Comparison of variables between different SII groups after PSM
| Variables | High SII (n=121) | Low SII (n=121) | t/χ2 | P value |
| Age, years | 59.14±11.97 | 58.28±11.35 | 0.573 | 0.567 |
| SBP, mm Hg | 135.34±39.26 | 129.52±39.11 | 1.155 | 0.249 |
| Hb, g/L | 131.55±23.04 | 128.62±22.83 | 1.399 | 0.163 |
| ALB, g/L | 37.61±5.87 | 36.76±5.53 | 1.159 | 0.248 |
| NT-proBNP, pg/mL | 1621.12±405.65 | 1571.37±420.12 | 0.937 | 0.349 |
| LVEF, % | 56.71±11.38 | 58.73±10.92 | −1.409 | 0.160 |
| NYHA class .12 | 67 (55.37) | 56 (46.28) | 2.001 | 0.157 |
| Diabetes | 21 (17.36) | 16 (13.22) | 0.978 | 0.372 |
| CPB time, min | 97.65±29.76 | 91.89±27.76 | 1.557 | 0.121 |
| ACT time, min | 79.63±27.66 | 74.25±28.75 | 1.489 | 0.138 |
| Use of red blood cell, mL | 393.93±122.58 | 387.34±124.39 | 0.415 | 0.678 |
| Poor outcomes, n (%) | 78 (64.46) | 30 (24.79) | 38.527 | ＜0.001 |
| 30-day all-cause mortality, n (%) | 12 (9.92) | 3 (2.48) | 4.549 | 0.016 |
| 30-day readmission, n (%) | 8 (6.61) | 2 (1.65) | 3.856 | 0.050 |
ACT, aortic cross-clamping time; ALB, albumin; CPB, cardiopulmonary bypass; Hb, haemoglobin; LVEDD, left ventricular end-diastolic dimension; LVEF, left ventricular ejection fraction; NT-proBNP, N-terminal pro brain natriuretic peptide; NYHA, New York Heart Association; PSM, propensity score matching; SBP, systolic blood pressure; SII, systemic immune-inflammation index.