https://orcid.org/0000-0001-7715-2799
Abstract
Coherent mapping (CM) uses a new algorithm to identify critical conduction isthmuses of atrial tachycardias (ATs). We analysed our experience of ablation of AT in patients with congenital heart disease (CHD) with this new technology.
All patients with CHD who had CM of AT using the high-density mapping PENTARAY™ catheter and three-dimensional electroanatomic mapping system Carto3 between June 2019 and June 2021 were included retrospectively (n = 27). As a control group, 27 patients with CHD and mapping of AT without CM between March 2016 and June 2019 were included. In total, 54 ablation procedures were performed in 42 patients [median age 35 (interquartile range, IQR 30–48) years] and 64 ATs were induced and mapped (thereof 50 AT intraatrial re-entrant tachycardia and 14 AT ectopic AT). The median procedure duration was 180 (120–214) min and median fluoroscopy time was 10 (5.2–14) min. Acute success was 100% (27/27) in the Coherence group and 74% (20/27) in the non-Coherence group (P = 0.01). During follow-up [median 26 (12–45) months], AT recurred in 28/54 patients, thereof 15 patients needed a re-ablation procedure. Log-rank test showed no difference in recurrence rate between the two groups (P = 0.29). Three minor complications occurred (5.5%).
Mapping of AT in patients with CHD using the PENTARAY™ mapping catheter and the CM algorithm led to excellent acute success. All ATs were possible to map and no complications related to the PENTARAY™ mapping catheter were observed. Thus, the use of the CM algorithm represents a promising tool in patients with CHD and complex AT.
First experience of mapping of atrial tachycardias (ATs) using the PENTARAY™ mapping catheter and the Coherent mapping algorithm in patients with congenital heart disease.
Better identification of critical conduction isthmuses of intraatrial re-entrant tachycardias or the origin of focal ATs in a cohort with complex atrial arrhythmias.
Introduction
Atrial tachycardias (ATs) in patients with congenital heart disease (CHD) are recognized as a major source of morbidity and mortality in this patient population.1 Radiofrequency catheter ablation (RFA) of the substrates for these tachycardias is the first-line therapy with an efficacy superior to pharmacological therapy as discussed by the consensus statements of the US and European societies.1–3 Acute success rates of RFA of AT are satisfactory (65–96%).2 However, during follow-up, recurrence rates remain high (34–54%) necessitating multiple repeat ablation procedures,1,2 especially in patients after an atrial switch procedure for d-transposition of the great arteries or after Fontan procedure.4
The majority of re-entry circuits of intraatrial re-entrant tachycardias (IARTs) are dependent on the cavotricuspid isthmus (CTI); however, especially in patients with complex CHD non-CTI-dependent IARTs are also common.5 Slow conduction zones due to surgical scars, fibrosis, and hypertrophy may lead to complex re-entry circuits in these patients.6 Thus, the identification of the critical isthmus or the origin of a focal AT (FAT) remains often difficult despite the use of electroanatomic mapping systems (EAMs). Recently, high-density mapping has further improved acute success.7–10 In our study, we used the 20-electrode PENTARAY™ (CARTO®; Johnson & Johnson, New Brunswick, NJ, USA) catheter for high-density mapping and a new algorithm [Coherent mapping (CM), CARTO®; Johnson & Johnson] for mapping of AT. The aim of this study was to evaluate this new technology for efficacy and safety in a group of patients with CHD and complex AT.
Methods
Patients
All patients with CHD scheduled for RFA of AT and high-density mapping of AT with the Coherent algorithm between June 2019 and June 2021 were enrolled (n = 27). As a control group, 27 procedures before usage of Coherence with mapping and RFA of AT were included (n = 27, March 2016–June 2019). Patients or their parents/legal guardians provided written informed consent prior to RFA. The study was approved by the institutional review board and fully complies with the Declaration of Helsinki.
