Abstract Body (Do not enter title and authors here): Purpose: MicroRNAs (miRs) have been proposed as biomarkers of myocardial infarction (MI), but prior evidence has demonstrated that heparin, commonly administered to patients presenting with MI, inhibits amplification during quantitative PCR (qPCR). The purpose of this study was to determine whether qPCR amplification of miRs is reduced in plasma of patients receiving heparin and if heparinase reverses this effect.
Methods: Blood samples were collected and plasma recovered from patients with normal coronary arteries who had undergone CT coronary angiography (N=5) or who had received intravenous heparin at the time of invasive coronary angiography(N=8). Blood was also collected at the time of invasive coronary angiography from patients presenting with ST elevation MI (N=9). RT-qPCR was performed to quantify levels of 84 cardiac miRs, and Cel-miR-39-3p was utilized as a spike-in control. MiR qPCR was also performed following the addition of heparinase to plasma from 2 patients without MI treated with heparin and 2 patients presenting with MI who had received heparin.
Results: Mean age of patients was 57 years, and 55% of patients were male. As compared with control patients, the cycle number for cel-miR-39-3p was significantly increased for patients receiving heparin (Figure 1a). No difference was seen in levels of cel-39-3p in heparin-treated patients with respect to the presence or absence of MI. Cel-miR-39-3p cycle times decreased when heparinase was added to samples from heparin-treated patients (Figure 1b). In contrast, heparin did not increase cycle times in any of the cardiac miRs tested, and cycle times decreased even further for miRs 499a-5p and 208b-3p in patients with MI (Figure 2).
Conclusions: Systemic heparin treatment inhibits qPCR amplification of cel-mir-39-3p but does not inhibit endogenous miR amplification under these conditions. MiRs 499a-5p and 208b-3p are potentially important candidates for MI detection and quantification.