Abstract 18427: Impact of Medication on Quantification of Plasma MicroRNAs in Patients With Cardiovascular Disease

Abstract

Background: MicroRNAs are small non-coding RNAs that are detectable in the blood. Circulating levels of microRNAs have been measured in various epidemiological studies, but the effects of medication are unclear. To address these uncertainties, we assessed how plasma microRNAs change in response to platelet inhibition and heparin administration. We also correlated plasma levels of microRNAs with existing markers of platelet activation. Methods and Results: 92 microRNAs were assessed in a dose-escalation study with aspirin and prasugrel in healthy volunteers (n=11). Plasma levels of platelet microRNAs, such as miR-223, miR-191 and others decreased on platelet inhibition. Findings were confirmed by individual TaqMan qPCR assays and validated in an independent cohort of patients with symptomatic carotid stenosis (n=33). In a cohort of patients on dual anti-platelet therapy 30 days post myocardial infarction (n=129), plasma levels of most platelet microRNAs were positively correlated to the VASP assay. Levels of miR-126 were also significantly associated with results from the VerifyNow P2Y12 aggregation assay. No association was observed with optical aggregometry with arachidonic acid or ADP. When platelet-poor plasma was collected at different time points from patients undergoing PCI (n=20) or diagnostic angiography with (n=7) and without (n=10) heparin administration, heparin was found to have pronounced effects on the assessment of the exogenous C. elegans spike-in control (decrease by >3 cycles), which disappeared six hours after the heparin bolus. Normalisation of individual microRNAs with the average cycle threshold value of all microRNAs provided a suitable alternative to normalization with exogenous C. elegans spike-in control in this setting. Conclusions: Our studies provide evidence for a correlation of plasma microRNAs with commonly used methods in platelet testing. They also highlight that microRNA levels are sensitive to medication, in particular antiplatelet and anticoagulation therapy. This has to be taken into account when designing studies to investigate the relation of circulating microRNAs to cardiovascular disease.