Electrophysiological study
Procedures were performed under conscious sedation. Antiarrhythmic therapy was discontinued at least five half-lives prior to the study. Studies were performed by three different operators. Heparin was administered 50 IU/kg body weight (max. 5000 IU) as a bolus. If mapping of the left atrium/pulmonary venous atrium (LA/PVA) was necessary, transseptal/transbaffle access was achieved using a long steerable sheath (Agilis™) and a transseptal needle. Transoesophageal echo was used in patients with extracardiac total cavopulmonary connection (TCPC) tunnel. Heparin was administered so that activated clotting time exceeded 250 s in those patients. Electroanatomic mapping systems were used in all patients. Merged imaging of cardiac magnetic resonance imaging (MRI) or cardiac computed tomography and 3D mapping were used in all patients. For stimulation and as a stable reference for activation mapping, a steerable decapolar 6 Fr catheter was placed in the coronary sinus or in another stable position [e.g. in the left atrial appendage (part of systemic venous atrium, SVA)] in patients after atrial switch procedure (see Figure 1B) or in the central part of the left pulmonary artery in patients with an extracardiac conduit after Fontan palliation (see Figure 3). For ventricular pacing, a quadripolar 5 F catheter was placed in the subpulmonary ventricle if possible. Access was always obtained through the groin vessels. Since June 2019, mapping was performed using the PENTARAY™ high-density mapping catheter and the CM algorithm (n = 27). Before June 2019, different EAMs were used [CARTO® n = 22; EnSite Precision™ (Abbott, North Chicago, IL, USA) n = 7] and mapping was performed with various mapping or ablation catheters (PENTARAY™ without the CM algorithm n = 3). The PENTARAY™ mapping catheter is a multipolar 7 Fr catheter with 5 soft, flexible spines and 4 electrodes each (20 electrodes in total), enabling a high-density mapping (Figure 1). Mapping settings were set as follows: local activation time (LAT)-stability 5 ms, cycle length stability: 5% range, LAT calculation: greatest deflection (not onset). In voltage mapping, low-voltage areas were defined as signals <0.5 mV and scar was defined as signals <0.05 mV. The CM algorithm uses the points acquired during activation- and voltage-mapping, separates the entire map surface into many equilateral triangles, calculates conduction velocity vectors between these points and removes outlier vectors. Conduction velocities <10 cm/s and vector collisions are used to calculate zones of slow and non-conduction (SNO-Zones). A global best-fit solution for the pattern activation is finally calculated and velocity vectors are displayed (Figure 2).11 After induction of the AT, by means of entrainment mapping from the distal and proximal decapolar catheter in the coronary sinus (if possible depending on the underlying anatomy) mapping of the SVA or the PVA was performed, respectively. Atrial tachycardias were differentiated into IART [intraatrial macro-re-entrant tachycardia, CTI dependent (see Figure 2 and Supplementary material online, Videos S1–S3) and non-CTI dependent] and FAT depending on the activation pattern during (high-density) activation mapping of the whole cycle length of the AT. Focal atrial tachycardia was defined as a tachycardia with a centrifugal spread of atrial activation from a focus (due to enhanced automaticity or microre-entry) other than the sinoatrial node (see Figure 3 and Supplementary material online, Video S4). Radiofrequency ablation was performed using various open-irrigated ablation catheters as point-by-point ablations in a power-controlled mode with 30–50 W. Most ablations were performed with Thermocool SmartTouch® (n = 29) or Thermocool SF Nav® (n = 18; both Biosense Webster, Johnson & Johnson). Pulmonary vein isolation (PVI) was performed in 10 of 54 procedures using radiofrequency ablation. Acute procedural success was defined as termination of all tachycardia during ablation. In cases when termination of AT occurred mechanically and AT could not be reinduced, substrate-guided ablation was performed. Non-inducibility of AT after ablation and a waiting period of 30 min as well as documentation of bidirectional conduction block across the critical isthmus/RF lesion line in case of IART or complete isolation of the pulmonary veins in case of PVI needed to be present in order for a procedure to be classified as successful.
