Extending clopidogrel treatment from one to two years after drug-eluting stent placement is associated with a reduction in very late thromboses, new registry data suggest.
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These results, from the TYCOON (Two-Year Clopidogrel Need) registry, were published online on September 28, 2009 in the American Journal of Cardiology.
Current guidelines recommend at least 9-12 months of dual antiplatelet therapy (aspirin plus clopidogrel) following intervention with a drug-eluting stent to prevent thromboses, but authors of the TYCOON paper, wanted to investigate whether longer treatment would be better.
The TYCOON database includes 897 consecutive patients who received a coronary stent in 2003 and 2004, about half of whom received a drug-eluting stent. Patients given a drug-eluting stent in 2003 were treated with clopidogrel for 12 months, whereas those given a drug-eluting stent in 2004 continued on clopidogrel for two years.
Results showed that there were four very late thromboses in the 173 drug-eluting stent patients who stopped clopidogrel after one year, but none in those who stayed on the drug for a further year.
The authors note that these results appear to conflict with other studies showing no difference in stent thrombosis in patients stopping or continuing clopidogrel after one year. They suggest that all the studies so far conducted are too small to show definitive results as very late stent thrombosis is such a rare event.
A randomised trial – the Dual Antiplatelet Therapy (DAPT) Study – is underway to answer this question. This study is comparing 12 and 30 months of dual antiplatelet therapy and is powered to show differences in rates of stent thrombosis and major adverse cardiovascular and cerebrovascular events.