Usefulness of the VerifyNow P2Y12 assay to evaluate the antiplatelet effects of ticagrelor and clopidogrel therapies
ABSTRACT We analyzed the antiplatelet effects of different P2Y(12) receptor blockers with VerifyNow P2Y12 assay (VN-P2Y12) and light transmittance aggregometry (LTA).
The point-of-care VN-P2Y12 has been used to assess the antiplatelet effects in clopidogrel-treated patients but has not been evaluated in detail in patients treated with ticagrelor.
Patients were randomly assigned to either ticagrelor [180 mg loading/90 mg twice daily (n = 37)] or clopidogrel [600 mg loading/75 mg daily (n = 39)] on top of aspirin treatment, and platelet reactivity was measured serially during onset, maintenance, and offset phases. High on-treatment platelet reactivity (HPR) was defined as 5 and 20 μM adenosine diphosphate-induced maximal platelet aggregation ≥46% and ≥59%, respectively, and P2Y12 reaction units ≥235.
Platelet function measured by VN-P2Y12 correlated well with LTA (.812 ≤ ρ ≤ .823, P < .001). VN-P2Y12 "BASE" values were consistent during administration of both agents. Calculated and reported percent inhibitions by VN-P2Y12 were similar (difference, -0.6%; 95% agreement limits, -22.9% to 21.6%). Platelet inhibition by VN-P2Y12 during clopidogrel and ticagrelor administrations was comparable to platelet inhibition by LTA. HPR determined by LTA and VN-P2Y12 were well matched, and the risk stratification between the two methods showed strong agreement after both therapies (κ > .7).
The VerifyNow P2Y12 assay is effective in assessing the antiplatelet effects and in identifying HPR during clopidogrel or ticagrelor therapy.
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ABSTRACT: In physiological hemostasis a prompt recruitment of platelets on the vessel damage prevents the bleeding by the rapid formation of a platelet plug. Qualitative and/or quantitative platelet defects promote bleeding, whereas the high residual reactivity of platelets in patients on antiplatelet therapies moves forward thromboembolic complications. The biochemical mechanisms of the different phases of platelet activation - adhesion, shape change, release reaction, and aggregation - have been well delineated, whereas their complete translation into laboratory assays has not been so fulfilled. Laboratory tests of platelet function, such as bleeding time, light transmission platelet aggregation, lumiaggregometry, impedance aggregometry on whole blood, and platelet activation investigated by flow cytometry, are traditionally utilized for diagnosing hemostatic disorders and managing patients with platelet and hemostatic defects, but their use is still limited to specialized laboratories. To date, a point-of-care testing (POCT) dedicated to platelet function, using pertinent devices much simpler to use, has now become available (ie, PFA-100, VerifyNow System, Multiplate Electrode Aggregometry [MEA]). POCT includes new methodologies which may be used in critical clinical settings and also in general laboratories because they are rapid and easy to use, employing whole blood without the necessity of sample processing. Actually, these different platelet methodologies for the evaluation of inherited and acquired bleeding disorders and/or for monitoring antiplatelet therapies are spreading and the study of platelet function is strengthening. In this review, well-tried and innovative platelet function tests and their methodological features and clinical applications are considered.Vascular Health and Risk Management 02/2015; 11:133. DOI:10.2147/VHRM.S44469
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ABSTRACT: Factors associated with PR during ticagrelor maintenance dose (MD) are not well defined. We aimed to examine factors that influence levels of platelet reactivity (PR) during chronic ticagrelor therapy. Methods We performed individual participant data meta-analysis of 445 patients from 8 studies who had PR assessment with the VerifyNow P2Y12 assay (Accumetrics Inc, San Diego, CA) while on ticagrelor 90 mg bid MD for at least 14 days. Results Distribution of PR during ticagrelor MD was highly skewed towards lower values. No case of high PR (≥230 PRU) was observed. Age and body mass index (BMI) positively affected PR, with every increase in decade and 5 units of BMI resulting in 7.9% and 4.1% increase in PR, respectively. Current smoking status negatively affected PR with 13.7% decrease in PR in current smokers, compared to non-smokers. Low PR (LPR) was defined as the lowest quartile of PR values (<10 PRU). In multivariate analysis, diabetes mellitus and age >70 years were independently associated with lower probability for LPR with a relative risk (95% confidence intervals) of 0.570 (0.361 to 0.899) and 0.554 (0.325 to 0.944), p = 0.016 and p = 0.030, respectively. Conclusions Age, BMI and current smoking status affect PR during ticagrelor MD. Diabetes mellitus and age >70 years were found to be associated with lower probability for LPR. Further research is required to assess the clinical implications of these findings in ticagrelor treated patients.American Heart Journal 10/2014; 168(4). DOI:10.1016/j.ahj.2014.06.026 · 4.56 Impact Factor
Journal of Neurointerventional Surgery 07/2014; 4(8). DOI:10.1136/neurintsurg-2014-011357 · 1.38 Impact Factor