缺血性脑卒中患者阿司匹林或氯吡格雷及其联合应用抗血小板治疗的研究

目的 研究缺血性脑卒中患者阿司匹林或氯吡格雷及其联合应用抗血小板治疗的效果.方法 180例缺血性脑卒中患者分为阿司匹林组(阿司匹林肠溶片100 mg/d)、氯吡格雷组(氯吡格雷75 mg/d)和联合用药组(阿司匹林肠溶片+氯吡格雷,剂量相同);每组60例.在治疗前、治疗14 d后,用血栓弹力图检测患者的花生四烯酸(AA)和二磷酸腺苷(ADP)途径诱导的血小板抑制率.结果 治疗后,3组AA、ADP途径诱导的血小板抑制率显著高于治疗前(均P＜0.05);3组间AA、ADP途径诱导的血小板抑制率的差异有统计学意义(均P＜0.05).联合用药组和阿司匹林组AA途径诱导的血小板抑制率显著高于氯吡格雷组(均P＜0.05);联合用药组和氯吡格雷组ADP途径诱导的血小板抑制率显著高于阿司匹林组(均P＜0.05);联合用药组与阿司匹林组AA途径、联合用药组与氯吡格雷组ADP途径诱导的血小板抑制率的差异无统计学意义.结论 阿司匹林和氯吡格雷对缺血性脑卒中患者均有显著的抗血小板作用;而阿司匹林联合氯吡格雷能从两个途径抑制血小板聚集,抗血小板的效果更好.     

血栓弹力图评价脑梗死患者阿司匹林、氯吡格雷及其联合应用抗血小板治疗的作用研究

目的探讨采用血栓弹力图测定血小板抑制率评价脑梗死患者口服阿司匹林、氯吡格雷单药及其合用双联抗血小板治疗的作用。方法 98例住院的急性脑梗死患者按口服抗血小板药物分为阿司匹林组(39例)、氯吡格雷组(37例)及氯吡格雷+阿司匹林组(22例)。在患者服药21 d时,采用血栓弹力图仪(TEG-5000)检测花生四烯酸(AA)途径和二磷酸腺苷(ADP)途径诱导的血小板抑制率值,并与正常对照组(52人)进行比较。结果阿司匹林组和阿司匹林+氯吡格雷组AA途径诱导的血小板抑制率均显著高于正常对照组及氯吡格雷组(均P 0. 05)。氯吡格雷组和阿司匹林+氯吡格雷组ADP途径诱导的抑制率均明显高于正常对照组(均P 0. 05)。结论血栓弹力图可用于评价临床抗血小板药物的效果。服用阿司匹林能起到很好的抗血小板作用,氯吡格雷的效果稍差;而阿司匹林联合氯吡格雷的抗血小板作用更强。     

用血栓弹力图评价阿司匹林及氯吡格雷在缺血性卒中患者中血小板抑制效应的研究

目的用血栓弹力图评价缺血性卒中患者正规使用阿司匹林及氯吡格雷后血小板抑制率的变化。方法血栓弹力图检测我院123例住院患者抗血小板药物治疗后花生四烯酸(AA)通路和ADP受体途径诱导的血小板抑制率,患者抗血小板药物治疗包括阿司匹林组(n=7)、氯吡格雷组(n=8)、阿司匹林+氯吡格联合组(n=108)。结果 123例患者中,阿司匹林组AA诱导的血小板抑率为(87.04±22.71)%,氯吡格雷组ADP诱导的血小板抑制率平均值为(46.61±24.43)%,阿司匹林+氯吡格雷组AA和ADP诱导的血小板抑制率为分别(77.87±27.98)%和(50.23±29.27)%。服用阿司匹林和氯吡格雷的患者分别有115和116例,其AA和ADP途径血小板抑制率分别为(78.42±27.69)%;(49.99±28.88)%,差异具有显著统计学意义(P=0.000)。其中对阿司匹林和氯吡格雷敏感者(血小板抑制率≥50%)分别为97例(84.34%)和89例(75.72%),而不敏感者(血小板抑制率<50%)分别为18例(15.65%)和27例(23.28%),两种药物疗效间差异无显著统计学意义(χ2=3.706,P=0.054)。结论服用100mg/d阿司匹林,在绝大多数缺血性脑血管病患者中能产生较强的血小板抑制效应,而服用75mg/d氯吡格雷对血小板抑制稍弱,但多数患者仍能达有效的血小板抑制作用。     

