| Objective: Currently, percutaneous coronary intervention(PCI) has gradually become an important therapy to improve symptoms in patients with stable angina. However, with the increase in number of elective PCI procedures, studies have shown that PCI procedures may lead to high platelet aggregation, which serves as the core mechanism of ischemic complications after PCI operation. At present, the application of dual antiplatelet therapy(DAPT) at loading dose before PCI operation is the standardized treatment regimen for elective PCI. Although guidelines recommend oral administration of 300 mg aspirin and 300 mg clopidogrel six hours before the operation for elective PCI patients, the specific administration time for this loading dose is not explicitly prompted, thereby resulting in the relatively confusing dosing regimens in clinical practice. Meanwhile, the related studies that investigate the advantages and disadvantages of different preoperative dosing regimens are poorly documented.This experiment is a single-center, randomized and prospective clinical study. Based on MAADP determined by thrombelastograph, this paper aims to observe whether the effects of the loading dose of 300 mg clopidogrel, which is orally administrated in four days with 75 mg each day and administrated within 6-24 hours before surgery at a time respectively, are different in patients with stable angina before elective PCI, thus further standardizing the preoperative antiplatelet regimen for these patients. Nevertheless, the research whether additional clopidogrel loading before PCI is required for patients undergoing long-term clopidogrel therapy can also be potentially instructive.Methods:Two hundred patients admitted to Department of Cardiology, The Second Hospital of Hebei Medical University from November 2013 to May 2014 were selected. The patients meeting inclusion criteria were randomly divided into the maintenance dose group and loading dose group. 75 mg qd clopidogrel bisulfate was administrated from four days before surgery in the maintenance dose group, while 300 mg clopidogrel bisulfate was administrated 6-24 hours before surgeryin the loading dose group, with 75 mg qd given in both group after surgery. Patients of two groups were detected using thrombelastograph platelet imaging before surgery, at the first seven days and one month after surgery; adverse events within 7 days and from 7th day to 6 months after surgery were collected respectively. The MAADP, the platelet inhibition rate in the ADP pathways and the adverse event rate of two groups were statistically recorded. SPSS19.0 software package was used to process all data, where P<0.05 was defined as statistical significance. Measurement data was represented with mean ± standard deviation, inter-group comparison with t test, count data with percentage, and inter-group mean with chi-square test.Results:1 Clinical data of the two groups: In this study, a total of 346 patients were screened and randomized with 173 cases in the maintenance dose group and the loading dose group respectively. Patients, who failed to undergo stent implantation, were excluded, and finally 198 cases were successfully screened with 100 cases in the maintenance dose group and 98 cases in the loading dose group. No statistically significant difference was reported in terms of clinical features, intervention therapeutic situation.2 Before surgery, MAADP in the maintenance dose group was higher than that in the loading dose group, showing a statistically significant difference.MAADP(mm) 35.72±12.27 vs. 31.74±11.22, P=0.018;3 Before surgery, the platelet inhibition rate under ADP pathway was lower than that in the loading dose group, showing a statistically significant difference.the platelet inhibition rate(%)51.03±22.66 vs. 59.45±19.56, P=0.006;Combine the result 2 with 3 shows the patients receiving 300 mg clopidogrel within 6-24 hours before surgery show less effective platelet inhibition than those achieving this loading dose of 300 mg by daily administration of 75 mg preoperatively.4 At the seventh day after operation, MAADP in the maintenance dose group was higher than that in the loading dose group, indicating a statistically significant difference.MAADP(mm) 46.81±11.23 vs. 42.71±13.93, P= 0.024;5 At the seventh day after operation, the platelet inhibition rate under ADP pathway in the maintenance dose group was lower than that in the loading dose group, indicating a statistically significant difference.the platelet inhibition rate(%)31.13±16.24 vs. 38.94±21.03, P= 0.004;Result 4 and 5 show that the effect can last at least 7 days.6 Within 1 month after operation, the difference in MAADP and the platelet inhibition rate under ADP pathway between two groups was not statistically significant.MAADP(mm) 41.80±11.00 vs. 41.82±12.28, P= 0.994;the platelet inhibition rate(%)40.38±19.83 vs. 40.90±21.35, P= 0.859;Result 6 shows that the platelet inhibition differences may not continue a month.7 The rate of primary events(1% vs. 0),ischemia driven vessel revascularization(1.00% vs. 0) between two groups was not statistically significant. Within 7 days after operation, the incidence of the angina recurrence was higher in the maintenance dose group(6.00% vs. 1.02%, P=0.058), but it not statistically significant. Within 6 month after operation, the angina recurrence was higher in the maintenance dose group(12% vs. 4.18%, P=0.041) and the difference was statistically significant. Both of the groups didn’t occur primary bleeding events, Within 7 days after operation, the incidence of bleeding events was not statistically significant in minor(1.00% vs. 0) and minimal(3.00% vs. 2.04%), so Within 6 month after operation, minor(1.00% vs. 1.02%) and minimal(7.00% vs. 9.18%)The expected platelet inhibition effect may not be achieved in patients, who receive only maintenance dose before surgery, and this effect can last at least 7 days.Conclusion:This experiment shows that administration of 300 mg clopidogrel at different time will lead to different platelet inhibitory effects. Compared with patients receiving 300 mg clopidogrel within 6-24 hours before surgery, those achieving this loading dose of 300 mg by daily administration of 75 mg preoperatively show less effective platelet inhibition and higher incidence of the angina recurrence within 6 month after surgery. As a result, for patients with stable angina admitted to our hospital for PCI, the loading dose of 300 mg clopidogrel shall be administrated within 6-24 hours before surgery to the greatest extent. |
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