阿托伐他汀对氯吡格雷抗血小板活性影响的研究

目的:观察阿托伐他汀对氯吡格雷抗血小板活性的影响。方法:29例急性冠脉综合征(ACS)病人被随机分入阿托伐他汀组(n=10)、普伐他汀组(n=9)和对照组(n=10),每组病人均接受阿斯匹林(ASA)、氯吡格雷和低分子量肝素(LMWH)治疗。采用流式细胞仪检测血小板活化指标。结果:治疗3d后,三组血小板活化指标PAC-1和CD62P较治疗前均明显降低,P均<0.05;各组上述两个指标的下降值两两比较均无明显差异,P均>0.05。结论:经细胞色素P4503A4(CYP3A4)途径代谢的阿托伐他汀不抑制氯吡格雷的抗血小板活性。     

阿托伐他汀与氯吡格雷对ACS患者氯吡格雷羧酸衍生物血浓度与血小板聚集率的影响

目的:测定急性冠状动脉综合征(ACS)患者氯吡格雷羧酸衍生物血浓度和血小板聚集率,观察阿托伐他汀和氯吡格雷有无相互作用。方法:对照组为25例健康受试者,ACS组为66例ACS患者。均口服阿司匹林100mg/d、氯吡格雷75mg/d、阿托伐他汀20mg/d,5d后暂停阿托伐他汀,继续氯吡格雷和阿司匹林口服4d,分别于第5天、第9天采用液相色谱串联质谱法测量氯吡格雷羧酸衍生物血浓度,流式细胞仪测定血小板聚集率,比较两组差异。结果:对照组第5天和第9天氯吡格雷羧酸衍生物血浓度分别为(5.76±0.87)ng/dl和(5.67±0.88)ng/dl(P=0.351),血小板聚集率分别为(44.25±16.37)%与(47.61±16.67)%(P=0.083)。ACS组第5天和第9天氯吡格雷羧酸衍生物血浓度分别为(5.96±0.87)ng/dl和(5.86±0.97)ng/dl(P=0.115),血小板聚集率分别为(47.70±15.07)%与(47.02±15.45)%(P=0.622)。相关性分析显示,血氯吡格雷羧酸衍生物浓度和血小板聚集率呈正相关。结论:氯吡格雷羧酸衍生物血浓度和血小板聚集率相关性良好,氯吡格雷和阿托伐他汀未见相互作用。     

瑞舒伐他汀和阿托伐他汀对氯吡格雷抗血小板活性的影响

目的观察瑞舒伐他汀和阿托伐他汀对氯吡格雷抗血小板活性的影响。方法选择60例冠心病患者接受阿司匹林100mg/d、氯吡格雷75 mg/d及低分子肝素5000 U/12 h治疗,5 d后随机分为阿托伐他汀20mg/d(阿托伐他汀组,30例)和瑞舒伐他汀10 mg/d(瑞舒伐他汀组,30例)。在服用氯吡格雷之前(基线值)、加用他汀类药物之前及服用他汀类药物3d后,用全血阻抗法分别测定不同浓度二磷酸腺苷(5、10、20μmol/L)诱导的血小板聚集率。结果与基线值比较,服用氯吡格雷5 d后和加服他汀类药物治疗3 d后,2组患者血小板聚集率明显降低,差异有统计学意义(P<0.05);与治疗前比较,阿托伐他汀组患者血小板聚集率有所升高,而瑞舒伐他汀组患者血小板聚集率有所下降,但差异无统计学意义(P>0.05)。结论经细胞色素3A4途径代谢的阿托伐他汀及不经细胞色素3A4代谢的瑞舒伐他汀,短期内对氯吡格雷抗血小板活性无影响。     

