Table 2.

The circuit number and the location of the isthmus of AFL in our study cohort.

	Atypical AFL, n = 27	Typical AFL, n = 45
Total circuit number	55	45
RA
Circuit number	37/55 (67.3%)	45/45 (100%)
Isthmus location
CTI	17/37 (45.9%)	45/45 (100%)
CT areaa	7/37 (18.9%)	–
RA septal	6/37 (16.2%)	–
RA free wall	5/37 (13.5%)	–
SVC	2/37 (5.5%)	–
LA
Circuit number	18/55 (32.7%)	–
Isthmus location
LA septal	4/18 (22.2%)	–
LA anterior free wall	2/18 (11.1%)	–
LA posterior wall	1/18 (5.6%)	–
LA roof	3/18 (16.7%)	–
Mitral	5/18 (27.7%)	–
Pulmonary vein	3/18 (16.7%)	–
Mean circuit number per patient	2.04 ± 0.85	1

AFL, atrial flutter; RA, right atrium; CTI, cavotricuspid isthmus; CT, crista terminalis; SVC, superior vena cava; LA, left atrium.

^aThe mechanism of AFL and the location of the isthmus were defined as in previous studies (21, 22).