Early Discontinuation of DAPT May Increase Risk of Stent Thrombosis

SAN FRANCISCO, CALIF.—Timing and discontinuation of dual anti-platelet therapy (DAPT) following stent implantation remains an open question, but evidence is growing that stopping the therapy early could increase the risk of stent thrombosis.

Current recommendations regarding DAPT encourage its use for 1 year following DES implantation, based on studies suggesting an increased risk of stent thrombosis in patients who stopped the therapy prematurely. There are limited data on newer stents, however. “Whether premature DAPT and thienopyridine discontinuation is safe in patients receiving [everolimus-eluting stents] is unknown,” said James B. Hermiller Jr., MD, director of the interventional cardiology fellowship at the University of Indiana, Ind. He discussed some of the available evidence on DAPT discontinuation at a scientific symposia session.

The SPIRIT III trial compared 669 patients receiving the everolimus-eluting Xience V stent (Abbott Vascular) with 333 patients receiving the paclitaxel-eluting Taxus stent (Boston Scientific). There was some suggestion of harm with early DAPT discontinuation: Two of the 73 EES patients and two of the 35 PES patients who discontinued DAPT before 6 months developed stent thrombosis (P=.59). However, there was little difference between stent thrombosis rates among those who did not discontinue DAPT during the full course of the study and those who discontinued DAPT after 6 months (see Figure).

The larger SPIRIT IV trial compared 2,458 Xience V patients with 1,229 Taxus patients. Multivariate analysis showed a significantly increased risk of stent thrombosis among those who discontinued DAPT within 6 months and those who did not discontinue (HR, 8.06 [95% CI, 1.79-36.22]; P=.007). In contrast, there appeared to be no difference in risk between patients who discontinued DAPT after 6 months and those who never discontinued.

Hermiller also discussed results from the XIENCE V USA trial, which included 5,054 patients who received Xience V stents. The study showed a very low occurrence of stent thrombosis in all patients. In the overall cohort, two of 435 patients who had DAPT interruption after 30 days developed stent thrombosis. In patients considered standard risk, there was a total absence of stent thrombosis, even when DAPT was discontinued after only 30 days.

A pooled analysis of seven trials including SPIRIT and the XIENCE USA and Indian trials will be presented on Tuesday, according to Hermiller. He added that in the more than 13,000 patients in that analysis there was a strong suggestion that stopping DAPT before 30 days increased the risk of stent thrombosis among those who received everolimus-eluting stents. Discontinuation after 30 days, however, did not appear to increase the risk.

Consideration of DAPT cessation

At the same session, Ajay J. Kirtane, MD, SM, an assistant professor of clinical medicine at Columbia University Medical Center in New York, discussed some of the issues that can arise when stopping DAPT is being considered.

“I think the first question that we all need to ask is, does DAPT really need to be stopped, and why is it going to be stopped?” Kirtane said. With surgical procedures – the primary reason for DAPT discontinuation – he said the best option is to delay the procedure if at all possible. One registry study from 2009 showed a much greater risk of adverse outcomes among patients with zotarolimus-eluting stents (Endeavor, Medtronic) who discontinued DAPT within 1 year if they had surgery earlier (within 3 months) rather than later (P<.001). Kirtane noted also that if the surgery is urgently needed and the bleeding risk is deemed acceptable, then DAPT could be continued on through the surgery.

“If you address the issue of why the patient needs to stop, maybe you could continue patients that otherwise might be stopped,” Kirtane said.