Radiofrequency Catheter Ablation of Atrial Tachycardias in Congenital Heart Disease

Fate After the Mustard Procedure for d-Transposition of the Great Arteries: Impact of Age, Complexity, and Atrial Tachyarrhythmias: A Single Center Experience

Patients with dextro transposition of the great arteries (d-TGA) after atrial switch procedure are at risk to develop heart failure and arrhythmias during long-term follow-up. The present study aims to add knowledge on the fate of subjects after Mustard procedure during long-term follow-up into adulthood. A single center, retrospective chart review analysis was conducted. All subjects who had Mustard-type atrial switch procedure between 1969 and 1994 at our institution were included. A total of 92 subjects were included. Early postoperative death was reported in 2 subjects. Long-term follow-up was available in 49 survivors. Of those, 6 individuals died during further follow-up. Sudden cardiac death was the most prevalent cause for fatal outcome. Mortality during long-term follow-up was associated with the presence of additional cardiovascular malformations (complex d-TGA). Sinus node dysfunction was observed in 65% of the patients and atrial tachyarrhythmias were common in adult survivors (63%). Implantation of a pacemaker or a cardioverter defibrillator was required in 31% and 45% of those surviving into adulthood. Complications were frequently observed during follow-up after either pacemaker or cardioverter defibrillator implantation (43%) with lead failure being the most frequent complication. The aging population of patients after Mustard procedure is facing challenging problems mainly resulting from a failing systemic right ventricle, presence of associated cardiac malformations and the presence of atrial baffles associated with relevant atrial scars. Age, associated cardiac malformations, and atrial tachyarrhythmias seem to play a major role in determining the fate of patients with d-TGA after atrial switch procedures.

Advancing the science of management of arrhythmic disease in children and adult congenital heart disease patients within the last 25 years

This review article reflects how publications in EP Europace have contributed to advancing the science of management of arrhythmic disease in children and adult patients with congenital heart disease within the last 25 years. A special focus is directed to congenital atrioventricular (AV) block, the use of pacemakers, cardiac resynchronization therapy devices, and implantable cardioverter defibrillators in the young with and without congenital heart disease, Wolff-Parkinson-White syndrome, mapping and ablation technology, and understanding of cardiac genomics to untangle arrhythmic sudden death in the young.

Clinical Impact of Cardiac Fibrosis on Arrhythmia Recurrence after Ablation in Adults with Congenital Heart Disease

BACKGROUND

Adults with congenital heart disease (ACHD) are often affected by cardiac arrhythmias requiring catheter ablation. Catheter ablation in this setting represents the treatment of choice but is flawed by frequent recurrencies. Predictors of arrhythmia relapse have been identified, but the role of cardiac fibrosis in this setting has not been investigated. The aim of this study was to determine the role of the extension of cardiac fibrosis, detected by electroanatomical mapping, in predicting arrhythmia recurrencies after ablation in ACHD.

MATERIALS AND METHODS

Consecutive patients with congenital heart disease and atrial or ventricular arrhythmias undergoing catheter ablation were enrolled. An electroanatomical bipolar voltage map was performed during sinus rhythm in each patient and bipolar scar was assessed according to the current literature data. During follow-up, arrhythmia recurrences were recorded. The relationship between the extent of myocardial fibrosis and arrhythmia recurrence was assessed.

RESULTS

Twenty patients underwent successful catheter ablation of atrial (14) or ventricular (6) arrhythmias, with no inducible arrhythmia at the end of the procedure. During a median follow-up period of 207 weeks (IQR 80 weeks), eight patients (40%; five atrial and three ventricular arrhythmias) had arrhythmia recurrence. Of the five patients undergoing a second ablation, four showed a new reentrant circuit, while one patient had a conduction gap across a previous ablation line. The extension of the bipolar scar area (HR 1.049, CI 1.011-1.089, p = 0.011) and the presence of a bipolar scar area >20 cm² (HR 6.101, CI 1.147-32.442, p = 0.034) were identified as predictors of arrhythmia relapse.

CONCLUSION

The extension of the bipolar scar area and the presence of a bipolar scar area >20 cm² can predict arrhythmia relapse in ACHD undergoing catheter ablation of atrial and ventricular arrhythmias. Recurrent arrhythmias are often caused by circuits other than those previously ablated.

