Recurrence and late block of accessory pathway conduction following radiofrequency catheter ablation

Half versus normal saline irrigation during catheter ablation of outflow tract ventricular arrhythmias (HALF): a multi-center, parallel, open-label, randomized controlled study

BACKGROUND

Animal studies demonstrated that deeper lesions could be achieved during radio-frequency catheter ablation (RFCA) by using half saline (HS) compared to normal saline (NS) as irrigation.

OBJECTIVES

This study sought to compare the efficiency and safety of HS and NS for irrigation during RFCA of idiopathic outflow tract ventricular arrhythmia (OT-VA).

METHODS

In this multicenter, randomized controlled study, 167 patients undergoing RFCA of OT-VA were randomized 1:1 to receive HS- or NS-irrigated ablation. Acute success was defined as the absence of induced targeted premature ventricular contraction (PVC) at the end of the procedure. The 6-month success was defined as a ≥ 80% reduction of pre-procedural PVC burden.

RESULTS

There were no differences of baseline characteristics between the HS and NS group. Patients in HS group had shorter total ablation time (259.5 ± 155.5 S vs. 355.6 ± 230.7 S, P = 0.04) than that in NS group. The acute and 6-month success rates were similar between the HS and NS group (92.8 vs. 91.7%, P = 0.79; 90.9 vs. 92.1%, P = 0.79, respectively). No significant difference was observed in the incidence of steam pops between the HS and NS group (2.4 vs. 1.2%, P = 0.62).

CONCLUSIONS

The ablation using HS irrigation achieved similar success rate and safety compared to that using NS irrigation but was associated with a shorter total ablation time.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2200059205).

Six-Year Follow-Up Outcomes of Catheter Ablation of Para-Hisian Accessory Pathways

Background: Ablation of para-hisian accessory pathways (APs) remains challenging due to anatomic characteristics, and a few studies have focused on the causes for recurrence of radiofrequency ablation of para-hisian APs.

Objective: This retrospective single center study aimed to explore the risk factors for recurrence of para-hisian APs.

Methods: One hundred thirteen patients who had para-hisian AP with an acute success were enrolled in the study. In the 6-year follow-up, 15 cases had a recurrent para-hisian AP. Therefore, 98 patients were classified into the success group, while 15 patients were classified into the recurrence group. Demographic and ablation characteristics were analyzed.

Results: Gender difference was similar in two groups. The median age was 36.2 years old and was younger in the recurrence group. Maximum ablation power was significantly higher in the success group (29 ± 7.5 vs. 22.9 ± 7.8, p < 0.01). Ablation time of final target sites was found to be markedly higher in the success group (123.4 ± 53.1 vs. 86.7 ± 58.3, p < 0.05). Ablation time <60 s was detected in 12 (12.2%) cases in the success group and 7 (46.7%) cases in the recurrence group (p < 0.01). Occurrence of junctional rhythm was significantly higher in the recurrence group (25.5% vs. 53.3%, p < 0.05). No severe conduction block, no pacemaker implantation, and no stroke were reported. Junctional rhythm during ablation (OR = 3.833, 95% CI 1.083–13.572, p = 0.037) and ablation time <60 s (OR = 5.487, 95% CI 1.411–21.340, p = 0.014) were independent risk factors for the recurrence of para-hisian AP.

Conclusions: With careful and accurate mapping, it is relatively safe to ablate para-hisian AP. If possible, proper extension of ablation time could reduce the recurrence rate of para-hisian APs.

Late cure of focal ventricular arrhythmias post-catheter ablation: electrophysiological characteristics and long-term outcome

PURPOSE

Late cure after a previously failed ablation of ventricular arrhythmias (VAs) is a relatively common phenomenon. The present study sought to delineate the incidence and electrophysiological characteristics of late cure in idiopathic VA patients.

METHODS

Totally, 45 idiopathic VA cases (mean age 44 ± 18 years, 27 males) either failed acutely or recurred within 12 h were enrolled in this study. Based on intensive clinical observations in the acute period, 19 (42%) patients demonstrated late cure in the first week after the procedure.

