Randomized comparison of atrioventricular node re-entry tachycardia and atrial flutter catheter ablation with and without fluoroscopic guidance: ZeroFluoro study.

AIMS: Interventional cardiology procedures may expose patients and staff to considerable radiation doses. We aimed to assess whether exposure to ionizing radiation during catheter ablation of supraventricular tachycardia (SVT) can be completely avoided. METHODS AND RESULTS: In this prospective randomized study, patients with SVT (atrioventricular re-entrant tachycardia n = 94, typical atrial flutter n = 29) were randomly assigned in a 1:1 ratio to catheter ablation with conventional fluoroscopic guidance (CF group) or with the EnSite Precision mapping system [zerofluoro (ZF) group]. Acute procedural parameters, increased stochastic risk of cancer incidence and 6-month follow-up data were assessed. Between May 2019 and August 2020, 123 patients were enrolled. Clinical parameters were comparable. Median procedural time was 60.0 and 58.0 min, median fluoroscopy time and estimated median effective dose were 240 s vs. 0 and 0.38 mSv vs. 0 and arrhythmia recurrence was 5% and 7.9% in the CF and ZF groups, respectively. The acute success rate was 98.4% in both groups. No procedure-related complications were reported. At an average age of 55.5 years and median radiation exposure of 0.38 mSv, the estimate of increased incidence was approximately 1 in 14 084. The estimated mortality rate was 1 per 17 857 exposed persons. CONCLUSIONS: The procedural safety and efficacy of the zero-fluoroscopic approach are similar to those of conventional fluoroscopy-based ablation for atrioventricular nodal re-entrant tachycardia and atrial flutter. Under the assumption of low radiation dose, the excessive lifetime risk of malignancy in the CF group due to electrophysiology procedure is reasonably small, whilst totally reduced in zero fluoroscopy procedures.

Randomized trial of intracardiac echocardiography-guided slow pathway ablation.

PURPOSE: Radiofrequency (RF) catheter ablation of the slow pathway (SP) in atrioventricular nodal reentry tachycardia (AVNRT) is highly effective; however, it may require prolonged fluoroscopy and RF time. We postulated that visualization of the SP region with intracardiac echocardiography (ICE) could decrease ablation time, minimize radiation exposure, and facilitate SP ablation compared to the standard, fluoroscopy-guided approach. METHODS: In our study, we randomized 91 patients undergoing electrophysiologic study and SP ablation for AVNRT into 2 groups: fluoroscopy-only (n = 48) or ICE-guided (n = 43) group. Crossover to ICE-guidance was allowed after 8 unsuccessful RF applications. RESULTS: Mapping plus ablation time (mean ± standard deviation: 18.8 ± 16.1 min vs 11.6 ± 15.0 min, p = 0.031), fluoroscopy time (median [interquartile range]: 4.9 [2.93-8.13] min vs. 1.8 [1.2-2.8] min, p < 0.001), and total ablation time (144 [104-196] s vs. 81 [60-159] s, p = 0.001) were significantly shorter in the ICE group. ICE-guidance was associated with reduced radiation exposure (13.2 [8.2-13.4] mGy vs. 3.7 [1.5-5.8] mGy, p < 0.001). The sum of delivered RF energy (3866 [2786-5656] Ws vs. 2283 [1694-4284] Ws, p = 0.002) and number of RF applications (8 [4.25-12.75] vs. 4 [2-7], p = 0.001) were also lower with ICE-guidance. Twelve (25%) patients crossed over to the ICE-guided group. All were treated successfully thereafter with similar number, time, and cumulative energy of RF applications compared to the ICE group. No recurrence occurred during the follow-up. CONCLUSIONS: ICE-guidance during SP ablation significantly reduces mapping and ablation time, radiation exposure, and RF delivery in comparison to fluoroscopy-only procedures. Moreover, early switching to ICE-guided ablation seems to be an optimal choice in challenging cases.

