Abstract 2483: Revisit of Typical Atrial Flutter Wave in the ECG: Electroanatomical Analysis of the Component Between the Negative Deflections of Flutter Wave in Isthmus-Dependent Counterclockwise Atrial Flutter
Typical cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) is characterized by flutter wave (F-wave) with negative saw-tooth morphology. It was reported that there are three types of F-wave, type 1 with purely negative F-wave inferiorly, type 2 with F-wave inferiorly with a small positive terminal deflection, and type 3 with F-wave inferiorly with a broad positive deflection. Negative deflection of F-wave is explained by caudo-cranial activation of the interatrial septum and left atrium, but the component between the negative deflections in each of 3 types of AFL is not fully defined. In the consecutive 40 patients with CTI-dependent, counterclockwise AFL, a complete electroanatomical (CARTO) map of the right atrium (RA) was obtained by sampling from 102±26 points. By comparing F-wave on the ECG with the CARTO activation map, we determined which part of the atrium the activation corresponded to the component between the negative deflections. We further sought the determinant for F-wave variation. There were 6 type 1 (15%), 22 type 2 (55%), and 12 type 3 of AFL (30%). Any of the clinical characteristics including underlying age, gender, heart disease, previous atrial fibrillation and left atrial enlargement were different among the 3 types. CARTO map revealed that the activation in the RA free wall and CTI starting from a mean of 11 p.m. counterclockwisely to a mean of 4:30 a.m. around the tricuspid annulus corresponded to the ECG component between the negative deflections. There was no difference in the activation pattern in the RA among the 3 types. We analyzed bipolar voltage map of the RA and compared the extent (percentage to the whole RA) of the low voltage area (LVA) defined as the area consisting of sites with amplitude <0.5mV between type 1 AFL without any positive deflection and types 2 and 3 with a positive deflection. LVA was present exclusively in the RA free wall in type 1 AFL, and the extent was greater in type 1 than in types 2 and 3 (45±20% vs 6±4%, P<.0001). In conclusion, the ECG component between the negative deflections in typical AFL is explained by the counterclockwise activation in the RA free wall and CTI. Whether a positive deflection is present in F-wave is not related to any of the clinical characteristics but the voltage of the RA free wall.