RESULTS

The late cure patients had significantly better acute and cumulative ablation effects during the procedure than did those without a late cure. Additionally, they had a prediction that originated from the right ventricular outflow tract, aortic-mitral continuum, and left summit area relative to other sites (13/18 vs 6/27, p < 0.01). In a median follow-up of 24 [14, 46] months, 7/19 (37%) patients had their VAs recurred. The late cure group had significantly more patients cured at long-term follow-up than those without (12/19 vs 0/26, p < 0.01). A cutoff value of the "time to eliminate VAs" > 7.0 s was able to predict a long-term recurrence of the VAs with 62.5% sensitivity and 85.7% specificity.

CONCLUSIONS

The late cure of VAs occurs in more than one third of patients who have a seemingly unsuccessful ablation session, which is clustered in the first week after the procedure. However, long-term recurrence of VAs occurred in 37% of the late cure patients, emphasizing the importance of long-term follow-up.

Late cure after radiofrequency catheter ablation in a pediatric patient

A 12-year-old female with the Wolff-Parkinson-White syndrome underwent an electrophysiologic study followed by radiofrequency catheter ablation of the left-lateral accessory pathway. After several unsuccessful attempts, the procedure was stopped because of early recurrence of accessory pathway conduction. Twenty-four hours after the procedure, the patient was found without ventricular pre-excitation pattern on the electrocardiogram. During a 12-month follow-up, the Wolff-Parkinson-White pattern was no longer present. A transesophageal electrophysiologic study showed no further tachycardia induction and the patient is still asymptomatic. This report raises the issue that ablation-induced lesions may evolve considerably during the first few days after ablation, leading to either recurrent accessory pathway conduction or long-lasting complete cure.

Supraventricular tachycardia

Supraventricular tachycardias (SVT) comprise those tachycardias that originate above the bifurcation of the bundle of His. They can be classified broadly as AV node dependent and AV node independent. The mechanism and clinical manifestation of SVTs, which is essential to their correct diagnosis, is reviewed. The therapeutic management of SVTs, including acute and chronic drug therapy and catheter ablation, is discussed also.

[High frequency current catheter ablation of accessory conduction pathways]

Radiofrequency catheter ablation has established as the first line therapy for the curative treatment of patients with accessory pathway. Atrioventricular accessory pathways irrespective of the exact localisation can be successfully ablated in more than 90% of all cases. Severe complications associated with the ablation procedure are rare and occur in approximately 2% of patients treated. The recurrence rate after successful ablation is approximately 8 to 10%. Recurrence of accessory pathway conduction occurs almost exclusively within the first 3 months following successful ablation, late recurrences are rare. Patients with variants of accessory pathways such as atriofascicular pathways or retrogradely conducting accessory pathways with decremental conduction properties can also be cured with a high success rate. Because of its well balanced efficacy-risk profile radiofrequency catheter ablation should be recommended as the first line therapy to all symptomatic patients with accessory pathway.

Clinical recurrences after successful accessory pathway ablation: the role of "dormant" accessory pathways

INTRODUCTION

Recurrence of clinical symptoms after radiofrequency catheter ablation of an accessory atrioventricular pathway (AP) may be due to the late manifestation of an additional AP that was not detected during the initial ablation session. It was the purpose of this study to elucidate the phenomenon of these "dormant" APs.

METHODS AND RESULTS

Of 1280 consecutive patients who underwent radiofrequency catheter ablation of an AP, 54 patients (4.2%) developed clinical symptoms postablation, necessitating a repeat ablation session. Recurrence of conduction over the AP targeted at the initial ablation session was found in 45 patients, whereas in the other 9 patients (0.7%) the manifestation of a previously unnoticed AP had caused symptom recurrence. Retrospective analysis of the data from these patients' ablation sessions revealed that the late manifesting AP was ablated at a site clearly different from that of the initially targeted AP, and that the manifestation of conduction over a previously "dormant" AP occurred significantly later than the recovery of a presumably ablated AP. Seven (78%) of the 9 "dormant" APs were concealed, and none exhibited decremental conduction properties.

CONCLUSION

The incidence of clinical recurrences mediated by the late manifestation of conduction over a previously "dormant" AP is low. The lack of an anatomic vicinity of these predominantly concealed APs with the initially targeted AP and the lack of evidence for their presence during the initial ablation session suggest intermittent conduction as the most likely explanation for their late manifestation.

