Efficacy and safety between radiofrequency ablation and types of cryoablation catheters for atrioventricular nodal reentrant tachycardia: A Network Meta-analysis and Systematic Review

INTRODUCTION

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common supraventricular tachycardia referred for ablation. Periprocedural conduction system damage was a primary concern during AVNRT ablation. This study aimed to assess the incidence of permanent atrioventricular (AV) block and the success rate associated with different types of catheters in slow pathway ablation.

METHOD

A literature search was performed to identify studies that compared various techniques, including types of radiofrequency ablation (irrigated and nonirrigated) and different sizes of catheter tip cryoablation (4, 6, and 8-mm), in terms of their outcomes related to permanent atrioventricular block and success rate. To assess and rank the treatments for the different outcomes, a random-effects model of network meta-analysis, along with p-scores, was employed.

RESULTS

A total of 27 studies with 5110 patients were included in the analysis. Overall success rates ranged from 89.78% to 100%. Point estimation showed 4-mm cryoablation exhibited an odds ratio of 0.649 (95%CI: 0.202-2.087) when compared to nonirrigated RFA. Similarly, 6-mm cryoablation had an odds ratio of 0.944 (95%CI: 0.307-2.905), 8-mm cryoablation had an odds ratio of 0.848 (95%CI: 0.089-8.107), and irrigated RFA had an odds ratio of 0.424 (95%CI: 0.058-3.121) compared to nonirrigated RFA.

CONCLUSION

Our study found no significant difference in the incidence of permanent AV block between the types of catheters. The success rates were consistently high across all groups. These findings emphasize the potential of both RF ablation (irrigated and nonirrigated catheter) and cryoablation as viable options for the treatment of AVNRT, with similar safety and efficacy profile.

Atrioventricular nodal reentry tachycardia treatment using CARTO 3 V7 activation mapping: a new era of slow pathway radiofrequency ablation is under coming

Background

Slow pathway (SP) ablation is the cornerstone for atrioventricular nodal reentry tachycardia (AVNRT) treatment, and a low-voltage bridge offers a good target during mapping using low x-ray exposure. We aimed to assess a new tool to identify SP by activation mapping using the last CARTO3® version, i.e., CARTO PRIME® V7 (Biosense Webster, Diamond Bar, CA, USA).

Methods and results

Right atrial septum and triangle of Koch 3D-activation map were obtained from intracardiac contact mapping during low x-ray CARTO 3® procedure. In 60 patients (mean age 60.3 ± 14.7, 61% females) undergoing ablation for AVNRT, an automatic activation map using a DECANAV® mapping catheter and CARTO® Confidense™, Coherent, and FAM DX software modules were obtained. The SP was identified in all patients as the latest atrioventricular node activation area; RF catheter ablation (RFCA) in that region elicited junctional beats. The mean procedural time was 150.3 ± 48.3 min, the mean fluoroscopy time exposure was 2.9 ± 2 min, the mean dose-area product (DAP) was 16.5 ± 2.7 cGy/cm2. The mean number of RF applications was 3.9 ± 2, the mean ablation index was 428.6 ± 96.6, and the mean contact force was 8 ± 2.8 g. There were no adverse event during the procedure, and no AVNRT recurrences occurred during a mean follow-up of 14.3 ± 8.3 months.

Conclusion

Ablation of the SP by automatic mapping using Confidense™, Coherent, and FAM DX software modules is an innovative, safe, and effective approach to AVNRT ablation. The CARTO3® V7 system shows on a 3D map the latest AV node activation area during sinus rhythm allowing low fluoroscopy time and highly effective RFCA.

Transitioning from Radiofrequency Ablation to Cryoablation for Treatment of Pediatric Atrioventricular Nodal Reentrant Tachycardia: A Single Tertiary Center Experience

