The results showed that NT-proBNP was negatively correlated with SDANN (r = –0.4581, P < 0.0001) and SDNN (r = –0.4795, P < 0.0001) and positively correlated with LF/HF (r = 0.3877, P = 0⋅0011) in COVID-19 patients. The gene discussed is NPPB; the disease is COVID-19.