Evaluating systemic immune-inflammation index in patients with implantable cardioverter defibrillator for heart failure with reduced ejection fraction

Background Pro-inflammatory pathways play an important role in the follow-ups of patients with intracardiac defibrillators (ICDs) for heart failure (HF) reduced with ejection fraction (HFrEF). A newly defined index - the systemic immune-inflammation index (SII)-has recently been reported to have prognostic value in patients with cardiovascular disease. This study's aim is to evaluate the SII value regarding its association with long-term mortality and appropriate ICD therapy during a 10-year follow-up. Methods This retrospective study included 1011 patients with ICD for HFrEF. The SII was calculated as the neutrophil-to-lymphocyte ratio x total platelet count in the peripheral blood. The study population was divided into two groups according to the SII's optimal cut-off value to predict long-term mortality. The long-term prognostic impact of SII on these patients was evaluated regarding mortality and appropriate ICD therapy. Results The patients with a higher SII (>= 1119) had significantly higher long-term mortality and appropriate ICD therapy rates. After adjustment for all confounding factors, the long-term mortality rate was 5.1 for a higher SII. (95% CI: 2.9-8.1). The long-term appropriate ICD therapy rate was 2.0 for a higher SII (95% CI: 1.4-3.0). Conclusion SII may be an independent predictive marker for both long-term mortality and appropriate ICD therapy in patients with HFrEF.