SUMMARYIntroduction: There is considerable interindividual variation in response to the antiplatelet agent clopidogrel. Hyporesponse predicts negative outcomes in patients presenting with a variety of ischemic cardiac conditions and following intracoronary stent placement. Many tests of clopidogrel activity are time consuming and complex. Short thromboelastography (s-TEG) allows rapid measurement of platelet clopidogrel response. Aims: We initiated this study to investigate the utility of s-TEG in assessing the response to clopidogrel in patients presenting with acute coronary syndromes (ACS) and to compare these results with established clopidogrel monitoring techniques. Methods: Patients admitted with unstable angina (UA) or Non ST elevation myocardial infarction (NSTEMI) undergoing coronary angiography were recruited. After routine loading with clopidogrel, all patients were tested with s-TEG and Accumetrics Verify-Now rapid platelet function analyzer (VN-RPFA). We used the modified TEG technique of measuring area under the curve at 15 min (AUC15), which allows a rapid estimation of antiplatelet response. Vasodilator-stimulated phosphoprotein phosphorylation (VASP) was also tested in a subgroup of patients. Clinical follow-up was obtained at 1 year. s-TEG results were correlated with VN-RPFA and VASP findings. Results: A total of 49 patients (33 male, mean age 63) were recruited and tested with s-TEG and VN-RPFA and a total of 39 patients were also assessed with VASP. s-TEG readings correlated well with VN-RPFA (r 2 = 0.54, P < 0.0001) and VASP (r 2 = 0.26, P = 0.001). Conclusion: s-TEG provides timely results which compare to current tests of clopidogrel activity. This technique can also be used to measure a variety of other clotting parameters and as such could develop into a valuable near patient test for the interventional cardiologist.

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We sought to assess the relationships between platelet reactivity at different time points, CYP2C19*2 and ABCB1 status and clinical outcomes in patients with acute coronary syndromes (ACS). Anti-platelet response to clopidogrel was studied prospectively using the VerifyNow (VN) P2Y12 assay at the time of angiography and at 30 days post procedure in 151 patients admitted with ACS who underwent percutaneous coronary intervention (PCI). Troponin T levels were measured at angiography and 16-24 hour following PCI. DNA was extracted and the presence of CYP2C19*2 allele and ABCB1 polymorphisms were determined. Adverse cardiovascular and cerebral events (ACCE) were assessed at 12 months. High VN P2Y12 response at angiography was associated with a greater peri-procedural rise in troponin T, but not ACCE. However, VN P2Y12 response measured at 30 days was associated with ACCE (p = 0.017). CYP2C19*2 status was associated with higher VN P2Y12 response at angiography (p < 0.0001) and 30 days (p = 0.006) but not ACCE. Near-patient testing for clopidogrel response was associated with subsequent ACCE when performed 30 days following PCI, but not at angiography.

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