Differentiating atrial tachycardias with centrifugal activation: Lessons from high-resolution mapping.

ABSTRACT Background A centrifugal activation is not always the origin of a focal-AT (True-Focal), but a passive activation from the other structures (Pseudo-Focal). Objective We aimed to establish a method to differentiate ‘True-focal’ from ‘Pseudo-Focal’. Methods In 49 centrifugal activations in 35 AT-patients, 12-lead ECG, activation map, atrial global activation histogram (GAH), and local electrograms were analyzed. GAH demonstrates the relation between the activation area and timing through the cycle-length, displayed with a normalized-value, ranging from 0 (smallest activation-area) to 1.0 (largest activation-area). Results Of 30 centrifugal activations observed in the septal region, 6 were ‘True-Focal’. The remaining 24 were ‘Pseudo-Focal’, of which 23/24 (95.8%) were from the opposite chamber. P-wave/flutter-waves duration Of 19 centrifugal activations observed outside septal regions, 7 were ‘True-Focal’ and 12 were ‘Pseudo-Focal’ exited from an epicardial structure: 10/12 (83.3%) were located around the LAA and ridge. Flutter-wave, GAH 0.05, and GAH Conclusion Centrifugal activation is not necessarily due to a focal AT but a passive activation. The activation map with the GAH in addition to 12-lead ECG and local-EGMs enables an accurate differentiation.