Several works have endorsed a significant role of the immune system and inflammation in the pathogenesis of heart failure. As indirect evidence, an association between a low relative lymphocyte count (RLC%) and worse outcomes found in this population has been suggested. Nevertheless, the role of RLC% for risk stratification in a large and nonselected population of patients with acute heart failure (AHF) has not yet been determined. Thus, the aim of this study was to determine the association between low RLC% and 1-year mortality in patients with AHF and consequently to define whether it has any role for early risk stratification. A total of 1,192 consecutive patients admitted for AHF were analyzed. Total white blood cell and differential counts were measured on admission. RLC% (calculated as absolute lymphocyte count/total white blood cell count) was categorized in quintiles and its association with all-cause mortality at 1 year assessed using Cox regression. At 1 year, 286 deaths (24%) were identified. A negative trend was observed between 1-year mortality rates and quintiles of RLC%: 31.5%, 27.2%, 23.1%, 23%, and 15.5% in quintiles 1 to 5, respectively (p for trend <0.001). After thorough covariate adjustment, only patients in the lowest quintile (<9.7%) showed an increased risk for mortality (hazard ratio 1.76, 95% confidence interval 1.17 to 2.65, p = 0.006). When RLC% was modeled with restricted cubic splines, a stepped increase in risk was observed patients in quintile 1: those with RLC% values <7.5% and <5% showed 1.95- and 2.66-fold increased risk for death compared to those in the top quintile. In conclusion, in patients with AHF, RLC% is a simple, widely available, and inexpensive biomarker, with potential for identifying patients at increased risk for 1-year mortality.
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