Prevalence and Treatment Outcomes of Arrhythmias in Patients with Single Ventricle Physiology over the Age of 40 Years

Background: Arrhythmias are a well known complication in patients with single ventricle physiology (SVP). However, there is still a lack of data regarding arrhythmias in older patients. The aim of this study was to analyze arrhythmia type and frequency, treatment and recurrence rates in patients with SVP over the age of 40 years. Methods: Data was obtained retrospectively from clinical records. All patients > 40 years with SVP with arrhythmias between 2005 and 2018 were included in the study. Treatment was classified as medical, interventional (electrophysiological studies (EPS) in combination with catheter ablation) or direct current cardioversion (DCCV). Results: Altogether, 29 patients (11 female; mean 47.5 ± 4.6 years) with 85 arrhythmia episodes were identified. The median follow-up time was 6.3 years. Cavo-tricuspid (CTI) and non-CTI related intra-atrial reentrant tachycardia (IART) and atrial fibrillation (AF) were most common (48.2% and 37.6%, respectively). In total, 18 EPS/ablations were performed in 9 patients and 52 DCCVs in 20 patients. Acute success was 98% for DCCV and 72.2% for EPS/ablation. Recurrence rate was high (70% for DCCV and 55% for EPS). AT recurrences occurred after a median of 8 and 2.5 months, respectively. On multivariate analyses, age was the only risk factor for arrhythmia recurrence (HR 0.58, 95% C.I. 0.43−0.78, p < 0.0001). Pacemaker implantation was necessary in seven patients (AV block n = 4, sinus node dysfunction n = 3) and one patient received an ICD for secondary prophylaxis. Sudden death occurred in three patients. Conclusions: The most common arrhythmias in patients with SVP > 40 years are IART and AF. Arrhythmia recurrence following EPS or DCCV is frequent. Older age is an independent risk factor for arrhythmia recurrence.

Catheter Ablation for Atrial Fibrillation in Adult Congenital Heart Disease: An International Multicenter Registry Study

BACKGROUND

Data on atrial fibrillation (AF) ablation and outcomes are limited in patients with congenital heart disease (CHD). We aimed to investigate the characteristics of patients with CHD presenting for AF ablation and their outcomes.

METHODS

A multicenter, retrospective analysis was performed of patients with CHD undergoing AF ablation between 2004 and 2020 at 13 participating centers. The severity of CHD was classified using 2014 PACES/HRS guidelines. Clinical data were collected. One-year complete procedural success was defined as freedom from atrial tachycardia or AF in the absence of antiarrhythmic drugs or including previously failed antiarrhythmic drugs (partial success).

RESULTS

Of 240 patients, 127 (53.4%) had persistent AF, 62.5% were male, and mean age was 55.2±0.9 years. CHD complexity categories included 147 (61.3%) simple, 69 (28.8%) intermediate, and 25 (10.4%) severe. The most common CHD type was atrial septal defect (n=78). More complex CHD conditions included transposition of the great arteries (n=14), anomalous pulmonary veins (n=13), tetralogy of Fallot (n=8), cor triatriatum (n=7), single ventricle physiology (n=2), among others. The majority (71.3%) of patients had trialed at least one antiarrhythmic drug. Forty-six patients (22.1%) had reduced systemic ventricular ejection fraction <50%, and mean left atrial diameter was 44.1±0.7 mm. Pulmonary vein isolation was performed in 227 patients (94.6%); additional ablation included left atrial linear ablations (25.4%), complex fractionated atrial electrogram (19.2%), and cavotricuspid isthmus ablation (40.8%). One-year complete and partial success rates were 45.0% and 20.5%, respectively, with no significant difference in the rate of complete success between complexity groups. Overall, 38 patients (15.8%) required more than one ablation procedure. There were 3 (1.3%) major and 13 (5.4%) minor procedural complications.

CONCLUSIONS

AF ablation in CHD was safe and resulted in AF control in a majority of patients, regardless of complexity. Future work should address the most appropriate ablation targets in this challenging population.