替格瑞洛与西洛他唑对氯吡格雷抵抗的急性缺血性脑卒中患者的疗效及安全性比较

目的 探讨替格瑞洛与西洛他唑对氯吡格雷抵抗的急性缺血性脑卒中(AIS)患者的疗效及安全性的影响。方法 将80例对氯吡格雷抵抗(血小板聚集率>50%)AIS患者按照数字表法随机分为替格瑞洛组(入组40例,完成37例)和西洛他唑组(入组40例,完成39例); 在AIS常规治疗的基础上替格瑞洛组将氯吡格雷换用替格瑞洛治疗(90 mg/次,2次/d); 西洛他唑组将氯吡格雷换用西洛他唑治疗(100 mg/次,2次/d)。于改变治疗方案前及改变治疗方案后1、3、6、12个月分别检测血小板聚集率(PIR),观察2组治疗12个月内的缺血事件、出血事件及药物的不良反应。结果 改变治疗方案后12个月替格瑞洛组总有效率显著高于西洛他唑组(z=-2.086,P=0.037)。替格瑞洛组缺血事件发生率低于西洛他唑组(χ²=4.057,P=0.034); 替格瑞洛组的出血事件发生率高于西洛他唑组(χ²=4.501,P=0.034); 替格瑞洛组的呼吸困难发生率高于西洛他唑组(χ²=4.505,P=0.034); 替格瑞洛组的其他不良反应发生率高于西洛他唑组(χ²=4.021,P=0.045)。改变治疗方案后1、3、6、12个月替格瑞洛组患者的PAR低于西洛他唑组(F=15.320,P=0.000)。结论 对氯吡格雷抵抗的AIS患者,替格瑞洛比西洛他唑的血小板抑制作用更强,缺血事件发生率更低,但出血事件、呼吸困难及其他不良反应的发生率更高,因此对于血栓风险较高、出血风险较低的患者,建议换用替格瑞洛; 对于血栓风险较低、出血风险较高的患者,建议换用西洛他唑。     

血小板功能检测在高血压合并急性脑梗死非溶栓患者抗栓治疗中的应用

目的评价血小板功能检测在高血压合并急性脑梗死非溶栓患者的抗栓治疗监测中的应用价值,探讨抗血小板药物治疗反应多样性。方法选择335例于2018-01—2019-06住院的未溶栓的确诊高血压合并急性脑梗死患者为研究对象,根据不同的抗血小板药物种类和剂量分组:阿司匹林200mg治疗组、阿司匹林100mg治疗组、氯吡咯雷治疗组、替格瑞洛治疗组。采用比浊法分别检测各组治疗前后AA、ADP、Col、EPI诱导的MAR。结果治疗7d后,各治疗组MARADP、MARAA、MARCol、MAREPI较治疗前均下降,差异有统计学意义(P0.05)。氯吡格雷治疗组及替格瑞洛治疗组MARADP差值高于不同剂量阿司匹林治疗组,差异有统计学意义(P0.05)。不同剂量阿司匹林治疗组MARAA差值均高于氯吡格雷治疗组及替格瑞洛治疗组,差异有统计学意义(P0.05);阿司匹林200mg治疗组MARAA差值高于阿司匹林100mg治疗组,差异有统计学意义(P0.05)。结论阿司匹林、氯吡咯雷、替格瑞洛均能有效降低高血压合并急性脑梗死非溶栓患者的血小板最大聚集率,阿司匹林200mg比阿司匹林100mg剂量的抗血小板效果更佳。     