冠脉支架术后阿托伐他汀联用氯吡格雷两药相互作用的随访研究

目的研究在冠脉支架术后随访患者中不同剂量的阿托伐他汀与氯吡格雷长期联用产生的药物相互影响。方法105例冠心病患者,入院第2天随机服用阿托伐他汀和普伐他汀,66例行PC I术者入院当日加服氯吡格雷。共分为5组,A组23例,阿托伐他汀20 mg/d+氯吡格雷,B组20例,阿托伐他汀40 mg/d+氯吡格雷,C组23例,普伐他汀20 mg/d+氯吡格雷,D组20例,单用阿托伐他汀20 mg/d,E组19例,单用阿托伐他汀40 mg/d。分别在入院第1天及出院随访1、3月测定A、B、C组患者的血小板功能指标,并进行比较,测定各组的血脂等指标,分别比较A和D组、B和E组血脂等指标的差异。结果各组患者临床特征基线资料比较,差异无统计学意义;A、B、C组患者首次及随访1、3月测定的血小板功能指标CD62P、CD63、MPAR,组间差异无统计学意义,3组中各指标1、3月比基线均略有所下降（P<0.05）,但1月和3月比较差异无统计学意义,CD62P、CD63、MPAR互为正相关（P<0.05）;A和D组、B和E组在首次及治疗1、3月后相比较,血脂等在两对应组间差异均无统计学意义。结论冠脉支架术后40 mg/d以下的阿托伐他汀与常规剂量氯吡格雷较长时间联用,两药之间相互无明显影响,合用是安全的。     

氯吡格雷和他汀联用对急性冠脉综合征患者临床观察

目的探讨急性冠脉综合征患者氯吡格雷和不同他汀联用在短期内对血小板聚集的影响,并观察对PCI术后心肌损伤以及临床事件的影响。方法60名ACS患者随机分为氯吡格雷和阿托伐他汀(10mgqd)组(30例)以及氯吡格雷和氟伐他汀(40mgqd)组(30例),分别测定联合用药前、用药后24小时、1周血小板聚集率,PCI术后24小时测定心肌损伤标志物,观察术后1周、半年临床心血管事件。结果两组联合用药24小时、1周血小板聚集率无统计学差异(P>0.05),PCI术后心肌损伤标志物未显著升高,两组导致不良心血管事件发生无统计学差异。结论ACS患者常规用量阿托伐他汀、氟伐他汀与氯吡格雷联合应用是安全、有效的,对氯吡格雷的抗血小板作用未见影响。     

氯吡格雷联合阿托伐他汀用于冠心病PCI术后的临床效果研究

目的探讨氯吡格雷联合阿托伐他汀用于冠脉支架术后冠心病患者的临床效果。方法选取2015年2月到2017年2月在我院成功实施冠脉支架术的冠心病患者120例,根据随机分组的方式分为对照组和实验组,两组均有60例患者。对照组患者药物治疗使用氯吡格雷+阿司匹林,实验组患者药物治疗使用氯吡格雷+阿司匹林+阿托伐他汀。接受治疗后,比较两组的心血管事件(Major Adverse Cardial and Cerebral Events,MACCE)发生率、亚急性支架内血栓(Subacute Instent Thrombosia,SAT)发生率以及出血率。结果经过治疗后,实验组患者的心血管事件发生率以及亚急性支架内血栓发生率低于对照组患者,结果对比差异显著,具有统计学意义,P0.05。结论氯吡格雷联合阿托伐他汀用于冠脉支架术后冠心病患者可以有效降低心血管事件和亚急性支架内血栓的发生率,临床效果显著,值得在临床上推广应用。     

阿托伐他汀可以消弱氯吡格雷抗血小板聚集的能力

氯吡格雷 (Clopidogrel)是一种无活性的前体药物 ,需要在肝脏内转化成活性物质 ,并通过与血小板P2YacADP受体结合而发挥其抗血小板聚集的作用。而氯吡格雷在人体肝内活性转化的机制 ,目前仍不清楚。在用一种新型的床旁血小板聚集度计测定氯吡格雷对血小板的功能影响时 ,该文的作者发现当患者同时服用阿托伐他汀 (Atorvastatin)时 ,氯吡格雷的抗血小板聚集作用就会显著降低。由于阿托伐他汀通过肝内的CyP3 A4酶代谢 ,因此该文的作者推测 ,阿托伐他汀可能抑制氯吡格雷通过P45 0CyP3 A4酶进行活性转化这一过程 ,从而消弱氯吡格雷抗血小板…     