Twenty electrode, 7 Fr PENTARAY™ mapping catheter (CARTO®, Johnson & Johnson). (A) Photograph of the PENTARAY™ with five soft, flexible spines, four electrodes each. (B) Anatomical CARTO®-image in LAO view of the PENTARAY™ positioned in the SVA of a patient after Mustard procedure for d-transposition of the great arteries. A decapolar catheter is positioned in the LAA (part of SVA) as a reference. IB, inferior baffle; LAA, left atrial appendage; SB, superior baffle; SVA, systemic venous atrium.
Paused presentation of a Coherent map of the PVA in LAO view from below (from the IB) in a patient after Senning procedure for d-transposition of the great arteries. (A) CM of the tachycardia showed an intraatrial re-entrant tachycardia around the TV with a critical isthmus between the IVC/IB and the TV (CTI). Thicker arrows indicate areas with low conduction velocity (white asterisk). (B) After creation of a CTI-ablation line, tachycardia could not be terminated, so a remap was performed, showing a continued slow conduction (thick arrows) through the SNO-Zone of the CTI-ablation line. (C) After closing the gaps and termination of AT, the remap during atrial pacing near to CS ostium showed a completed SNO-Zone and CM showed no remaining conduction through the CTI-ablation line. AT, atrial tachycardias; CM, Coherent mapping; CTI, cavotricuspid isthmus; IVC/IB, inferior vena cava/inferior baffle; MV, mitral valve; P, PENTARAY™ catheter; PVA, pulmonary venous atrium; RUPV, right upper pulmonary vein; SNO, area of slow or no conduction; SVA, systemic venous atrium; TV, tricuspid valve. See also Supplementary material online, Videos S1–S3.
Merged view (cardiac MRI and CARTO) from right lateral in a patient with hypoplastic left heart syndrome after TCPC with an extracardial conduit. Access to the PVA (former right atrium) was obtained through puncture of the TCPC-Conduit in the PVA. A decapolar catheter is situated in the LPA. (A) Coherent map of the PVA of the AT showed an FAT with a centrifugal spread with its origin postero-lateral of the atriotomy scar (white asterisk). Ablation at this site led to termination of the FAT. (B) Voltage map of the PVA showed a low-voltage area at the site of the origin of the FAT. AT, atrial tachycardias; FAT, focal atrial tachycardia; LPA, left pulmonary artery; MRI, magnetic resonance imaging; P, PENTARAY™ catheter; PVA, pulmonary venous atrium; RPA, right pulmonary artery; TCPC-Conduit, extracardial total cavopulmonary connection conduit. See also Supplementary material online, Video S4.
Statistical analysis
Statistical analysis was performed using SPSS version 28.0 (IBM, Somers, NY, USA). Continuous data are presented as median with IQR. Comparison between the two groups was performed using the t-test or Mann–Whitney U test depending on variable distribution (Shapiro–Wilk test) for continuous data. For categorical data, two-sided χ2 test was used or Fisher’s exact test if assumption for χ2 test was not satisfied. The log-rank test was used for analysis of tachycardia recurrences. Statistical significance was given at a level of P < 0.05.
Results
Patient population
In total, 54 procedures were performed in 42 patients, thereof 20 procedures in 17 female patients. Table 1 summarizes an overview of the complexity of CHD in the two groups. Number of procedures with complex CHD was higher in the Coherence group (70 vs. 30%, P = 0.006). Most common CHD in the Coherence group was d-transposition of the great arteries after Senning/Mustard procedure and most common CHD in the non-Coherence group was tetralogy of Fallot. The median age was 35 years and the median body weight was 80 kg and both were not different between the two groups (Table 2). Of the 54 procedures, 42 procedures (78%) were primary procedures and 12 procedures (22%) were repeat ablation procedures. The number of primary procedures was not different between the two groups [n = 22 (81%) in the Coherence group and n = 20 (74%) in the non-Coherence group (P = 0.37); Table 2]. Antiarrhythmic medication was administered in 41 patients (75%) before ablation. As all procedures were elective procedures, all patients were in clinical stable status, no patients had severe valve regurgitations or severe heart failure.
