Dual Antiplatelet Therapy: 6 Months as Good as 12?

During a question-and-answer session at the American Heart Association (AHA) Scientific Sessions 2014, Schüpke discussed the results of her ISAR-SAFE study of the dual antiplatelet therapy (DAPT) after drug-eluting stent (DES) implantation is still unknown.

The investigative initiated international, multicenter randomized double blind placebo controlled trial, ISAR-SAFE, hypothesized that patients with DES in 6 months are not inferior to those at 12 months in terms of clinical outcome. Primary endpoint was a composite endpoint of death, myocardial infarction, stent thrombosis, stroke, and major bleeding at 9 months after randomization — that is 15 months after DES.

Secondary endpoints were the individual components of the primary endpoints. She included patients that went on clopidogrel therapy at 6 months after DES.

Schüpke’s major exclusion criteria excluded patients who exhibited clinical symptoms of ischemia, active bleeding, previous stent thrombosis; DES in left main coronary artery, oral anticoagulation, or had planned significant surgery within a 6-month period.

Schüpke and her team, “Assumed an incidence of 10% the primary endpoint in the patients designed for 12-month clopidogrel group. The margin of non-inferiority was set at 2% with a power of 80% and one-sided alpha level of 0.05. “

However as a planned blinded interim analysis showed event rates much lower than expected, she warned that the results should be cautiously interpreted.

A total of 4,005 patients wererandomly selected and enrolled at 6 months after DES implantation and randomly assigned to either further months of clopidogrel therapy or placebo.

Although the trial was stopped prematurely, after inclusion of two thirds of patients, Schüpke believed, “It has the potential to provide major insights into the optimal DAPT duration after DES implantation.”

Schüpke concluded, “In the ISAR-SAFE trial, we did not observe a significant difference in net clinical outcome between 6 months and 12 months of clopidogrel therapy after DES implantation. However, the results of the trial must be considered in view of its premature termination and lower than expected event rates.”