The Additive Prognostic Value of Serial Plasma Interleukin-6 Levels over Changes in Brain Natriuretic Peptide in Patients with Acute Heart Failure

Background: Elevated plasma interleukin-6 (IL-6) concentrations are frequently observed in patients with acute heart failure (AHF). However, the predictive value of serial IL-6 measurements beyond brain natriuretic peptide (BNP) remains poorly characterized. Methods and Results: This was a retrospective analysis of the PROTECT cohort (2033 patients with AHF). Plasma IL-6 and BNP levels were determined on days 1, 2, 7 and 14 after admission for AHF in 1591 (78.3%), 1462 (71.9%), 1445 (71.1%) and 1451 (71.4%) patients, respectively. The primary endpoint was 180-day all-cause mortality. The median day-1 IL-6 concentration was 11.1 pg/mL (IQR: 6.6, 20.9) and decreased to 10.1 pg/mL (IQR: 5.6-18.5) at day-7. Higher cross-sectional IL-6 concentrations at all time-points predicted the primary endpoint, independent of a risk model for this cohort and changes in BNP. Each doubling of IL-6 between day-1 and day-7 predicted the primary endpoint independent of baseline IL-6 concentrations, the risk model, baseline BNP and changes in BNP [HR (95% CI): 1.18 (1.07-1.30), p=0.0013]. Collectively, 214 (17%) patients experienced at least a doubling of their IL-6 concentrations between day-1 and day-7. Conclusions: We demonstrate that the temporal evolution patterns of IL-6 in patients with AHF have additive prognostic value independent of changes in BNP.