Koch's triangle voltage mapping for cryoablation of slow pathway in children: preliminary data of a novel high-density technique.

PURPOSE: Different authors have described three-dimensional (3D) voltage mapping of the Koch's triangle (KT) in order to find low-voltage bridges (LVB) as targets for a successful transcatheter ablation (TCA) of the slow pathway (SP) in children. Recently, the Advisor High Density (HD) Grid™ mapping catheter was introduced as new multipolar catheter for HD mapping. The aim of the study was to describe our preliminary experience with the use of HD Grid™ catheter in LVB and electrophysiologically guided cryoablation of SP in children. METHODS: Twenty-one children (mean age 13±3 years) with atrioventricular nodal re-entrant tachycardia (AVNRT) underwent cryoablation of SP guided by voltage HD mapping of the KT using HD Grid™ catheter. In order to better highlight the differences with conventional mapping, point collection was performed in each patient with this new multipolar catheter and with a quadripolar catheter. RESULTS: The conventional mapping collected 871±262 points and used 211±80 points in 887±275 s, whereas HD mapping collected 7468±2947 points, using 604±165 points in 513±181 s (p<0.001). Moreover, the LVB area mapped with HD Grid™ was about one-half smaller and clearly delineated. Cryoablation acute success rate was 100%. Overall median fluoroscopy exposure was 0.08 (0.01-5.42) µGy/m2, with a median fluoroscopy time of 0.1 (0.0-0.6) min. During the follow-up (4.8 ± 3.7 months), there were no recurrences. No complications occurred. CONCLUSIONS: Our preliminary experience shows that HD mapping is faster and offers higher spatial resolution and definition. Procedural time can be reduced maintaining the TCA safe, with reduced fluoroscopy use and success.

Cryoablation with an 8-mm tip catheter for typical AVNRT in children: a single center 5-year experience.

BACKGROUND: In children with typical atrioventricular nodal reentrant tachycardia (tAVNRT), cryoablation is preferred over radiofrequency ablation (RFA) because of its safety profile and acceptable long-term success rates. In this study, we have assessed the utility of 8-mm tip cryocatheters for tAVNRT ablation in our center. METHODS: All pediatric AVNRT patients who underwent cryoablation with an 8-mm tip cryocatheter in our center between 2013 and 2018 were included. EnSite™ (St. Jude Medical Inc., St. Paul, MN, USA) was used in all patients. RESULTS: A total of 120 patients (64 females, 53%) were included in this study, and the mean age was 13.9 years with a standard deviation of 2.5 years. Eleven patients (9.1%) had structural heart disease, and 12 patients (10%) had additional arrhythmia substrate. The mean number of effective cryolesions was 8 with a standard deviation of 2.3. Fluoroscopy was used in three patients (2.5%). There were minor complications in only four patients (3.3%)-transient first-degree atrioventricular block or transient incomplete right bundle branch block. Acute success rate of cryoablation was 108/120 (90%). In twelve patients, cryoablation was suboptimal, or it failed. The procedure was completed successfully with RFA in the same session in ten patients. Overall acute success rate of ablation (Cryo ± RFA) was 98.5%. During a mean follow-up period of 24.6 months with a standard deviation of 11.3 months, three patients had recurrence (2.5%). Time between the beginning of the effective cryolesion and termination of AVNRT was found associated with acute success of cryoablation (p = 0.013). CONCLUSIONS: Cryoablation of AVNRT with an 8-mm tip catheter in children appears to be safe, with an acceptable acute success rate and a low recurrence rate. A faster termination of AVNRT during the cryolesion, slowing down before ending with atrioventricular block, is a good indicator for acute success.

High-density mapping of Koch's triangle during sinus rhythm and typical AV nodal reentrant tachycardia: new insight.

