Ultrahigh‐density mapping supplemented with global chamber activation identifies noncavotricuspid‐dependent intra‐atrial re‐entry conduction isthmuses in adult congenital heart disease

Atrial tachycardia in patients with repaired tetralogy of Fallot; its characteristics and catheter ablation outcome

Background

Patients with repaired tetralogy of Fallot (TOF) now live longer. However, dysrhythmia becomes prevalent in adults with repaired TOF, especially atrial tachyarrhythmia.

Objective

To identify the characteristics of patients who develop atrial tachycardia (AT) and the mechanism of the clinical AT and the induced one.

Method

Seventy-seven patients with repaired TOF were enrolled. The patients were divided into two groups (AT and non-AT). Clinical and electrophysiologic data were studied.

Results

The mean age was 34 years. Twenty-three patients had AT (30 %). In AT group, the left ventricular ejection fraction was lower (58 ± 6 vs 62 ± 5; P = 0.011), the right and left atrial area (cm2) was larger (29 ± 13 vs 15 ± 5; P < 0.001, and 19 ± 3 vs 16 ± 4; P < 0.001, respectively), and the right ventricular S' wave (cm/s) was smaller (8 ± 2 vs 10 ± 3; P = 0.029).Patients with AT underwent catheter ablation, and 32 AT were ablated. The mechanism of AT was intra-atrial reentrant tachycardia in 14 AT (44 %), cavotricuspid isthmus-dependent in 12 AT (37 %), and focal activity in the remaining 6 AT (19 %). An important finding was that after the first AT was ablated, another AT was induced in 7 patients. The mechanism was focal in about half of them, in contrast to the first ablated AT, where the focal mechanism was the least common. After a median follow-up of 37 months, four patients had AT recurrence.

Conclusion

The patients with AT had biventricular dysfunction and bi-atrial dilatation. Aggressive induction and ablation of the induced AT may reduce the future AT recurrence.

Characterization of temporal electrical activity patterns for detection of critical isthmus regions of recurrent atypical atrial flutter

INTRODUCTION

Identifying the critical isthmus region (CIR) of atrial re-entry tachycardias (AT) is challenging. The Lumipoint® (LP) software, developed for the Rhythmia® mapping system, aims to facilitate the successful ablation of ATs by identifying the CIR.

OBJECTIVE

The objective of this study was to evaluate the quality of LP regarding the percentage of arrhythmia-relevant CIR in patients with atypical atrial flutter (AAF).

METHODS

In this retrospective study, we analyzed 57 AAF forms. Electrical activity (EA) was mapped over tachycardia cycle length resulting in a two-dimensional EA pattern. The hypothesis was that EA minima suggest potential CIRs with slow-conduction-zone.

RESULTS

A total of n = 33 patients were included, with the majority of patients being already preablated (69.7%). LP algorithm identified a mean of 2.4 EA minima and 4.4 suggested CIRs per AAF form. Overall, we observed a low probability of identifying only the relevant CIR (POR) at 12.3% but a high probability that at least one CIR is detected (PALO) at 98.2%. Detailed analysis revealed EA minima depth (≤20%) and width (>50 ms) as the best predictors of relevant CIRs. Wide minima occurred rarely (17.5%), while low minima were more frequently present (75.4%). Minima depth of EA ≤ 20% showed the best PALO/POR overall (95% and 60%, respectively). Analysis in recurrent AAF ablations (five patients) revealed that CIR in de novo AAF was already detected by LP during the index procedure.

CONCLUSION

The LP algorithm provides an excellent PALO (98.2%), but poor POR (12.3%) to detect the CIR in AAF. POR improved by preselection of the lowest and widest EA minima. In addition, there might be the role of initial bystander CIRs becoming relevant for future AAFs.

Burden and Impact of Arrhythmias in Repaired Tetralogy of Fallot

PURPOSE OF REVIEW

Arrhythmias are a leading cause of morbidity and mortality following repair of tetralogy of Fallot (TOF). This review will highlight current understanding of arrhythmia pathogenesis in this patient population and review novel therapeutic options.

RECENT FINDINGS

Risk factors for developing ventricular arrhythmias in repaired TOF have thus far been better defined than for atrial arrhythmias. Growing understanding of the pathophysiology of arrhythmias, development of risk stratification models, and novel techniques such as electrophysiologic ultrahigh-density mapping should help to better identify patients that benefit from advanced therapies such as ablation and implantable cardioverter defibrillators. Atrial and ventricular arrhythmias are common in TOF patients. Methods of risk stratification and therapeutic approaches are rapidly evolving, leading to ever improving clinical outcomes in this patient population.

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.

Impact of specialized electrophysiological care on the outcome of catheter ablation for supraventricular tachycardias in adults with congenital heart disease: Independent risk factors and gender aspects

BACKGROUND

Limited data exist on the impact of gender and specialized care on the requirement of repeat treatment of supraventricular tachycardia (SVT) in adult patients with congenital heart disease (ACHDs).

OBJECTIVE

The study aimed to assess independent predictors of a combined end point of re-catheter ablation (CA) or cardioversion at 3 years of follow-up, including the impact of gender and specialized ACHD care.

METHODS

All ACHDs registered in a database of one of the largest German health insurers (≈9.2 million members) who underwent CA for SVT were analyzed.