Catheter ablation of the slow pathway is the recommended treatment for atrioventricular nodal reentrant tachycardia (AVNRT) in children. Both radiofrequency ablation (RF) and cryoablation (CA) have been used for this purpose. In this report, we describe our experience during the transition period from RF to CA for the treatment of pediatric AVNRT. Between January 2012 and August 2021, a retrospective evaluation was conducted of the clinical features, procedural outcomes, and follow-ups of pediatric AVNRT patients who underwent catheter ablation at a pediatric electrophysiology center. The catheter ablation outcomes of 89 pediatric AVNRT patients were evaluated: 29 patients were ablated using RF (RF group) and 60 patients were ablated using CA (CA group). No significant difference was found between the groups in terms of gender, age, weight, and success and recurrence rates. The procedure duration and total lesion numbers were statistically significantly lower in the RF group compared with the CA group (86.67 ± 45.8 and 156.1 ± 37.7 min; p = 0.01, 4 [3-6] and p < 0.01, 8 [7-9] lesions, respectively). Catheter ablation was successful in all patients. There were no permanent complete atrioventricular blocks in both groups. A total of six patients (6.8%) developed recurrences. The cryoablation of pediatric AVNRT is a safe and effective procedure with comparable acute and mid-term follow-up success rates compared with RF, even during a period of transition from RF to CA.

Focal cryoablation of atrioventricular node reentrant tachycardia: a review and comparison of data

PURPOSE OF REVIEW

Atrioventricular node reentrant tachycardia (AVNRT) is the most common mechanism of supraventricular tachycardia. Radiofrequency ablation has been the most prevalent method for slow pathway ablation but carries risk of atrioventricular node injury. Focal cryoablation has been utilized as an alternative ablation modality; however, there has been concern about decreased efficacy, resulting in a higher rate of recurrence postablation. We also report outcomes from two international centers using an 8-mm cryocatheter and complete a thorough comparison of existing data on ablation of AVNRT.

RECENT FINDINGS

Previous reviews included studies from 2006 onward. These studies included use of the 4 mm focal cryocatheter, which has largely been abandoned in current adult practice. We will cite more contemporary studies within the past 10 years, which also includes use of the 6 and 8 mm cryocatheter.

SUMMARY

The use of focal cryoablation allows for reversible injury during AVNRT ablation, providing safety from permanent atrioventricular node injury. With the appropriate ablation endpoints, 8 mm focal cryoablation is more effective for permanent lesion formation, leading to lower recurrences.

Efficacy of cryo-ablation during atrioventricular nodal reentrant tachycardia

Because of the low atrioventricular (AV) block risk during cryo-ablation, it has become possible to treat AV nodal reentrant tachycardia (AVNRT) during arrhythmia. This study aimed to investigate the clinical outcomes of performing cryo-ablation for AVNRT during arrhythmia. Twenty-three patients with AVNRT treated by cryo-ablation during arrhythmia were enrolled. Cryo-ablation was performed gradually from the bottom to above the paraseptal tricuspid annulus until AVNRT was terminated. If the slow pathway was not eliminated despite cryo-ablation terminating the AVNRT, additional cryo-ablation was performed at a higher site until the slow pathway elimination was achieved. AVNRT was terminated by cryo-ablation in all 23 patients. However, the slow pathway was only eliminated in 6 patients. Among the remaining 17 patients, the slow pathway could not be ablated because transient AV block occurred during cryo-ablation at a higher site in 8 patients; however, cryo-ablation at a higher site successfully eliminated the slow pathway in the other 9 patients. In these 9 patients, the distance from the bottom of tricuspid annulus to the site of slow pathway elimination was significantly longer than that from bottom of tricuspid annulus to the AVNRT termination site (20.1 ± 5.3 vs 14.7 ± 4.5 mm: p = 0.027). During follow-up, AVNRT recurrence was confirmed in 3 patients. In 1 of these 3 patients, even a slow pathway elimination was achieved by cryo-ablation at the AVNRT termination site. The AVNRT termination site may not be the ideal site for performing cryo-ablation.

Permanent and Transient Electrophysiological Effects During Cardiac Cryoablation Documented by Optical Activation Mapping and Thermal Imaging

OBJECTIVE

Cardiac catheter cryoablation is a safer alternative to radiofrequency ablation for arrhythmia treatment, but electrophysiological (EP) effects during and after freezing are not adequately characterized. The goal of this study was to determine transient and permanent temperature induced EP effects, during and after localized tissue freezing.

METHODS

Conduction in right (RV) and left ventricles (LV) was studied by optical activation mapping during and after cryoablation in paced, isolated Langendorff-perfused porcine hearts. Cryoablation was performed endocardially (n=4) or epicardially (n=4) by a cryoprobe cooled to -120 °C for 8 minutes. Epicardial surface temperature was imaged with an infrared camera. Viability staining was performed after ablation. Motion compensation and co-registration was performed between optical mapping data, temperature image data, and lesion images.

