Background It has been known that radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) affects the left atrial (LA) size and function with long-term effects. However, it remains to be elucidated how circumferential LA ablation and additional linear ablation effect on the LA dimension and ejection fraction (EF) of the LA. Methods and Results The left atriogram (LAG; RAO 45째, LAO 45째 with 25째 cranial angulation) was performed by contrast injection directly into the LA through pigtail catheter (20cc/sec) before and after RFCA in 58 patients with AF (49.4짹12.3 years old; 47 male; 39 paroxysmal AF (PAF), 19 persistent AF (PeAF)). Transverse, longitudinal, AP diameters and ejection fractions (EF) of LA were measured. In all patients, circumferential pulmonary veins (PVs) ablation (CPVA) was performed, and 17 of them received additionally linear roof and/or perimitral ablation (Linear group). We also measured serum troponin I (TpI) level as marker of tissue damage after RFCA. Results: 1. RFCA reduced LA diastolic longitudinal (52.6짹3.9 mm to 49.4짹4.4 mm, p=0.006), transverse (43짹4.1 mm to 41.2짹4.5 mm, p=0.05), AP (41.6짹4.5 mm to 39.3짹5.4 mm, p=0.02), systolic longitudinal (42.6짹3.7 mm to 40.3짹5.2 mm, p=0.019) and AP diameters (34.3짹5.1 mm to 32.3짹6.4 mm, p=0.043). However, there were no significant changes of systolic transverse diameters. 2. LA EF was not significantly changed (50.2짹10.6% to 47.5짹9.3%, p=NS). 3. There was no difference in LA function and dimension between CPVA and Linear group. 4. All patients showed increased TpI level (0.02짹0.01 ng/mL to 1.55짹0.70 ng/mL, P<0.0001). But, there was no correlation between TpI and the parameters of LAG. Conclusion CPVA with or without linear LA ablation acutely changed the geometry and size of LA without attenuating LA systolic function.