The areas under the ROC curves based on the multivariate Cox models had a C-index of 0.822 for Total NT-proBNP and 0.829 for NT-proBNP, the difference was not statistically significant (P = 0.263) between the two models (Additional file 1: Fig. 1A ROC curves for first episode of recurrent atrial fibrillation. Here, NPPB is linked to atrial fibrillation.