Transcoronary concentration gradients of circulating microRNAs in heart failure

Aims: Circulating levels of microRNAs (miRNAs) are emergent promising biomarkers for cardiovascular disease. Altered expression of miRNAs has been related to heart failure (HF) and cardiac remodelling. We measured the concentration gradients across the coronary circulation to assess their usefulness to diagnose HF of different aetiologies. Methods and results: Circulating miRNAs were measured in plasma samples simultaneously obtained from the aorta and the coronary venous sinus in patients with non-ischaemic HF (NICM-HF, n = 23) ischaemic HF (ICM-HF, n = 41), and in control patients (n = 11). A differential modulation of circulating levels of miR-423, -34a, -21-3p, -126, -199 and -30a was found across the aetiology groups. Interestingly, a positive transcoronary gradient was found for miR-423 (P < 0.001) and miR-34a (P < 0.001) only in the ICM-HF group. On the contrary, a positive gradient was found for miR-21-3p (P < 0.001) and miR-30a (P = 0.030) only in the NICM-HF group. Finally, no significant variations were observed in the transcoronary gradient of miR-126 or miR-199. Conclusions: The present findings suggest that circulating levels of miRNAs are differentially expressed in patients with HF of different aetiologies. The presence of a transcoronary concentration gradient suggests a selective release of miRNAs by the failing heart into the coronary circulation. The presence of aetiology-specific transcoronary concentration gradients in HF patients might provide important information to better understand their role in HF, and suggests they could be useful biomarkers to distinguish HF of different aetiologies.