[[Clopidogrel]] resistance is a condition in which the drug clopidogrel is less effective than normal in people who are treated with it. 
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Kim et al. from the [[Asan Medical Center]] [[retrospective]]ly analyzed the [[data]] of 427 [[patient]]s with [[unruptured intracranial aneurysm]]s who underwent [[endovascular treatment]] between July [[2011]] and June [[2014]]. When [[clopidogrel]] resistance was confirmed via [[platelet reactivity unit]] (PRU) assay after [[dual antiplatelet therapy]] ([[aspirin]] plus [[clopidogrel]]) administration for 5 days, triple [[antiplatelet]] therapy with [[cilostazol]] was administered (Group I, 274 patients). The other group was placed on standard [[dual antiplatelet therapy]] (Group II, 153 patients). All patients underwent magnetic resonance [[diffusion-weighted imaging]] within 2 days after [[endovascular coiling]].

No significant associations with the occurrence of a [[thromboembolic event]] and microembolic event were found between the groups. The occurrence of thromboembolic and microembolic events showed no statistical difference between groups I and II (p = 0.725 for thromboembolic events and p = 0.109 for microembolic events). Also, the PRU value and the occurrence of microembolic events, using a PRU cutoff value of 240, showed no statistical difference (p = 0.114 in group I and 0.064 in group II). There was significant increase in microembolic events after the use of a stent-assisted endovascular procedure. As the PRU value increased, there was a trend toward an increase in the mean number of microembolic lesions without statistical significance.

Even though there is a presumed anti-thromboembolic effect for [[clopidogrel resistance]] in other literature, the clinical efficacy of adjustment of additional [[cilostazol]] for endovascular [[coiling]] of [[unruptured aneurysm]]s may be limited due to the unspecified cutoff value of the PRU assay for evaluating the resistance
((Kim GJ, Heo Y, Moon EJ, Park W, Ahn JS, Lee DH, Park JC. [[Thromboembolic event]]s during [[endovascular coiling]] for [[unruptured intracranial aneurysm]]s: Clinical significance of [[platelet reactivity unit]] and adjunctive [[cilostazol]]. Clin Neurol Neurosurg. 2022 Jan 15;213:107133. doi: 10.1016/j.clineuro.2022.107133. Epub ahead of print. PMID: 35065532.)).