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

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.

The Assessment of a Novel Endoscopic Ultrasound-Compatible Cryocatheter to Ablate Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease that may be treated utilizing thermal therapies. Cryoablation is an effective, minimally invasive therapy that has been utilized for the treatment of various cancers, offering patients a quicker recovery and reduced side effects. Cryoablation has been utilized on a limited basis for the treatment of PDAC. With the recent reports on the success of cryoablation, there is a growing interest in the use of cryoablation as a standalone, minimally invasive procedure to treat PDAC. While offering a promising path, the application of cryoablation to PDAC is limited by current technologies. As such, there is a need for the development of new devices to support advanced treatment strategies for PDAC. To this end, this study investigated the performance of a new endoscopic ultrasound-compatible cryoablation catheter technology, FrostBite. We hypothesized that FrostBite would enable the rapid, effective, minimally invasive delivery of ultra-cold temperatures to target tissues, resulting in effective ablation via an endoscopic approach. Thermal properties and ablative efficacy were evaluated using a heat-loaded gel model, tissue-engineered models (TEMs), and an initial in vivo porcine study. Freeze protocols evaluated included single and repeat 3 and 5 min applications. Isotherm assessment revealed the generation of a 2.2 cm diameter frozen mass with the -20 °C isotherm reaching a diameter of 1.5 cm following a single 5 min freeze. TEM studies revealed the achievement of temperatures ≤ -20 °C at a diameter of 1.9 cm after a 5 min freeze. Fluorescent imaging conducted 24 h post-thaw demonstrated a uniformly shaped ellipsoidal ablative zone with a midline diameter of 2.5 cm, resulting in a total ablative volume of 6.9 cm3 after a single 5 min freeze. In vivo findings consistently demonstrated the generation of ablative areas measuring 2.03 cm × 3.2 cm. These studies demonstrate the potential of the FrostBite cryocatheter as an endoscopic ultrasound-based treatment option. The data suggest that FrostBite may provide for the rapid, effective, controllable freezing of cancerous pancreatic and liver tissues. This ablative power also offers the potential of improved safety margins via the minimally invasive nature of an endoscopic ultrasound-based approach or natural orifice transluminal endoscopic surgery (NOTES)-based approach. The results of this pre-clinical feasibility study show promise, affirming the need for further investigation into the potential of the FrostBite cryocatheter as an advanced, minimally invasive cryoablative technology.

Late pacemaker implantation after atrioventricular nodal reentrant tachycardia ablation: A systematic review and meta-analysis

INTRODUCTION

Catheter ablation (CA) of atrioventricular nodal reentrant tachycardia (AVNRT) is associated with late pacemakers for AV block (AVB). We performed a systematic review and meta-analysis of the pooled incidence of late pacemakers for AVB after CA of AVNRT.

METHODS AND RESULTS

Relevant studies were identified from 4 electronic databases (PubMed, EMBASE, Scopus, Cochrane Trial Register) from inception to 2022. A random effects model was used to calculate the odds of late pacemakers in CA of AVNRT compared to atrioventricular reentrant tachycardia (AVRT). Of 533 articles screened, 13 were included in systematic review. CA for AVNRT was performed in 16,471 patients (mean age 54±17 years, 63% females), of which 68 (0.4%) underwent pacemaker implantation for late AVB. Meta-analysis was performed in 5 of the 13 studies (mean follow-up duration 7±4 years). Patients who underwent CA of AVNRT were older (58±17 vs 52±20 years, p<0.001), and more likely female (60% vs 41%, p<0.001) than AVRT. Pooled estimates of late pacemakers for AVB were higher in CA of AVNRT than AVRT (0.5% vs 0.2%, p=0.006), with CA in AVNRT associated with almost 2-fold increased odds of late pacemakers indicated for AVB (OR 1.94, 95%CI 1.08-3.47, p=0.027) compared to AVRT.

CONCLUSION

AVNRT ablation is safe but associated with a low but definitely increased risk of requiring pacing in the later years due to AVB. This association is confirmed by pooling over 16,000 AVNRT patients receiving clinically indicated ablation and is helpful in providing informed consent for prospective patients undergoing ablation for AVNRT. This article is protected by copyright. All rights reserved.

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.

Evaluation of a Novel Cystoscopic Compatible Cryocatheter for the Treatment of Bladder Cancer