阿托伐他汀联合氯吡格雷对急性冠脉综合征血小板聚集率的影响

目的:探讨急性冠脉综合征(ACS)患者急性期负荷剂量氯吡格雷联合阿托伐他汀或普伐他汀对血小板聚集率和主要不良心血管事件发生率的影响。方法:102例ACS患者被随机分成两组:普伐他汀组(P组)和阿托伐他汀组(A组),两组均予氯吡格雷300mg顿服后,75mg/d维持。P组予普伐他汀。入院后24h内和第14天分别测定TC、HDL-C、LDL-C、血小板聚集率(PAR)、肝功能,并统计两组主要不良心血管事件的发生率。结果:(1)两组TC、HDL-C、LDL-C水平在基础状态和第14d,差异无显著性(P>0.05);(2)P组或A组PAR在治疗后和基线相比,差异有显著性(P<0.05);但P、A两组在治疗后相比,差异无显著性(P>0.05);(3)心血管死亡、再发心肌梗塞复合终点发生率在两组间差异无显著性(P>0.05)。结论:阿托伐他汀或普伐他汀与负荷剂量氯吡格雷联合治疗急性冠脉综合征安全有效,两组效果相似,无显著差异。     

阿托伐他汀或瑞舒伐他汀与氯吡格雷合用在非ST段抬高型急性冠状动脉综合征患者支架置入术后的近期疗效比较

目的比较阿托伐他汀或瑞舒伐他汀与氯吡格雷合用在非ST段抬高型急性冠状动脉综合征(NSTE-ACS)支架置入术后患者的近期疗效。方法共154例NSTE-ACS的患者接受支架置入术后,随机分为服用阿托伐他汀组(74例)及服用瑞舒伐他汀组(80例),术前服用阿司匹林(100mg)5 d、氯吡格雷(75 mg)5 d以上或术前12 h以上顿服氯吡格雷300 mg及阿司匹林片300 mg,于术前服抗血小板药前、手术当天、术后3、7 d及术后1、6个月抽取静脉血测定二磷酸腺苷(ADP)(浓度为10μmol/L)诱导的血小板聚集功能,观察住院期间及6个月的主要不良心脏事件(MACE)。结果两组患者的临床基线资料及服药情况差异无统计学意义,服用氯吡格雷(75 mg)5 d或顿服300 mg能达到明显的血小板聚集率抑制作用,血小板聚集率在阿托伐他汀组由基线的(57.2±10.3)%降至手术当日的(32.5±11.2)%,而瑞舒伐他汀组分别为(59.1±9.8)%和(30.4±10.1)%(均为P<0.01),而且这种抑制作用稳定持续至6个月之后。6个月时两组间总的MACE发生率差异无统计学意义(13.0%比15.0%,P>0.05),两组心原性死亡、非致死性心肌梗死、靶血管重建术、支架内血栓形成及出血事件差异均无统计学意义(均为P>0.05)。结论接受冠脉支架置入术的NSTE-ACS患者,服用阿托伐他汀或瑞舒伐他汀后,短期内未发现对氯吡格雷抗血小板作用产生显著影响,且两组间的近期疗效相近。     

