Level of serum NT-proBNP and EF after surgery Time EF% NT-proBNP (pg / ml) r ± SD Median N1 ≤ 50 (n=50) 571.65 ± 2196.71 949.15 - 0.396; > 0.05 > 50 (n=57) 447 ± 609.45 195.4 p < 0.001 N2 ≤ 50 (n=49) 4450.07 ± 4417.48 2964 - 0.49; > 0.05 > 50 (n=58) 1514.91 ± 1384.37 1063 p < 0.001 N3 ≤ 50 (n=50) 6026.43 ± 5597.83 4819 - 0.489; > 0.05 > 50 (n=57) 2301.03 ± 2081.84 1816 p < 0.001 N4 ≤ 50 (n=44) 5958.9 ± 5865.69 5066 - 0.408; > 0.05 > 50 (n=63) 2600.93 ± 2608.74 1873 p < 0.001 N5 ≤ 50 (n=43) 5202.64 ± 5311.8 4069 - 0.392; > 0.05 > 50 (n=64) 2285.5 ± 2480.12 1743 p < 0.001 Comment: At time points of N1, N2, N3, N4, and N5 after surgery, the mean of NT-proBNP level in the group with EF ≤ 50% was higher than in the group with EF> 50%. The difference was statistically significant with a p-value <0.001.