吸烟状态对氯吡格雷疗效的影响

目的通过血栓弹力图检测,观察吸烟状态是否会对缺血性卒中患者的氯吡格雷疗效产生影响。方法回顾性连续纳入2013年1月-2014年10月首次发病的急性非心源性栓塞所致的缺血性脑血管病并接受氯吡格雷治疗的患者202例,分为吸烟组和不吸烟组。连续服用氯吡格雷每日75 mg,5 d后,抽取外周静脉血,用血栓弹力图仪测定氯吡格雷对血小板的抑制率。结果与非吸烟组相比,吸烟组患者氯吡格雷诱导的二磷酸腺苷抑制率更高(55.29%±25.92%vs 53.25%±27.02%,P=0.589),出现氯吡格雷反应低下(二磷酸腺苷抑制率30%)的患者比例更低(15.8%vs 19.5%,P=0.498),但差异无统计学意义。结论在非心源性栓塞的缺血性卒中患者中,吸烟有提高氯吡格雷反应性,增强其抗血小板聚集作用的趋势。但吸烟者中氯吡格雷治疗后血小板反应的变异性仍有待进一步研究证实。     

短暂性脑缺血发作与轻型卒中抗血小板治疗

目的：探讨短暂性脑缺血发作与轻型卒中抗血小板治疗效果。方法选取63例缺血性脑卒中患者为研究对象,并随机分成A、B、C 3组,每组21例,C组采用氯吡格雷治疗,B组采用阿司匹林治疗,A组采用氯吡格雷联合阿司匹林治疗,对比3组治疗前后血栓弹力图（TEG）检测二磷酸腺苷（ADP）及花生四烯酸（AA）途径诱导的血小板抑制率。结果治疗后3组患者ADP、AA途径诱导的血小板抑制率均明显高于治疗前（P＜0.05）,AA途径诱导下血小板抑制率中 A组和B组显著高于C组（P＜0.05）,ADP途径诱导的血小板抑制率中A组、C组显著高于B组（P＜0.05）。结论氯吡格雷联合阿司匹林从两个途径抑制血小板聚集的效果优于单用阿司匹林或氯吡格雷,且出血风险低,值得推广应用。     

氯吡格雷在急性脑梗死的糖尿病患者中血小板抑制效应的研究

目的用血栓弹力图(thromboelastograms,TEG)评价合并糖尿病的急性脑梗死患者正规使用氯吡格雷后血小板抑制率的变化及氯吡格雷抵抗情况。方法收集住院的急性脑梗死患者80例,其中糖尿病患者33例,非糖尿病患者47例,所有患者予以顿服氯吡格雷负荷量300 mg继以75 mg/d维持,在服用氯吡格雷3 d后和7 d后空腹抽取肘静脉血标本,用血栓弹力图(thromboelastograms,TEG)测定10μmol/L二磷酸腺苷(adenosine diphosphate,ADP)受体途径诱导的血小板抑制率,分析比较两组患者临床特征、血小板抑制率的差异和氯吡格雷抵抗情况。结果糖尿病组的空腹血糖(Fasting plasma glucose,FPG)和糖化血红蛋白(%)显著高于非糖尿病组,差异具有统计学意义(P<0.05)。糖尿病组3 d后和7 d的血小板抑制率显著低于非糖尿病组,差异具有统计学意义(P<0.05)。糖尿病组3 d和7 d后分别有11例(33.3%)、12例(36.4%)患者出现氯吡格雷抵抗的现象,显著高于非糖尿病组的6例(12.8%)、5例(10.6%),差异具有统计学意义(P<0.05)。结论糖尿病患者的血小板抑制率明显低于非糖尿病患者,更容易发生氯吡格雷抵抗现象。     

