TCT: Dual-antiplatelet therapyis two years superior to one for late thrombosis?
SAN FRANSISCO—A two-year dual-antiplatelet regimen with aspirin and clopidogrel (Plavix, Bristol-Myers Squibb) can prevent the occurrence of very late stent thrombosis after PCI with drug-eluting stents (DES), according to the TYCOON (Two-Year ClOpidOgrel Need) registry presented at the annual Transcatheter Cardiovascular Therapeutics (TCT) meeting this week.

The current U.S. guidelines encourage 12 months of treatment for patients undergoing PCI with DES who are at low risk for bleeding. However, recent studies have “cast doubt” on whether this approach is effective in preventing late and very late thrombosis, according to study presenter and lead author Gaetano Tazilli, MD, from the department of cardiovascular medicine at San Filippo Neri Hospital in Rome.

“A particular concern to the cardiology community derives from the fact that DES are routinely being used off-label and in higher risk patients beyond the setting of clinical trials,” according to Tazilli. “Particularly in these large populations of patients, there is a paucity of data on the incidence and timing of DES-associated thrombosis."

Tazilli and colleagues sought to assess if the “real-world” risk of late and very late thrombosis could be reduced by an extended use of Plavix. The registry was designed to compare the long-term impact of 12-month versus 24-month dual-antiplatelet regimens in an unselected population of consecutive patients who received DES and were followed for four years.

Between January 2003 and December 2004, 897 were eligible for the registry. Of these, 50 percent received at least one bare-metal stent (BMS) and 50 percent received at least one DES. In the DES group, dual-antiplatelet therapy after PCI was administered for 12 months in 173 patients treated in 2003 (one-year group) and for 24 months in 274 patients treated in 2004 (two-year group).

There were no significant differences in age, gender, risk factors, clinical history, left ventricular dysfunction and extracardiac disease, nor were there significant differences in the main clinical features between patients with BMS and DES implantation. Also, there were no significant differences between groups in angiographic features. However, bifurcation lesions were more commonly treated in the two-year group compared with the one-year group.

During the follow up, Tazilli reported three cases of stent thrombosis in the 450 patients with BMS implantation.

“In patients with DES implantation, there were five cases of stent thrombosis in the one-year versus one case in the two-year group,” he said. “Specifically, there were two cases of subacute thrombosis [one in each group], no cases of late thrombosis and four cases of very late thrombosis.”

The cases of very late thrombosis occurred at 13, 15, 17 and 23 months after DES implantation in the one-year group only. These findings have lead Tazilli and his colleagues to call for more, larger studies of a randomized, controlled nature to evaluate two-year dual-antiplatelet therapy as a means to reducing late thrombosis for patients who receive DES.