STOCKHOLM — Less than 1% of patients who receive a drug-eluting coronary stent develop late stent thrombosis during the first 1.5 years after implantation, on the basis of a study in more than 2,000 patients.
While these and earlier findings showed that drug-eluting stents are “relatively safe” during the long term, they also highlighted the need for patients who receive a drug-eluting stent to unceasingly remain on daily aspirin therapy, Andrew T.L. Ong, M.D., said at the annual congress of the European Society of Cardiology.
Stopping aspirin is an “absolute contraindication,” he said in an interview. “In today's day and age there is no surgery that requires stopping aspirin,” said Dr. Ong, a cardiologist at Thoraxcenter Rotterdam (the Netherlands).
“Every patient who gets a drug-eluting stent should receive a 'passport'” that tells all of the patient's other physicians not to stop aspirin without consulting the ones who placed the stent, commented Luis Gruberg, M.D., director of the division of invasive cardiology at the Rambam Medical Center in Haifa, Israel.
The link between late stent thrombosis and stopping aspirin and other antiplatelet therapy was underscored by the new incidence data, collected on all 2,006 patients who received a drug-eluting, coronary stent at Thoraxcenter since April 2002. The total included 1,017 patients who received a sirolimus-eluting stent (Cypher), and 989 who received a paclitaxel-eluting stent (Taxus).
During an average follow-up of 1.5 years, seven patients (0.35%) developed late stent thrombosis, defined as an abrupt stent occlusion that developed more than 30 days after stent placement. One patient had two stents that each had late thrombosis.
When analyzed statistically, the upper 95% confidence interval on the rate of late thrombosis was 0.72%, which means that it is very likely that the “real” rate of late thrombosis is 0.72% or less, said Dr. Ong. The rate in this series was strikingly similar to a 0.7% rate reported last May for a series of 2,229 patients who were treated at three hospitals in Germany and Italy (JAMA 2005;293:2126–30).
That study and the one presented by Dr. Ong are the first two reports to calculate a rate of late thrombosis in a large, well-defined number of patients who got drug-eluting stents. This rate is also similar to what has been reported for bare metal stents, said Dr. Ong.
Of the eight stents with late thrombosis in the Thoraxcenter series, three were in patients who had stopped both aspirin and clopidogrel (Plavix) treatment, while the other five were in patients who had stopped clopidogrel but had continued aspirin.
Clinicians at Thoraxcenter now usually prescribe clopidogrel for 6 months following stent implantation. The drug can be continued longer, but in the Netherlands most insurers will only pay for a 6-month course.
All seven patients had ST-segment elevation MIs as a result of the stent thrombosis; two patients also had shock and died.
Following Dr. Ong's talk, several in the audience spoke about the need for patients with drug-eluting coronary stents to stay on daily aspirin, and how to best get this message to primary care physicians who care for these patients with stents. Many spoke in favor of giving each patient a “passport” reviewing their medical history that patients would be told to show to all of their other physicians.