应用血栓弹力图指导急性非心源性卒中患者选择敏感抗血小板聚集药物的临床研究

目的 应用血栓弹力图（thromboelastography,TEG）指导急性非心源性卒中患者选择敏感抗血小板聚 集药物,并评价临床治疗效果。 方法 连续选取首都医科大学附属北京朝阳医院西区神经内科2013年1月至2014年12月期间急性非心 源性卒中住院患者162例,分为个体化治疗组54例（阿司匹林100 mg联合氯吡格雷75 mg应用14 d,后 根据TEG结果选择阿司匹林或氯吡格雷单抗）,阿司匹林组（n =54）,氯吡格雷组（n =54）。三组患者 均于住院第7天抽静脉血,应用TEG仪检测花生四烯酸（arachidonic acid,AA）途径诱导的血小板抑制 率和二磷酸腺苷（adenosine diphosphate,ADP）受体途径诱导的血小板抑制率,并于入院时、第14天、3 个月行美国国立卫生研究院卒中量表（National Institutes of Health Stroke Scale,NIHSS）评分及日常生 活能力量表（Activity of Daily Living Scale,ADL）评分。比较三组之间基线资料及AA途径、ADP途径 诱导的血小板抑制率,并评估14 d及3个月NIHSS评分、ADL评分及再发缺血性卒中及脑出血发生事件。 结果 三组之间在年龄、性别、高血压、糖尿病、高血脂、吸烟、饮酒、既往卒中、冠状动脉粥样性 心脏病以及入院时NIHSS评分、ADL评分方面比较差异无显著性（P＞0.05）。个体化治疗组AA及ADP 途径诱导的血小板抑制率中位数分别为93.2%（77.45%,98.35%）、50.4%（27.62%,67.25%）,阿 司匹林组AA途径及氯吡格雷组ADP诱导的血小板抑制率中位数分别为73.05%（40.8%,92.75%）、 20.5%（5.1%,53.5%）,个体化治疗组AA或ADP途径诱导血小板抑制率较阿司匹林组及氯吡格雷组 相比差异有显著性（P＜0.05）。个体化治疗组、阿司匹林组、氯吡格雷组三组患者入院第14天NIHSS 评分中位数分别为3（2,4）、3.5（3,4）、4（3,4）,ADL评分中位数分别为80（70,90）、75（70,85）、 70（65,85）;第3个月NIHSS评分中位数分别为2（2,3）、3（2,3）、3（2,3）,ADL评分中位数分别为90 （85,95）、87.5（80,90）、85（80,90）,三组间两两比较个体化治疗组优于阿司匹林组及氯吡格雷组 （P＜0.05）,阿司匹林组与氯吡格雷组比较差异无显著性（P ＞0.05）。随访3个月三组均无脑出血发 生,个体化治疗组有1例再发缺血性事件,阿司匹林组有3例、氯吡格雷组有4例再发缺血性事件。 结论 急性非心源性卒中患者急性期给予双抗治疗后根据TEG结果选择敏感抗血小板聚集药物能 提高患者临床预后,不增加出血风险。     

替格瑞洛在氯吡格雷抵抗的颅内动脉瘤病人介入术后的应用

目的 探讨替格瑞洛联合阿司匹林在氯吡格雷抵抗的颅内动脉瘤病人支架辅助栓塞术后的应用效果。方法 回顾性分析2014年1月至2021年12月收治的214例支架辅助栓塞治疗的颅内动脉瘤的临床资料。术后112例应用阿司匹林+氯吡格雷抗血小板治疗（A+C组）,102例应用阿司匹林+替格瑞洛抗血小板治疗（A+T组）。术后随访3个月,观察缺血事件和出血事件发生情况。结果 术后3个月,共发生缺血性事件37例（17.3%）,其中A+T组10例,A+C组27例;无严重出血事件,轻中度出血8例,其中A+T组5例,A+C组3例。A+T组脑梗死或短暂性脑缺血发作发生率（8.9%）明显低于A+C组（21.4%;P<0.05）,而两组出血事件发生率无统计学差异（P>0.05）。多因素Cox回归分析显示,高血压病（HR=1.18;95% CI 1.05~1.51;P=0.025）、年龄≥50岁（HR=1.23;95% CI 1.07~1.89;P=0.012）是术后缺血事件的独立危险因素,而基于血小板功能换用替格瑞洛（HR=0.57;95% CI 0.38~0.85;P=0.011）是术后缺血事件的保护因素。结论 颅内动脉瘤支架辅助栓塞术后应血栓弹力图检测结果合理选择抗血小板治疗药物。对于存在氯吡格雷抵抗的病人,建议更换为替格瑞洛,可显著降低术后缺血性卒中事件发生率。     