RESULTS

Cryoablation produced lesions 14.9 +/- 3.1 mm in diameter and 5.8 +/- 1.7 mm deep. A permanent lesion was formed in tissue cooled below -5 +/- 4 °C. Transient EP changes observed at temperatures between 17 and 37 °C during cryoablation surrounding the frozen tissue region directly correlated with local temperature, and include action potential (AP) duration prolongation, decrease in AP magnitude, and slowing in conduction velocity (Q10=2.0). Transient conduction block was observed when epicardial temperature reached <17 °C, but completely resolved upon tissue rewarming, within 5 minutes.

CONCLUSION

Transient EP changes were observed surrounding the permanent cryo lesion (<-5 °C), including conduction block (-5 to 17 °C), and reduced conduction velocity (>17 °C).

SIGNIFICANCE

The observed changes explain effects observed during clinical cryoablation, including transient increases in effective refractory period, transient conduction block, and transient slowing of conduction. The presented quantitative data on temperature dependence of EP effects may enable the prediction of the effects of clinical cryoablation devices.

A comparative analysis of clinical outcomes and disposable costs of different catheter ablation methods for the treatment of atrioventricular nodal reentrant tachycardia

Background

Catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) is a commonly performed electrophysiology (EP) procedure. Few data exist comparing conventional (CONV) versus novel ablation strategies from both clinical and direct cost perspectives. We sought to investigate the disposable costs and clinical outcomes associated with three different ablation methodologies used in the ablation of AVNRT.

Methods

We performed a retrospective review of AVNRT ablations performed at Augusta University Medical Center from 2006 to 2014. A total of 183 patients were identified. Three different ablation techniques were compared: CONV manual radiofrequency (RF) (n=60), remote magnetic navigation (RMN)-guided RF (n=67), and cryoablation (CRYO) (n=56).

Results

Baseline demographics did not differ between the three groups except for a higher prevalence of cardiomyopathy in the RMN group (p<0.01). The clinical end point of interest was recurrent AVNRT following the index ablation procedure. A significantly higher number of recurrent AVNRT cases occurred in the CRYO group as compared to CONV and RMN (p=0.003; OR =7.75) groups. Cost-benefit analysis showed both CONV and RMN to be dominant compared to CRYO. Cost-minimization analysis demonstrated the least expensive ablation method to be CONV (mean disposable catheter cost = CONV US$2340; CRYO US$3515; RMN US$5190). Despite comparable clinical outcomes, the incremental cost of RMN over CONV averaged US$3094 per procedure.

Conclusion

AVNRT ablation using either CONV or RMN techniques is equally effective and associated with lower AVNRT recurrence rates than CRYO. CONV ablation carries significant disposable cost savings as compared to RMN, despite similar efficacy.

Pseudo cryomapping for ablation of atrioventricular nodal reentry tachycardia: A single center North American experience

Background

Most literature for cryoablation of atrioventricular nodal reentry tachycardia (AVNRT) is based on −30 degree celsius cryomapping with 4 & 6 mm distal electrode catheters. The cryomapping mode is not available on the 6 mm cryocatheter in the United States. We describe a technique for ‘pseudo’ mapping at −80° using a 6 mm cryocatheter and report on short and long term outcomes.

Methods

A retrospective analysis of all index cases (n = 253) of cryoablation of AVNRT at a single North American institution during the period of 2003–2010 was performed. The majority of cases utilized a 6 mm distal electrode tip catheter. Long term follow up (2.4 ± 1.8 years) was performed via review of the medical record and by questionnaire or telephone if necessary.

Results

Acute ablation success was achieved in 93% of cases, with transient conduction defects noted in 39% of cases, and long term conduction defects in 1.6% of cases (4 patients with PR prolongation, 2 of which were permanent). General anesthesia, male gender and presence of structural heart disease were more common in the acute failure cohort. The recurrence rate for AVNRT was 8%. These patients tended to be younger and had more transient A-V conduction defects during the index procedure than those without a recurrence.

Conclusions

In conclusion, anatomic cryoablation of AVNRT utilizing a 6 mm electrode catheter with mapping performed at −80° Celsius is a safe procedure with good long term efficacy. Transient A-V block during the index procedure increases the risk of late recurrence.

