The present invention relates to a system for automatically distinguishing atrial flutter from atrial fibrillation based on a sequence of R-R-intervals of ECG-data. The system of the invention comprises means adapted to calculate or simulate an R-R-pattern from a model which is based on a periodic or almost periodic signal representing peaks of an atrial flutter signal, a first AV -block scheme blocking respective ones of the atrial excitations while transmitting the others with a predetermined transmittal delay and at least one more AV-block scheme blocking respective ones of the excitations transmitted by the previous AV-block scheme and transmitting the others with a predetermined transmittal delay. The excitations transmitted by the last AV-block scheme constitute the calculated R-R-pattern. The system further comprises consistency checking means adapted to automatically check whether said sequence of R-R- intervals of the ECG-data is to some predetermined degree consistent with said calculated or simulated R-R-pattern. The system is configured to identify the ECG-data to be based on atrial flutter if said predetermined degree of consistency is found.La présente invention concerne un système pour distinguer automatiquement un flutter auriculaire dune fibrillation auriculaire sur la base dune séquence dintervalles R-R de données délectrocardiogramme (ECG). Le système de linvention comprend un moyen conçu pour calculer ou simuler un motif R-R à partir dun modèle qui est basé sur un signal périodique ou presque périodique représentant des pics dun signal de flutter auriculaire, une première technique de bloc atrioventriculaire (AV) bloquant des excitations auriculaires respectives parmi les excitations auriculaires tout en transmettant les autres avec un retard de transmission prédéterminé et au moins une autre technique de bloc AV bloquant des excitations respectives parmi les excitations transmises par la technique de bloc AV précédente et transmettant les autres