高龄老年冠心病患者抗血小板药物使用及效果

目的分析高龄老年冠状动脉粥样硬化性心脏病(冠心病)患者服用抗血小板药物情况及治疗效果。方法回顾性纳入2013年6月至2014年12月间在北京军区总医院干四科住院治疗的高龄老年(年龄≥75岁)冠心病患者75例,分为双联抗血小板组(n=32)、单用阿司匹林组(n=16)、单用氯吡格雷组(n=12)及未服用抗血小板药物组(n=15)。比较双联抗血小板组、阿司匹林组、氯吡格雷组患者凝血功能及血栓弹力图指标。结果 75例高龄老年冠心病患者中双联抗血小板占42.7%,单用阿司匹林占21.3%,单用氯吡格雷占16.0%,未服用抗血小板药物占20.0%。双联抗血小板组、阿司匹林组、氯吡格雷组3组患者在年龄、性别构成、常规凝血指标及血小板计数方面无统计学差异(P0.05)。97.9%服用阿司匹林治疗者花生四烯酸(AA)诱导的血小板聚集抑制率(IRAA)50%,70.5%服用氯吡格雷治疗者二磷酸腺苷(ADP)诱导的血小板聚集抑制率(IRADP)≥30%。双联抗血小板组、阿司匹林组、氯吡格雷组3组患者R、K、Angle、MA值水平无统计学差异(P0.05),MAADP、IRADP、IRAA存在统计学差异(P0.05),双联抗血小板组MAADP显著低于阿司匹林组及氯吡格雷组(P0.05),IRADP显著高于阿司匹林组及氯吡格雷组(P0.05),氯吡格雷组IRAA显著低于双联抗血小板组及阿司匹林组(P0.05)。结论高龄老年冠心病患者抗血小板药物使用率较高,阿司匹林与氯吡格雷均获得较好的抗血小板疗效,但阿司匹林反应低下的发生率明显低于氯吡格雷。     

Multiple antiplatelet effects of clopidogrel are not modulated by statin type in patients undergoing percutaneous coronary intervention

We investigated whether statin type or dose influenced the inhibition of platelet function induced by clopidogrel in a prospective, open, parallel group study in patients undergoing elective percutaneous coronary intervention. Patients were taking CYP3A4 metabolised atorvastatin (n = 20) or simvastatin (n = 21), non-CYP3A4 metabolised pravastatin (n = 11) or fluvastatin (n = 2), or no statin therapy (n = 5). ADP and TRAP-induced platelet aggregation were measured using optical aggregometry, whole-blood single-platelet counting, and the Ultegra and Plateletworks point-of-care systems. Platelet pro-coagulant activity (annexin V binding and microparticle formation), P-selectin expression and platelet-leukocyte conjugate formation were assessed by flow cytometry. Platelet responses were measured at baseline, 4 h post clopidogrel 300 mg, and after 10 and 28 days with clopidogrel 75 mg daily. Clopidogrel significantly inhibited both ADP and TRAP-induced platelet responses over time, with steady state inhibition achieved by day 10. This was demonstrated by all techniques used. There was no significant effect of statin type or dose on platelet responses by any method at any time-point. In conclusion, statins do not influence the inhibitory effects of clopidogrel on multiple platelet responses, including aggregation, P-selectin expression, platelet-leucocyte conjugate formation and pro-coagulant responses, in patients undergoing elective PCI.     

Effect of atorvastatin and pravastatin on platelet inhibition by aspirin and clopidogrel treatment in patients with coronary stent thrombosis

We sought to determine a potential interaction between statins and antiplatelet therapy with aspirin and clopidogrel. Previous laboratory studies have shown a possible drug-drug interaction of statins metabolized by cytochrome P450 3A4 and clopidogrel (prodrug metabolized by cytochrome P450 3A4), resulting in an impaired inhibitory effect of clopidogrel on platelet aggregation. However, conclusive prospective data assessing this potentially relevant interaction are lacking. In 73 patients, 23 with previous coronary stent thrombosis (ST) (ST group) and 50 without coronary ST (control group), platelet aggregation was measured 3 times in monthly intervals using light transmission aggregometry (adenosine diphosphate [ADP] and arachidonic acid induction). Measurements were carried out with aspirin monotherapy (100 mg/day), dual antiplatelet therapy with aspirin plus clopidogrel (75 mg/day), and additional treatment of 20 mg/day of atorvastatin or 40 mg/day of pravastatin. ADP (5 and 20 micromol)-induced platelet aggregation was significantly decreased with clopidogrel (p <0.001) but remained stable under additional treatment with atorvastatin or pravastatin in the 2 groups. Patients with previous ST showed a higher ADP-induced aggregation level than control subjects. This difference was not influenced by clopidogrel or statin treatment. In conclusion, patients with previous ST show a higher aggregation level than control subjects independent of statin treatment. Atorvastatin and pravastatin do not interfere with the antiaggregatory effect of aspirin and clopidogrel. In conclusion, drug-drug interaction between dual antiplatelet therapy and atorvastatin or pravastatin seems not to be associated with ST.     

