VIENNA — The incidence of stent thrombosis following placement of drug-eluting coronary stents suggested a possibly rising, curvilinear incidence during 3 years of follow-up of more than 5,000 patients.
In addition, almost half of the stent thromboses that occurred a year or more after stent placement happened while patients were still on dual antiplatelet therapy, said Dr. Gregory J. Mishkel said while presenting a poster at the annual congress of the European Society of Cardiology.
The finding “calls into question the necessity of clopidogrel continuation beyond the current prescribed recommendations” of 1 year, said Dr. Mishkel, co-director of the coronary catheterization laboratory at the Prairie Heart Institute at St. John's Hospital in Springfield, Ill., and his associates in their poster.
The review included 5,342 patients at Prairie Heart who received their first DES during May 2003-December 2006. Follow-up data on stent thrombosis was available for 5,173 (97%) of the patients; the average duration of follow-up was 1.8 years.
During follow-up, 50 patients had a definite stent thrombosis, 13 had a probable event, and 54 had a possible stent thrombosis. Among the 50 definite thromboses, 34 (68%) occurred a year or more after placement; and of those, 15 (44%) occurred while the patients were still on dual antiplatelet therapy.
After the first 30 days, the rate of definite or probable stent thrombosis during the next 11 months was 0.2%. During the second 12 months the thrombosis rate increased by 0.6%, to a cumulative rate of 0.8%. During the last 12 months, the rate increased by another 0.7%, to a cumulative rate of 1.5%, said Anna L. Moore, a database coordinator who collaborated on the study.