In a preliminary study, we used cryosections of human atrial samples of subjects without any diagnosed heart failure for autoradiography with [18F]FLUDA and determined an A2A-AR-specific binding of 36.3 ± 5.3% (n = 2) (Figure 4), which is comparable to the values determined in the WT group of mice, representing a low A2A-AR availability in the healthy heart tissue. This evidence concerns the gene AR and heart failure.