Atrial septal pouches and ridges: Morphological features and potential implications in clinical practice.

Incomplete or irregular fusion of the interatrial septum may result in several anatomic variants, including atrial septal pouches and ridges, whose knowledge and recognition are still poorly widespread in clinical practice. An educational review focused on the definition, clinical significance and diagnostic work-up of these anatomic findings was performed using PubMed, MEDLINE, Embase and Cochrane Central databases up to June 2023. Atrial septal pouches and ridges have been associated with an increased difficulty of catheter-based interventions requiring a transseptal approach, due to procedural challenges for transseptal puncture and the restricted motion of guidewires and catheters through the transseptal access. Additionally, left atrial septal pouch may serve as a thrombogenic nidus and a source of systemic embolism, mostly in the presence of factors leading to higher left atrial pressure and/or atrial blood stasis, which increase the risk of thrombus formation and embolic events, rather than for the only presence of left atrial septal pouch itself. Further investigations are needed in order to better elucidate the implications of such anatomic findings in daily clinical practice, and to provide the most appropriate decision-making strategies.

Asymptomatic Patients With Brugada ECG Pattern: Long-Term Prognosis From a Large Prospective Study.

BACKGROUND: Brugada syndrome poses significant challenges in terms of risk stratification and management, particularly for asymptomatic patients who comprise the majority of individuals exhibiting Brugada ECG pattern (BrECG). The aim of this study was to evaluate the long-term prognosis of a large cohort of asymptomatic patients with BrECG. METHODS: Asymptomatic patients with BrECG (1149) were consecutively collected from 2 Italian centers and followed-up at least annually for 2 to 22 years. For the 539 asymptomatic patients (men, 433 [80%]; mean age, 46±13 years) with spontaneous type 1 documented on baseline ECG (87%) or 12-lead 24-hour Holter monitoring (13%), an electrophysiologic study (EPS) was proposed; for the 610 patients with drug-induced-only type 1 (men, 420 [69%]; mean age, 44±14 years), multiple ECGs and 12-lead Holter were advised in order to detect the occurrence of a spontaneous type-1 BrECG. Arrhythmic events were defined as sudden death or documented ventricular fibrillation or tachycardia. RESULTS: Median follow-up was 6 (4-9) years. Seventeen (1.5%) arrhythmic events occurred in the overall asymptomatic population (corresponding to an event-rate of 0.2% per year), including 16 of 539 (0.4% per year) in patients with spontaneous type-1 BrECG and 1 of 610 in those with drug-induced type-1 BrECG (0.03% per year; P<0.001). EPS was performed in 339 (63%) patients with spontaneous type-1 BrECG. Patients with spontaneous type-1 BrECG and positive EPS had significantly higher event rates than patients with negative EPS (7 of 103 [0.7% per year] versus 4 of 236 [0.2% per year]; P=0.025). Among 200 patients who declined EPS, 5 events (0.4% per year) occurred. There was 1 device-related death. CONCLUSIONS: The entire population of asymptomatic patients with BrECG exhibits a relatively low event rate per year, which is important in view of the long life expectancy of these young patients. The presence of spontaneous type-1 BrECG associated with positive EPS identifies a subgroup at higher risk. Asymptomatic patients with drug-induced-only BrECG have a minimal arrhythmic risk, but ongoing follow-up with 12-lead Holter monitoring is recommended to detect the appearance of spontaneous type-1 BrECG pattern.

The Brugada syndrome: risk stratification.

Thirty years after its first description, the knowledge regarding Brugada syndrome has greatly increased. Spontaneous type 1 ECG pattern (BrECG) is a well-defined prognostic marker in asymptomatic patients and is associated with a double risk of arrhythmic events during follow-up as compared to drug-induced ECG pattern. Due to the extreme variability of the ECG pattern over time, the spontaneous type 1 BrECG must be carefully sought, not only through periodic ECGs but especially with repeated 12-lead 24-h Holter monitoring, with V1 and V2 electrodes placed also on the second and third intercostal space, in order to explore the right ventricular outflow tract. 12-lead 24-h Holter should also be performed in all the patients with a dubious BrECG pattern even before the drug challenge with sodium channel blockers, which carries a low but definite risk of complications. In addition to spontaneous type 1, other electrocardiographic markers of increased arrhythmic risk have been described, such as first-degree AV block, QRS fragmentation, S wave in lead I and II, and increased QRS duration. The electrophysiological study in asymptomatic patients with a spontaneous ECG Brugada pattern is still under jury and further studies need to clarify its precise role.

