Abstract 3735: Hyper-Responder to Dual Antiplatelet Therapy and Bleeding Complications
Background: There are few reports about the relationship between marked suppression of platelet aggregation and the increasing risk of bleeding, although non-responder to antiplatelet therapy has been reported to be associated with an increase of adverse cardiac events.
Methods and results: In the early morning before PCI with drug eluting stent, peripheral blood samples were obtained from 90 patients treated with 100mg/day aspirin and a Japanese standard dose thienopyridine (200mg/day ticlopidine or 75mg/day clopidogrel) at least for 7 days (68 men; mean age, 68 years). With screen filtration pressure method, platelet aggregation threshold index (PATI) was determined by the response to the aggregatory agents adenosine diphosphate (ADP) or collagen. Patients with ADP-induced PATI > 16μM were defined as hyper-responder to ADP (n=34) and the remainder defined as normal-responder to ADP (n=56). Dual antiplatelet therapy was performed at least for 12 months after stent implantation. No difference was observed in patient characteristics including age, sex, body surface area, coronary risk factors between 2 groups. A rate of incidence of TIMI major bleeding was higher in hyper-responder to ADP than in normal-responder to ADP (9 vs 2%, p<0.10), however, stent thrombosis did not occur and there were no significant differences in adverse events (defined as death, acute coronary syndrome or angioplasty for new lesion of coronary artery) between 2 groups (12 vs 13%) during 12 months follow-up. Moreover, dual hyper-responder defined as those with both ADP-induced PATI > 16μM and collagen-induced PATI > 2μg/ml (n=23) had TIMI major bleeding more frequently than the rest patients (n=67) (13 vs 1%, p<0.05), in contrast, there were no significant differences in above adverse events between 2 groups (9 vs 13%, p=NS).
Conclusion: Hyper-responder to dual antiplatelet therapy was associated with a higher rate of bleeding complications but not attributed to reduction of adverse events. The measurement of pre-PCI platelet reactivity may be useful for risk stratification of bleeding in patients treated with dual antiplatelet therapy.