Comparison of Heart Rate Variability Parameters Between Slow Pathway Complete Ablation and Modification/Ablation for AVNRT

Background: Atrioventricular nodal reentry tachycardia (AVNRT) is the most common type of supraventricular tachycardia, and catheter slow pathway ablation is the first-line therapy in this arrhythmia. The endpoint for the successful ablation of AVNRT is the noninducibility of the tachycardia rather than the complete ablation or modification/ablation of slow pathways. We aimed to compare heart rate variability (HRV) parameters between slow pathway complete ablation and slow pathway modification/ablation for AVNRT.Methods: The current study enrolled 78 eligible patients with AVNRT. Slow pathway complete ablation was performed on 49 patients, and 29 patients underwent slow pathway modification/ablation. HRV parameters on 24-hour Holter monitoring were compared before and 30 days after ablation between these 2 groups.Results: HRV parameters, consisting of the mean heart rate, the standard deviation of normal-to -normal RR intervals over 24 hours (SDNN), the standard deviation of the average NN intervals for all 5-minute intervals in a 24-hour continuous electrocardiographic recording (SDANN), and a percent NN interval exceeding 50 milliseconds from the prior interval (PNN50), were not significantly different in the group with complete slow pathway ablation. The comparison between pre and post-intervention entities revealed statistically significant differences in SDNN (P=0.041) and PNN50 (P=0.008) in the group with slow pathway modification/ablation. Additionally, PNN50 was significantly lower in the modification/ablation group than in the complete ablation group.Conclusions: We noted negligible differences regarding HRV-associated indices between the slow pathway complete ablation and modification/ablation for AVNRT groups. (Iranian Heart Journal 2023; 24(2): 62-68)