Atrial Flutters in Adults with Congenital Heart Disease

The macroreentrant atrial tachycardia is very frequent in the adults with congenital heart disease. The impact of the arrhythmias on this type of patients is related to several factors: the anatomy and physiopathology of the specific congenital heart disease (CHD), the sequelae of the corrective surgery or surgical palliation, the presence of residual lesions (shunt, regurgitation), and the age and the clinical status of the patient and the comorbidities. In turn, the mechanism of the MAT depends on the peculiar features of the conduction's system in the CHD and native and acquired (post-surgery) substrates.

Catheter ablation of atrial fibrillation using 2nd-generation cryoballoon in congenital heart disease patients - significance of RF ablation of additional atrial macro-reentrant tachycardia

Background

Prevalence of atrial fibrillation (AF) is increasing in adult patients with congenital heart disease (CHD). Experience using the cryoballoon to achieve pulmonary vein isolation (PVI) in adult CHD patients is limited. The aim of the present study was to assess the value of PVI by cryoballoon in adult CHD patients and to evaluate the significance of additional radiofrequency (RF) ablation of atrial tachycardia (AT).

Patients and methods

Prospective data analysis; all patients with CHD and AF and PVI using the cryoballoon from January 2017 through November 2021 were included.

Results

Nineteen patients with various types of CHD were included. Median age was 58 (IQR 47–63) years. A total of 12/19 (63%) patients had had RF ablation of right atrial AT before. Median procedure duration was 225 (IQR 196–261) min. Median fluoroscopy time was 12.3 (IQR 5.2–19.5) min and median freeze time was 32 (IQR 28–36.3) min. Procedural success was achieved in all patients. Additional RF catheter ablation of intraatrial reentrant tachycardia within the left atrium was performed in 3/19 (16%) subjects and within the right atrium in 6/19 (32%) patients. Median follow-up was 26 (IQR 9–49) months. Excluding a 90-day blanking period, recurrence of AF was observed in 6/19 subjects (32%). After one redo procedure deploying RF energy only, 84% of all patients remained free from recurrence. Phrenic nerve palsy was observed in 1 subject.

Conclusion

Results after PVI using the cryoballoon plus additional RF ablation of AT were promising (84% success including one redo procedure). Success of AF ablation was unsatisfactory in all patients who had no additional AT ablation. Ablation of any AT in these patients should therefore be considered in addition to PVI.

Repeat Radiofrequency Catheter Ablation of Atrial Tachycardias in Patients with Congenital Heart Disease

INTRODUCTION

Atrial tachycardias (AT) in patients with congenital heart disease (CHD) are significantly contributing to morbidity and mortality. Aim of this study was to evaluate the long-term course of CHD patients requiring repeat ablation procedures (RAP) of AT.

PATIENTS AND METHODS

All 144 patients with CHD who had undergone ablation of AT at our center between January 2003 and October 2018 were enrolled. Patients were classified according to complexity of CHD: complex CHD (cCHD), moderate CHD (mCHD) and simple CHD (sCHD).

RESULTS

A total of 101 RAP were performed in 64 patients. One RAP was performed in n=40, two in n=13, three in n=10 and 5 in n=1. Acute success rate was 82% (83/101) and was not associated with complexity of CHD (p=1.0). Number of procedures was lower in patients with sCHD than in patients with mCHD and cCHD (sCHD 1.3±0.6, mCHD 1.8±1.0 and cCHD 1.8±1.1, p=0.04). RAP were most frequent in patients after Fontan palliation or Atrial switch procedure (2.0±1.1 (n=41) vs. 1.6±0.9 all others, p=0.016) and in patients with multiple unstable AT´s (2.5±1.1 (n=11) vs. 1.7±1.0, p=0.008). Major complications occurred in 4/101 procedures. Complete follow-up was available in 125 patients. Since last RAP 73% of the patients were in sinus/atrial rhythm and 34/125 patients (27%) with AT recurrence did not require re-ablation with mean follow-up of 52±40 months.

CONCLUSIONS

Recurrences after ablation of AT in CHD patients were frequent. After RAP promising long-term results could be achieved. Data encourage repetitive ablation procedures in this patient population. This article is protected by copyright. All rights reserved.