Types of CHD by complexity
| Complexity of CHD | Coherence | No coherence | ||
|---|---|---|---|---|
| Patients (N = 22) | Procedures (n = 27) | Patients (n = 20) | Procedures (N = 27) | |
| Simple CHD | N = 1 (5%) | N = 1 (4%) | N = 0 | N = 0 |
| ȃASD | 1 | 1 | 0 | 0 |
| Moderate CHD | N = 6 (27%) | N = 7 (26%) | N = 13 (65%) | N = 19 (70%) |
| ȃPAPVD | 2 | 2 | 2 | 2 |
| ȃVSD with associated lesions | 2 | 2 | 1 | 1 |
| ȃAVSD | 0 | 0 | 4 | 5 |
| ȃAortic stenosis | 0 | 0 | 1 | 3 |
| ȃTOF | 2 | 3 | 5 | 8 |
| Complex CHD | N = 15 (68%) | N = 19 (70%) | N = 7 (35%) | N = 8 (30%) |
| ȃd-TGA (Senning/Mustard) | 8 | 10 | 4 | 5 |
| ȃSV TCPC | 2 | 2 | 0 | 0 |
| ȃSV intracardial tunnel | 1 | 2 | 2 | 2 |
| ȃPulmonary atresia | 1 | 2 | 0 | 0 |
| ȃDORV | 1 | 1 | 1 | 1 |
| ȃFallot-Conduit repair | 1 | 1 | 0 | 0 |
| ȃMod. Mustard (AVSD, common atrium) | 1 | 1 | 0 | 0 |
| Complexity of CHD | Coherence | No coherence | ||
|---|---|---|---|---|
| Patients (N = 22) | Procedures (n = 27) | Patients (n = 20) | Procedures (N = 27) | |
| Simple CHD | N = 1 (5%) | N = 1 (4%) | N = 0 | N = 0 |
| ȃASD | 1 | 1 | 0 | 0 |
| Moderate CHD | N = 6 (27%) | N = 7 (26%) | N = 13 (65%) | N = 19 (70%) |
| ȃPAPVD | 2 | 2 | 2 | 2 |
| ȃVSD with associated lesions | 2 | 2 | 1 | 1 |
| ȃAVSD | 0 | 0 | 4 | 5 |
| ȃAortic stenosis | 0 | 0 | 1 | 3 |
| ȃTOF | 2 | 3 | 5 | 8 |
| Complex CHD | N = 15 (68%) | N = 19 (70%) | N = 7 (35%) | N = 8 (30%) |
| ȃd-TGA (Senning/Mustard) | 8 | 10 | 4 | 5 |
| ȃSV TCPC | 2 | 2 | 0 | 0 |
| ȃSV intracardial tunnel | 1 | 2 | 2 | 2 |
| ȃPulmonary atresia | 1 | 2 | 0 | 0 |
| ȃDORV | 1 | 1 | 1 | 1 |
| ȃFallot-Conduit repair | 1 | 1 | 0 | 0 |
| ȃMod. Mustard (AVSD, common atrium) | 1 | 1 | 0 | 0 |
ASD, atrial septal defect; AVSD, atrioventricular septal defect; CHD, congenital heart disease; DORV, double outlet right ventricle; d-TGA, d-transposition of the great arteries; PAPVD, partial anomalous pulmonary venous drainage; SV, single ventricle; TCPC, total cavopulmonary connection; TOF, tetralogy of Fallot; VSD, ventricular septal defect.
