Dr. Karch et al., from the Deutsches Herzzentrum München and Medizinische Klinik, Klinikum rechts der Isar, Technische Universität München, in Munich, Germany In this study, the authors investigated the differences between sustained and non-sustained forms of atrial fibrillation (AF) using multielectrode endocardial recordings. Sixty-four pole basket catheters were deployed in the right atrium (RA) of 3 groups of patients. Persistent AF showed the shortest FF intervals and lowest overall degree of AF organization, while induced non-sustained AF the longest FF intervals and highest degree of organization. FF intervals of induced sustained AF were only slightly longer, compared to persistent AF. Within each AF group, the lateral wall showed the highest degree of organization, the septal region the lowest. They concluded that FF interval and overall degree of AF organization were found to increase significantly from sustained to non-sustained AF. Persistent and induced sustained AF, however, only slightly differed in these parameters.