Tachyarrhythmias in Congenital Heart Diseases: From Ion Channels to Catheter Ablation

Major advances in pediatric cardiology in recent decades, especially surgical techniques, have resulted in an increasing number of patients with congenital heart disease (CHD) surviving to adulthood. This has generated new challenges, particularly with regards to the late onset of complex arrhythmias. Abnormal anatomy, surgical scarring, chronic hypoxemia, hemodynamic compromise, neuro-hormonal abnormalities, and genetic factors can all contribute to creating a unique substrate for arrhythmia development. This review attempts to synthesize the current state of knowledge spanning the spectrum from underlying mechanisms of arrhythmias in patients with congenital heart disease to current ablative strategies. We discuss existing knowledge gaps and highlight important areas for future research.

Progress of Pathogenesis in Pediatric Multifocal Atrial Tachycardia

Multifocal atrial tachycardia (MAT) is defined as irregular P-P, R-R, and P-R intervals, isoelectric baseline between P waves, and ventricular rate over 100 beats/min. Although the prognosis of pediatric MAT in most patients is favorable, adverse outcomes of MAT have been reported, such as cardiogenic death (3%), respiratory failure (6%), or persistent arrhythmia (7%), due to delayed diagnosis and poorly controlled MAT. Previous studies demonstrated that pediatric MAT is associated with multiple enhanced automatic lesions located in the atrium or abnormal automaticity of a single lesion located in the pulmonary veins via multiple pathways to trigger electrical activity. Recent studies indicated that pediatric MAT is associated with the formation of a re-entry loop, abnormal automaticity, and triggering activity. The occurrence of pediatric MAT is affected by gestational disease, congenital heart disease, post-cardiac surgery, pulmonary hypertension, and infectious diseases, which promote MAT via inflammation, redistribution of the autonomic nervous system, and abnormal ion channels. However, the pathogenesis of MAT needs to be explored. This review is aimed to summarize and analyze the pathogenesis in pediatric MAT.

Ablation of intra-atrial reentrant tachycardias in adults with congenital heart disease: islands, isthmuses, channels, and walls

PURPOSE OF REVIEW

The adult congenital heart patient population is rapidly growing due to increasing survival rates, and they often face chronic physiologic challenges as sequalae of both their defects and repairs. Among the most common sequalae are arrhythmias. Here we describe intra-atrial reentrant tachycardia (IART), one of the most commonly seen arrhythmias in the adult congenital heart population, and the approaches to successful ablation in adult congenital heart patients.

RECENT FINDINGS

IART has increasing ablation success rates due to the increasing exposure of electrophysiologists to congenital cases, advances in technology, and the increasing application of both our pediatric congenital knowledge and adult acquired knowledge to the adult congenital population.

SUMMARY

IART is a frequently seen arrhythmia in the adult congenital population, and it can have life-threatening consequences in the setting of congenital disease. Ablation techniques and treatment rates have improved over time, despite the challenges these cases present to clinicians; success of the ablation depends on careful, often creative, preplanning, and understanding of the complex individualized anatomy and circuits of the patient.

Fluoroscopy-free ablation in congenital heart disease of moderate or great complexity

BACKGROUND

Fluoroscopy-free (FF) ablation has been demonstrated to be safe and successful in patients with structurally normal hearts, but has not been systematically evaluated in patients with congenital heart disease (CHD) of moderate or great (M/G) complexity. This study aimed to evaluate and compare feasibility, safety, and outcomes of FF ablation in patients with or without M/G-CHD.

METHODS

Consecutive patients undergoing electrophysiologic study and intended catheter ablation over a 24-month period were included. Subgroups were created based on presence and complexity of CHD-M/G-CHD or simple complexity/no CHD (S/N-CHD). Cases with total radiation dose of zero qualified as FF. Demographic and peri-procedural variables and outcome data were analyzed.

RESULTS

A total of 89 procedures were included with 62 comprising the S/N-CHD group and 27 comprising the M/G-CHD group. Of the M/G-CHD patients, 13 had CHD of great complexity (including 6 single ventricle/Fontan and 2 atrial switch patients). Patients with M/G-CHD were older, had higher BMI, had higher incidence of ventricular dysfunction, and greater incidence of complex arrhythmias. Fluoroscopy-free ablation was achieved in 59% of M/G-CHD and 69% of S/N-CHD patients. Both groups had similar rates of acute procedural success, recurrence, and complications. Fluoroscopy was primarily used to visualize pre-existing transvenous leads and peripheral venous anomalies or to guide transbaffle/transseptal puncture.