Ablation therapy for cardiac arrhythmias

Ablation has become an important and, in some cases, the first-line therapy for a number of tachyarrhythmias. The feasibility of treating arrhythmias with ablation was initially demonstrated with surgical ablation techniques. Recently, catheter ablation techniques have replaced the surgical approach in nearly all cases. Catheter ablation is highly effective for the Wolff-Parkinson-White syndrome, atrioventricular nodal reentry, and atrial ectopic tachycardia. It is effective for atrial flutter, although approximately one quarter of patients treated with catheter ablation continue to require therapy for concomitant atrial fibrillation. The surgical maze procedure has proved to be feasible for preventing atrial fibrillation. The risks and long-term efficacy of catheter ablation maze procedures for atrial fibrillation need to be defined. The efficacy of ablation for ventricular tachycardia varies with the type of tachycardia. Catheter ablation is very effective for the rare idiopathic ventricular tachycardias that occur in structurally normal hearts and for bundle-branch reentry ventricular tachycardia, which occurs most frequently in patients with dilated cardiomyopathy. When performed at an experienced center, surgical ablation is an excellent option for selected patients with ventricular tachycardia due to prior myocardial infarction who have a discrete aneurysm but otherwise well-preserved ventricular function. Catheter ablation shows promise for this arrhythmia, but it can be offered only to those patients who have relatively slow tachycardias that allow catheter mapping. Substantial advances in mapping and ablation technology will continue to occur, allowing nonpharmacologic control of cardiac arrhythmias to be achieved in an ever greater number of patients.

Inadvertent atrioventricular block during radiofrequency catheter ablation. Results of the Pediatric Radiofrequency Ablation Registry. Pediatric Electrophysiology Society

BACKGROUND

Inadvertent atrioventricular block is a complication of radiofrequency ablation. The present study is an analysis of the incidence, significance, and factors associated with inadvertent atrioventricular block during radiofrequency catheter ablation in childhood and adolescence.

METHODS AND RESULTS

The records of the Pediatric Radiofrequency Ablation Registry were reviewed. Between January 1, 1991, and April 1, 1994, atrioventricular block occurred in 23 of 1964 radiofrequency ablations (1.2%): 14 as third-degree block (3 transient) and 9 as second-degree block (5 transient). Atrioventricular block occurred from 5 seconds to 2 months (mean, 4.1 days; median, 15 seconds) after the onset of the energy application. Eight transient cases lasted 1 hour to 1 month (mean, 9.4 days; median, 7 days). Inadvertent atrioventricular block was related to the ablation anatomic site: 3 of 111 (2.7%) anteroseptal, 11 of 106 (10.4%) midseptal, and 2 of 197 (1.0%) right posteroseptal sites (P = .0007) for anteroseptal, P = .0001 for midseptal, and P = .17 for right posteroseptal versus nonright septal sites). Five of 314 (1.6%) ablations for atrioventricular nodal reentrant tachycardia resulted in atrioventricular block (P = .004 versus nonright septal sites). Compared with a matched subgroup, radiofrequency ablation experience was the only significant risk factor (32.7 versus 106.6, P = .002) for the occurrence of atrioventricular block.

CONCLUSIONS

Inadvertent atrioventricular block may occur during or late after radiofrequency catheter ablation. It is associated with ablations for (1) anterior and midseptal accessory pathways and atrioventricular nodal reentry and (2) relative institutional inexperience.

Insights into the electrophysiology of accessory pathway-mediated arrhythmias provided by the catheter ablation experience: "learning while burning, part III"

The success of catheter ablation has greatly improved the care of patients with paroxysmal tachycardias and has caused a revolution in the practice of electrophysiology. Some investigators have expressed that concern over procedural success in an increasingly interventional specialty threatens to eclipse attempts to understand the physiology of arrhythmia syndromes. Alternatively, due to the precise and directed nature of the lesions created with radiofrequency energy, catheter ablation procedures have allowed investigation to continue at a more focused level. In this article, the insights provided by the catheter ablation experience into the physiology of arrhythmias mediated by accessory AV pathways will be reviewed. Although the learning process was sometimes delayed by the nearly immediate success of radiofrequency catheter ablation, difficult situations have continued to renew efforts for understanding at a deeper level. Conscious attempts at "learning while burning" will provide the opportunity to investigate aspects of bypass tract physiology that remain incompletely characterized, such as partial response to therapy and late recurrence.

