Interleukin-6, infection and cardiovascular outcomes in acute heart failure: Findings from the EDIFICA registry.

Abstract

Interleukin-6 (IL-6) is upregulated in response to infectious and inflammatory triggers and independently predicts all-cause mortality in acute heart failure (AHF). However, the association of IL-6 with cardiovascular outcomes and its interplay with C-reactive protein and infection, a major precipitating factor in AHF, remains poorly understood. The association between IL-6 and clinical outcomes (180days) in AHF was evaluated using a cohort of 164 patients from the EDIFICA registry. Median IL-6 levels at admission were 17.4pg/mL. Patients in the higher admission IL-6 tertile presented with lower blood pressure and more congestion, were diagnosed more frequently with infection, and had a longer hospital stay. Higher IL-6 levels were associated with increased risk of HF rehospitalization (hazard ratio per log₂ 3.69, 95% confidence interval (CI) 1.26-10.8, p=.017) and the composite of HF rehospitalization or cardiovascular death (hazard ratio per log₂ 3.50; 95% CI 1.28-9.57; p=.014), independently of major AHF prognosticators, including B-type natriuretic peptide and renal function. However, no independent associations were found for all-cause rehospitalization or mortality. Despite a moderate correlation of IL-6 with C-reactive protein (CRP) levels (R=.51), the latter were not associated with clinical outcomes in this population. IL-6 levels associate with higher rate of cardiovascular events in AHF, independently of classical prognosticators and evidence of infection, outperforming CRP as an inflammatory outcome biomarker.