BACKGROUND: Atrial activation during typical atrioventricular nodal reentrant tachycardia (AVNRT) exhibits anatomic variability and spatially heterogeneous propagation inside the Koch's triangle (KT). The mechanism of the reentrant circuit has not been elucidated yet. Aim of this study is to describe the distribution of Jackman and Haïssaguerre potentials within the KT and to explore the activation mode of the KT, in sinus rhythm and during the slow-fast AVNRT. METHODS: Forty-five consecutive cases of successful slow pathway (SP) ablation of typical slow-fast AVNRT from the CHARISMA registry were included. RESULTS: The KT geometry was obtained on the basis of the electroanatomic information using the Rhythmia mapping system (Boston Scientific) (mean number of points acquired inside the KT = 277 ± 47, mean mapping time = 11.9 ± 4 min). The postero-septal regions bounded anteriorly by the tricuspid annulus and posteriorly by the lateral wall toward the crista terminalis showed a higher prevalence of Jackman potentials than mid-postero-septal regions along the tendon of Todaro and coronary sinus (CS) (98% vs. 16%, p < 0.0001). Haïssaguerre potentials seemed to have a converse distribution across the KT (0% vs. 84%, p < 0.0001). Fast pathway insertion, as located during AVNRT, was mostly recorded in an antero-septal position (n = 36, 80%), rather than in a mid-septal (n = 6, 13.3%) or even postero-septal (n = 3, 7%) location. During typical slow-fast AVNRT, two types of propagation around the CS were discernible: anterior and posterior, n = 31 (69%), or only anterior, n = 14 (31%). During the first procedure, the SP was eliminated, and acute procedural success was achieved (median of 4 [3-5] RF ablations). CONCLUSION: High-density mapping of KT in AVNRT patients both during sinus rhythm and during tachycardia provides new electrophysiological insights. A better understanding and a more precise definition of the arrhythmogenic substrate in AVNRT patients may have prognostic value, especially in high-risk cases. TRIAL REGISTRATION: Catheter Ablation of Arrhythmias With High Density Mapping System in the Real World Practice (CHARISMA) URL: http://clinicaltrials.gov/ Identifier: NCT03793998.

Fluoroless radiofrequency and cryo-ablation of atrioventricular nodal reentry tachycardia in adults and children: a single-center experience.

BACKGROUND: Radiofrequency ablation (RFA) and cryo-ablation (CRA) have been traditionally performed with fluoroscopy which exposes patients and medical staff to the potential harmful effects of the X-ray. Therefore, we aimed to assess the feasibility, safety, and effectiveness of RFA and CRA of atrioventricular nodal reentry tachycardia (AVNRT) guided by the three-dimensional (3D) electro-anatomical mapping (EAM) system without the use of fluoroscopy. METHODS: We analyzed 168 consecutive patients with AVNRT, 62 of whom were under 19 years of age (128 in RFA (age 34.04 ± 21.0 years) and 40 in CRA (age 39.41 ± 22.8 years)). All procedures were performed completely without the use of the fluoroscopy and with the 3D EAM system. RESULTS: The acute success rates (ASR) of the two ablation methods were very high and similar (for RFA 126/128 (98.4%) and for CRA 40/40 (100%); p = 0.43). Total procedural time (TPT) was similar in RFA and CRA groups (75.04 ± 42.31 min and 73.12 ± 30.54 min, respectively; p = 0.79). Recurrence rates (1 (2.5%) and 8 (6.25%); p = 0.35) were similar. There were no complications associated with procedures in either group. In pediatric group, ASR (61/62 (98.38%) and 105/106 (99.05%), respectively; p = 0.69) and TPT (75.16 ± 42.2 min and 74.23 ± 38.3 min, respectively; p = 0.88) were similar to the adult group. High ASR was observed with both ablation methods (for RFA 49/50, 98%, and for CRA 12/12, 100%; p = 0.62] with very high arrhythmia-free survival rates (for RFA 98% and for CRA 100%; p = 0.62). CONCLUSION: Based on these results, it can be suggested that fluoroless RFA or CRA guided by the 3D EAM system can be routinely performed in all patients with AVNRT without compromising safety, efficacy, or duration of the procedure.

