- Serum NT-proBNP level has prognostic significance in LCOS by VIS: 23 The cut-off of NT-proBNP levelmay predict acute heart failure in the group with high VIS (VIS ≥ 15) on the first postoperative day was 1682 pg / ml (with a sensitivity of 93.7% and a specificity of 72.7%; J index of 0.664); on the second postoperative day was 8844 pg / ml (with 90% sensitivity and 60% specificity; J index of 0.5); on the third postoperative day was 7152 pg / ml (with 63.2% sensitivity and 100% specificity; J index of 0.63).