Comparison of 6-mm Versus 8-mm-Tip Cryoablation Catheter for the Treatment of Atrioventricular Nodal Reentrant Tachycardia in Children: A Prospective Study

Due to its safety profile, cryoablation (Cryo) for atrioventricular nodal reentrant tachycardia (AVNRT) is more commonly preferred over radiofrequency (RF) ablation in children in recent years. Recent studies demonstrated high long-term success rates comparable to radiofrequency ablation. The aim of this prospective study was to compare the efficacy and safety of an 8-mm-tip versus 6-mm-tip Cryo catheter in the treatment of AVNRT in children. A total of 125 consecutive patients over 10 years of age with AVNRT were included. EnSite system (St. JudeMedical, St Paul, MN, USA) was used to reduce or eliminate fluoroscopy. The acute procedural success was 100% in both groups. The prodecure duration for the 8-mm-tip group was shorter (151.6 ± 63.2 vs. 126.6 ± 36.7 min, p < 0.01, respectively). Fluoroscopy was used in only 7 patients. The mean follow-up duration was 14.6 ± 8.4 months (median 13.5 months, min. 3 months and max. 27 months). The recurrence rate for AVNRT was also comparable between the two groups (6-mm tip: 9.6 vs. 8-mm tip: 8%). Cryo of AVNRT is a safe and effective procedure with comparable acute and mid-term follow-up success rates using 6-mm and 8-mm-tip catheters in children. In addition, procedure duration is shorter with an 8-mm-tip Cryo catheter.

Slow Pathway Radiofrequency Ablation Using Magnetic Navigation: A Description of Technique and Retrospective Case Analysis

BACKGROUND

The Magnetic Navigation System (MNS) catheter was shown to be stable in the presence of significant cardiac wall motion and delivered more effective lesions compared to manual control. This stability could potentially make AV junctional re-entrant tachycardia (AVNRT) ablation safer. The aim of this study is to describe the method of mapping and ablation of AVNRT with MNS and 3-D electro-anatomical mapping system (CARTO, Biosense Webster, Diamond bar, CA, USA) anatomical mapping, with a view to improve the safety of ablation.

METHODS

The method of precise mapping and ablation with MNS is described. Consecutive AVNRT cases (n=30) from 2012 January to 2015 November, in which magnetic navigation was used, are analysed.

RESULTS

Ablation was successful in 27 (90%) out of 30 patients. In three cases, ablation was abandoned due to the proximity of the three-dimensional His image to the potential ablation site. No complications, including AV nodal injury, occurred. The distance from the nearest His position to successful ablation site in both LAO and RAO projections of CARTO images was 26.4±8.8 and 27±7.7mm respectively. Only in two (9%) patients, ablation needed to be extended superior to the plane of coronary sinus ostium, towards the His bundle region, to achieve slow pathway modification.

CONCLUSION

AVNRT ablation with MNS allows for accurate mapping of the AV node and stable ablation at a safe distance, which could help avoid AV nodal injury. We recommend this modality for younger patients with AVNRT.

Yamaguchi syndrome presenting as atrioventricular nodal re-entrant tachycardia in an African-American patient

Apical hypertrophic cardiomyopathy (Yamaguchi syndrome) is a rare subtype of hypertrophic cardiomyopathy. The syndrome is more common in Japan where it was first described. Outside Asia, it is a very rare cause of hypertrophic cardiomyopathy. Apical hypertrophic cardiomyopathy is usually detected incidentally and has a good long-term outcome. We present a case of apical hypertrophic cardiomyopathy in an African-American patient manifesting as atrioventricular nodal re-entrant tachycardia.

Time-limited cryomapping during tachycardia: improved long-term outcomes for cryoablation of AVNRT

Purpose

Cryothermal ablation (CTA) for atrioventricular nodal reentrant tachycardia (AVNRT) is considered safer than radiofrequency ablation (RFA) since it eliminates the risk of inadvertent AV block. However, it has not been widely adopted due to high late recurrence rate (LRR). In an effort to improve LRR, we evaluated a new approach to cryothermal mapping (CTM): “time to tachycardia termination” (TTT).

Methods

This single-center study had 88 consecutive patients who underwent CTA using TTT for AVNRT. The CTA catheter was positioned in sinus rhythm at the posteroseptal tricuspid annulus, and then AVNRT was induced. The CTA target site was identified by prompt tachycardia termination in ≤20 s during CTM. Procedural success was defined as no inducible AVNRT and ≤1 single AV nodal echoes.

Results

Acute procedural success was achieved in 87 of 88 patients (98.9 %) and was similar to prior studies for both CTA and RFA. No permanent AV block was observed. LRR was 3.7 % at a mean follow-up of 19.7 months. LRR was equivalent to that commonly reported for RFA and improved when compared to conventional CTA.

