Relationship between systemic immune inflammation index and development of complete atrioventricular block in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention

Background The systemic immune-inflammation index (SII), based on white blood cell, neutrophil, and platelet counts, is a proposed marker of systemic inflammation and immune activation. This study aimed to explore the relationship between SII and complete atrioventricular block (CAVB) development in STEMI patients undergoing primary PCI. Methods We retrospectively analyzed data from 883 patients who underwent primary PCI for STEMI between January 2009 and December 2017. Patients were categorized into two groups based on CAVB development. SII levels were calculated from blood samples taken on admission. Results Of the included patients, 48 (5.03%) developed CAVB. SII was higher in patients with CAVB compared to those without CAVB (1370 [1050–1779]x109/L vs. 771 [427–1462] x109/L, p < 0.001). Multivariate analysis showed a significant positive correlation between SII and the risk of CAVB development (OR:1.0003, 95%CI:1.0001–1.0005, P = 0.044). The cut-off value for the SII in the estimation of CAVB was 1117.7 × 10 9 /L (area under the ROC curve [AUC]: 0.714, 95% CI = 0.657–0.770 with a sensitivity of 70.8% and specificity of 65.6%, p < 0.001). Conclusion This study showed a significant link between high SII levels and CAVB development in STEMI patients undergoing PCI. Our findings suggest that SII may be a valuable, routinely available, and inexpensive marker for identifying patients at increased risk of CAVB.