CONCLUSIONS

A fluoroscopy-free ablation approach is feasible, safe, and successful even in patients with M/G-CHD with comparable outcomes to those with S/N-CHD.

Electrophysiological characteristics of atrial tachycardia recurrence: Relevance to catheter ablation strategies in adults with congenital heart disease

BACKGROUND

Catheter ablation outcomes for adults with congenital heart disease (ACHDs) are described, but recurrence mechanisms remain largely unknown.

OBJECTIVE

The purpose of this study was to identify the electrophysiological characteristics of atrial tachycardia (AT) recurrence in ACHD.

METHODS

ACHD AT procedures over a 10-year period were explored for AT or atrial fibrillation (AF) recurrence.

RESULTS

At 299 procedures in 250 ACHD (mean age 39 ± 15 years; 52% male), 464 ATs (360 intra-atrial reentrant tachycardia, 104 focal AT; median 2 [IQR 1-3] ATs per procedure) were targeted. Complete (n = 256 [86%]) or partial (n = 37 [12%]) success was achieved in 98% of procedures. Over a median of 3.0 (IQR 1.4-5.3) years of follow-up, 67 patients (27%) developed AT/AF recurrence after the index procedure. Recurrent vs index tachycardias were more often focal AT (38% vs 19%; P < .001), demonstrated longer cycle length (325 ms vs 280 ms; P = .003), required isoproterenol (50% vs 32%; P = .03), and involved the pulmonary venous atrium (PVA)/septum (53% vs 27%; P < .001). AF history (hazard ratio [HR] 2.0; interquartile range [IQR] 1.2-3.4; P = .01), incomplete success (HR 3.6; IQR 2.1-6.4; P < .001), and PVA substrate (HR 2.1; IQR 1.2-3.5; P = .006) were independently associated with AT/AF recurrence. After complete index procedure success and no AF history, 5-year actuarial freedom from AT/AF and AT alone were 77% and 80%.

CONCLUSION

After catheter ablation in ACHD, repeat ATs were frequently focal, requiring isoproterenol administration, or involved intra-atrial reentrant tachycardia within the PVA or atrial septum. Negative factors were partial success, index PVA substrate, and remote history of AF. These data support aggressive pharmacological provocation to eliminate all inducible tachycardias and coexisting PVA substrates at index procedures for ACHD.

Contemporary Patients With Congenital Heart Disease: Uniform Atrial Tachycardia Substrates Allow for Clear Ablation Endpoints With Improved Long-Term Outcome

[Figure: see text].

Catheter ablation in adults with congenital heart disease: A 15-year perspective from a tertiary centre

BACKGROUND

With the growing adult congenital heart disease (ACHD) population, the number of catheter ablation procedures is expected to dramatically increase. Data reporting experience and evolution of catheter ablation in patients with ACHD, over a significant period of time, remain scarce.

AIM

We aimed to describe temporal trends in volume and outcomes of catheter ablation in patients with ACHD.

METHODS

This was a retrospective observational study including all consecutive patients with ACHD undergoing attempted catheter ablation in a large tertiary referral centre over a 15-year period. Acute procedural success rate and freedom from recurrence at 12 and 24 months were analysed.

RESULTS

From November 2004 to November 2019, 302 catheter ablations were performed in 221 patients with ACHD (mean age 43.6±15.0 years; 58.9% male sex). The annual number of catheter ablations increased progressively from four to 60 cases per year (P<0.001). Intra-atrial reentrant tachycardia/focal atrial tachycardia was the most common arrhythmia (n=217, 71.9%). Over the study period, acute procedural success rate increased from 45.0% to 93.4% (P<0.001). Use of irrigated catheters (odds ratio [OR] 4.03, 95% confidence interval [CI] 1.86-8.55), a three-dimensional mapping system (OR 3.70, 95% CI 1.72-7.74), contact force catheters (OR 3.60, 95% CI 1.81-7.38) and high-density mapping (OR 3.69, 95% CI 1.82-8.14) were associated with acute procedural success. The rate of freedom from any recurrence at 12 months increased from 29.4% to 66.2% (P=0.001). Seven (2.3%) non-fatal complications occurred.