BACKGROUND: As the acceptance of cryoablative therapies for the treatment of non-metastatic cancers continues to grow, avenues for novel cryosurgical technologies and approaches have opened. Within the field of genitourinary tumors, cryosurgical treatments of bladder cancers remain largely investigational. Current modalities employ percutaneous needles or transurethral cryoballoons or sprays, and while results have been promising, each technology is limited to specific types and stages of cancers. OBJECTIVE: This study evaluated a new, self-contained transurethral cryocatheter, FrostBite-BC, for its potential to treat bladder cancer. METHODS: Thermal characteristics and ablative capacity were assessed using calorimetry, isothermal analyses, in vitro 3-dimensional tissue engineered models (TEMs), and a pilot in vivo porcine study. RESULTS: Isotherm assessment revealed surface temperatures below – 20°C within 9 sec. In vitro TEMs studies demonstrated attainment of ≤– 20°C at 6.1 mm and 8.2 mm in diameter following single and double 2 min freezes, respectively. Fluorescent imaging 24 hr post-thaw revealed uniform, ablative volumes of 326.2 mm3 and 397.9 mm3 following a single or double 2 min freeze. In vivo results demonstrated the consistent generation of ablative areas. Lesion depth was found to correlate with freeze time wherein 15 sec freezes resulted in ablation confined to the sub-mucosa and ≥30 sec full thickness ablation of the bladder wall. CONCLUSIONS: These studies demonstrate the potential of the FrostBite-BC cryocatheter as a treatment option for bladder cancer. Although preliminary, the outcomes of these studies were encouraging, and support the continued investigation into the potential of the FrostBite-BC cryocatheter as a next generation, minimally invasive cryoablative technology.

Assessment of a novel cryoablation device for the endovascular treatment of cardiac tachyarrhythmias

Objectives

Cryoablation is an effective alternative treatment for cardiac arrhythmias offering shortened recovery and reduced side effects. As the use of cryoablation increases, the need for new devices and procedures has emerged. This has been driven by technological limitations including lengthy periods to generate a single lesion (3-5 min), uncertain transmurality, and differential efficacy. Furthermore, due to limited ablation capacity under high heat loads, cryo has had limited success in the treatment of ventricular arrhythmias. To this end, in this study we evaluated a new cryoablation catheter, ICEolate, for the targeted ablation of cardiac tissue.

Methods

Performance assessment included calorimetry, freeze zone isothermal distribution characterization and catheter ablation capacity in a submerged, circulating, heat-loaded ex vivo tissue model. A pilot in vivo study was also conducted to assess ablative capacity of the cryocatheter in a fully beating heart.

Results

Ex vivo studies demonstrated ice formation at the tip of a cryocatheter within 5 s and a tip temperature of ~-150°C within 10 s. The device repeatedly generated freeze zones of 2 cm × 3 cm in less than 2 min. Tissue model studies revealed the generation of a full thickness (5-10 mm) cryogenic lesion within 1 min with an opposite (transmural) surface temperature of <-60°C under a circulating 37°C heat load. Pilot in vivo studies demonstrated the delivery of an ablative "dose," producing a continuous full thickness transmural linear lesion in <60 s at both atrial and ventricular sites.

Conclusion

These studies suggest that the supercritical nitrogen cryodevice and ICEolate cryocatheter may provide for rapid, effective, controllable freezing of targeted tissue. The ablative power, speed, and directional freeze characteristics also offer the potential of improved safety via a reduction in procedural time compared to current cryoablation devices. These technological developments may open new avenues for the application of cryo to treat other cardiac arrhythmogenic disorders.

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.

Cryoablation of atrioventricular nodal re-entrant tachycardia: 7-year follow-up in 515 patients-confirmed safety but very late recurrences occur

Aims

Cryoablation is an alternative method to radiofrequency ablation for treatment of atrioventricular nodal re-entrant tachycardia (AVNRT). This study investigates the long-term safety and efficacy of cryoablation in AVNRT.

Methods and results

We studied 515 consecutive patients (317 women, mean age 50 years, range 13-89 years) undergoing a first cryoablation for AVNRT between 2003 and 2008. Ablations were performed with a 6-mm Freezor Xtra catheter. Six patients were acute failures; 494 out of 509 (97%) primarily successfully ablated patients were followed up for a mean of 7.1 years (range 2-12 years). About 11% (54/494 patients) of patients had recurrences of the index arrhythmia. Time to recurrence varied from days to 9 years; 14 patients (3%) had recurrences later than 2 years, 8 patients (2%) later than 3 years, and 6 patients (2%) later than 4 years. Recurrence rate was higher in patients with slow-slow or fast-slow AVNRT (n = 24) compared with the common slow-fast variant (25 vs. 10%; P = 0.04). Recurrence rate was not higher in patients with residual slow pathway conduction (jump with or without echo beat, n = 199, 39%). Transient atrioventricular (AV) block of the first-, second-, or third-degree during ablation was observed in 45 patients but had no impact on the risk of AVNRT recurrence. No late AV block occurred. Single vs. multiple applications or total amount of cryoenergy delivered did not differ between patients with and without recurrences.

Conclusion

Cryoablation in AVNRT is safe with a long-term efficacy of 88%; however, very late recurrences occur.

Radiofrequency ablation versus cryoablation for atrioventricular nodal re-entrant tachycardia in children: a value comparison

BACKGROUND

It is unclear whether cryoablation or radiofrequency ablation offers better value for treating atrioventricular nodal re-entrant tachycardia in children. We aimed to compare the value of these procedures for treating atrioventricular nodal re-entrant tachycardia in children, with value being outcomes relative to costs.

