Background: Few studies have examined whether high-responsiveness to antiplatelet therapy is associated with an increased risk of bleeding in patients receiving dual antiplatelet therapy.
Methods and results: Elective drug-eluting stent implantation was performed in 184 patients treated with aspirin and a thienopyridine (200 mg/day of ticlopidine or 75 mg/day of clopidogrel). The subjects were divided into 3 groups according to post-treatment platelet reactivity before stenting as measured by the response to adenosine diphosphate: the 1(st) quartile group was defined as high-responders, the 4(th) as low-responders, and the other 2 quartiles as middle-responders. Major bleeding occurred more frequently in high-responders than in middle- or low-responders during an average of 16 months' follow-up (15 vs 4, 2%, P=0.02). High-responsiveness was the independent predictor of major bleeding (odds ratio 4.26, P=0.03). Adverse cardiac events were less frequent in high- and middle-responders than in low-responders (24, 16 vs 37%, P=0.02). Middle-responders had better net clinical outcomes, defined as the sum of major bleeding and adverse cardiac events, than did high- or low-responders (21 vs 39, 39%, P=0.02).
Conclusions: In the present study high-responsiveness to antiplatelet therapy was associated with an increased risk of bleeding with no reduction in adverse cardiac events. Measuring platelet reactivity may be useful for risk stratification according to bleeding complications, as well as adverse cardiac events, in patients treated with drug-eluting stents.