CONCLUSIONS

The number of catheter ablation procedures in patients with ACHD has increased considerably over the past 15 years. Growing experience and advances in ablative technologies appear to be associated with a significant improvement in acute and mid-term outcomes.

Lone Atrial Flutter in Children and Adolescents: Is It Really "Lone"?

Atrial flutter (AFL) in children and adolescents beyond the neonatal period in the absence of any underlying myocardial disease ("lone AFL") is rare and data is limited. Our study aims to present clinical and electrophysiological data of presumed "lone AFL" in pediatric patients and discuss the role of endomyocardial biopsy (EMB) and further follow-up. Since July 2005, eight consecutive patients at a median age of 12.7 (range 10.4-16.7) years presenting with presumed "lone AFL" after negative non-invasive diagnostic work-up had electrophysiological study (EPS) and induction of cavotricuspid isthmus (CTI) conduction block by radiofrequency (RF) current application. In 6/8 patients EMB could be taken. Induction of CTI conduction block was achieved in all patients. Histopathological examination of EMB from the right ventricular septum exhibited myocarditis or cardiomyopathy in 4/6 patients, respectively. During follow-up, 4/8 patients had recurrent arrhythmia (AFL n = 2, wide QRS complex tachycardia n = 1, monomorphic premature ventricular contractions n = 1) after the ablation procedure. 3/4 patients with recurrent arrhythmia had pathological EMB results. The remaining patient with recurrent arrhythmia had a negative EMB but was diagnosed with Brugada syndrome during further follow-up. Taking together results of EMB and further clinical course, only 3/8 patients finally turned out to have true "lone AFL". Our study demonstrates that true "lone AFL" in children and adolescents is rare. EMB and clinical course revealed an underlying cardiac pathology in the majority of the individuals studied. EMB was very helpful in order to timely establish the diagnosis of myocarditis or cardiomyopathy.

Impact of Catheter Ablation for Atrial Arrhythmias on Repeat Cardioversion in Adults With Congenital Heart Disease

BACKGROUND

Atrial tachyarrhythmias (AAs) are the main source of morbidity and mortality in adult congenital heart disease (ACHD). Direct-current cardioversion (DCCV) is an effective method to acutely terminate AAs, but many patients require repeated DCCV. Little is known about the impact of radiofrequency catheter ablation (RFCA) of AAs on the incidence of repeated DCCV in patients with ACHD. The purpose of this study was to evaluate the impact of RFCA on the incidence of DCCV in patients with ACHD.

METHODS

A total of 157 patients with ACHD undergoing DCCV in our hospital from 2011 to 2018 (female n = 76 [48.4%], mean age 37.8 ± 12.5 y), were reviewed. The median follow-up period was 31.8 months (interquartile range 16.3-55.1 mo).

RESULTS

Out of the total of 157 patients, 102 (65.0%) underwent RFCA for AAs, and 55 (35.0%) were treated without RFCA. Successful RFCA with termination of AAs during ablation was 62.7%. More than one-half of the patients had complex forms of CHD (62.4%). During follow-up, 57 patients (55.9%) who had RFCA developed recurrence of AAs, and 36 patients (35.2%) underwent repeated DCCV. Thirty-three (60.0%) out of 55 patients without RFCA required repeated cardioversion. Compared with patients without RFCA, RFCA significantly reduced the need for repeated DCCV by 40% (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.23-0.80; P = 0.009). In multivariate analysis, successful RFCA was associated with reduced risk of DCCV (HR 0.41, 95% CI 0.19-0.92; P = 0.031).

CONCLUSIONS

AAs remain common despite RFCA in patients with ACHD. Nevertheless, RFCA is associated with a marked reduction in the need for repeated DCCV.

Recent advances in three-dimensional electroanatomical mapping guidance for the ablation of complex atrial and ventricular arrhythmias

PURPOSE

To provide a brief overview of some relevant technological advances in the field of three-dimensional electroanatomical mapping (3D-EAM) that have recently entered the clinical arena and their role in guiding catheter ablation (CA) of complex atrial and ventricular arrhythmias.

