The aim of this work is to present different markers resulting from the analysis of a single ECG lead recorded during sinus rhythm. To this purpose, the ECGs from three populations were compared: healthy subjects, patients subject to paroxysmal AF selected for catheter ablation, under general anesthesia or not. In addition to standard temporal P-wave parameters (P-wave duration and PQ interval), an index of P-wave stability over time defined as the Euclidean distance between beat-to-beat P waves, and morphologic characteristics of biphasic P-wave, such as P-wave initial force and terminal force, were studied. Significant differences between the healthy and pathological groups were obtained for the considered parameters. Moreover, a classification of the two groups based on the joint analysis of P-wave duration and PQ interval was suggested. In parallel, the analysis revealed that there are no significant differences in parameters between the groups under anesthesia or not. In conclusion, this study provides valuable markers for the early recognition of patients at high risk for atrial fibrillation which may guide upstream therapy.