Proteinuria Predicts Resistance to Antiplatelet Therapy in Ischemic Stroke

Biomarkers for Antiplatelet Therapies in Acute Ischemic Stroke: A Clinical Review

Stroke is one of the world's leading causes of disability and death. Antiplatelet agents are administered to acute ischemic stroke patients as secondary prevention. Clopidogrel involves biotransformation by cytochrome P450 (CYP) enzymes into an active metabolite, and single nucleotide polymorphisms (SNPs) can influence the efficacy of this biotransformation. Despite the therapeutic advantages of aspirin, there is significant inter-individual heterogeneity in response to this antiplatelet drug. In this clinical review, the recent advances in the biomarkers of antiplatelet agents in acute ischemic stroke are discussed. The studies reviewed herein highlight the clinical relevance of antiplatelet resistance, pharmacotherapy of antiplatelet agents predicting drug response, strategies for identifying aspirin resistance, pharmacogenetic variants of antiplatelet agents, miRNAs, and extracellular vesicles (EVs) as biomarkers toward the personalized approach in the management of acute ischemic stroke. The precise pathways contributing to antiplatelet resistance are not very well known but are presumably multi-factorial. It is essential to understand the clinical relevance of clopidogrel and aspirin-related single nucleotide polymorphism (SNPs) as potential predictive and prognostic biomarkers. Prasugrel is a next-generation antiplatelet agent that prevents ADP-platelet activation by binding irreversibly to P2Y12 receptor. There are sporadic reports of prasugrel resistance and polymorphisms in the Platelet endothelial aggregation receptor-1 (PEAR1) that may contribute to a change in the pharmacodynamics response. Ticagrelor, a direct-acting P2Y12-receptor antagonist, is easily absorbed and partly metabolized to major AR-C124910XX metabolite (ARC). Ticagrelor's primary active metabolite, ARC124910XX (ARC), is formed via the most abundant hepatic cytochrome P450 (CYP) enzyme, CYP3A4, and CYP3A5. The integration of specific biomarkers, genotype as well as phenotype-related data in antiplatelet therapy stratification in patients with acute ischemic stroke will be of great clinical significance and could be used as a guiding tool for more effective, personalized therapy.

Periprocedural Variability of Platelet Functions in Carotid Artery Stenting: An Analysis Using VerifyNow

Objective

The assessment of platelet functions is necessary to prevent both thromboembolic and hemorrhagic complications under dual antiplatelet therapy (DAPT). Using the VerifyNow (Accumetrics, Inc., San Diego, CA, USA) assay, this study aimed to reveal time-dependent changes in platelet functions after carotid artery stenting (CAS).

Methods

We enrolled retrospectively 43 patients who underwent CAS under DAPT. Aspirin reaction unit (ARU) and P2Y12 reaction unit (PRU) values were determined on the day before and on days 1, 3, and 7 after the procedure. Multiple comparison tests (MCTs) were performed among ARU and PRU measurement points, and the proportions of hypo- and hyper-responses were compared.

Results

The median ARU values were 408 (interquartile range: 392-497) before CAS and 418 (405-470) on day 1, 405 (393.0-460.5) on day 3, and 402 (388.5-477.5) on day 7 (not significant in MCTs). The percentages of hypo-responses were 16.3%, 7.0%, 2.3%, and 7.0%, respectively (p = 0.11). The significantly different median PRU values were 173 (116.5-209.5), 233 (166.5-273.5), 139 (70.5-205.5), and 51 (9.0-79.5), respectively. The median PRU was before the procedure within the therapeutic range but exceeded the upper cutoff on day 1 and was below the lower cutoff on day 7. The percentages of hypo-responses were 14.0%, 51.2%, 18.6%, and 11.6%, respectively (p <0.001) and the percentages of hyper-responses were 9.3%, 2.3%, 23.3%, and 62.8%, respectively (p <0.001).

Conclusion

In the periprocedural CAS period, ARU values were stable, but PRU values showed time-dependent changes. PRU values were above the therapeutic range the day after CAS but decreased below this range on day 7.

Investigating the Effect of Demographics, Clinical Characteristics, and Polymorphism of MDR-1, CYP1A2, CYP3A4, and CYP3A5 on Clopidogrel Resistance

Clopidogrel is an antiplatelet agent that is indicated for cardiovascular emergencies and procedures. The drug, however, is subject to response variability leading to therapy resistance. In this research, we explored the demographic, clinical, and genetic factors associated with clopidogrel resistance. Data analysis among our 280 subjects receiving clopidogrel showed some risk factors that are significantly associated with clopidogrel resistance compared with responders. Those were: female sex (P = 0.021), advanced age (P = 0.011), obesity (P = 0.002), and higher body mass index (P = 0.008) and higher platelets count (P = 0.002). However, known polymorphisms of MDR-1, CYP1A2, CYP3A4, and CYP3A5 were not associated with treatment resistance when compared to responders to clopidogrel therapy. Knowledge about such risk factors might provide recommendation in the future about starting doses or monitoring recommendations.