RESULTS

Of 38,892 ACHDs 16 years or older, 485 (49.5% women; median age 58.4 years; interquartile range 42.1-70.8 years) underwent CA for SVT. Over 3-year follow-up, the number of yearly CA procedures increased significantly, particularly for atrial fibrillation (+195%) and atrial flutter (+108%). Moderate to severe complexity heart disease (odds ratio [OR] 1.66; P = .01), advanced age (OR 1.85 per year; P = .02), chronic kidney disease (OR 1.70; P = .01), and atrial fibrillation (OR 2.02; P = .002) emerged as independent predictors of retreatment. Retreatment was significantly less often performed if primary CA was carried out at a specialized CHD center (P = .009) in patients with moderate to severe complexity heart disease. Women treated in specialist centers had a 1.6-fold reduced risk of undergoing retreatment (P = .01).

CONCLUSION

CA for SVT is increasingly performed in ACHDs, especially for atrial flutter and atrial fibrillation. Patients with moderate and severe complexity congenital heart defects and female ACHDs benefit from upfront referral to specialized CHD centers for CA. Centralization of care for ACHD arrhythmias should thus be advocated.

Mechanisms and outcomes of catheter ablation for biatrial tachycardia in adults with congenital heart disease

BACKGROUND

Biatrial tachycardia (BiAT) is a rare form of macroreentry not previously characterized in adults with congenital heart disease (ACHD).

OBJECTIVE

The purpose of this study was to determine the prevalence, mechanisms, and outcomes of catheter ablation for BiAT in ACHD.

METHODS

All ACHD undergoing catheter ablation for macroreentrant atrial tachycardia over a 10-year period were evaluated for evidence of BiAT. Patients were categorized as prior Senning, Fontan, or other biventricular operation. A novel biatrial global activation histogram (GAH) analysis was used to demonstrate the presence of interatrial connections (IACs).

RESULTS

Among 263 ACHD, BiAT was identified at 11 procedures in 10 patients (4.2%; median age 35 years; 30% male). The congenital category was Fontan in 6, Senning in 3, and biventricular in 2. Diagnosis of BiAT was associated with ablation era and mapping technology (P <.001) and could be confirmed with a novel GAH mapping approach for normally septated atrial connections. Catheter ablation targeted an IAC in 5 cases (Bjork Fontan and biventricular operations), a posterior isthmus in 3 (Senning operation), and the cavotricuspid isthmus or equivalent in 3 (lateral tunnel [LT] Fontan). Recurrence was isolated to ablation to sites at the expected location of the Bachmann bundle, and durable success could be achieved after repeat ablation.

CONCLUSION

BiAT occurs in approximately 4% of ACHD but is likely underrecognized. BiAT could be targeted at an IAC for normally septated atria and at a conventional critical isthmus after Senning and LT Fontan operations.

Electrophysiological Characteristics of Intra-Atrial Reentrant Tachycardia in Adult Congenital Heart Disease: Implications for Catheter Ablation

Background

Ultra‐high‐density mapping enables detailed mechanistic analysis of atrial reentrant tachycardia but has yet to be used to assess circuit conduction velocity (CV) patterns in adults with congenital heart disease.

Methods and Results

Circuit pathways and central isthmus CVs were calculated from consecutive ultra‐high‐density isochronal maps at 2 tertiary centers over a 3‐year period. Circuits using anatomic versus surgical obstacles were considered separately and pathway length <50th percentile identified small circuits. CV analysis was used to derive a novel index for prediction of postablation conduction block. A total of 136 supraventricular tachycardias were studied (60% intra‐atrial reentrant, 14% multiple loop). Circuits with anatomic versus surgical obstacles featured longer pathway length (119 mm; interquartile range [IQR], 80–150 versus 78 mm; IQR, 63–95; P<0.001), faster central isthmus CV (0.1 m/s; IQR, 0.06–0.25 versus 0.07 m/s; IQR, 0.05–0.10; P=0.016), faster non‐isthmus CV (0.52 m/s; IQR, 0.33–0.71 versus 0.38 m/s; IQR, 0.27–0.46; P=0.009), and fewer slow isochrones (4; IQR, 2.3–6.8 versus 6; IQR 5–7; P=0.008). Both central isthmus (R²=0.45; P<0.001) and non‐isthmus CV (R²=0.71; P<0.001) correlated with pathway length, whereas central isthmus CV <0.15 m/s was ubiquitous for small circuits. Non‐isthmus CV in tachycardia correlated with CV during block validation (R²=0.94; P<0.001) and a validation map to tachycardia conduction time ratio >85% predicted isthmus block in all cases. Over >1 year of follow‐up, arrhythmia‐free survival was better for homogeneous CV patterns (90% versus 57%; P=0.04).

Conclusions

Ultra‐high‐density mapping‐guided CV analysis distinguishes atrial reentrant patterns in adults with congenital heart disease with surgical obstacles producing slower and smaller circuits. Very slow central isthmus CV may be essential for atrial tachycardia maintenance in small circuits, and non‐isthmus conduction time in tachycardia appears to be useful for rapid assessment of postablation conduction block.

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.

Adults with Congenital Heart Disease and Arrhythmia Management

Arrhythmia management in adult congenital heart disease (ACHD) encompasses a wide range of problems from bradyarrhythmia to tachyarrhythmia, sudden death, and heart failure-related electrical dyssynchrony. Major advances in the understanding of the pathophysiology and treatments of these problems over the past decade have resulted in improved therapeutic strategies and outcomes. This article attempts to define these problems and review contemporary management for the patient with ACHD presenting with cardiac arrhythmia.