Different microRNA expression in the right ventricular outflow tract myocardium of tetralogy of Fallot

Abstract Background When repairing tetralogy of Fallot (TOF), there are two surgical options according to the size of the pulmonary valve: transannular patch repair and valve-preserving repair. Since the development of the pulmonary valve depends on the degree of obstruction of the right ventricular outflow tract (RVOT), molecular profiles of the RVOT muscles may be associated with the surgical decision. As a recent study shows altered microRNA expression of the right ventricular myocardium even in TOF patients, microRNA expression of the RVOT infundibular muscle may be different between the two procedures. Purpose To evaluate differences in microRNA expression levels of RVOT infundibular muscles between the transannular patch repair and valve-preserving repair groups. Methods Surgically resected infundibular muscles from TOF patients are frozen in liquid nitrogen and stored in our hospital biobank. Nine samples collected between August 2020 and July 2022 were used in this study. Five patients underwent a valve-preserving repair and the others underwent a transannular patch repair. Six patients were female and mean age at operation was 453 ± 240 days. These samples were homogenized and total RNA including microRNAs were extracted. MicroRNA expression levels were measured using a microRNA array capable of detecting over 2000 microRNAs simultaneously. Results 1171 microRNAs were detected in all nine samples. The expression levels of 22 microRNAs were significantly different between the transannular patch repair group and the valve-preserving repair group (P<0.05). The expression levels of 19 microRNAs were significantly higher in the transannular patch repair group and the others were significantly higher in the valve-preserving repair group. More than 2-fold changes were observed in 2 microRNAs between the transannular patch repair and valve-preserving repair groups. Conclusion MicroRNA expression of RVOT infundibular muscle differs between the transannular patch repair and valve-preserving repair groups. Therefore, microRNA analysis will be useful to evaluate the pathophysiology of TOF. In addition, microRNAs may become a useful biomarker for surgical decision making in TOF.