Types of CHD by complexity
| Complexity of CHD | Coherence | No coherence | ||
|---|---|---|---|---|
| Patients (N = 22) | Procedures (n = 27) | Patients (n = 20) | Procedures (N = 27) | |
| Simple CHD | N = 1 (5%) | N = 1 (4%) | N = 0 | N = 0 |
| ȃASD | 1 | 1 | 0 | 0 |
| Moderate CHD | N = 6 (27%) | N = 7 (26%) | N = 13 (65%) | N = 19 (70%) |
| ȃPAPVD | 2 | 2 | 2 | 2 |
| ȃVSD with associated lesions | 2 | 2 | 1 | 1 |
| ȃAVSD | 0 | 0 | 4 | 5 |
| ȃAortic stenosis | 0 | 0 | 1 | 3 |
| ȃTOF | 2 | 3 | 5 | 8 |
| Complex CHD | N = 15 (68%) | N = 19 (70%) | N = 7 (35%) | N = 8 (30%) |
| ȃd-TGA (Senning/Mustard) | 8 | 10 | 4 | 5 |
| ȃSV TCPC | 2 | 2 | 0 | 0 |
| ȃSV intracardial tunnel | 1 | 2 | 2 | 2 |
| ȃPulmonary atresia | 1 | 2 | 0 | 0 |
| ȃDORV | 1 | 1 | 1 | 1 |
| ȃFallot-Conduit repair | 1 | 1 | 0 | 0 |
| ȃMod. Mustard (AVSD, common atrium) | 1 | 1 | 0 | 0 |
| Complexity of CHD | Coherence | No coherence | ||
|---|---|---|---|---|
| Patients (N = 22) | Procedures (n = 27) | Patients (n = 20) | Procedures (N = 27) | |
| Simple CHD | N = 1 (5%) | N = 1 (4%) | N = 0 | N = 0 |
| ȃASD | 1 | 1 | 0 | 0 |
| Moderate CHD | N = 6 (27%) | N = 7 (26%) | N = 13 (65%) | N = 19 (70%) |
| ȃPAPVD | 2 | 2 | 2 | 2 |
| ȃVSD with associated lesions | 2 | 2 | 1 | 1 |
| ȃAVSD | 0 | 0 | 4 | 5 |
| ȃAortic stenosis | 0 | 0 | 1 | 3 |
| ȃTOF | 2 | 3 | 5 | 8 |
| Complex CHD | N = 15 (68%) | N = 19 (70%) | N = 7 (35%) | N = 8 (30%) |
| ȃd-TGA (Senning/Mustard) | 8 | 10 | 4 | 5 |
| ȃSV TCPC | 2 | 2 | 0 | 0 |
| ȃSV intracardial tunnel | 1 | 2 | 2 | 2 |
| ȃPulmonary atresia | 1 | 2 | 0 | 0 |
| ȃDORV | 1 | 1 | 1 | 1 |
| ȃFallot-Conduit repair | 1 | 1 | 0 | 0 |
| ȃMod. Mustard (AVSD, common atrium) | 1 | 1 | 0 | 0 |
ASD, atrial septal defect; AVSD, atrioventricular septal defect; CHD, congenital heart disease; DORV, double outlet right ventricle; d-TGA, d-transposition of the great arteries; PAPVD, partial anomalous pulmonary venous drainage; SV, single ventricle; TCPC, total cavopulmonary connection; TOF, tetralogy of Fallot; VSD, ventricular septal defect.
