In this study,maximum platelet aggregation rate of Light transmittance aggregometry (LTA) for coronary heart disease (CHD) patients taking antiplatelet drug and patients without antiplatelet therapy was measured in non-adjusted and platelet count-adjusted platelet-rich plasma (PRP).The aim of this study is to compare which method is superior in evaluation of antiplatelet drug effect.

This is a methodology comparative research.560 CHD outpatients and inpatients that visited Beijing Anzhen Hospital of the Capital University of Medical Sciences from May to June,2012 were chosen,who were treated with aspirin monotherapy,or patients on combination therapy with aspirin and clopidogrel,as well as patients without antiplatelet therapy.LTA was performed in non-adjusted (improved method) and platelet count (200×10⁹/L) -adjusted PRP (original method),using 6μmol/L adenosine diphosphate (ADP) and 0.5 mmol/L arachidonic acid (ARA) as agonists.The maximum aggregation rates in 5 min were detected,and consistency and differences of the two methods were compared.

There is no statistically significant correlation between maximum aggregation rate and platelet count in PRP with 6μmol/L ADP or 0.5 mmol/L ARA as agonists in all subgroups including aspirin monotherapy,combination therapy with aspirin and clopidogrel and patients without antiplatelet therapy (-0.21≤r≤0.111,P>0.05).The maximum aggregation rate using ADP as agonists in original method is decreased compared with improved method,there is statistically significant difference in all subgroups including patients without antiplatelet therapy,aspirin monotherapy,combination therapy with aspirin and clopidogrel less than one week and more than one week.The variability of platelet aggregation rate using ADP as agonists with improved method is lower than that with original method in all subgroups.Yet the maximum aggregation rates using ADP as agonists with improved method and original method correlate well with each other in all subgroups (r=0.78,0.73,0.40,0.71,P<0.01).In the subgroup of subjects without antiplatelet therapy using ARA as agonist,platelet aggregation rate is decreased in original method compared with improved method,there is statistically significant difference,and the variability of the aggregation rate with improved method is also lower than that with original method,ranging from 62%-98% relative to 5%-89%.The decrease of aggregation rate using ARA as agonist for patients taking antiplatelet drug compared with patients without antiplatelet therapy can be detected both with improved method and original method.

Non-adjusted PRP in LTA is more convenient and time-saving,and it also means less effects on platelet in vitro.Therefore,non-adjusted PRP is more suitable for monitoring efficacy of antiplatelet therapy in clinical laboratory.(Chin J Lab Med,2013,36:405-409)

Platelet aggregation inhibitors; Platelet count; Platelet aggregation; Nephelometry and turbidimetry; Treatment outcome