Adjunctive hypnotic communication for analgosedation in subcutaneous implantable cardioverter defibrillator implantation. A prospective single center pilot study.

BACKGROUND: Subcutaneous implantable cardioverter defibrillator (S-ICD) is a well-established therapy for sudden death prevention. Considering the painful nature of the procedure anaesthesia may be required for analgo-sedation. Hypnosis is emerging as a promising therapeutic strategy for pain control. Few data are available regarding the use of hypnosis as adjunctive technique for pain control during S-ICD implantation. METHODS: Thirty consecutive patients referred to our centre for S-ICD implantation were prospectively and alternatively allocated with 1:1 ratio in two groups: A) Standard analgo-sedation approach (Hypnosis non responder patients) B) Standard analgo-sedation approach with the addition of hypnotic communication (Hypnosis responder patients). Peri-procedural pain perception and anxiety, perceived procedural length, type and dosage of administered analgesic drugs have been measured using validate scores and compared. RESULTS: Hypnotic communication was offered to 15 patients of which was successful in 11 patients (73%). There were no statistical differences between the two study groups according to baseline characteristics. Hypnosis communication resulted in significant pain perception reduction (Group A 6,9 ± 1,6 Vs Group B 1,1 ± 0,9, p value < 0,01), peri-procedural anxiety (Group A 3,5 ± 1,6 Vs Group B 1,9 ± 0,5, p value < 0,01) and reduced perceived procedural length (Group A 58,7 ± 13,4 min Vs Group B 44,7 ± 5,5 min, p value < 0,01). Fentanyl dosage was significantly lower in Group B patients. CONCLUSIONS: Our results demonstrated a significant reduction of perceived pain, anxiety, procedural time and use of analgesic drugs in hypnosis responder patients. These results reinforce the beneficial effects of the hypnotic technique in patients undergoing S-ICD implantation.

Zero-fluoroscopy atrial fibrillation ablation in the presence of a patent foramen ovale: a multicentre experience.

INTRODUCTION: Atrial fibrillation ablation has historically been guided by fluoroscopy, with the related enhanced risk deriving from radiation. Fluoroscopy exposure may be confined to guide the transseptal puncture. Small sample size study presented a new methodology to perform a totally fluoroless atrial fibrillation ablation in the case of a patent foramen ovale (PFO). We evaluated this methodology in a large sample size of patients and a multicentre experience. METHODS AND RESULTS: Two hundred and fifty paroxysmal atrial fibrillation patients referred for first atrial fibrillation ablation with a CARTO3 electroanatomic mapping system were enrolled. In 58 out of 250 patients, a PFO allowed crossing of the interatrial septum, and a completely fluoroless ablation was performed applying the new method (Group A). In the remaining patients, a standard transseptal puncture was performed (Group B). Pulmonary vein isolation was achieved in all patients with comparable procedural and clinical outcomes at short- and long-term follow-up. CONCLUSION: The presence of a PFO may allow a completely fluoroless well tolerated and effective atrial fibrillation ablation. Probing the fossa ovalis looking for the PFO during the procedure is desirable, as it is not time-consuming and can potentially be done in every patient undergoing atrial fibrillation ablation.

Subaxillary approach to cardiac electronic device implantation using a single surgical incision: a single-centre experience.

