. Taxus
REALITY, a randomized study, comparing the sirolimus-eluting Cypher stent and the paclitaxel-eluting Taxus stent, involved 1,386 patients with coronary artery disease. The primary endpoint, restenosis at eight months, showed a strong trend favoring Cypher at 9.6 percent versus 11.1 percent for Taxus. "This is not statistically significant," Dr. Bauer said. "However, other measurements in angiographic studies were statistically significant and favored Cypher."
The study also found a four-fold difference in stent clotting, a rate of 1.8 percent for the Taxus stent versus 0.4 percent for Cypher. "This is the only study that has shown a difference in thrombosis rates," Dr. Bauer said.
SIRTAX compared the sirolimus-eluting Cypher stents and paclitaxel-eluting Taxus stents for revascularization. The study involved more than 1,000 patients with 1,400 lesions. The endpoint at nine months showed a MACE rate of 6.2 percent with Cypher versus 10.8 percent with Taxus, a statistically significant difference. Target lesion revascularization was 4.8 percent in patients with the Cypher stents, 6.3 percent for patients with Taxus. The study showed no difference between the two stents in the rate of thrombosis.
ISAR-Diabetes involved 250 patients, all diabetics, randomized to Taxus or Cypher stents. The study endpoint showed target lesion revascularization of 6.4 percent with Cypher versus 12 percent for Taxus. "The Cypher stent was shown to be superior to Taxus in preventing restenosis in diabetics," Dr. Bauer said.
Plavix with thrombolytic therapy
In the CLARITY-TIMI 28 study, in which Associated Cardiovascular Consultants participated, 3,500 patients with ST-elevated myocardial infarction (STEMI) who received thrombolytic therapy at 319 centers, also received a 300 mg load of Plavix followed by 75 mg a day or they received a placebo. This was followed by angiography in two to eight days and a clinical follow-up at 30 days.
"At the time of catheterization, patients who got Plavix had a 36-percent decrease in vessel occlusion, death or re-infarction," Dr. Bauer said. "At 30 days, those patients showed a 20 percent decrease in MACE."
Take Home Messages
- Drug eluting stents (both Cypher and Taxus) continue to show marked benefit over bare metal stents in complex subsets, including saphenous vein grafts and multi-vessel disease. The benefit is particularly pronounced for diabetics. However, longer courses of Plavix are mandatory (minimum of three months for Cypher, six months for Taxus vs. one month for bare metal).
- Head-to-head trials have generally favored Cypher over Taxus drug-eluting stents for preventing restenosis.
- Acute thrombosis rates for drug-eluting stents have been similar to bare metal stents. Whether Taxus stents have a higher thrombosis rate than Cypher stents is still not clear.
- Plavix (300 mg load, then 75 mg daily) provides additional benefit to thrombolytic therapy for acute ST-elevation myocardial infarction (STEMI) without any significant increase in bleeding.
Permission to reprint materials in this publication is hereby granted provided credit is given to Associated Cardiovascular Consultants, PA.
Dr. Hans H. Bauer
is medical director of the Cardiac Catheterization Labs at Our Lady of Lourdes Medical Center in Camden and at Lourdes Medical Center of Burlington County. He received his medical degree from New York Medical College, Valhalla, NY. After residency at New England Deaconess Hospital, Harvard Medical School, he completed fellowships in Cardiology and Interventional Cardiology at Hartford Hospital, University of Connecticut School of Medicine. Board certified in Cardiovascular Diseases and Interventional Cardiology, he is a fellow of the American College of Cardiology and a member of the Society for Cardiac Angiography and Interventions. He is Clinical Professor of Medicine, Department of Medicine, Drexel/Hahnemann School of Medicine, Philadelphia.