The diagnostic value and clinical relevance of thrombelastography and light transmission aggregometry based identification of low response to clopidogrel in ACS patients after percutaneous coronary intervention

Abstract

Objective To obtain the incidence of low response (CLR) of acute coronary syndrome (ACS) patients after percutaneous coronary intervention(PCI) by Thrombelastography(TEG) and Light transmission aggregometry(LTA), and explore the correlation of CLR with clinical related factors and major adverse cardiac events. Methods This study is a cohort study.214 ACS patients in the Department of Cardiology of Peking University People′s Hospital, who were ready to treat with PCI between May 2014 and November 2014 were enrolled.Among them, 168 cases(78.5%) were male with an average age of (61.32±10.79) years; 46 cases(21.5%) were female with an average age of (68.72±8.38) years.The clinical data were recorded, such as history of present illness, the past medical history, clinical medication, and the results of coronary angiography.After taken clopidogrel 75 mg per day at least for 4 days, all patients were detected the contribution from ADP-stimulated platelets to maximal clot strength by TEG(TEG-ADP-Inhib), and detected ADP induced maximal platelet aggregation ratio by LTA(LTA-ADPMAX). The occurrence rate of CLR was calculated, and the correlation between results of the two assays were anylysed.Patients were divided into two groups according to CLR.Univariate analysis was used to compare the difference of clinical data between CLR group and non-CLR group, then Logistic regression analysis was conducted to find out the related risk factors that may influence the occurrence rate of CLR. Compare the correlation between CLR and MACE according to 6-month followed-up. Results There was negative correlations between LAT and TEG in the adenosine diphosphate induced platelet reactivity (r=-0.282, P=0.000). CLR was found in 115 (53.7%) patients by LTA and in 74(34.6% ) patients by TEG and the difference between the two CLR ratio was significant (χ2=10.486, P=0.001) .There were significant differences in age, smoking history and prior PCI/CABG history between CLR group and non-CLR group according to LTA grouping(t=2.829, P=0.005; χ2=11.058, P=0.001; χ2=4.252, P=0.039), and there was significant differences in history of cerebrovascular accident between CLR group and non-CLR group according to TEG grouping(χ2=4.584, P=0.032). Logistic regression analysis showed smoking history was the protective factor for CLR (OR=0.390, P=0.001), while history of cerebrovascular accident was the independent risk factor (OR=2.499, P=0.037) for CLR. According to 6-month followed-up, the incidence of clinical ischemic events and bleeding events in CLRLTA group was 5.2% and 0 respectively, in N-CLRLTA group was 10.1% and 3% respectively; the occurrence rate of clinical ischemic events and bleeding events was no significant difference between two groups(χ2=1.834, P=0.176; χ2=1.682, P=0.195). The incidence of clinical ischemic events and bleeding events in CLRTEG group was 8.1% and 0 respectively, in N-CLRTEG group was 7.1% and 2.1% respectively; the occurrence rate of clinical ischemic events and bleeding events was no significant difference between two groups(χ2=0.065, P=0.798; χ2=0.432, P=0.511). Conclusions The correlation between the testing results of TEG and LTA in ACS patients treated with clopidogrel was poor, CLR ratios detected by two assays were significantly different.Smoking history was the protective factor for CLR , while history of cerebrovascular accident was the independent risk factor for CLR.CLR was not the risk factor for MACE in ACS patients.(Chin J Lab Med, 2016, 39: 187-191) Key words: Thrombelastography; Densitometry; Ticlopidine; Acute coronary syndrome