Effect of radiofrequency ablation on atrial mechanical function in patients with atrial flutter.

Atrial stunning, as assessed by left atrial appendage emptying and increased spontaneous echo contrast, is known to occur following direct-current cardioversion of atrial fibrillation (AF) and atrial flutter (AFI). Little is known on atrial mechanical function and the time course of atrial recovery following radiofrequency ablation of AFI. Fourteen patients undergoing radiofrequency ablation of persistent typical counterclockwise AFI were enrolled. Two-dimensional and pulse Doppler transesophageal echocardiography (TEE) were performed before ablation and immediately following restoration of sinus rhythm. Left atrial spontaneous echo contrast grades, left atrial appendage emptying fractions, and peak left atrial appendage emptying velocities were measured. Transthoracic echocardiography (TTE) was performed immediately after ablation, then repeated after 1 day, 1 week, and 6 weeks to measure peak transmitral velocities and percent atrial contribution to ventricular filling. Left atrial appendage emptying velocities decreased significantly following AFI termination (44 +/- 23 cm/s before ablation vs 25 +/- 14 cm/s after ablation, p = 0.01). Left atrial appendage emptying fractions also decreased significantly (0.48 +/- 0.1 preablation vs 0.34 +/- 0.17 postablation, p = 0.02). New spontaneous echo contrast developed in 4 patients (29%) after ablation. Four patients had complete atrial standstill after ablation, and 1 patient developed a new left atrial appendage thrombus. The percent atrial contribution to ventricular filling recovered progressively over 6 weeks with significant improvement in peak transmitral velocities at day 7. Thus, atrial stunning occurs after catheter ablation of AFI and may lead to rapid formation of thrombus in the left atrial appendage. Significant improvement in left atrial function occurs in 7 days.