Outcomes of junctional ectopic tachycardia ablation in adult population-a multicenter experience.

PURPOSE: Idiopathic junctional ectopic tachycardia (JET) is typically refractory to antiarrhythmic agents. Catheter ablation for JET is feasible but is associated with high risk of unintended atrioventricular (AV) block. There is limited data on the appropriate procedural technique and clinical outcomes with catheter ablation for idiopathic JET in adults. METHODS: This is a multicenter, retrospective study of all adult patients (age ≥ 18 years) who underwent catheter ablation for idiopathic JET. Patient, procedural characteristics, and long-term outcomes were evaluated. RESULTS: Fifteen patients [radiofrequency ablation (RF) = 14 and cryoablation = 1) were treated with catheter ablation. The median age was 58 years with 67% males. All patients underwent mapping of the right atrium and the aortic cusps prior to energy delivery. The location of earliest activation in relation to the atrioventricular (AV) node was postero-superior in 73% (11/15), posterior in 13% (2/15), and superior in 13% (2/15) respectively. Acute success was 100%. Arrhythmia recurrence occurred in 53% (8/15) all of whom underwent a repeat ablation. High-grade AV block requiring permanent pacemaker occurred in 20% (3/15). At 12-month follow-up in the redo-ablation group, 37.5% (3/8) had recurrence of the arrhythmia two of which underwent a third ablation procedure. CONCLUSION: Catheter ablation of idiopathic JET in adults is associated with a high rate of recurrence requiring multiple procedures and high risk of AV block requiring a permanent pacemaker. Mapping and ablation of the non-coronary cusp can be considered as the arrhythmia was controlled in 3 patients with no inadvertent AV block.

Revisiting right anterior oblique projections for the triangle of Koch: implications from computed tomography.

BACKGROUND: Variability in the anatomy and orientation of the triangle of Koch (TK) complicates ablation procedures involving the atrioventricular (AV) node. We used CT angiography (CTA) to assess the anatomical TK orientation, the CS ostium direction, and the relationship between the two, and we validated an individualized CS-guided projection during ablation procedures. METHODS: In 104 patients without structural heart disease undergoing computed tomography (CT) angiography, TK orientations were determined in relation to the coronary sinus ostium (CSo) as well as two standard right anterior oblique (RAO) projection angles (30o and 45o) commonly used in ablation procedures. RESULTS: A CS-guided RAO projection (RAOCS) was shown to best track the orientation of the TK compared to RAO30° and 45°, with TK orientation strongly correlating with the CSo direction (r = 0.86, P < 0.001). In addition, the mean relative difference between the angle of the CSo and TK orientation was 5.54 ± 0.48°, consistent with a reduction in the degree of image shortening compared to traditional RAOs. Moreover, in vivo validation following ablation revealed that using a CS-guided projection limited the degree of on-screen image shortening compared to both the RAO30° and 45° in 25 patients with catheter ablation procedures. CONCLUSION: In hearts with a normal structure, the CSo direction offers a reliable predictor of the TK orientation which can be used to guide the projection of the TK during ablation procedures.

Treatment of left-sided extension of AV node: A valuable integration of advance imaging modalities and cryoablation.

We present a case of successful cryoablation of the left extension of the atrioventricular (AV) node for treatment of a recurrent atrioventricular nodal reentry tachycardia without the use of fluoroscopy. Three-dimensional electroanatomic mapping system and intracardiac echocardiography were used to navigate catheters in the heart and position them according to anatomical landmarks. Due to the nature of cryoablation lesion formation, lesions were able to be applied safely in right atrium, as well as in left atrium, without damaging AV node or bundle of His.

Predictors of zero X ray procedures in supraventricular arrhythmias ablation.

