Preoperative systemic immune inflammation index predicts early complications and 30-day mortality after heart valve...

The systemic immune-inflammation index (SII) is considered a promising inflammatory index for predicting adverse outcomes in cardiovascular diseases. However, its prognostic value in patients undergoing heart valve surgery remains unclear. This study aimed to investigate the predictive significance of preoperative SII for early postoperative complications and 30-day mortality.

This was a retrospective, single-center cohort study conducted at the National Cardiovascular Center Harapan Kita in Jakarta, Indonesia, a tertiary cardiac surgery referral hospital. It included adults (> 18 years) who underwent elective aortic, mitral, or combined valve surgery between January 2020 and December 2024. After applying exclusion criteria, 1347 patients were stratified by SII into low (< 551 × 10³/mm³, n = 927) and high (≥ 551 × 10³/mm³, n = 420) groups.

High preoperative SII was significantly associated with acute kidney injury (AKI) (p = 0.002), prolonged mechanical ventilation (p = 0.039), extended total hospital length of stay (LOS-H) (p = 0.004), and 30-day mortality (p = 0.026). Multivariate logistic regression identified SII (OR 2.169; 95% CI 1.600-2.941; p < 0.001) as independent predictor of adverse postoperative outcomes. When analyzed as a continuous variable, preoperative SII remained independently associated with adverse postoperative outcomes (adjusted OR per 100-unit increase 1.196; 95% CI 1.148-1.245; p < 0.001). Subgroup analysis revealed the highest predictive value in patients undergoing aortic valve surgery, with an area under the curve (AUC) of 0.797 (95% CI 0.728-0.866).

Elevated preoperative SII is independently associated with an increased risk of early postoperative complications and 30-day mortality in patients undergoing heart valve surgery. As a simple and cost-effective inflammatory index, SII may aid in preoperative risk stratification and support more personalized perioperative care.