急性冠状动脉综合征冠状动脉支架术后应用他汀类药物对氯吡格雷抗血小板作用无影响

目的探讨急性冠状动脉综合征（ACS）患者行冠状动脉支架术后服用阿托伐他汀或普伐他汀对氯吡格雷抗血小板作用的影响。方法研究对象为150例2006年4至12月成功实施冠状动脉支架术的住院ACS患者,术后第1天起随机接受阿托伐他汀20mg／d（n=50）、普伐他汀20mg／d（／7,=50）或无他汀（n=50）治疗。围术期抗血小板治疗为阿司匹林300mg／d,当天氯吡格雷负荷量300mg,继以维持量75mg／d。观测各组患者术后第1天（基线值）及第3天的血小板膜糖蛋白P-选择素（CD62P）、血小板活化复合物（PAC-1）表达及20μmol／L二磷酸腺苷（ADP）诱导的血小板最大聚集率（MPAR）。结果三组患者临床及CD62P、PAC-1和MPAR的基线值差异均无统计学意义。各观测指标第二次测定值与基线值的差值显示,阿托伐他汀、普伐他汀和无他汀组的ACD62P[（4．69±16．78）％、（1．35±10．86）％和（2．97±10．21）％]、APAC-1[（12．78±22．07）％、（8．01±21．23）％和（10．65±21．39）％l及AMPAR[（5．44±18．68）％、（7．15±19．59）％和（3．76±23．42）％]差异均无统计学意义（P〉0．05）。急性心肌梗死患者亚组分析结果表明,ACD62P[（7．50±19．35）％、（3．24±11．18）％和（2．53±8．87）％]、APAC-1[（13．40±24．62）％、（11．28±19．90）％和（10．11±21．29）％]及AMPAR[（7．56±19．11）％、（7．87±23．60）％和（6．75±23．30）％]三组间差异亦均无统计学意义（P〉0．05）。结论接受冠状动脉支架术的ACS患者服用阿托伐他汀或普伐他汀后,短期内未发现对氯吡格雷的抗血小板作用产生显著影响。     

强化他汀治疗对急性冠脉综合征行介入治疗患者的疗效与安全性

目的观察强化他汀治疗对于急性冠脉综合征（ACS）患者介入治疗术后的疗效及安全性。方法纳入2010年1月~2011年6月于中国医科大学第一附属医院心血管内接受介入治疗的ACS患者239例,随机分为常规治疗组（n=119）和强化治疗组（n=120）,常规治疗组予阿托伐他汀20 mg（qN）,强化治疗组入院采血后即刻予阿托伐他汀80mg口服,后予阿托伐他汀40mg（qN）维持治疗。比较两组治疗前、治疗后第7天和治疗后1个月血脂[包括胆固醇（TC）、低密度脂蛋白（LDL-C）]、谷丙转氨酶（ALT）、肌酐（Cr）、高敏C反应蛋白（hs-CRP）、ADP诱导的血小板聚集率及治疗后1个月内主要心血管不良事件（MACE,包括心肌梗死后心绞痛、心力衰竭、再发心肌梗死、心源性死亡）。结果两组治疗后TC、LDL-C、hs-CRP均较治疗前下降,且随时间延长而下降,其中强化治疗组下降更为明显,两组间差异有统计学意义（P＜0.05）;但血浆ALT、Cr、血小板聚集率和氯吡格雷抵抗发生率无改变（P＞0.05）;强化治疗组心绞痛复发率和心力衰竭发生率低于常规治疗组（心绞痛：15.0%vs.26.9%;心力衰竭：9.2%vs.18.5%,P＜0.05）,但两组再发心肌梗死及心源性死亡率无统计学差异（P＞0.05）。结论ACS患者接受介入治疗术后早期服用大剂量的阿托伐他汀可进一步降低血脂水平,减少不良心脏事件发生率,且不影响抗血小板药物的作用强度。     

