Junctional Rhythm-A Suitable Surrogate Endpoint in Catheter Ablation of Atrioventricular Nodal Reentry Tachycardia?

Radiofrequency ablation for pre-excitation syndromes and AV nodal re-entrant tachycardia

Radiofrequency catheter ablation for supraventricular tachycardia was introduced in 1990. Since then it has become the standard for definitive treatment of pre-excitation syndromes and atrioventricular re-entrant tachycardia. In general, catheter ablation of supraventricular tachycardia results in improved outcomes compared to pharmacologic treatment. Over 95% of patients will be successfully treated with catheter ablation with less than a 5% chance of recurrence and <1% risk of major complications.

Can successful radiofrequency ablation of atrioventricular nodal reentrant tachycardia be predicted by pattern of junctional ectopy?

BACKGROUND

Emergence of junctional rhythm (JR) during radiofrequency (RF) current delivery directed at the periatrioventricular nodal region has been shown to be a marker of success in atrioventricular nodal reentrant tachycardia (AVNRT). Whereas the characteristics of JR during RF ablation of slow pathway have already been studied, the electrophysiologic features of different patterns of JR are yet to be evaluated. The aim of this study was to investigate in detail the characteristics of the JR that develops during the RF ablation of the slow pathway.

MATERIALS AND RESULTS

The study population consisted of 95 patients: 56 women and 33 men (mean age, 47.2 +/- 16.3 years) who underwent slow pathway ablation because of AVNRT. A combined anatomical and electrogram mapping approach was used, and AVNRT was successfully eliminated in all patients. This study identified 7 patterns for JR during the RF ablation of slow pathway: junction-junction-junction, sinus-junction-sinus, intermittent burst, sparse, no junction, sinus-junction-junction, and sinus-junction-block . The characteristics of JR, such as mean cycle length and total number, were gathered. The incidence of JR was significantly higher during effective applications of RF energy than during ineffective applications (P = .001). The mean number of junctional ectopy was 19.6 +/- 19. The total number of junctional ectopy was significantly higher during effective applications of RF energy than during ineffective applications (24.6 +/- 18.8 vs 8.4 +/- 13.2; P < .001). We found a significant difference between the effective and ineffective applications of RF energy in the mean cycle length of the junctional ectopy (464.6 +/- 167.5 vs 263.4 +/- 250.2; P < .01). The patterns of JR were compared between effective and ineffective applications. We managed to show a significant correlation between patterns of JR and successful ablation (P = .01). Logistic regression analysis revealed that the presence of sinus-junction-sinus, sinus-junction-junction, and sinus-junction-block patterns of JR was a predictor of a successful RF ablation (confidence interval [CI], 1.67-15.92 [P < .004]; CI, 1.02-85.62 [P = .048]; and CI, 1.06-32.02 [P = .042], respectively).

CONCLUSION

This study confirms that JR is often present during successful slow pathway ablation. The pattern of JR is useful as indicator of success.

Cryoablation versus radiofrequency ablation for treatment of pediatric atrioventricular nodal reentrant tachycardia: Initial experience with 4-mm cryocatheter

BACKGROUND

Initial reports have shown cryoablation to be safe and efficacious for treatment of atrioventricular nodal reentrant tachycardia (AVNRT). No direct comparisons of cryoablation vs radiofrequency (RF) catheter ablation in pediatric patients have been made.

OBJECTIVES

The purpose of this study was to compare the outcomes of cryothermal vs RF catheter ablation for treatment of AVNRT in pediatric patients.

METHODS

We retrospectively reviewed consecutive ablation procedures for treatment of AVNRT at a single arrhythmia center. The RF group consisted of patients who underwent RF ablation from 2002 until cryothermy became available. The cryoablation group consisted of patients who underwent cryothermal ablation from 2004 to 2005. The groups were compared for procedural and electrophysiologic outcomes.

RESULTS

RF (n = 60, age 14 +/- 4 years) and cryoablation (n = 57, age 14 +/- 4 years) groups had similar demographic and baseline parameters. Procedural times were shorter in the RF group (RF ablation 112 +/- 31 minutes vs cryoablation 148 +/- 46 minutes, P < .001). Fluoroscopy times were comparable (RF ablation 21 +/- 15 minutes vs cryoablation 20 +/- 13 minutes, P = .77). In an intention-to-treat analysis, success of the procedure was 100% for RF ablation and 95% for cryoablation (P = .11). No permanent AV block occurred in either group. Recurrence rates were higher for the cryoablation group, but this did not reach statistical significance (RF ablation 2% vs cryoablation 8%, P = .19).

CONCLUSION

Cryoablation appears to be similar to RF for ablation of AVNRT with respect to short-term efficacy and safety of the procedure in a pediatric population. Recurrence rates are higher with cryoablation.