Different electrophysiological characteristics of cavo-tricuspid isthmus dependent atrial flutter guided by robotic magnetic navigation in patients with and without prior cardiac surgery

Backgroud: Cavo- tricuspid isthmus dependent atrial flutter (CTI- AFL) is a common atrial arrhythmia in patients with prior cardiac surgery (postsurgical AFL) and without prior cardiac surgery (nonsurgical AFL). However, there is only limited data regarding the eletrophysiological differences between the CTI- AFL in the postsurgical patients and the nonsurgical patients.

Hypothesis: We aimed to investigate the differences in clinical and electrophysiological characteristics between the postsurgical group and nonsurgical group and to evaluate the acute and long-term outcomes after ablation guided by robotic magnetic navigation (RMN) in both the groups. Methods Fourty-two consecutive patients with nonsurgical AFL and 21 with postsurgical AFL were retrospectively analyzed in our center. Electrocardiographic (ECG) analysis and three-dimensional electrophysiological study were performed in all the patients.

Results: The results revealed that only 55.6% of postsurgical patients with proven counterclockwise (CCW) AFL presented with a typical ECG suggesting this mechanism. In contrast, 86.1% of nonsurgical patients demonstrated a typical ECG pattern for CCW AFL. In addition, we employed a reverse "U-curve" to facilitate radiofrequency delivery when ablating near the inferior vena cava ostium in the present study. Compared with the nonsurgical group, electroanatomical mapping showed the mean AFL cycle length was significantly longer (253.3 ± 40.4 vs. 234.1 ± 24.2 ms, p = 0.03) and the right atrium volume was larger (114.8 ± 26.0 vs. 97.5 ± 19.1 mL, p = 0.004) in the postsurgical group. Additionally, the procedural time (75.9 ± 21.3 vs. 61.6 ± 26.6 minutes, p = 0.03) and ablation time (53.0 ± 21.4 vs. 36.7 ± 25.6 minutes, p = 0.02) are much longer in the postsurgical group. However, the navigation index in the postsurgical group was significantly smaller (0.35 ± 0.08 vs. 0.43 ± 0.13, p = 0.01). Moreover, the acute and long-term success rates were comparable between the two groups.

Conclusions: Catheter ablation of CTI-AFL with and without prior cardiac surgery guided by RMN are associated with high acute and long-term success rates, despite the procedural and ablation times are much longer in the postsurgical patients. However, ECG characteristics of the tachycardia may be misleading as they are more often atypical in patients after cardiac surgery.