Left atrial “stunning” following radiofrequency catheter ablation of chronic atrial flutter

Objectives. This study examined the effect of radiofrequency ablation (RFA) on left atrial (LA) and left atrial appendage (LAA) function in humans with chronic atrial flutter (AFL). Background. Atrial stunning and the development of spontaneous echocardiographic contrast (SEC) is consequence of electrical cardioversion of AFL to sinus rhythm. This phenomenon has been termed “stunning” and is associated with thrombus formation and embolic stroke. Radiofrequency ablation is now considered to be definitive treatment for chronic AFL, but whether this procedure is complicated by L stunning is unknown. Methods. Fifteen patients with chronic AFL undergoing curative RF underwent transesophageal echocardiography to evaluate L and LA function and SEC before and immediately, 30 minutes and 3 weeks after RFA. To control for possible direct effects of RF on atrial function, seven patients undergoing RF for paroxysmal AFL were also studied. In this group, RF energy was delivered in sinus rhythm and echocardiographic parameters were assessed before and immediately and 30 minutes following RFA. Results. Chronic AFL: Mean arrhythmi duration was 17.2 ± 13.3 months. Twelve patients (80%) developed SEC following RF energy application and reversion to sinus rhythm. LA velocities decreased significantly from 54.0 ± 14.2 cm/s in AFL to 18.0 ± 7.1 cm/s in sinus rhythm after arrhythmi termination (p < 0.01). These changes persisted for 30 minutes. Following 3 weeks of sustained sinus rhythm, significant improvements in LA velocities (68.9 ± 23.6 vs. 18.0 ± 7.1 cm/s, p < 0.01) and mitral A-wave velocities (49.8 ± 10.3 vs. 13.4 ± 11.2 cm/s, p < 0.01) were evident and SEC had resolved in all patients. Paroxysmal AFL: Radiofrequency energy delivered in sinus rhythm had no significant effect on any of the above indexes of L or LA function and no patient developed SEC following RFA. Conclusions. Radiofrequency ablation of chronic AFL is associated with significant L stunning and the development of SEC. Left atrial stunning is not secondary to the RF energy application itself. Sustained sinus rhythm for 3 weeks leads to resolution of these acute phenomena. Left atrial stunning occurs in the absence of direct current shock or antiarrhythmic drugs, suggesting that its mechanism may be function of the preceding arrhythmi rather than the mode of reversion.