Clinical importance of aspirin and clopidogrel resistance

Table 2 Clinical studies based on optical aggregometry

Study	Method	Patient population	Dosage	Adjunct antiplatelet therapy	No. of patients (clopidogrel sensitive/clopidogrel resistant)	Outcome measures	Result
Geisler et al[96]	Optical aggregometry	PCI	600 mg	No	363 (341/22)	Cardiovascular event within a 3-mo follow-up	Low responder had a significantly higher risk of major cardiovascular events (22.7 vs 5.6%, OR, 4.9, 95% CI: 1.66–14.96, P = 0.004)
Buonamici et al[97]	Optical aggregometry	PCI	Loading dose of clopidogrel followed by 75 mg daily	GP IIb/IIIa inhibitor, 325 mg aspirin	804 (699/105)	Stent thrombosis during a 6-mo follow-up	The predictors of stent thrombosis was: nonresponsiveness to clopidogrel (HR 3.08, 95% CI: 1.32-7.16, P = 0.009)
Müller et al[98]	Optical aggregometry	PCI	600 mg loading dose followed by 75 mg daily	100 mg aspirin	105 (90/15)		Their data showed that 5 patients who developed a stent thrombosis were non-responders
Wenaweser et al[99]	Optical aggregometry	PCI	300 mg loading dose followed by 75 mg daily	100 mg aspirin	82 (60/21)	Presence of stent thrombosis	Combined ASA and clopidogrel resistance was more prevalent in patients with stent thrombosis (52%) compared with controls (38%, P = NS) and volunteers (11%, P < 0.05)
Soffer et al[100]	Optical aggregometry	PCI	450 mg clopidogrel before the procedure	325 mg aspirin	72 (divided into two groups based on angina classification)	Angina class	In multivariate analysis, higher angina class was independently associated with lower inhibition of platelet aggregation (P = 0.018)
Buonamici et al[97]	Optical aggregometry	PCI	600 mg loading dose followed by 75 mg daily	GP IIb/IIIa inhibitor, 325 mg aspirin	804 (699/105)	Stent thrombosis	The incidence of stent thrombosis was 8.6% in nonresponders and 2.3% in responders (P < 0.001)

ASA: Acetylsalicylic acid; GP: Glycoprotein; NS: Not significant.