To evaluate predictors of zero-X ray procedures for supraventricular arrhythmias (SVT) using minimally fluoroscopic approach (MFA). Patients referred for RF catheter ablation of SVT were admitted for a MFA with an electro-anatomical navigation system or a conventional fluoroscopic approach (ConvA). Exclusion criterion was the need to perform a transseptal puncture. 206 patients (98 men, age 53 ± 19 years) underwent an EP study, 93 (45%) with an MFA and 113 (55%) with a ConvA. Fifty-five had no inducible arrhythmias (EPS). Fifty-four had AV nodal reentrant tachycardia (AVNRT), 49 patients had typical atrial flutter (AFL), 37 had AV reciprocating tachycardia (AVRT/WPW), 11 had focal atrial tachycardia (AT), and underwent a RF ablation. X-ray was not used at all in 51/93 (58%) procedures (zero X ray). MFA was associated with a significant reduction in total fluoroscopy time (5.5 ± 10 vs 13 ± 18 min, P = 0.01) and operator radiation dose (0.8 ± 2.5 vs 3 ± 8.2 mSV, P < 0.05). The greatest absolute dose reduction was observed in AVNRT (0.1 ± 0.3 vs 5.1 ± 10 mSV, P = 0.01, 98% relative dose reduction) and in AFL (1.3 ± 3.6 vs 11 ± 16 mSV, P = 0.003, 88% relative dose reduction) groups. Both AVNRT or AFL resulted the only statistically significant predictors of zero x ray at multivariate analysis (OR 4.5, 95% CI 1.5-13 and OR 5, 95% CI 1.7-15, P < 0.001, respectively). Success and complication rate was comparable between groups (P = NS). Using MFA for SVT ablation, radiological exposure is significantly reduced. Type of arrhythmia is the strongest predictor of zero X ray procedure.

Differentiating Atrioventricular Reentry Tachycardia and Atrioventricular Node Reentry Tachycardia Using Premature His Bundle Complexes.

BACKGROUND: Current maneuvers for differentiation of atrioventricular node reentry tachycardia (AVNRT) and atrioventricular reentry tachycardia (AVRT) lack sensitivity and specificity for AVRT circuits located away from the site of pacing. We hypothesized that a premature His complex (PHC) will always perturb AVRT because the His bundle is obligatory to the circuit. Further, AVNRT could not be perturbed by a late PHC (≤20 ms ahead of the His) due to the retrograde His conduction time. Earlier PHCs can advance the AVNRT circuit but only by a quantity less than the prematurity of the PHC. METHODS: High-output pacing at the distal His location delivered PHCs. AVRT was predicted when late PHCs perturbed tachycardia or when earlier PHCs led to atrial advancement by an amount equal or greater than the degree of PHC prematurity. RESULTS: Among the 73 supraventricular tachycardias, the test accurately predicted AVRT (n=29) and AVNRT (n=44) in all cases. Late PHC advanced the circuit in all 29 AVRTs and none of the AVNRTs (sensitivity and specificity, 100%). With earlier PHCs, the degree of atrial advancement was equal or greater than the PHC prematurity in 26/29 AVRTs and none of the AVNRTs (90% sensitivity and 100% specificity). The mean prematurity of the PHC required to perturb AVNRT was 48 ms (range, 28-70 ms) and the advancement less than the prematurity of the PHC (mean, 32 ms; range, 18-54 ms). CONCLUSIONS: The responses to PHCs distinguished AVRT and AVNRT with 100% specificity and sensitivity.

Efficacy and safety of catheter ablation of atrioventricular nodal re-entrant tachycardia by means of flexible-tip irrigated catheters.

