Although HF in the present participants was hemodynamically and clinically mild and 85% of HF participants were under the control of beta-blockades, the quantitative sound analysis revealed that (1) a beat-to-beat alteration of S1 intensity (dB) and its audio frequency (Hz) was significantly associated with the level of NT-proBNP and (2) the size of CTR correlated negatively with eS4 intensity (p = 0.035) and positively with S1 audio frequency (p = 0.010) (Table 1). The gene discussed is NPPB; the disease is hydrops fetalis.