Conclusion

TTT for CTA of AVNRT provides enhanced safety and similar long-term efficacy when compared to RFA. Based upon this experience, TTT provides an enhancement to conventional CTA that appears to result in improved long-term outcomes. In light of these findings, it seems reasonable to undertake additional randomized trials to determine whether RFA or CTA using TTT is the optimal approach for the catheter ablation of AVNRT.

Cryoablation versus radiofrequency ablation of atrioventricular nodal reentrant tachycardia

BACKGROUND

Ablation of the slow pathway is an established cure for atrioventricular nodal reentrant tachycardia (AVNRT). Periprocedural damage to the conduction system is a major concern during AVNRT ablation, and cryoablation (CRYO) has been suggested to improve the procedural safety compared to standard radiofrequency (RF) ablation, without reducing the procedural success.

OBJECTIVE

We performed a systematic review and meta-analysis of studies comparing CRYO with RF ablation of AVNRT.

METHODS

We searched PubMed, CENTRAL, the BioMed Central, EMBASE, CardioSource, clinicaltrials.gov, and ISI Web of Science (January 1980 to July 2013). No language restriction was applied. Two independent reviewers screened titles and abstracts to identify studies that compared the procedural outcomes of AVNRT ablation with either CRYO or RF energy. Two independent reviewers assessed the risk of bias according to the Cochrane Collaboration, and extracted patient, study characteristics, and procedural outcome data. Results are expressed as odds ratio (OR) or as weighted mean difference (WMD) with their 95 % confidence interval (CI).

RESULTS

Fourteen studies (5 prospective randomized and 9 observational) with 2,340 patients (mean age range 13 to 53 years, 1,522 (65 %) females) were included in the analysis. RF ablation was performed in 1,262 (54 %) patients, while CRYO in 1,078 (46 %) patients. Acute success (abolition of dual atrioventricular node physiology or single echo beats) was achieved in 88 % of patients treated with RF versus 83 % of those treated with CRYO (OR = 0.72, 95 % CI 0.46 to 1.13; P = 0.157). RF ablation was associated with shorter total procedure time (WMD = -13.7 min, 95 % CI -23 to -4.3 min; P = 0.004), but slightly longer fluoroscopy time (WMD = +4.6 min 95 % CI +1.7 to +7.6 min; P = 0.002). Permanent atrioventricular block occurred in 0.87 % RF cases and in no CRYO case (OR = 3.60, 95 % CI 1.09 to 11.81; P = 0.035). Over a median follow-up of 10.5 months (range 6 to 12 months), freedom from recurrent AVNRT was 96.5 % in the RF group versus 90.9 % in the CRYO group (OR = 0.40, 95 % CI 0.28 to 0.58; P < 0.001). At meta-regression analysis, no clinical or procedural variable had a significant interaction with the results above.

CONCLUSIONS

In patients undergoing AVNRT ablation, RF significantly reduces the risk of long-term arrhythmia recurrence compared to CRYO, but is associated with a higher risk of permanent atrioventricular block.

Cryoablation therapy for atrioventricular nodal reentrant tachycardia in children: a multicenter experience of efficacy

Atrioventricular nodal reentrant tachycardia (AVNRT), a common tachycardia in children, is routinely treated by catheter ablation using radiofrequency or cryothermal energy. Acute success rates of 95-97 % are reported for cryoablation, similar to those achieved with radiofrequency ablation (RFA). However, early studies reported higher recurrence rates after cryoablation for treatment of AVNRT than those reported for RFA. This study evaluated the success and recurrence rates for cryoablation in a current cohort of pediatric patients across several institutions. Patients 21 years old or younger with AVNRT who underwent cryoablation at five participating centers between 2004 and 2009 were retrospectively reviewed. Patient demographics and procedural data were extracted from patient records and analyzed. A total of 434 patients with AVNRT who underwent cryoablation were identified. Cryoablation was used as the exclusive ablation method for 379 patients. For 97 % (368/379) of these patients, cryoablation was acutely successful. A higher acute success rate was found with the 6-mm-tip catheter (99 %) than with the 4-mm-tip catheter (91 %) (p < 0.01). Recurrence was experienced by 7.3 % of the patients. Recurrence was more likely for those treated with the 4-mm-tip catheter (6/42, 14 %) than for those who had the larger catheters (12/204, 6 %) No patient experienced permanent heart block. Success and recurrence rates for this cohort of patients were similar to those reported for RFA used to treat AVNRT in pediatric patients. The findings show a higher success rate and a lower recurrence rate after cryoablation with a 6-mm-tip catheter than after use of the 4-mm-tip catheter, with an associated excellent safety profile.