OBJECTIVES: Pacemakers and implantable cardioverter defibrillators have become more common in younger individuals, owing to broader indications and technological advances. Our goal was to report our long-term experience of implanting cardiac devices in young adults via a subaxillary approach with a hidden single incision, to minimize the aesthetic impact of the device. METHODS: From 2003 to 2012, 23 patients underwent cardiac device implantation via a subaxillary approach while they were under general anaesthesia. The axillary vein was punctured under contrast-medium radiological guidance. The devices were positioned into the pocket under the pectoralis major muscle and over the fascia that envelopes the pectoralis minor muscle, through a lateral surgical access along the midaxillary line. RESULTS: Twenty-two single- and dual-chamber implantable cardioverter defibrillator and 1 dual-chamber pacemaker were implanted (mean age 32.2 ± 13.4 years). All procedures were successfully performed without complications; overall hospitalization after implantation was 3.3 days. During mean a follow-up of 65 ± 18 months, no deaths, infections or device migrations occurred. Two ventricular lead dislodgements requiring repositioning occurred within 1 month, and 1 defibrillation lead fracture occurred 5 years after implantation. All patients were extremely satisfied with the aesthetic result. A mild increase in the pacing threshold (0.88 ± 0.6 V at 0.4/0.5 ms at implantation vs 1.00 ± 0.3 V at 0.4/0.5 ms at 2-year follow-up, P = 0.063) and a statistically significant decrease in the pacing impedance (637 ± 161 ohm at implantation vs 499 ± 81 ohm at 2-year follow-up, P = 0.001) were observed, without any consequences. CONCLUSIONS: The subaxillary approach is a safe, feasible technique that requires a simple surgical procedure. The implantable cardioverter defibrillator functions properly at implantation and at long-term follow-up.

Very long-term outcome following transcatheter ablation of atrial fibrillation. Are results maintained after 10 years of follow up?

Aims: Atrial fibrillation (AF) transcatheter ablation is a safe and effective procedure. However, outcome over 10 years of follow-up has never been reported. The aim of this study is to assess outcome, describe predictors of recurrences, and report on quality of life (QoL) the decade after an AF ablation. Methods and results: Patients referred for AF ablation in a single high volume centre from June 2004 to June 2006 were enrolled and followed in a prospective fashion by yearly clinical assessment and Holter monitoring. Among 255 patients (42.7% paroxysmal AF, 77% males, after a follow-up of 125 ± 7 months), 132 (52%) were arrhythmia-free including (58, 32% after a single procedure) while 27 (10%) progressed to permanent AF. At multivariate analysis, a greater left atrium antero-posterior diameter (HR 1.05 95% CI 1.02-1.09, P = 0.02) related to arrhythmic recurrences, while no increase in blood pressure (HR 0.06 95% CI 0.02-0.20, P = 0.01), BMI (HR 0.06 95% CI 0.02-0.09, P < 0.001), and fasting glucose (HR 0.58 95% CI 0.36-0.92, P = 0.02) during follow-up were protective for arrhythmic recurrences. Overall QoL improved significantly, significantly related to the absence of recurrences, arrhythmic burden reduction and blood pressure, and BMI control (P < 0.001). Conclusion: The outcome of AF ablation over more than 10 years is characterized by a low incidence of progression towards permanent AF. Greater LA anteroposterior diameter related to arrhythmic recurrences, while blood pressure, BMI, and fasting blood glucose control emerged as predictors of sinus rhythm maintenance. Eventually, QoL improved significantly over the follow-up.

Safety and efficacy of pulmonary vein isolation using a surround flow catheter with contact force measurement capabilities: A multicenter registry.

INTRODUCTION: Pulmonary vein (PV) isolation is the cornerstone of catheter ablation in patients with atrial fibrillation (AF). Surround flow and contact force (CF) measurement capabilities might enhance procedure efficacy and safety. We report on the safety and midterm efficacy of a novel ablation catheter for PV isolation in patients with AF. METHODS AND RESULTS: Two hundred thirty-three consecutive patients (57 ± 11 years, 76% males, 51% with structural heart disease), referred for paroxysmal (157) or persistent (76) AF, underwent PV isolation by a surround flow catheter with CF measurement capability in four centers. Ablation was guided by electroanatomic mapping allowing radiofrequency (RF) energy delivery in the antral region aiming at PV isolation. Mean overall procedure time was 100 ± 42 minutes with a mean fluoroscopy time of 6 ± 5 minutes. Mean ablation time was 31±15 minutes; 99% of the targeted veins were isolated. The mean CF value during ablation was 13 ± 4 g. Intraprocedural early (30 minutes) PV reconnection occurred in 12% PVs, and all PVs were effectively reisolated. One pericardial effusion and five groin hematomas were reported. During a mean follow-up of 12 ± 6 months, 30 (12.9%) (10% paroxysmal AF vs. 18% persistent AF, P = 0.07) patients had an atrial arrhythmias recurrence. CONCLUSIONS: In this multicenter registry, RF ablation using a new surround flow catheter, with CF sensor, resulted as feasible, achieving a high rate of isolated PVs. Procedural and fluoroscopy times and success rates were comparable with other techniques with a low complication rate.