PURPOSE: Irrigated-tip ablation catheters increase safety and efficacy of ablation procedures, but their use in atrioventricular nodal re-entrant tachycardia (AVNRT) ablation has not been systematically evaluated. The aim of this study is to evaluate the safety and efficacy of radiofrequency (RF) catheter ablation of AVNRT by means of the novel flexible-tip open-irrigated catheter FlexAbility™ and a 3D electroanatomic mapping (EAM) system. METHODS: This is a single-center and single-operator study on 80 patients referred for AVNRT catheter ablation. Outcome included acute and long-term procedural success as well as complications reported over a median follow-up of 19 months (interquartile range 6-24 months). RESULTS: Acute success was achieved in all 80 patients. One procedure-related major complication, involving the vascular access, occurred. Mean fluoroscopy time was 106 ± 71 s. One patient (1.2%) suffered long-term AVNRT recurrence. Five patients (6.2%) underwent ablation for AVNRT combined with ablation for other clinical arrhythmias. CONCLUSIONS: Irrigated RF ablation of AVNRT by means of the novel flexible-tip open-irrigated catheter associated to 3D EAM system is effective and safe. Success rates are comparable to those of other techniques. Complication rate is very low.

Supraventricular arrhythmia with discordant electrocardiographic features: What is the arrhythmia mechanism?

Junctional and AV nodal reentrant tachycardia share common electrocardiographic features, but they differ in their management and outcomes after catheter ablation. This case concerns a 60-year-old female who presented with recurrent episodes of a relatively slow, regular supraventricular arrhythmia. Electrocardiographic features of the arrhythmia were discordant regarding its underlying mechanism. However, careful analysis of 12-lead electrocardiograms, with focus on the effect of spontaneous premature beats, pointed out the arrhythmia etiology. Electrophysiological study and pacing maneuvers defined the arrhythmic substrate that was successfully treated by catheter ablation.

High-Detailed evaluation of the right atrial anatomy by three-dimensional rotational angiography during ablation procedures for atrioventricular nodal reentrant tachycardia and atrial flutter.

AIM: 3D Rotational angiography (3DRA) allows for detailed reconstruction of atrial anatomy and is often used to facilitate pulmonary vein isolation. This study aimed to reappraise the anatomy of the right atrium (RA) using 3DRA, specifically looking at Koch's triangle and the cavotricuspid isthmus (CTI) in atrio-ventricular reentrant tachycardia (AVNRT) and atrial flutter (AFl) ablation. METHODS AND RESULTS: 3DRA was performed in 97 patients: AVNRT = 51 and AFl = 46. Dimensions of Koch's triangle and CTI were highly variable between individuals but were not different in both ablation groups. RA volume was significantly larger in AFl patients (p = .004) while indexed RA volume to the body surface area (RAVI) was lightly different (p = .024). In univariate Cox analysis, age (p = .003), RAVI (p < .001) and previous ablation of AFl (p = .003) were predictors of AF occurrence . In multivariate Cox analysis, RAVI was the only independent predictor of AF occurrence. RAVI >80 ml/m2 was a strong predictor for AF during follow-up. CONCLUSION: 3DRA allows for detailed per-procedural evaluation of RA anatomy and revealed a great variability in Koch's triangle and CTI dimensions and morphology. RA enlargement as measured by RAVI was an independent predictor for AF occurrence during follow-up.

Bundle branch reentrant ventricular tachycardia: review and case presentation.

Bundle branch reentrant ventricular tachycardia (BBRVT) is characterized by a unique, fast (200-300 beats/min), monomorphic wide complex tachycardia (WCT) associated with syncope, hemodynamic compromise, and cardiac arrest. It is challenging to diagnose, requiring a His bundle recording and specific pacing maneuvers. The overall incidence has been reported to be up to 20% among patients with non-ischemic cardiomyopathy (NICM) undergoing electrophysiologic studies. We report a case of BBRVT in a patient with ischemic cardiomyopathy (ICM) presenting as a WCT with recurrent implantable-cardioverter-defibrillator (ICD) shocks. We describe all the characteristic features of BBRVT and discuss its differential. We also discuss the role of ablation for this condition.