Right atrial substrate properties associated with age in patients with typical atrial flutter

Background: Data detailing the age-related difference in the atrial substrate for formation of typical atrial flutter (AFL) are sparse. Objective: The purpose of this study was to characterize the difference in the right atrial substrate related to aging using noncontact mapping of the right atrium. Methods: A total of 54 patients (23 young [<60 years; 45 ± 12 years] and 31 old [≥60 years; 74 ± 6 years]) with typical AFL who underwent three-dimensional noncontact mapping of typical AFL were enrolled in the study. The atrial substrate was characterized according to (1) regional wavefront activation mapping, (2) regional conduction velocity, and (3) regional voltage distribution by dynamic substrate mapping. Results: During activation mapping of the crista terminalis, two activation patterns were observed: (1) around the upper end of the crista terminalis (67%) and (2) through a gap in the crista terminalis. The presence of a crista terminalis gap was associated with a high incidence of induced atypical AFL/atrial fibrillation (P <.001). The conduction velocities of the medial cavotricuspid isthmus were slower in the old group than in the young group. In regional activation mapping of the AFL, the location of the slowest conduction shifted from the lateral cavotricuspid isthmus (71%) in the young group to the medial cavotricuspid isthmus (40%) in the old group. More cases with a low-voltage zone (≤30% peak negative voltage) extending to the medial side of the cavotricuspid isthmus occurred in the old group than in the young group (55% vs 17%, P = .012). Conclusion: The atrial substrate responsible for formation of typical AFL differed between young and old patient groups.