Introduction
Worldwide, atrial fibrillation (AF) is one of the most prevalent cardiac
arrhythmias in adults1. Owing to extended longevity
and intensifying search for undiagnosed AF, approximately 4% experience
AF in general population2 and a 2.3-fold rise is
expected3. AF, which is associated heart
failure4 and stroke5, worsens
patient quality of life6 and increases significant
burden to patients and societal health due to the high morbidity and
mortality. Previous studies7-11 have shown that
inflammation is associated with AF development and progression in
general population and patients after cardioversion, cardiac surgery and
catheter ablation. Increasing evidence supports the essential role of
inflammatory factors10,12-14 in predicting the onset
of AF and recurrence. Some inflammatory factors including
platelet-to-lymphocyte ratio (PLR)15,16,
IL-617, IL-1018 and high sensitivity
C-reactive protein19, were proven to be simple
biomarkers to predict the incidence of AF in patients with or without
history of AF. However, these biomarkers only involve one or two types
of immune- inflammatory cells and may not accurately reflect
inflammation status.
The systemic immune-inflammation index (SII) is a novel and integrated
inflammatory index based on neutrophil, platelet and lymphocyte counts.
SII was initially demonstrated to be associated with prognosis of
various cancers, such as prostate cancer20,
hepatocellular carcinoma21 and gastric
cancer22. Up to now, the relationships of SII and
coronary artery disease23,24, heart
failure25 were reported by many studies. SII is now
considered to comprehensively reflect inflammation status. However, the
association between SII and AF still remains unclear. Therefore, we
conducted this study to investigate the association between SII levels
and AF to determine the prognostic value of SII in patients with AF.