| Objective: The aim of this study was to assess the efficacy and safety of the high clopidogrel maintenance dose in acute coronary syndromes(ACS)patients with inadequate response to clopidogrel undergoing selective percutaneous coronary intervention (PCI).Methods: From December 2006 to November 2007, 132 patients ( 80 male and 52 female, average age was 64.7±4.4 years old ) who had been diagnosed as ACS with inadequate response to clopidogrel were enrolled into this study. Inadequate response to clopidogrel was defined as absolute reduction of platelet aggregation rate<30%. patients with bleeding diathesis, thrombocytopenia, recent stroke, and received GPIIb/IIIa receptor antagonist therapy were excluded. These 132 cases were randomly divided into two groups, that is, the high maintenance dose group (n=65, 40 males, 25 females, 150mg clopidogrel per day) and the control group (n=67,40 males, 27 females 75mg clopidogrel per day). we collected detailed clinical information including: age, gender, risk factors, TIMI risk score. We measured the platelet aggregation rate of the two groups at the time of baseline, 5 hours after loading dose and 7 days later. All patients received selective PCI. All patients received 300mg oral clopidogrel loading dose, aspirin and Low Molecular Heparin injection in both groups. We used QCA and TMPG to analyse the lesion and reperfusion of the culprit vessel and myocardium. We used SAS 6.12 statistics software to analyse all data. The variables were presented as the means and the SD. Differences between two groups means were assessed with the t test. TheΧ2 analysis or the Fisher exact test were used to test differences between proportions. Statistical significance was indicated by P value <0.05.RESULT: There is no significant differences in age, gender, TIMI risk score, risk factors between the high maintenance dose group and standard dose group. There is no significant differences in basal the platelet aggregation rate(PAR), the platelet aggregation rate after 300mg clopidogrel(PAR1)and△PAR1 among the UA, the NSTEMI and the STEMI groups. 7 days later, the platelet aggregation rate(PAR2) of the high maintenance dose group was lower than the standard dose group among the UA,NSTEMI and STEMI people(40.62±9.62 vs. 33.78±7.54, 43.84±6.52 vs. 32.83±8.81, 40.19±6.21 vs. 36.33±3.49 ,p<0.05). The change of the platelet aggregation rate(△PAR2) of the high maintenance dose group was larger than the standard dose group(22.43±4.52 vs. 30.73±3.46; 22.46±4.38 vs. 34.17±3.52; 24.21±5.96 vs. 34.11±4.50,p<0.05).The CTFC of the high maintenance dose group after PCI was smaller than the standard dose group among the UA, the NSTEMI, the STEMI groups(24.54±3.62 vs. 28.37±2.95, P>0.05; 26.57±4.62 vs. 30.42±3.09,P>0.05; 28.37±4.68 vs. 30.29±4.54,P>0.05). The percentage of TMPG beyond 2 grade was higher in the high maintenance dose group (83.06% vs 76.57%, P>0.05). But there was no significant difference. There were less acute and subacute thrombosis cases in the high maintenance dose group than the standard dose group in hospital (4.5% vs 1.4% p<0.05).There was no significant difference in hemorrhage events between two groups.Conclusion: The high maintenance dose clopidogrel(150mg per day) can strongly inhibit platelet aggregation and improve platelet response to clopidogrel. There is potential benefit in increasing coronary blood flow and improving myocardium perfusion. High maintenance dose clopidogrel decreases the acute and subacute thrombosis but do not increase the hemorrhage events. |
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