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Point of care platelet function tests (POCP) are used to study the effects of P2Y12 antagonists and their role in day to day practice is yet to be established. It is unknown if POCP indices reflect whole blood thrombogenicity in high risk patients.
We aimed to evaluate the relationship between whole blood thrombus and POCP indices in patients with high risk coronary artery disease (CAD). 66 patients with type 2 diabetes mellitus (T2DM) and proven stable CAD received one week therapy of clopidogrel 75mg od or placebo in a double blinded randomised trial. Thrombus was measured by ex-vivo Badimon chamber and POCP indices were obtained from VerifyNow (VN), Thromboelastography(TEG) and Multiplate (MP). All patients were on ACC/AHA recommended secondary prevention therapy including aspirin 75mg od.
The baseline clinical characteristics were well matched between the groups as with TEG, VN and MP indices. In the overall population, one week clopidogrel therapy reduced thrombus area significantly (thrombus area μ2/mm, mean±SD, 14015±5230 vs 11025±4050, p=0.038). VN PRUz values (324±42 vs 261±58, p=0.001), TEG Platelet mapping ™ (maximum amplitude ADP, mm 60±7.4 vs 54±10.8 p=0.007) and MP ADP AU (807±350 vs 475±235, p=0.007) showed significant reduction in clopidogrel group. All parameters were unchanged in placebo group (p>0.05). Poor responders to clopidogrel were 54.5% based on VN cutoff of 240 PRUZ, 60.6% based on TEG MA-ADP cutoff of 47mm, 42.5% based on MP ADP AU cutoff of 490. However, reduction in thrombus area did not differ between good responders and poor responders based on either of these cutoff values (thrombus area μ2/mm, VN: 12170±4593 vs 10262±3576, p=0.212, TEG: 10177±4521 vs 12113±3737, p=0.264, MP:9759±3570 vs 12972±2090, p=0.074).
Clopidogrel lowered whole blood thrombus irrespective of the higher rate of poor response shown by POCP's in patients with T2DM and CAD. Our findings imply that current cutoffs do not reflect whole blood thrombogenicity. POCP indices are likely very platelet-centric and do not account non platelet mediators of thrombus. These findings may explain some of the limitations of POCPs in routine practice.
Moderated Poster Contributions
Poster Sessions, Expo North
Saturday, March 09, 2013, 3:45 p.m.-4:30 p.m.
Session Title: Chronic CAD: Inflammation, Thrombosis and Calcification
Abstract Category: 9. Chronic CAD/Stable Ischemic Heart Disease: Basic
Presentation Number: 1153M-59
- 2013 American College of Cardiology Foundation