血小板活化状态检测在颅内动脉瘤支架置入术中的应用

目的探讨流式检测血小板活化状态对颅内动脉瘤支架置入术治疗的患者调整抗血小板药物的临床价值。方法对66例颅内动脉瘤患者行支架置入术治疗,术前给予常规抗血小板治疗[阿司匹林（100 mg,1次/d）＋氯吡格雷（75 mg,1次/d）]。利用流式细胞术方法监测血小板活化状态,血小板激活率〈20%,减少氯吡格雷药量;血小板激活率〉50%,增加氯吡格雷药量;血小板激活率为20%~50%,不调整药量。所有患者阿司匹林药量均不调整。结果氯吡格雷剂量未调整32例,调整为35 mg 6例、150 mg 26例、225 mg 1例,改用西洛他唑1例。药物调整后用药不当发生率（1.5%,1/66）较调整前（51.5%,34/66）明显降低（P〈0.05）。35例患者出院后随访1年,1例调整用药前即发生再缺血事件,调整用药方案后随访6个月未见再狭窄;4例药物调整前有明显的临床出血症状,调整用药方案后临床症状消失。结论流式细胞术是一种检测血小板活化状态有效的方法。流式检测结果对临床调整抗血小板药物治疗具有重要的指导作用。     

Prevalence of clopidogrel non-responders among patients with stable angina pectoris scheduled for elective coronary stent placement

Dual antiplatelet therapy with aspirin and clopidogrel decreases the rate of stent thrombosis in patients undergoing percutaneous coronary intervention (PCI). However, despite intensified antiplatelet treatment, up to 4.7% of the patients undergoing coronary stenting develop thrombotic stent occlusion, suggesting incomplete platelet inhibition due to clopidogrel resistance. We evaluated the percentage of clopidogrel non-responders among 105 patients with coronary artery disease (CAD) undergoing elective PCI. All patients were treated regularly with aspirin 100 mg/d and received a loading dose of 600 mg clopidogrel followed by a maintenance dose of 75 mg/d before PCI. Clopidogrel non-responders were defined by an inhibition of ADP (5 and 20 Mol/L) induced platelet aggregation that was less than 10% when compared to baseline values 4 h after clopidogrel intake. Semi-responders were identified by an inhibition of 10 to 29%. Patients with an inhibition over 30% were regarded as responders. We found that 5 (ADP 5 Mol/L) to 11% (ADP 20 Mol/L) of the patients were non-responders and 9 to 26% were semi-responders. Among the group of non-responders there were two incidents of subacute stent thrombosis after PCI. We conclude that a subgroup of patients undergoing PCI does not adequately respond to clopidogrel, which may correspond to the occurrence of thromboischemic complications. Point-of-care testing may help to identify these patients who may then benefit from an alternative antiplatelet therapy.     

Comparison of turbidimetric aggregation and in vitro bleeding time (PFA-100) for monitoring the platelet inhibitory profile of antiplatelet agents in patients undergoing stent implantation