Does antiarrhythmic drugs premedication improve electrical cardioversion success in persistent atrial fibrillation?

AIMS: Aim of this study is to evaluate the impact of antiarrhythmic drugs (AADs) administration for at least one month before ECV on the acute and long term success rate of the procedure. METHODS: 1313 consecutive persistent AF patients were enrolled in 3 different centers (Turin, Asti and Avellino): 692 patients received AADs before and after ECV (group A), 621 patients were treated only after the procedure, at discharge (group B). Primary end point was the restoration and maintenance of sinus rhythm acutely and at a long-term follow up. RESULTS: Acute ECV success was higher in group A compared with group B (99% vs. 88%, p=0.0001) and a fewer number of shock attempts were administered (1.15±0.42 vs. 1.27±0.53 p<0.0001). Moreover group A maintained SR more often than group B at one month (99% vs. 89%, log-rank p<0.0001), at one year (55% vs. 48% log-rank p=0.01) and at the end of follow up (mean 2.7±2.1years, 45% vs. 29%, log-rank p<0.0001). At multivariate analysis AADs premedication was the strongest independent predictor of acute and long-term ECV success (respectively p<0.0001 OR 10.71 CI 5.10-22.50 and p=0.004, OR 1.50 CI 1.14-1.97). At sensitivity analysis no differences were found between ADDs in terms of acute success improvement (p=0.605), number of shock attempts (p=0.853) and long term SR maintenance (log-rank p=0.480). CONCLUSIONS: AADs administration for at least 4weeks before the ECV in persistent AF increases significantly the acute success rate and this result was maintained over a long-term follow-up.

Cooling dynamics: a new predictor of long-term efficacy of atrioventricular nodal reentrant tachycardia cryoablation.

PURPOSE: Catheter ablation of the slow pathway is the most effective treatment for atrioventricular nodal reentrant tachycardia (AVNRT). Cryoenergy, compared to radiofrequency, relates to lower heart block risk but higher incidence of AVNRT recurrences. The aims of this study are to confirm the safety and efficacy of AVNRT cryoablation and to identify predictors of long-term recurrences. METHODS: Among 241 patients undergoing AVNRT cryoablation, 239 (99.2%) experienced acute effective cryoablation of the slow pathway, and no procedure-related complications were reported. RESULTS: After a follow-up of 44.9 ± 31.7 months, 28 (11.7%) patients presented AVNRT recurrences. A shorter preablation (p = 0.05) and postablation anterograde Wenckebach cycle length (p < 0.01), a shorter postablation atrioventricular node refractory period (p = 0.04), and persistence of the crossover sign (p = 0.03) were associated with higher incidence of long-term recurrences. Considering cooling dynamics, a longer time to reach temperature ≤-70 °C (p = 0.03) and a higher minimal temperature during ablation (p = 0.04) were related to recurrences. Patients without residual markers of dual AV node physiology (AH jump, single atrial echo beat, crossover) reported a lower recurrence rate (p = 0.05) compared to those without. At multivariate analysis, a longer time to -70 °C was the strongest independent predictor of long-term recurrence (OR 1.75, 95% CI 1.01-3.03, p = 0.04). CONCLUSIONS: AVNRT cryoablation is safe and effective. Long-term recurrence rate was 11.7%. An ablation approach directed to the complete elimination of dual AV node physiology, along with assessment of the tissue's cooling dynamics, holds the potential to improve long-term AVNRT cryoablation efficacy.

Zero-Fluoroscopy Ablation of Accessory Pathways in Children and Adolescents: CARTO3 Electroanatomic Mapping Combined with RF and Cryoenergy.

