Background: Numerous but relatively small observational studies have recently described an association between neutrophil-to-lymphocyte ratio (NLR), a general inflammatory marker, and various prevalent cardiovascular and diabetes associated conditions. The purpose of the current study was to examine the relation between NLR and new onset atrial fibrillation (AF) in one large observational cohort. Methods: We investigated 18,563 men and women who were annually screened in a tertiary medical center. All subjects were free of AF at baseline and had their serum NLR calculated based on their blood count at the first annual visit. Subjects were divided into two prespecified groups based on their baseline NLR: Low (<3; N=16,172) and high (≥3; N=2,391). The primary endpoint was new onset AF during follow-up. Results: Mean age of study population was 49 ± 11 years and 73% were men. A total of 288 incident events occurred during an average follow-up of 6 years. Unadjusted cox regression analysis demonstrated that each 1 unit increase in NLR was associated with a significant 12% increase in risk of occurrence of a first AF event (HR 1.12; 95% CI [1.01-1.25], p=0.03). Subgroup analysis showed that NLR-related risk was age-dependent, such that in the younger age-group (Conclusions: Our findings suggest that high NLR is associated with increased risk of new onset AF in among young adults.
