To investigate the effect of bradyarrhythmia on the plasma levels of NT-proBNP, patients without defined ventricular diseases were enrolled in this study: group A, 42 patients without arrhythmia; group B, 43 patients with sick sinus syndrome; group C, 22 patients with II degrees atrioventricular block (AVB); group D, 35 patients with III degrees AVB and group E, 35 patients with persistent atrial fibrillation. The plasma levels of NT-proBNP were determined and analyzed. The NT-proBNP levels were lower in group A and B than in group C, D and E (P<0.01), and in group C than in group D and E (P<0.001). Multivariate analysis revealed age and the severity of atrioventricular asynchrony were independent determinants of NT-proBNP levels (P<0.001). These results implicated that the plasma levels of NT-proBNP in patients with bradyarrhythmia increased in proportion to aggravation of atrioventricular asynchrony.