Qingwang Hou,1,* Yipin Zhao,2,* Zebin Lin,3,* Tongfeng Chen,2 Xinlong Di,4 Xiaohu Wang,2 Jiangtao Cheng,2 Xiaoyan Guo,2 Chong Chen,2 Dan Hu,2 Chang Liu,2 Yapeng Jiang,2 Yancun Liu,2 Ying Li,2 Mai Su,2 Yuhao Liu2 1Department of Cardiology, Henan University People’s Hospital, Henan Provincial People’s Hospital, Zhengzhou, 450000, People’s Republic of China; 2Department of Cardiology, Fuwai Central China Cardiovascular Hospital, Zhengzhou, 450000, People’s Republic of China; 3Department of Geriatrics, Zhongshan Hospital Xiamen University, Xiamen, 361000, People’s Republic of China; 4Department of Cardiology, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yuhao Liu, Email camsliu@163.comBackground: The Systemic Immune-Inflammation Index (SII) is a key indicator for assessing inflammatory status. This study aims to determine the association between SII and prognosis following occlusion in patients with post-infarction ventricular septal rupture (PIVSR).Methods: A total of 130 patients admitted to Fuwai Central China Cardiovascular Hospital between 2018 and 2023 were included in this retrospective study. Based on the tertiles of the Systemic Inflammatory Index (SII), the patients were categorized into two groups: 65 patients in the low SII group and 65 in the high SII group. Variable screening was performed using the Least Absolute Shrinkage and Selection Operator (LASSO) analysis. We conducted multivariable logistic regression analyses to rigorously assess the independent association between SII and short-term outcomes in PIVSR patients. After variable selection, a nomogram was constructed using R, and Restricted Cubic Splines (RCS) were employed to flexibly model nonlinear relationships. Subsequently, the predictive abilities of the screened variables and SII for the outcome were independently evaluated using Receiver Operating Characteristic (ROC) curve analysis.Results: A nomogram model incorporating ALT, UREA, NT-proBNP, and SII was developed to predict the short-term prognosis of PIVSR patients following occlusion surgery. ROC curve analysis demonstrated that the area under the curve (AUC) for SII level was 0.702 (95% CI: 0.599– 0.804, P < 0.001). Incorporating the Systemic Immune-Inflammation Index (SII) significantly improved prognostic accuracy, with Model 2 demonstrating superior discriminatory power (AUC 0.845 vs 0.828) over Model 1.Conclusion: The Systemic Immune-Inflammation (SII) is a convenient and effective prognostic indicator, and the model incorporating SII can facilitate personalized prognostic assessment for patients with post-infarction ventricular septal rupture (PIVSR).Keywords: acute myocardial infarction, perforation of ventricular septum, systemic immune inflammation index, interventional occlusion