Recurrence of conduction following radiofrequency catheter ablation procedures: relationship to ablation target and electrode temperature. The Atakr Multicenter Investigators Group

INTRODUCTION

More than 1 in 10 patients may develop recurrence of conduction after undergoing a successful radiofrequency catheter ablation procedure. The physiologic basis for recurrence following successful ablation procedures remains uncertain. The purpose of this study was to evaluate the role of electrode temperature as a predictor of recurrence following radiofrequency catheter ablation procedures.

METHODS AND RESULTS

The subjects of this study were 538 patients who underwent a successful attempt at radiofrequency catheter ablation of AV nodal reentrant tachycardia, an accessory pathway, and/or the AV junction. Patients were followed for a mean of 215 +/- 138 days. Conduction recurred in 35 (6.5%) of the 538 patients. Recurrence of conduction occurred in 25 (9.3%) of 270 patients undergoing ablation of an accessory pathway, 7 (3.5%) of 201 patients undergoing ablation of AV nodal reentrant tachycardia, and in 3 (4.5%) of 67 patients undergoing ablation of the AV junction. The electrode temperature achieved at successful sites associated with recurrence was not different from the temperature achieved at successful sites without recurrence (61.1 +/- 8.9 vs 61.6 +/- 9.1; P = 0.8). The likelihood of developing a recurrence was higher following ablation of accessory pathways than following ablation of AV nodal reentrant tachycardia or the AV junction (P = 0.03). Patients experiencing a recurrence following ablation of an accessory pathway had longer procedure durations (P = 0.0001). Ablation of left free-wall pathways was associated with a lower incidence of recurrence as compared with all other locations (P = 0.008).

CONCLUSION

The results of this study suggest that electrode temperature at the successful ablation site cannot be used to identify patients at highest risk of recurrence.

Localization and radiofrequency catheter ablation of left-sided accessory pathways during atrial fibrillation. Feasibility and electrogram criteria for identification of appropriate target sites

OBJECTIVES

The purpose of the present study was to assess the feasibility of and electrophysiologic criteria for successful radiofrequency catheter ablation of left-sided accessory pathways during atrial fibrillation in patients with Wolff-Parkinson-White syndrome.

BACKGROUND

The onset of recurrent or sustained atrial fibrillation can complicate or significantly prolong accessory pathway catheter ablation procedures.

METHODS

We studied 19 consecutive patients (mean age [+/-SD] 44 +/- 16 years) with Wolff-Parkinson-White syndrome who had ongoing atrial fibrillation with rapid anterograde conduction over the accessory pathway (mean ventricular rate [+/-SD] 173 +/- 26 beats/min, range 130 to 220) at the beginning of the localization procedure during radiofrequency catheter ablation. Localization and ablation of the accessory pathway were performed with a 7F deflectable catheter (4-mm tip) that was placed underneath the mitral valve annulus. The electrophysiologic criteria from unipolar and bipolar local electrograms were compared for successful (n = 18) and unsuccessful (n = 39) sites.

RESULTS

The accessory pathways were localized in the left posteroseptal (n = 6), posterior (n = 1), posterolateral (n = 7) and lateral (n = 5) regions and successfully ablated during atrial fibrillation in 18 (95%) of 19 patients with a mean of 3 +/- 2 radiofrequency pulses (range 1 to 8, median 2). Presence of an accessory pathway potential (94% vs. 44%), early activation time of the ventricular electrogram (-3.2 +/- 9.2 vs. -15.3 +/- 12.6 ms) and recording of atrial activation (88% vs. 61%) from the ablation catheter were helpful in identifying successful sites (p < 0.001, p < 0.001 and p < 0.05, respectively, compared with unsuccessful sites). In addition, the ventricular activation time in relation to the intrinsic deflection of the unipolar electrogram was significantly earlier at successful than unsuccessful sites (18.1 +/- 4.8 vs. 24.4 +/- 6.6 ms, p < 0.01). A QS complex on the unipolar electrogram was observed at 96% of successful sites and at 94% of unsuccessful sites (p = 0.74). Multivariate logistic regression analysis revealed that the presence of an accessory pathway potential (p < 0.002) and early ventricular activation time in relation to the onset of the QRS complex (p < 0.001) were independent predictors of ablation success.

CONCLUSIONS

Localization and radiofrequency catheter ablation of left-sided accessory pathways is possible in patients with sustained atrial fibrillation and rapid anterograde conduction over the accessory pathway during the ablation procedure. The electrophysiologic criteria described here can be used to reliably identify successful sites for radiofrequency ablation.