Patients’ and procedural characteristics
| All procedures (N = 54) | Coherence (N = 27) | No coherence (N = 27) | P-value | |
|---|---|---|---|---|
| Median age (IQR) (years) | 35 (30–48) | 35 (31–54) | 37 (29–48) | 0.76 |
| Median body weight (IQR) (kg) | 80 (66–93) | 80 (64–99) | 79 (67–92) | 0.67 |
| Number complex CHD (%) | 27 (50%) | 19 (70%) | 8 (30%) | 0.006 |
| Intracardial PM/ICD | 21 (39%) | 12 (44%) | 9 (33%) | 0.40 |
| AAM before ablation | 41 (75%) | 19 (70%) | 22 (81%) | 0.34 |
| Number of primary procedures | 42 (78%) | 22 (81%) | 20 (74%) | 0.37 |
| Median fluoroscopy time (IQR) (min) | 10 (5.2–14) | 12 (4–15) | 9 (7,3−0.3) | 0.84 |
| Median procedure duration (IQR) (min) | 180 (120–214) | 180 (150–240) | 150 (120–210) | 0.047 |
| Tachycardia mechanism | ||||
| ȃIART | 50 (78%) | 25 (86%) | 25 (71%) | 0.31a |
| ȃȃIART CTI dependent | ȃȃ21 (42%) | ȃȃ14 (56%) | ȃȃ7 (28%) | 0.12b |
| ȃȃIART non-CTI-dependent | ȃȃ29 (58%) | ȃȃ11 (44%) | ȃȃ18 (72%) | |
| ȃFAT | 14 (22%) | 4 (14%) | 10 (29%) | |
| Atrial fibrillation | 13 (24%) | 9 (33%) | 4 (15%) | 0.11 |
| Ablation | ||||
| ȃSVA only | 24 (44%) | 10 (37%) | 14 (58%) | 0.5 |
| ȃPVA only | 12 (22%) | 7 (26%) | 5 (19%) | |
| ȃSVA and PVA | 18 (33%) | 10 (37%) | 8 (30%) | |
| ȃCTI (SVA/PVA) | 30 (56%) | 18 (67%) | 12 (44%) | 0.1 |
| ȃPVI | 10 (19%) | 4 (15%) | 6 (22%) | 0.48 |
| Ablation time (IQR) (s) | 1035 (598–1936) | 1380 (600–1929) | 899 (591–1957) | 0.59 |
| Success | 47/54 (87%) | 27/27 (100%) | 20 (74%) | 0.01 |
| AAM after ablation | 37 (68%) | 16 (59%) | 21 (78%) | 0.14 |
| All procedures (N = 54) | Coherence (N = 27) | No coherence (N = 27) | P-value | |
|---|---|---|---|---|
| Median age (IQR) (years) | 35 (30–48) | 35 (31–54) | 37 (29–48) | 0.76 |
| Median body weight (IQR) (kg) | 80 (66–93) | 80 (64–99) | 79 (67–92) | 0.67 |
| Number complex CHD (%) | 27 (50%) | 19 (70%) | 8 (30%) | 0.006 |
| Intracardial PM/ICD | 21 (39%) | 12 (44%) | 9 (33%) | 0.40 |
| AAM before ablation | 41 (75%) | 19 (70%) | 22 (81%) | 0.34 |
| Number of primary procedures | 42 (78%) | 22 (81%) | 20 (74%) | 0.37 |
| Median fluoroscopy time (IQR) (min) | 10 (5.2–14) | 12 (4–15) | 9 (7,3−0.3) | 0.84 |
| Median procedure duration (IQR) (min) | 180 (120–214) | 180 (150–240) | 150 (120–210) | 0.047 |
| Tachycardia mechanism | ||||
| ȃIART | 50 (78%) | 25 (86%) | 25 (71%) | 0.31a |
| ȃȃIART CTI dependent | ȃȃ21 (42%) | ȃȃ14 (56%) | ȃȃ7 (28%) | 0.12b |
| ȃȃIART non-CTI-dependent | ȃȃ29 (58%) | ȃȃ11 (44%) | ȃȃ18 (72%) | |
| ȃFAT | 14 (22%) | 4 (14%) | 10 (29%) | |
| Atrial fibrillation | 13 (24%) | 9 (33%) | 4 (15%) | 0.11 |
| Ablation | ||||
| ȃSVA only | 24 (44%) | 10 (37%) | 14 (58%) | 0.5 |
| ȃPVA only | 12 (22%) | 7 (26%) | 5 (19%) | |
| ȃSVA and PVA | 18 (33%) | 10 (37%) | 8 (30%) | |
| ȃCTI (SVA/PVA) | 30 (56%) | 18 (67%) | 12 (44%) | 0.1 |
| ȃPVI | 10 (19%) | 4 (15%) | 6 (22%) | 0.48 |
| Ablation time (IQR) (s) | 1035 (598–1936) | 1380 (600–1929) | 899 (591–1957) | 0.59 |
| Success | 47/54 (87%) | 27/27 (100%) | 20 (74%) | 0.01 |
| AAM after ablation | 37 (68%) | 16 (59%) | 21 (78%) | 0.14 |
AAM, antiarrhythmic medication; CHD, congenital heart defect; CTI, cavotricuspid isthmus; FAT, focal atrial tachycardia; IART, intraatrial re-entrant tachycardia; IQR, interquartile range; PVA, pulmonary venous atrium; PVI, pulmonary vein isolation; SVA, systemic venous atrium.
