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.