METHODS

In this technical report, we describe the general features of three novel algorithms featured in the updated CARTO PRIME™ mapping module for CARTO®3 version 7 3D-EAM system (Biosense Webster Inc., Diamond Bar, CA, USA): local activation time (LAT) hybrid, coherent mapping and map replay modules. We also report three challenging arrhythmia cases in which CA was successfully guided by these softwares.

RESULTS

The LAT hybrid module was used in a case of premature ventricular complex originating from the right coronary cusp. This algorithm facilitated safe positioning of the ablation catheter away from the right coronary ostium, avoiding potential harm to this vital structure. The coherent mapping module helped to identify the critical as well as a bystander isthmus of an atrial macro-re-entrant tachycardia in a grown-up patient with congenital heart disease. The map replay module allowed rapid retrospective activation mapping of two unstable ventricular tachycardias in a case of nonischemic cocaine-associated cardiomyopathy.

CONCLUSION

3D-EAM systems offer significant advantages in the management of challenging arrhythmias, and the introduction of novel algorithms underpins improvements in patients' outcomes. Given the increasing sophistication of these systems, however, a close collaboration among cardiac electrophysiologists, engineers and technicians is highly needed in order to get the best from the available technology.

Characterization of the Mechanism and Substrate of Atrial Tachycardia Using Ultra-High-Density Mapping in Adults With Congenital Heart Disease: Impact on Clinical Outcomes

Background

Atrial tachycardia (AT) is common in patients with adult congenital heart disease and is challenging to map and ablate. We used ultra‐high‐density mapping to characterize the AT mechanism and investigate whether substrate characteristics are related to ablation outcomes.

Methods and Results

A total of 50 ATs were mapped with ultra‐high‐density mapping in 23 procedures. Patients were followed up for up to 12 months. Procedures were classified to group A if there was 1 single AT induced (n=12) and group B if there were ≥2 ATs induced (n=11 procedures). AT mechanism per procedure was macro re‐entry (n=10) and localized re‐entry (n=2) in group A and multiple focal (n=6) or multiple macro re‐entry (n=5) in group B. Procedure duration, low voltage area (0.05–0.5 mV), and low voltage area indexed for volume were higher in group B (159 [147–180] versus 412 [352–420] minutes, P<0.001, 22.6 [12.2–29.8] versus 54.2 [51.1–61.6] cm², P=0.014 and 0.17 [0.12–0.21] versus 0.26 [0.23–0.27] cm²/mL, P=0.024 accordingly). Dense scar (<0.05 mV) and atrial volume were similar between groups. Acute success and freedom from arrhythmia recurrence were worse in group B (100% versus 77% P=0.009 and 11.3, CI 9.8–12.7 versus 4.9, CI 2.2–7.6 months, log rank P=0.004). Indexed low voltage area ≥0.24 cm²/mL could predict recurrence with 100% sensitivity and 77% specificity (area under the curve 0.923, P=0.007).

Conclusions

Larger low voltage area but not dense scar is associated with the induction of multiple focal or re‐entry ATs, which are subsequently associated with longer procedure duration and worse acute and midterm clinical outcomes.

High density mapping and catheter ablation of atrial tachycardias in adults with congenital heart disease

AIMS

We used a new grid-style multi-electrode mapping catheter (Advisor™ HD Grid, Abbott) and investigated its use for high density mapping of atrial tachycardias in adult patients with congenital heart disease.

PATIENTS AND METHODS

All patients with congenital heart disease who had mapping of atrial tachycardias using the new grid-style catheter between March 2018 and April 2019 were included.

RESULTS

A total of 24 adult patients had high density mapping of atrial tachycardias using the grid-style multi-electrode catheter. Mean procedure duration was 207 ± 72 min., mean fluoroscopy time was 7.1 ± 7.9 min. In patients with right atrial substrates, fluoroscopy time was shorter compared to biatrial or left atrial substrates (0.9 ± 2.2 min for right atrial substrates, n = 19 vs. 6.3 ± 8.3 min for left atrial substrates, n = 2 and 7.5 ± 4.3 min for biatrial substrates, n = 3, p = 0.01). A mean number of 14.814 ± 10.140 endocardial points were collected and 2.319 ± 1244 points were finally used to characterize the tachycardia. Procedural success was achieved in 21/24 (88%) subjects and partial success in 2/24 (8%) patients. Recurrence rate was low (12.5%). In one patient, radiofrequency ablation within the cavotricuspid isthmus resulted in occlusion of a branch of the right coronary artery. No complications related to the use of the mapping catheter itself occurred.

