Estimation of atrial fibrillation recency of onset and safety of cardioversion using NTproBNP levels in patients with unknown time of onset

OBJECTIVE: As shown previously in patients with new-onset atrial fibrillation (AF) without symptoms or signs of heart failure, N-terminal pro-brain natriuretic peptide (NTproBNP) increases rapidly, reaching a maximum within 24-36 h, and then decreases even if AF persists. A study was undertaken to use NTproBNP measurements in patients with AF of unknown time of onset to identify patients with presumed recent onset of the arrhythmia. DESIGN: Two-group open cross-sectional study. SETTING: Hospitalised patients in cardiology departments of four hospitals. PATIENTS: Patients presenting with AF of unknown onset and no signs or symptoms of heart failure were separated into two groups: group A with NTproBNP above the cut-off level and group B with a low NTproBNP level. INTERVENTIONS: No therapeutic intervention. All patients underwent transoesophageal echocardiography (TEE). MAIN OUTCOME MEASURES: Presence of left atrial thrombus on TEE. RESULTS: In group A (N=43) only two patients (4.7%) were found to have an atrial thrombus on TEE (negative predictive value of raised NTproBNP levels 95.3%) compared with 13 of 43 patients in group B (30.2%; p=0.002). Patients with a higher CHA(2)DS(2)VASc score (p=0.002) and a larger left atrium (p<0.001) were more likely to have an atrial thrombus. In the multivariate analysis, NTproBNP below the cut-off level was the most powerful predictor of the presence of thrombus (OR 25.0; p=0.016). CONCLUSION: The reported strong correlation between raised NTproBNP levels and the absence of atrial thrombi on TEE suggests that the short-term increase in NTproBNP levels after AF onset might be used to assess the age of the arrhythmia and thus the safety of cardioversion in patients with AF of unknown onset and no heart failure.