Efficacy and safety of antiplatelet-combination therapy after drug-eluting stent implantation.

Background/aims: Combination single-pill therapy can improve cost-effectiveness in a typical medical therapy. However, there is a little evidence about the efficacy and tolerability of combination single-pill antiplatelet therapy after percutaneous coronary intervention (PCI) with drug-eluting stents (DES).

Methods: From June to November 2012, in total, 142 patients who met the following criteria were enrolled: at least 18 years old; successful PCI with DES at least 3 months earlier; and regular medication of aspirin and clopidogrel with no side effects. After VerifyNow P2Y12 and aspirin assays, the combination single pill of aspirin and clopidogrel was given and laboratory tests were repeated 6 weeks later.

Results: At baseline, the incidence of aspirin resistance, defined as aspirin reaction unit (ARU) ≥ 550, was 9.2%, that of clopidogrel resistance, defined as P2Y12 reaction unit (PRU) ≥ 230, was 46.5%, and that of percent inhibition of PRU < 20% was 32.4%. At follow-up, the incidence of resistance by ARU value was 7.0%, 50.0% by PRU value, and 35.9% by percentage inhibition of PRU, respectively. The mean values of ARU (431.5 ± 63.6 vs. 439.8 ± 55.2; p = 0.216) and PRU (227.5 ± 71.4 vs. 223.3 ± 76.0; p = 0.350) were not significantly different before versus after antiplatelet-combination single-pill therapy. Five adverse events (3.5%) were observed during the study period.

Conclusions: Combination single-pill antiplatelet therapy, which may reduce daily pill burden for patients after PCI with DES, demonstrated similar efficacy to separate dual-pill antiplatelet therapy.