['The aim of the present study was: (1) to determine the predictive value of N-terminal pro-B-type natriuretic peptide (NT-proBNP) on the success of an elective direct-current cardioversion; and (2) to assess the ability to monitor rhythm stability after electrical cardioversion in patients with lone atrial fibrillation (AF).', 'Fifty-three patients with lone AF were provided with an Holter-ECG for a follow-up period of 4 weeks after elective cardioversion. NT-proBNP serum levels were measured before and 4 weeks after cardioversion. All patients presented with increased NT-proBNP serum levels (median 874 pg/ml, interquartile range 703-1,355) before cardioversion. Thirty patients were in sinus rhythm (SR) during follow-up. These patients showed a significant NT-proBNP-decrease (759 pg/ml, 618-1,139 to 318 pg/ml, 200-523, p<0.05). Nineteen patients experienced a relapse of AF. NT-proBNP was significantly higher prior to cardioversion in comparison to patients without relapse (p<0.05) and remained unchanged during follow-up (1,124 pg/ml, 925-1,542 vs 1,256 pg/ml, 945-1,509, p=NS). Four patients had short periods of silent AF detected by Holter ECG. These patients had a smaller decrease in NT-proBNP than patients with stable SR. The area under the curve of the receiver-operating characteristic curve was 0.8 for NT-proBNP to predict a successful cardioversion. Using an optimized cut-off level of 900 pg/ml, successful cardioversion can be predicted with high accuracy.'] Does nT-ProBNP predict rhythm stability after cardioversion of lone atrial fibrillation?