Clinical importance of aspirin and clopidogrel resistance

Table 4 Clinical studies based on optical aggregometry combined with activation-dependent changes on the platelet surface or with vasodilator-stimulated phosphoprotein phosphorylation

Study	Method	Patient population	Dosage	Adjunct antiplatelet therapy	No. of patients (clopidogrel sensitive/clopidogrel resistant)	Outcome measures	Result
Bonello et al[103]	VASP phosphorylation	PCI	300 mg loading dose followed by 75 mg daily	100 mg aspirin	144 patients were divided into quintiles according to PRI	Cardiovascular events	Patients in quintile 1 of VASP analysis had a significantly lower risk of MACE as compared with those among the four higher quintiles (0 vs 21, P < 0.01)
Barragan et al[104]	VASP phosphorylation	PCI	Ticlopidin or clopidogrel	250 mg aspirin	36 (20 healthy volunteers and 16 stented patients)	Presence of stent thrombosis	VASP phosphorylation analysis may be useful for the detection of coronary SAT
Serebruany et al[105]	Optical aggregometry, and whole blood flow cytometry	AICS or ischaemic stroke	75 mg	81-325 mg aspirin	359 (359/0)		Lack of nonresponse
Gurbel et al[106]	Optical aggregometry, GP IIb/IIIa receptor, VASP phosphorylation	PCI	300-600 mg loading dose followed by 75 mg daily	No information	120 (20 patients with stent thrombosis and 120 patients without stent thrombosis	Stent thrombosis	The SAT patients had significantly higher mean platelet reactivity than those without SAT by all measurements
Cuisset et al[107]	Optical aggregometry, P-selectin	NSTEMI followed by PCI	300-600 mg loading dose followed by 75 mg daily	160 mg aspirin	106 (94 patients without and 12 with cardiovascular event)	Cardiovascular event	Low responders to dual antiplatelet therapy had increased risk of recurrent CV events
Cuisset et al[108]	Optical aggregometry, P-selectin	NSTEMI followed by PCI	300-600 mg loading dose followed by 75 mg daily	160 mg aspirin	392 (146 patients with 300 mg loading dose clopidogrel and 300 patients with 600 mg loading dose of clopidogrel)	Cardiovascular event	The ADP-induced platelet aggregation and expression of P-selectin were significantly lower in patients receiving 600 mg than in those receiving 300 mg. During the 1-mo follow-up, 18 CV events (12%) occurred in the 300-mg group vs 7 (5%) in the 600-mg group (P = 0.02); this difference was not affected by adjustment for conventional CV risk factors (P = 0.035)

VASP: Vasodilator-stimulated phosphoprotein; GP: Glycoprotein; ADP: Adenosine diphosphate.