BACKGROUND: Fluoroscopic catheter ablation of cardiac arrhythmias in pediatric patients exposes the patients to the potential risk of radiation considering the sensitivity of this population and its longer life expectancy. We evaluated the feasibility, safety, and efficacy of accessory pathway (AP) ablation guided by CARTO3 electroanatomic mapping (EAM) system with both cryoenergy and radiofrequency (RF) energy in order to avoid x-ray exposure in pediatric patients. METHODS: We included 44 patients (mean age: 13.1 ± 3.3 years); nine of 44 presented concealed AP. An electrophysiological study with a three-dimensional EAM reconstruction was performed in every patient with a venous transfemoral direct right atrium approach or an arterial transfemoral retrograde approach to reach the mitral annulus. In two patients with left-sided AP, the ablation was performed via a patent foramen ovale. RESULTS: A total of 47 APs were present, left sided in 45% (21/47) of cases (15 lateral, one anterior, three posteroseptal, and two posterolateral) and right sided in 55% (26/47; one anterior, three anterolateral, one posterolateral, three lateral, five para-Hisian, 12 posteroseptal, and one anteroseptal). Ablation without the use of fluoroscopy was successfully performed in every patient (33 with RF and in 11 with cryoenergy). No complication occurred. At a mean follow-up of 16.0 ± 11.7 months, we observed seven recurrences, three of them successfully re-ablated without fluoroscopy. In one case cryoablation of a para-Hisian AP was ineffective in the long term. CONCLUSIONS: Three-dimensional EAM allowed a safe and effective fluoroless AP ablation procedure in a pediatric population both with RF and cryoenergy.

Pulmonary vein isolation with a new multipolar irrigated radiofrequency ablation catheter (nMARQ™): feasibility, acute and short-term efficacy, safety, and impact on postablation silent cerebral ischemia.

BACKGROUND: Simultaneous multipolar ablation catheters have been proposed to simplify pulmonary vein isolation (PVI) in paroxysmal atrial fibrillation (AF). Recently, a new multipolar irrigated radiofrequency (RF) ablation catheter (nMARQ™, Biosense Webster Inc., Diamond Bar, CA, USA) combining both 3-dimensional electroanatomic mapping and multipolar open-irrigated ablation capability has been developed. Aim of our study was to assess feasibility, acute and short-term success and safety of PVI by the use of this new technology with particular regard to the incidence of postablation silent cerebral ischemia (SCI). METHODS AND RESULTS: Twenty-five patients (76% males; age 57 ± 13 years) with paroxysmal AF underwent PVI using the nMARQ™ catheter. PVI, confirmed by Lasso catheter mapping, was achieved in 100 out of 102 pulmonary veins (98%) identified, and final PVI was obtained in 24 out of 25 (96%) patients. The overall concordance between Lasso and nMARQ™ signals in demonstrating PVI was 78%. No major procedural complications occurred and no patient suffered SCI, on the basis of cerebral magnetic resonance imaging performed before and after the procedure. Following a 6-month follow-up, 17/25 (68%) patients remained free from AF without antiarrhythmic drugs. CONCLUSIONS: In our preliminary experience, PVI with nMARQ™ catheter appears to be feasible and safe, without incidence of SCI. Long-term clinical efficacy has to be evaluated in further studies.

Very long-term results of electroanatomic-guided radiofrequency ablation of atrial arrhythmias in patients with surgically corrected atrial septal defect.

AIMS: Atrial tachycardias are common after repair of atrial septal defect (ASD). Although ablation has shown promising results in the short and mid-term follow-up, little data regarding the very long-term success exist. Our aim was to assess very long-term follow-up in patients who have undergone electroanatomic-guided radiofrequency (RF) ablation of late-onset atrial arrhythmias after ASD surgery. METHODS AND RESULTS: Forty-six consecutive patients with surgically repaired ASD were referred for atrial tachycardia ablation. Electrophysiological (EP) study and ablation procedure with the aid of an electroanatomic mapping (EAM) system were performed. Mean age was 49 ± 13 years (females 61%). The presenting arrhythmias were typical atrial flutter (48%), atypical atrial flutter (35%), and atrial tachycardia (17%). In 41% of patients, atrial fibrillation was also present. The EP study showed a right atrial macroreentrant circuit in all the patients. In 12 of 46 (26%), the circuit was localized in the cavo-tricuspid isthmus, whereas in the remaining 34 patients (74%) was atriotomy-dependent. Acute success was 100%. Clinical arrhythmia recurred in 24% of the patients. Nine patients underwent a second and two a third ablation procedure, reaching an overall efficacy of 87% (40 of 46) at a mean follow-up of 7.3 ± 3.8 years since the last procedure. With antiarrhythmic drugs the success rate increased to 96% (44 of 46). No complications occurred. CONCLUSION: In patients with surgically corrected ASD, EAM-guided RF ablation of late-onset macroreentrant atrial arrhythmias demonstrated a high success rate in a very long-term follow-up. Therefore, RF ablation could be considered early in the management of late-onset macroreentrant atrial tachycardias.

