Background: There is a growing body of evidence highlighting the role of neutrophil to lymphocyte ratio (NLR) as prognostic predictor in several cardiovascular diseases, as a marker of systemic inflammation. Therefore, our aim is to describe the association of NLR and myocardial injury and function in patients with myocarditis;
Methods: Data from patients discharged with the diagnosis of myocarditis, from January of 2008 and October of 2018, in one center, were retrospectively analysed. NLR was defined as the ration of absolute counts of neutrophils and lymphocytes, at admission;
Results: 63 patients were included. Mean age was 39.7 17 years and 89% (58 patients) were men. The NLR values ranged from 1.1 to 14.78 (median 3.48, interquartile range (IQR) 3.06), without significant differences between women and men. In this population, NLR positively correlates with peak troponin values (p= 0.004, r=0.35) and N-terminal pro B-type natriuretic peptide (NT- proBNP) values (p= 0.005, R= 0.35). NLR also positively correlates with other inflammatory makers, such as C-reactive protein (CRP) (p<0.001, r= 0.42), leukocytes (p<0.001, r=0.59) and monocytes (p=0.004, r=0.35). NLR was higher in patients with left ventricular systolic dysfunction (4.45 vs 3.43) but this difference was not statistically significant (p=0.341);
When the patients were divided into NLR>3.48 and NLR<3.48 groups, myocardial injury markers were significantly increased in the higher NLR group (peak troponin 1.53 vs 0.6, p <0.001 and NT- proBNP 654 vs 244, p= 0.044). There is a statistically significant association between higher NLR and need of inotropic support (p=0.024). No differences on in-hospital mortality (p=0.492) between groups were registered.
Conclusion: NLR is a predictor of myocardial injury and inflammation in this group of patients; Despite being nonspecific, it is a readily available marker and it could be a cost-effective predictor and a useful tool to guide the approach in these patients.