The present study compared classical ADP-induced platelet aggregation vs. PFA-100 closure times using collagen/ADP membrane cartridges to monitor the degree of platelet-inhibiting effect of three drug regimens: ticlopidin, abciximab/ticlopidin and loading dose clopidogrel, each on top of aspirin (acetylsalicylic acid, ASA) during and after elective stent placement (intervention) in a total of 31 patients with acute coronary syndrome. Ticlopidin was started directly after stent implantation, abciximab was started before coronary intervention and given intravenously for 12 h, and a clopidogrel loading dose was given before intervention. The 10 patients treated with ticlopidin (500 mg daily) showed no significant prolongation of PFA closure times and a slight increase of ADP-induced platelet aggregation shortly after intervention. In 11 patients treated with abciximab/ticlopidin, the PFA closure times were significantly prolonged, and ADP-induced platelet aggregation was reduced by more than 80% during the 12-h abciximab infusion after intervention. The 10 patients pretreated with loading dose clopidogrel (450 mg followed by 75 mg daily) showed an intermediate but significant prolongation of PFA closure times and reduction of ADP-induced platelet aggregation at levels between the ticlopidin/aspirin- and the abciximab/ticlopidin/aspirin-treated groups. At 20 h after intervention, a similar degree of PFA closure time prolongation and inhibition of ADP-induced aggregation was observed in the abciximab/ticlopidin/aspirin- and the clopidogrel/aspirin-treated patient groups. Both measurement of PFA-100 closure times and inhibition of ADP-induced platelet aggregation showed a similar degree of platelet inhibition, but had rather broad SD ranges, which limit their precision for the follow-up of individual patients. In conclusion, abciximab on top of ticlopidin/aspirin showed a stronger antiplatelet effect for only less than 20 h, as compared to loading dose clopidogrel/aspirin in acute coronary syndrome patients undergoing stent implantation. Whether such a short-term superiority of abciximab, as compared to loading dose clopidogrel, translates into an overall clinical benefit of thombotic and bleeding complications remains to be established in a randomized clinical trial.     

Functional impact of high clopidogrel maintenance dosing in patients undergoing elective percutaneous coronary interventions. Results of a randomized study

The currently recommended maintenance dose of clopidogrel is often associated with inadequate platelet inhibition, suggesting the need for a higher dose. The aim of this pilot study was to assess the functional impact of a high (150 mg/day) maintenance dose of clopidogrel in patients undergoing elective percutaneous coronary intervention (PCI). This is a prospective, randomized, platelet function study which was performed in elective PCI patients assigned to treatment with either a 75 mg (n = 20) or 150 mg (n = 20) daily maintenance dose of clopidogrel for 30 days; afterwards, all patients resumed standard dosing. Platelet aggregation was performed using light transmittance aggregometry following 20 microM and 5 microM adenosine diphosphate (ADP) stimuli 30 days after randomization and 30 days after resuming standard dosing. Patients treated with 150 mg/day clopidogrel had lower 20 microM ADP-induced platelet aggregation compared to patients on 75 mg/day (52.1 +/- 9% vs. 64.0 +/- 8%; p < 0.001; primary endpoint). The dose-dependent effect was confirmed by the absolute and relative increase in platelet aggregation after resuming standard dosing (p < 0.001). No changes were observed in patients randomized to standard dosing. Parallel findings were observed following 5 microM ADP stimuli for all assessments. A broad variability in clopidogrel-induced antiplatelet effects was observed irrespective of dosing. In conclusion, a 150 mg/day maintenance dose regimen of clopidogrel is associated with reduced platelet reactivity and enhanced platelet inhibition compared to that achieved with the currently recommended 75 mg/day in patients undergoing elective PCI.     

Reduced thrombus cohesion in an ex vivo human model of arterial thrombosis induced by clopidogrel treatment: kinetics of the effect and influence of single and double loading-dose regimens

