Abstract
Background: Inflammation plays a pivotal role in the pathogenesis of both acute and chronic heart failure. Recent studies showed that the neutrophil-to-lymphocyte ratio (NLR) could be related to adverse outcomes in patients with cardiovascular diseases. We sought to evaluate whether NLR could predict mortality in patients with acute heart failure by means of a meta-analysis. Methods: A comprehensive literature search was performed in PubMed, Embase, and Cochrane databases through January 2023 for studies evaluating the association of NLR with mortality in patients with acute heart failure. Primary outcomes were in-hospital mortality and long-term all-cause mortality. Endpoints were pooled using a random-effects DerSimonian-and-Laird model and were expressed as a hazard ratio (HR) or mean difference (MD) with their corresponding 95% confidence intervals. Results: A total of 15 studies with 15,995 patients with acute heart failure were included in the final study. Stratifying patients based on a cut-off NLR, we found that high NLR was associated with a significantly higher in-hospital mortality [HR 1.54, 95% CI (1.18-2.00), p < 0.001] and long-term all-cause mortality [HR 1.61, 95% CI (1.40-1.86), p < 0.001] compared to the low-NLR group. Comparing the highest against the lowest NLR quartile, it was shown that patients in the highest NLR quartile has a significantly heightened risk of long-term all-cause mortality [HR 1.77, 95% CI (1.38-2.26), p < 0.001] compared to that of lowest NLR quartile. However, the risks of in-hospital mortality were compared between both quartiles of patients [HR 1.78, 95% CI (0.91-3.47), p = 0.09]. Lastly, NLR values were significantly elevated among non-survivors compared to survivors during index hospitalization [MD 5.07, 95% CI (3.34-6.80), p < 0.001] and during the follow-up period [MD 1.06, 95% CI (0.54-1.57), p < 0.001]. Conclusions: Elevated NLR was associated with an increased risk of short- and long-term mortality and could be a useful tool or incorporated in the risk stratification in patients with acute heart failure.