The inhibitory potency of clopidogrel on ADP-induced platelet activation is not attenuated when it is co-administered with atorvastatin (20 mg/day) for 5 weeks in patients with acute coronary syndromes

The antiplatelet potency of clopidogrel may be attenuated by short-term co-administration of lipophilic statins metabolized through the cytochrome P-450, isoform 3A4. We investigated whether the co-administration of atorvastatin (20?mg/day) for 5 weeks, in patients with acute coronary syndromes (ACS) could affect the antiplatelet activity of clopidogrel. Fifty-one patients with the first episode of an ACS were included in the study. All patients underwent percutaneous coronary intervention (PCI) and received a loading dose of 375 mg of clopidogrel, followed by 75 mg/day for at least 3 months. Twenty-six of them presented with low density lipoprotein (LDL) cholesterol levels >100?mg/dl (2.6 mmol/l) (measured within 24 h from the onset of symptoms) and received daily 20 mg/day of atorvastatin. The ADP- or TRAP-induced platelet aggregation, as well as P-selectin and CD40L surface expression, were studied at baseline (within 30 min after admission) and 5 weeks afterwards. Atorvastatin did not influence either the clopidogrel-induced inhibition of platelet aggregation initiated by 5 or 10 microM ADP or the clopidogrel-induced reduction of the membrane expression of P-selectin and CD40L induced by ADP. In conclusion, atorvastatin, even at a dose of 20 mg/day does not affect the antiplatelet efficacy of clopidogrel when co-administered for 5 weeks in ACS patients.     

Markers of inflammation and platelet aggregation in patients with non ST elevation acute coronary syndrome treated with atorvastatin or pravastatin

AIM: To find out whether early use of atorvastatin and pravastatin in patients with non-ST elevation acute coronary syndrome is associated with rapid changes of platelet aggregation and plasma levels of markers of inflammation. MATERIAL AND METHODS: Ninety patients (<24h from pain onset, age 64+/-10 years) treated with aspirin and heparin were randomized to open atorvastatin 10 mg/day (n=30), atorvastatin 40 mg/day (n=29) or pravastatin 40 mg/day (n=31). Spontaneous and ADP induced platelet aggregation (light transmission), plasma levels of interleukin 6 (IL-6) and C-reactive protein (CRP) (immunoassay) were assessed at baseline, on days 7 and 14. RESULTS: Baseline clinical characteristics, platelet aggregation parameters, CRP and IL-6 levels were similar in all groups. In all groups levels of total and low-density lipoprotein (LDL) cholesterol (CH) were lowered by days 7 (p<0.01) and 14 (p<0.01 vs. baseline and for both atorvastatin groups vs. day 7). Spontaneous platelet aggregation decreased by 15% from baseline, p<0.01, on day 14 in patients receiving atorvastatin 40 and was unchanged in other groups. Changes of ADP induced platelet aggregation, IL-6 and CRP levels were not significant in all groups. However combination of 2 atorvastatin groups (n=59) revealed decrease of CRP by 18% from baseline on day 14 (from 6.94+/-0.97 to 4.76+/-0.76 mg/l, p=0.028). No correlations were found between changes of LDL CH and those of other parameters. CONCLUSION: In otherwise conventionally treated patients with non-ST elevation acute coronary syndrome early use of atorvastatin was associated with rapid (in 14 days) decrease of CRP level. Higher dose of atorvastatin (40 mg/day) induced favorable changes of spontaneous platelet aggregation. There were no significant changes of parameters studied in pravastatin treated patients.     

