Biomarkers of inflammation in atrial fibrillation

• Atrial fibrillation (AF) is common and associated with increased risk of stroke, heart failure (HF) and mortality. Inflammation is linked to AF.The overall aim of this thesis was to investigate inflammatory activity and cardiovascular outcomes and mortality in patients with AF on effective oral anticoagulation. Levels of the inflammatory biomarkers interleukin 6 (IL-6), C-reactive protein (CRP) and fibrinogen at study entry and serial changes of IL-6 over time were investigated and related to stroke or systemic embolism, mortality and other cardiovascular events, including major bleeding. Associations between IL-6, CRP and biomarkers of cardiorenal dysfunction (NT-proBNP, troponin, GDF-15 and cystatin C) and HF hospitalisation, recurrent HF hospitalisations and mortality, were also investigated in patients with AF stratified for HF symptoms and reduced or preserved ejection fraction.The study populations consisted of patients with AF included in the biomarker substudies of the large multicentre randomised controlled trials RE-LY (n=6,187) and ARISTOTLE (n=14,954) with a median follow-up of 2.0 and 1.9 years, respectively. Repeated IL-6 measurements were available at study entry and at any postbaseline time point at 3, 6 and 12 months in RE-LY (n=2,559), and at study entry and at 2 months in ARISTOTLE (n=4,830). For HF stratification, patients in ARISTOTLE with information on HF symptoms and left ventricular function at study entry and with IL-6, CRP, NT-proBNP, troponin T, GDF-15 and cystatin C available at randomisation (n=11,818) were included.Higher level of IL-6, but not of CRP, was significantly associated with higher risk of mortality in Cox models adjusted for established clinical risk factors and other cardiovascular biomarkers. The level of any of the studied inflammatory biomarkers was not independently associated with any other cardiovascular outcome, including stroke or systemic embolism or major bleeding, in presence of other strong cardiovascular biomarkers. Levels of IL-6 were stable over time and persistent inflammatory activity was associated with increased risk of mortality, independent of clinical risk factors and other prognostic biomarkers. All biomarkers (IL-6, CRP, NT-proBNP, troponin T, GDF-15 and cystatin C) were associated with higher risk of HF hospitalisation and mortality regardless of HF symptoms and reduced or preserved ejection fraction.In conclusion, in anticoagulated patients with AF, higher level of IL-6, but not of CRP, was associated with higher risk of mortality, independent of clinical risk factors and other cardiovascular biomarkers. IL-6 levels were stable over time and provided incremental information on the risk of mortality irrespective of when measured. IL-6 may therefore serve as a risk marker for fatal outcomes. Biomarkers improved the identification of patients with AF at risk of HF in addition to clinical and echocardiography data.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Kardiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cardiac and Cardiovascular Systems (hsv//eng)

Nyckelord

Atrial fibrillation

biomarkers

inflammation

inflammatory biomarkers

oral anticoagulation

heart failure

left ventricular function

ejection fraction

risk assessment

risk prediction

interleukin 6 (IL-6)

C-reactive protein (CRP)

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