OBJECTIVE: To compare the effects of clopidogrel on ex vivo thrombogenesis with those on ADP-dependent platelet aggregation, and to compare single and double loading-dose regimens. METHODS AND RESULTS: Step 1: Volunteers (n=12) received clopidogrel 75 mg/day for 8 days. ADP-induced platelet aggregation was measured in platelet-rich plasma (PRP). Thrombogenesis was measured in an ex vivo model. Clopidogrel produced rapid platelet inhibition, increasing up to day 5. Maximal intensity of platelet aggregation correlated with density of platelet thrombus, surface of collagen covered by platelets and thrombus cross-sectional surface (p<0.001). Step 2: On day 1, volunteers (n=60) randomly received clopidogrel 75 mg, a single 300-mg loading dose or two 300-mg loading doses separated by a 12-h interval. On day 2, all volunteers received clopidogrel 75 mg. Both loading dose regimens enhanced platelet inhibition at all time points (p<0.03 vs. clopidogrel 75 mg). After 3 h, the antiplatelet effect of a loading dose was substantial, and the mean decrease in dense thrombus surface was greater in the loading-dose groups than in the 75 mg group (p=0.041 for the single loading dose). Ex vivo, there were no significant differences between loading-dose groups. CONCLUSIONS: Clopidogrel reduces arterial thrombus cohesion by an effect that correlates with inhibition of ADP-induced platelet aggregation. A single 300-mg loading dose provides a rapid onset of such an antithrombotic effect, which was more significant at 24 h with the double loading dose.     

Role of newly formed platelets in thrombus formation in rat after clopidogrel treatment: comparison to the reversible binding P2Y₁₂ antagonist ticagrelor

Platelet P2Y?? receptors play an important role in arterial thrombosis by stimulating thrombus growth. Both irreversibly (clopidogrel) and reversibly binding (ticagrelor, AZD6140) P2Y?? antagonists are clinically used for restricted periods, but possible differences in platelet function recovery after drug cessation have not been investigated. We treated WKY rats with a single, high dose of 200 mg/kg clopidogrel or 40 mg/kg ticagrelor. Blood was collected at different time points after treatment. Flow cytometry confirmed full platelet protection against ADP-induced αIIbβ? activation shortly after clopidogrel or ticagrelor treatment. At later time points after clopidogrel treatment, a subpopulation of juvenile platelets appeared that was fully responsive to ADP. Addition of ticagrelor to clopidogrel-treated blood reduced αIIbβ? activation of the unprotected platelets. In contrast, at later time points after ticagrelor treatment, all platelets gradually lost their protection against ADP activation. Perfusion experiments showed abolishment of thrombus formation shortly after clopidogrel or ticagrelor treatment. Thrombus formation on collagen was determined under high shear flow conditions. At later time points, large thrombi formed in the clopidogrel but not in the ticagrelor group, and unprotected, juvenile platelets preferentially incorporated into the formed thrombi. However, platelets from both groups were still similarly reduced in assays of whole blood aggregation. Conclusively, recovery of rat platelet function after ticagrelor differs mechanistically from that after clopidogrel. This difference is masked by conventional platelet aggregation methods, but is revealed by thrombus formation measurement under flow. Juvenile platelets formed at later time points after clopidogrel treatment promoted thrombus formation.     

阿司匹林抵抗的危险因素分析和临床干预

目的探讨脑梗死患者阿司匹林抵抗的危险因素,研究阿司匹林抵抗者抗血小板药物调整后阿司匹林抵抗的发生情况及预后。方法选取269例新发脑梗死患者,口服阿司匹林100 mg/d,经血栓弹力图筛选出阿司匹林抵抗者90例,分析其危险因素,并将其随机分为3组:A组口服阿司匹林200 mg/d;B组口服阿司匹林100 mg/d+氯吡格雷75 mg/d;C组口服阿司匹林100 mg/d。1 m后复测血栓弹力图,比较血小板抑制率的变化。随访12 m观察血管事件和死亡的发生情况。结果阿司匹林抵抗的发生率为33.5%。单因素分析显示,阿司匹林抵抗组(AR)与阿司匹林敏感组(AS)年龄比较差异有统计学意义(P=0.029);Logistic回归分析显示,年龄是脑梗死患者阿司匹林抵抗的危险因素(OR=1.026,95%CI 1.002 1.049,P=0.030)。A组和B组患者AA诱导的血小板抑制率明显升高(P0.05),且B组患者血小板抑制率升高更明显;C组患者AA诱导的血小板抑制率较前无明显改变(P0.05)。随访12 m后3组患者总体缺血性事件发生率比较差异有统计学意义(P=0.002),C组总体缺血性事件发生率明显高于A组和B组;3组患者出血性事件发生率比较差异无统计学意义(P0.05)。结论年龄是脑梗死患者阿司匹林抵抗的危险因素;阿司匹林加量或联合氯吡格雷治疗可以有效改善阿司匹林抵抗现象,并可减少或避免缺血性事件发生。     