国产和进口氯吡格雷对经皮冠状动脉介入术后血小板功能的影响

目的观察国产氯吡格雷和进口氯吡格雷对冠心病患者经皮冠状动脉介入治疗(PCI)术后血小板功能的影响。方法将450例冠心病患者随机分为2组,其中国产氯吡格雷组230例,进口氯吡格雷组220例。另选健康对照组220例。两治疗组分别于PCI术前3天开始服用氯吡格雷,服用氯吡格雷前、PCI术前、术后10min及PCI术后1周检查血小板聚集率及血小板活化指标。结果冠心病患者血小板聚集率及血小板活化状态较健康对照组明显增高。治疗前国产和进口氯吡格雷组的血小板聚集率及血小板活化指标差异无统计学意义。两治疗组PCI术后10min血小板聚集率及血小板活化状态均较术前明显增高,PCI术后1周两治疗组之间差异无统计学意义。结论PCI术后血小板聚集率及血小板活化状态明显增高,国产和进口氯吡格雷均有良好的抗血小板作用,两者抗血小板聚集和活化的作用相似。     

Impact of angina class on inhibition of platelet aggregation following clopidogrel loading in patients undergoing coronary intervention: Do we need more aggressive dosing regimens in unstable angina?

Pretreatment with thienopyridines has been shown to improve clinical outcomes in patients undergoing percutaneous coronary intervention (PCI). We determine the impact of angina class on inhibition of platelet aggregation (IPA) following clopidogrel loading. Seventy-two patients (mean age, 64 +/- 11 years; 76% male) were pretreated with 450 mg of clopidogrel at least 3 hr prior to PCI. All patients received ASA 325 mg prior to the procedure. Patients were classified into two groups according to angina class: group 1 = stable angina or Braunwald class 1 unstable angina (UA; n = 33); group 2 = Braunwald class 2 or 3 UA (n = 39). IPA was measured prior to PCI, with the Ichor point-of-care platelet analyzer (Helena Laboratories, Beaumont, TX), using 20 microM of ADP. Group 2 patients were more likely to have prior MI (54% vs. 27%; P = 0.023), prior CABG (33% vs. 5%; P = 0.046), and received IV heparin (64% vs. 27%; P = 0.0018). Mean IPA was significantly lower in group 2 compared to group 1 (19% +/- 22% vs. 32% +/- 22%; P = 0.004). In multivariate analysis, higher angina class was independently associated with lower IPA (P = 0.018). Patients with UA undergoing PCI have a lower IPA following clopidogrel loading with 450 mg. This may indicate the possibility of clopidogrel resistance in such patients.     

Platelet function in clopidogrel-treated patients with acute coronary syndrome.

Percutaneous coronary intervention (PCI) in patients presenting with acute coronary syndrome (ACS) is associated with increased risk of thrombotic complications. ACS enhances platelet activation; whether pretreatment with clopidogrel is sufficient to suppress platelet function in patients with ACS is not known. This study assessed platelet function in patients with and without ACS prior to PCI and after pretreatment with a single dose of 600 mg clopidogrel. Blood samples of 402 patients prior to PCI with (n = 119) or without (n = 283) ACS were collected at least 2 h after 600 mg clopidogrel administration. Maximal platelet aggregation in response to ADP (5 and 20 micromol/l), collagen (4 microg/ml) and TRAP (25 micromol/l) was measured with optical aggregometry. Surface expression of glycoprotein IIb/IIIa and P-selectin was assessed with flow cytometry at baseline and after stimulation with 5 and 20 micromol/l ADP. Agonist-induced platelet aggregation did not differ significantly between patients with and without ACS (P > or = 0.15). Parameters of platelet activation (glycoprotein IIb/IIIa and P-selectin surface expression) were significantly higher in ACS patients at baseline and after 5 and 20 micromol/l ADP stimulation (P < 0.0001). Patients with ACS continue to exhibit increased platelet activation after pretreatment with 600 mg clopidogrel. This finding supports the need for additional platelet function inhibition during PCI in patients with ACS.