Impact of B-type natriuretic peptide level on the risk of left atrial appendage thrombus in patients with nonvalvular atrial fibrillation: a prospective study

BACKGROUND: The impact of B-type natriuretic peptide (BNP) level on the risk of left atrial appendage (LAA) thrombus in patients with nonvalvular atrial fibrillation (NVAF) has not been prospectively studied. METHODS: In two academic medical centers, we obtained BNP levels immediately prior to transesophageal echocardiogram performed to exclude LAA thrombus in patients with NVAF. RESULTS: Among 261 subjects (mean age 65 ± 12 years; 30 % women) with NVAF, 17 (6.5 %) had LAA thrombus and 85 (32.6 %) had at least mild spontaneous echo contrast (SEC). Mean BNP level was significantly higher in patients with LAA thrombus [775 ± 678 vs. 384 ± 537, P = 0.001]. Receiver operator characteristics analysis demonstrated that BNP has a good discriminatory capacity for LAA thrombus (area under the curve, 0.74; 95 % confidence interval [CI], 0.63–0.85; P = 0.001); BNP ≥ 67 pg/mL was 100 % sensitive and 20 % specific for LAA thrombus. Multivariate logistic regression analysis demonstrated that BNP was not independently associated with LAA thrombus (odds-ratio, 1.05 per 100 pg/mL increment; CI, 0.99–1.12; P = 0.127) after adjusting for CHA(2)DS(2)-VASc score; while the latter was independently associated with LAA thrombus after adjusting for BNP level (odds-ratio, 1.46 per CHA(2)DS(2)-VASc point; CI, 1.09–1.96; P = 0.011). Nonetheless, BNP was associated with SEC in univariate and multivariate analysis, after adjusting for the CHA(2)DS(2)-VASc score, (odds-ratio, 1.08; CI, 1.02–1.14; P = 0.005). CONCLUSIONS: BNP is predictive of SEC. However, it does not provide significant incremental value in the prediction of LAA thrombus.