METHODS

We performed a retrospective cohort study of all atrioventricular nodal re-entrant tachycardia ablations for children (age⩽18 years) from July, 2009 to June, 2011 at our institution. Costs included fixed costs, miscellaneous hospital costs, and labour costs, and key outcomes were acute and long-term success (6 months) of the ablations. We conducted T-tests and regression analyses to investigate the associations between the ablation procedure type and the cost and success of the ablations.

RESULTS

Of 96 unique cases performed by three paediatric electrophysiologists, 48 were cryoablation only, 42 radiofrequency ablation only, and six were a combination. Acute success was 100% for the cryoablation only and radiofrequency ablation only cases and 83% for the combination cases. There were no notable adverse events. The average total cost was $9636 for cryoablation cases, $9708 for radiofrequency ablation cases, and $10,967 for combination cases (p=0.51 for cryoablation only versus radiofrequency ablation only). The long-term success rate was 79.1% for cryoablation only, 92.8% for radiofrequency ablation only, and 66.7% for the combination (p=0.01 for cryoablation only versus radiofrequency ablation only), but long-term success varied notably by provider.

CONCLUSIONS

Cryoablation and radiofrequency ablation offer similar value in the short term for the treatment of atrioventricular nodal re-entrant tachycardia in children. Differences in long-term success may vary substantially by physician, and thus may lead to differences in long-term value.

Cryoablation of typical AVNRT: Younger age and administration of bonus ablation favor long-term success

BACKGROUND

Cryoablation (CA) is an emerging tool for the treatment of supraventricular tachyarrhythmias. Determinants of long-term success still need clarification.

OBJECTIVE

The purpose of this study was to assess which patients' and procedural features affect the long-term efficacy of CA for typical atrioventricular nodal reentrant tachycardia (AVNRT).

METHODS

Eighty-five consecutive patients undergoing CA for typical AVNRT were divided into 3 groups of age: group A, ≤20 years, n = 20 (23.5%); group B, 21-50 years, n = 30 (35.3%); group C, ≥51 years, n = 35 (41.2%). CA was performed for 5 minutes at -75°C in all; 4-minute bonus CA was delivered if not contraindicated (ie, transient PR interval lengthening during the first application and narrow triangle of Koch). The efficacy end point was the absence of recurrences at 12-month follow-up.

RESULTS

CA was acutely successful in all 85 patients (100%). Bonus ablation was performed in 69 (81.2%). No permanent complications were observed. At follow-up, AVNRT recurrences occurred in 9 patients (10.6%): group A, 0 (0%); group B, 2 (6.7%), group C, 7 (20%). Incidence of recurrences was significantly different between age groups (P = .047) and between patients receiving (7.2%) and not receiving (25.0%) bonus CA (P = .038). In multivariable analysis, age groups (odds ratio [OR] 5.917; 95% confidence interval [CI] 1.372-25.518; P = .017) and bonus CA (OR 0.115; 95% CI 0.018-0.724; P = .021) were the only independent predictors of recurrences. Furthermore, age as a continuous variable remained statistically associated with recurrences (OR 1.046; 95% CI 1.002-1.091; P = .038).

CONCLUSION

CA is effective and safe for typical AVNRT ablation. Younger age and bonus CA administration are independent predictors of success at 12 months. Incidence of recurrences is low in patients younger than 21 years.

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.

Single center experience of fluoroless AVNRT ablation guided by electroanatomic reconstruction in children and adolescents

BACKGROUND

Anatomical considerations and risks related to x-ray exposure make atrioventricular nodal reentrant tachycardia (AVNRT) ablation in pediatric patients a concerning procedure. We aimed to evaluate the feasibility, safety, and efficacy of performing fluoroless slow-pathway cryoablation guided by the electroanatomic (EA) mapping in children and adolescents.

METHODS

Twenty-one consecutive patients (mean age 13.5 ± 2.4 years) symptomatic for AVNRT were prospectively enrolled to right atrium EA mapping and electrophysiological study prior to cryoablation. Cryoablation was guided by slow-pathway potential and performed using a 4-mm-tip catheter.

RESULTS

Sustained slow-fast AVNRT was inducible in all the patients with a dual AV nodal physiology in 95%. Acute success was achieved in 100% of the patients with a median of two cryo-applications. Fluoroless ablation was feasible in 19 patients, while in two subjects 50 seconds and 45 seconds of x-ray were needed due to difficult progression of the catheters along the venous system. After a mean follow-up of 25 months, AVNRT recurred in five patients. All the recurrences were successfully treated with a second procedure. In three patients, a fluoroless cryoablation with a 6-mm-tip catheter was successfully performed, while in the remaining two patients, a single pulse of 60 seconds of radiofrequency energy was applied under fluoroscopic monitoring. No complications occurred.

CONCLUSIONS

Combination of EA mapping systems and cryoablation may allow to perform fluoroless slow-pathway ablation for AVNRT in children and adolescents in the majority of patients. Fluoroless slow-pathway cryoablation showed a high efficacy and safety comparable to conventional fluoroscopy guided procedures.

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.

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.