Abstract: AIM:To study the short- and long-term effects of radiofrequency catheter ablation on the left atrial structure and functions in patients with paroxysmal and persistent atrial fibrillation (AF) after radiofrequency ablation. METHODS: Transthoracic echocardiogram was performed in 79 patients with AF (65 cases in paroxysmal AF group and 14 cases in persistent AF group) at 1-3 days preoperation and 3, 6-9, and 12 months postoperation. Left atrial structure indexes were observed including the largest area of the left atrium (left atrial inferosuperior dimension×mediolateral dimension), the maximum volume of left atrium (LAVmax), the minimum volume of left atrium (LAVmin), and left atrial P volume (LAVp). The changes of left atrial functions were examined by calculating the left atrium passive ejection fraction (LAPEF), left atrial active ejection fraction (LAAEF), and left atrial emptying volume. Twenty-two cases without AF served as the control group. RESULTS: Preoperatively, the maximum left atrial area, the maximum left atrial volume and the minimum left atrial volume in the AF group were significantly larger than in the control group, with the indexes in the persistent AF group significantly higher than those in the paroxysmal AF group (P<0.05). The level of active ejection fraction in AF group was significantly lower than in the control group with the index in the persistent AF group significantly lower than in the paroxysmal AF group (P<0.05). There was no significant difference between passive ejection fraction and emptying volume between groups. Postoperatively, the size of the left atrial maximum area and the maximum left atrial volume decreased in both paroxysmal AF group and persistent AF group, but the changes occurred at different timepoints. The size in the paroxysmal AF group became significantly smaller (P<0.05) at 12 months postoperatively, whereas the size in the persistent AF group became significantly smaller (P<0.05) at 3 months postoperatively. There was no statistical significance in the changes of active ejection fraction, passive ejection fraction and emptying volume between groups. The short- and medium-term change rate of the postoperative maximum left atrial area in the persistent AF group was higher than in the paroxysmal AF group (P<0.05), but the difference of the change rate was not statistically significant at 12th months. CONCLUSION: Radiofrequency catheter ablation in patients with AF could reduce the increased left atrial structure, persistent AF more significantly in the short- and medium- term.Radiofrequency catheter ablation itself could not affect the left atrial function.