NT-proBNP in relation to clinical characteristics and cardiovascular outcomes in non-anticoagulated patients with atrial fibrillation

BACKGROUND: N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a well-established biomarker for cardiovascular risk; however, its prognostic value in patients with atrial fibrillation (AF) who are not receiving anticoagulation therapy has not been well established. We investigated the association between NT-proBNP levels, clinical characteristics and cardiovascular outcomes in non-anticoagulated patients with AF and assessed whether baseline heart rhythm modified these associations. METHODS: Plasma samples were obtained at baseline in two multicentre clinical trials involving 3183 patients with AF randomised to aspirin with a median follow-up of 18 months. NT-proBNP was analysed using the Elecsys immunoassay. Associations between NT-proBNP and clinical characteristics were assessed by multivariable linear regression. Associations with clinical outcomes were evaluated using Cox regression models. The prognostic value of NT-proBNP was evaluated with C-statistics. RESULTS: AF on the baseline ECG was the clinical factor most strongly associated with NT-proBNP levels, with concentrations 4.2 times higher in AF than in sinus rhythm. NT-proBNP was independently associated with ischaemic stroke (the third sample quartile compared with the first, HR 2.07, 95% CI 1.46 to 2.94), heart failure hospitalisation (HR 2.16, 95% CI 1.59 to 2.92), cardiovascular death (HR 2.43, 95% CI 1.79 to 3.30) and all-cause death (HR 2.09, 95% CI 1.65 to 2.65) during follow-up. There was no interaction between heart rhythm and the associations between NT-proBNP and outcomes (all p values ≥0.07). CONCLUSIONS: In non-anticoagulated patients with a diagnosis of AF, NT-proBNP levels were significantly associated with the risk of clinical outcomes. Baseline AF rhythm was the clinical factor most strongly associated with NT-proBNP levels. However, the associations between NT-proBNP and outcomes remained consistent regardless of baseline rhythm.