The difference between clopidogrel responsiveness and posttreatment platelet reactivity

BACKGROUND: Aggregation is the most common measure of platelet reactivity. The relative inhibition of platelet aggregation between pretreatment and posttreatment is the most common estimate of clopidogrel responsiveness. However, patients responsive to clopidogrel may remain with highly reactive platelets and thus have increased thrombotic risk. METHODS: Platelet reactivity was determined by ADP-induced aggregation (%) in 62 patients undergoing elective coronary stenting at pretreatment and 5 days postprocedure. All patients were on aspirin (325 mg) and received 300 mg of clopidogrel immediately poststenting and 75 mg qd. Pretreatment reactivity was divided into tertiles. Based on clopidogrel drug responsiveness, nonresponders were defined as <10% relative inhibition of pretreatment aggregation, semiresponders as 10-30%, and responders as >30%. We determined the relation between clopidogrel responsiveness and platelet reactivity. RESULTS: Pretreatment reactivity tertiles by 5 microM ADP were: low (47+/-9%), moderate (64+/-4%), and high (78+/-6%). Eight patients were nonresponders, 18 were semiresponders, and 36 were responders. Clopidogrel responsiveness directly correlated with pretreatment reactivity, 86% of responders had moderate or high pretreatment reactivity, whereas 75% of nonresponders had low pretreatment reactivity. Despite being more responsive, 16% of patients with high pretreatment reactivity and 17% with moderate pretreatment reactivity remained with moderate posttreatment reactivity. CONCLUSION: Measuring clopidogrel responsiveness may overestimate the risk of stent thrombosis in nonresponders with low pretreatment reactivity and underestimate risk in those responders who remain with high posttreatment platelet reactivity. Posttreatment platelet reactivity is a better measure of thrombotic risk than responsiveness to clopidogrel.     

Effect of clopidogrel treatment on stress-induced platelet activation and myocardial ischemia in aspirin-treated patients with stable coronary artery disease

Stress may counteract responses to antiplatelet drug treatment. We investigated if adding clopidogrel to aspirin treatment could attenutate stress-induced platelet activation and myocardial ischemia in patients with coronary artery disease (CAD). Thirty-one male patients with documented CAD-treated with aspirin (75-160 mg daily) were randomized to co-treatment with clopidogrel (n = 16) or placebo (n = 15). A symptom-limited exercise test and 48-hour (h) Holter monitoring were performed before and after two weeks of double-blind treatment. Platelet function was assessed by flow cytometry and impedance aggregometry in whole blood. Exercise-induced and ambulatory ischemia was assessed from electrocardiographic (ECG) recordings. Clopidogrel treatment inhibited ADP-induced platelet P-selectin expression by 64% (22-87%), and attenuated the P-selectin response to thrombin (p < 0.001), and platelet aggregation induced by low-dose collagen (p < 0.01). Exercise ( approximately 110W) increased heart rate similarly, and caused approximately 1.8 mm ST-segment depression both before and after treatment. Exercise caused platelet activation, i.e. increased circulating activated single platelets and platelet-platelet aggregates, enhanced the in-vitro responsiveness to ADP or thrombin stimulation, and increased platelet-leukocyte aggregation. Clopidogrel inhibited ADP-induced platelet activation to a similar relative degree at rest and during exercise, but did not attenuate the platelet activating effect of exercise. Addition of clopidogrel to aspirin treatment did not attenuate either ambulatory or exercise-induced ischemia. In conclusion, adding clopidogrel to aspirin treatment inhibited platelet activation by both ADP, thrombin and collagen in vitro, but did not influence the prothrombotic responses to exercise. Intensified antiplatelet treatment did not reduce ECG signs of either exercise-induced or ambulatory myocardial ischemia.