Aims: MicroRNAs (miRNAs) might be used as prospective biomarkers for the identification of unexplained heart failure caused by a viral and/or inflammatory process. The aim of this study was to identify and to evaluate prognostic miRNAs in serum of patients with inflammatory heart diseases diagnosed by endomyocardial biopsies.

Methods: After TaqMan^{® OpenArray® screening of 754 unique circulating miRNAs in serum of biopsy-proven patients (184 -with inflammatory and/or virally-induced myocardial diseases (DCMi), 25 - with dilated cardiomyopathy (DCM), and 25 healthy donors), we identified seven miRNAs of interest (P < 0.05). These data have been verified by single qRT-PCR assays in other biopsy-proven patients (159 - with viral and/or inflammatory myocardial diseases, 46 DCM patients, and 60 healthy donors).}

Results: The expression of let-7f, miR-197, miR-223, miR-93, miR-379 allowed us to differentiate between patients with a virus and/or inflammation and healthy donors (P < 0.05) with the specificity over 93 %. Based on the expression of miR-21 and miR-30a-5p we could sort out patients with DCM from all other study groups (P < 0.05) with the specificity over 95 %.

Conclusions: This miRNA profile provides for the first time a new non-invasive diagnostic perspective to identify patients with intramyocardial inflammation and/or viral persistence only from single serum sample, independently of prescribed therapy and time of symptoms onset. It allows the early finding of those patients relevant for myocardial biopsy for exact diagnosis and further proscription of causal etiology-driven specific treatment.