CONCLUSION

High density mapping of AT using the grid-style catheter showed promising results with respect to procedural and midterm outcome and fluoroscopy time. Using the grid-style catheter might offer advantages compared to other multi-electrode catheters used for high density mapping of AT in patients with CHD.

Missing pouches in high-density mapping of atrial tachyarrhythmia in congenital heart diseases

BACKGROUND

The use of high-density electroanatomical mapping in the Chinese population for congenital heart disease (CHD) is not well reported.

METHODS

Retrospective review of consecutive transcatheter ablation of atrial tachyarrhythmia using high-density mapping for CHD patients (at least moderate complexity) in the only tertiary congenital heart center in the territory from January 2017 to January 2019 was conducted. Orion mapping catheter in Rhythmia system (Boston Scientific) was used to create activation and voltage maps. Parameters including mechanism of arrhythmia, acute success, and follow-up data were recorded.

RESULTS

Eight patients were identified (median age 35.5 years) who underwent transcatheter ablation of atrial arrhythmia. More than one reentry circuits of IART were identified in five patients. It took a median of 32.4 minutes with 15,952 (IQR 13,395-18,530) mapping points per map. Cavo-annulus isthmus-dependent mechanism was the predominant reentry mechanism. Acute success with the elimination of all inducible tachycardia was achieved in six patients (75%), and partial success in two patients. There was recurrence of atrial arrhythmia in four patients (50%), in which three patients could be maintained in sinus rhythm with low-dose antiarrhythmic medication. Targeted substrate ablation was performed in six patients with multiple IART circuits. Critical anatomical pouches were identified in three patients, which were missed in the initial mapping using Orion basket mapping catheter.

CONCLUSIONS

High acute success rate of atrial arrhythmia ablation can be achieved using high-density anatomical mapping in CHD. Substrate ablation was required with multiple IART circuits identified. Vigilance should be sought to identify anatomical pouches.

Catheter Ablation for Atrial Tachycardia in Adults With Congenital Heart Disease: Electrophysiological Predictors of Acute Procedural Success and Post-Procedure Atrial Tachycardia Recurrence

OBJECTIVES

This study sought to determine the electrophysiological predictors of acute procedural success and of post-ablation recurrence of atrial tachyarrhythmias (ATs) in our adult congenital heart disease (ACHD) population undergoing catheter ablation for treatment of AT.

BACKGROUND

Catheter ablation is frequently performed to treat persistent AT in ACHD. The predictors of post-ablation AT recurrence have not been well studied in the ACHD population.

METHODS

The authors performed a retrospective study of all catheter ablations for treatment of AT performed in ACHD patients between December 1, 2005, and July 20, 2017, at Columbia University Medical Center. Pre-specified clinical and procedural data of interest and the time from ablation to recurrence were determined by chart and procedure report review.

RESULTS

A total of 140 patients (mean age: 45 years) underwent catheter ablation for 182 AT. Of the AT, 179 (93%) were intra-atrial macro-re-entrant tachycardia, and 12 (7%) had a focal origin. The presence of a single mechanism was a predictor of acute procedural success that could be achieved in 89% of the patients. At a median of 49.9 months, 62 patients (44%) had recurrent AT. Time to recurrence was significantly shorter (12.5 months) for recurrent AT in 13 of the 20 patients with previous Fontan procedure. By multivariable analysis, acute procedural success was a positive predictor and prior surgical maze procedure was a negative predictor of AT-free survival. Of the 62 patients with recurrent AT, 42 (68%) had a second catheter ablation procedure, and in 22 of these, the AT mechanism was different than previously observed.

CONCLUSIONS

Catheter ablation for AT in ACHD patients is an effective method of arrhythmia control. More than 1 AT mechanism per patient is common. Acute procedural success is a predictor of freedom from AT recurrence. The majority of patients achieve multiple arrhythmia-free years.