Post-ablation prolongation of atrioventricular nodal refractory period is correlated with long-term success of cryoablation for atrioventricular nodal reentrant tachycardia in the case of the persistence of a residual jump

PURPOSE

A residual slow pathway after successful cryoablation for atrioventricular nodal reentrant tachycardia (AVNRT) is correlated with a higher recurrence rate. We described determinants of recurrence in subjects with a residual jump.

METHODS

We analyzed the data of subjects with acute successful slow pathway cryoablation for AVNRT using a 6-mm-tip cryocatheter. Success was defined as AVNRT non-inducibility. Patients with no baseline elicitable jump, no inducible AVNRT, and transient first atrioventricular (AV) block at the last site were excluded.

RESULTS

From 371 patients who underwent cryoablation from May 2002 to March 2011, 303 fulfilled the entry criteria (mean age, 41 ± 16; 222 women). Baseline AV nodal effective refractory period (ERP) was 272 ± 57 ms, postprocedural 331 ± 64 (P < 0.001), and the mean of the difference (Δ ERP) 60 ± 41. At the end of the procedure, 64 patients (21 %) had a residual jump, of whom 22 with a single echo. At 12 months follow-up, the actuarial recurrence-free rate was 70.3 % in patients with a residual jump and 86 % in those without (P = 0.01). In patients with a jump, only Δ AV nodal ERP was correlated with recurrence (37 ± 41 vs. 68 ± 47 ms; P < 0.04) while a single echo was not. The actuarial rate of recurrence was 60.8 % in patients with a Δ AV nodal ERP ≤ 30 ms and 18.8 % in those with a Δ AV nodal ERP >30 ms (P < 0.01).

CONCLUSIONS

Suppression of slow pathway conduction is the optimal endpoint for AVNRT cryoablation. A residual jump can be tolerated if AV nodal ERP postcryoablation is prolonged >30 ms.

Long-term follow-up after catheter ablation for atrioventricular nodal reentrant tachycardia: a comparison of cryothermal and radiofrequency energy in a large series of patients

Background

Radiofrequency (RF) catheter ablation for atrioventricular nodal reentrant tachycardia (AVNRT) is highly successful but carries a risk for inadvertent atrioventricular block. Cryoablation (cryo) has the potential to assess the safety of a site before the energy is applied.

Purpose

The aim of this study was to evaluate the long-term efficacy and safety of cryothermal ablation in a large series of patients and compare it to RF.

Methods

All consecutive routinely performed AVNRT ablations from our centre between 1999 and 2007 were retrospectively analysed.

Results

In total, 274 patients were elegible: 150 cryoablations and 124 RF. Overall procedural success was 96% (262/274), and equal in both groups, but nine patients were crossed to another arm. Mean fluoroscopy time was longer in the group treated with RF (27 ± 22 min vs. cryo 19 ± 15 min; p = 0.002). Mean procedure time was not different (RF 138 ± 71 min vs. cryo 146 ± 60 min). A permanent pacemaker was necessary in two RF patients. The questionnaire revealed a high incidence of late arrhythmia related symptoms (48%), similar in both groups, with improved perceived quality of life. The number of redo procedures for AVNRT over 4.3 ± 2.5-years follow-up was not statistically different (11% after cryo and 5% after RF).

Conclusions

Our data confirm that cryo and RF ablation with 4-mm tip catheters for AVNRT are equally effective, even after long-term follow-up.

Cryoablation: how to improve results in atrioventricular nodal reentrant tachycardia ablation?

Ablation for atrioventricular nodal reentry tachycardia is very effective, with a potential for damage to the normal conduction system. Cryoablation is an alternative, as it allows cryomapping, which permits assessment of slow pathway elimination at innocent freezing temperatures, avoiding permanent damage to the normal conduction system. It is associated with shorter radiation times and the absence of heart block in all published data. We discuss in this overview different approaches of cryoenergy delivery (focusing on spot catheter ablation), and how lesion formation is influenced by catheter tip size, application duration, and freezing rate. Some advantages of cryoenergy are explained. Whether these features also apply for an approach with a cryoballoon, e.g. for atrial fibrillation is unclear.