Incidence of cerebral thromboembolic events during long-term follow-up in patients treated with transcatheter ablation for atrial fibrillation.

AIMS: Net clinical benefit of long-term oral anticoagulation therapy (OAT) continuation after successful atrial fibrillation (AF) ablation is still controversial. To evaluate long-term thromboembolic (TE) and haemorrhagic events incidence according to OAT strategy used after AF transcatheter ablation. METHODS AND RESULTS: Three months after AF ablation, OAT was discontinued in patients with CHADS2 ≤ 1 if no recurrences were documented, while OAT was maintained in patients with CHADS2 ≥ 2 regardless of AF recurrences. CHA2DS2VASc and HAS-BLED scores have been retrospectively evaluated. Seven hundred and sixty-six patients were followed for a median of 60.5 months. Six (6/267 = 2.2%) and five (5/499 = 1%) TE events occurred in the ON and the OFF-OAT patients, respectively (P = 0.145), all in concomitance with the AF recurrence. CHADS2 and CHA2DS2VASc ≥ 2 were associated with high TE incidence (P = 0.047 and P = 0.020). Among patients with a CHADS2 score of 0 or 1, a CHA2DS2VASc score ≥ 2 was predictive of TE events (P = 0.014). Overall, the incidence of the TE events in patients with CHA2DS2VASc ≥ 2 was 0.6 per 100 patient-years whereas seven haemorrhagic events occurred, all of them in the ON-OAT patients (7/267 = 2.6%). CONCLUSION: Patients with AF undergoing transcatheter ablation have a lower incidence of TE events as compared with the general AF population, regardless of OAT maintenance. The unpredictable risk of AF recurrence, mandate the routine use of the CHADS2, CHA2DS2VASc, and HAS-BLED scores to guide clinical decision regarding OAT management in this peculiar setting of patients. The potential protective role of rhythm control strategy in the TE events needs to be confirmed by future large randomized trials.

Very long-term results of surgical and transcatheter ablation of long-standing persistent atrial fibrillation.

BACKGROUND: New hybrid approaches for atrial fibrillation (AF) ablation, combining surgical and percutaneous procedures, are emerging to enhance the long-term success rate of these 2 procedures severally considered. Recent guidelines underline the need for long-term follow-up to really assess the efficacy of AF ablation. METHODS: From 2000 to 2002, 33 patients with long-standing persistent AF and valvular heart disease underwent valve surgery and cryoablation (pulmonary veins isolation and mitral isthmus and roof line lesions). The surgically created ablation scheme was validated with electroanatomic mapping and percutaneous radiofrequency ablation was performed in case of lesion incompleteness. RESULTS: In 19 of 33 patients (58%) the electroanatomic mapping showed a complete lesion scheme, which increased to 79% (26 of 33) with the addition of radiofrequency ablation. At the mean follow-up of 10.7 ± 3.1 years, 73% (24 of 33) of patients were in sinus rhythm (SR), whereas 27% had permanent AF. At the end of follow-up 81% of patients with a complete lesion scheme were in SR, while 43% with an incomplete one maintained SR (p = 0.048). CONCLUSIONS: In patients with long-standing persistent AF and valvular heart disease, the hybrid approach with surgical cryoablation consisting of pulmonary veins isolation and left atrial linear lesions combined with transcatheter radiofrequency ablation was highly effective in maintaining SR for a very long-term follow-up. Electrophysiological evaluation, to validate the transmurality of the surgical lesions and to complete the lesion scheme applying radiofrequency energy, improved the long-term efficacy.

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.