Comparison between IART and FAT.
Comparison between IART CTI dependent and IART non-CTI dependent.
The bold values are significant as statistical significance was given at a level of P < 0.05 as indicated in the section Statistical Analysis.
Patients’ and procedural characteristics
| All procedures (N = 54) | Coherence (N = 27) | No coherence (N = 27) | P-value | |
|---|---|---|---|---|
| Median age (IQR) (years) | 35 (30–48) | 35 (31–54) | 37 (29–48) | 0.76 |
| Median body weight (IQR) (kg) | 80 (66–93) | 80 (64–99) | 79 (67–92) | 0.67 |
| Number complex CHD (%) | 27 (50%) | 19 (70%) | 8 (30%) | 0.006 |
| Intracardial PM/ICD | 21 (39%) | 12 (44%) | 9 (33%) | 0.40 |
| AAM before ablation | 41 (75%) | 19 (70%) | 22 (81%) | 0.34 |
| Number of primary procedures | 42 (78%) | 22 (81%) | 20 (74%) | 0.37 |
| Median fluoroscopy time (IQR) (min) | 10 (5.2–14) | 12 (4–15) | 9 (7,3−0.3) | 0.84 |
| Median procedure duration (IQR) (min) | 180 (120–214) | 180 (150–240) | 150 (120–210) | 0.047 |
| Tachycardia mechanism | ||||
| ȃIART | 50 (78%) | 25 (86%) | 25 (71%) | 0.31a |
| ȃȃIART CTI dependent | ȃȃ21 (42%) | ȃȃ14 (56%) | ȃȃ7 (28%) | 0.12b |
| ȃȃIART non-CTI-dependent | ȃȃ29 (58%) | ȃȃ11 (44%) | ȃȃ18 (72%) | |
| ȃFAT | 14 (22%) | 4 (14%) | 10 (29%) | |
| Atrial fibrillation | 13 (24%) | 9 (33%) | 4 (15%) | 0.11 |
| Ablation | ||||
| ȃSVA only | 24 (44%) | 10 (37%) | 14 (58%) | 0.5 |
| ȃPVA only | 12 (22%) | 7 (26%) | 5 (19%) | |
| ȃSVA and PVA | 18 (33%) | 10 (37%) | 8 (30%) | |
| ȃCTI (SVA/PVA) | 30 (56%) | 18 (67%) | 12 (44%) | 0.1 |
| ȃPVI | 10 (19%) | 4 (15%) | 6 (22%) | 0.48 |
| Ablation time (IQR) (s) | 1035 (598–1936) | 1380 (600–1929) | 899 (591–1957) | 0.59 |
| Success | 47/54 (87%) | 27/27 (100%) | 20 (74%) | 0.01 |
| AAM after ablation | 37 (68%) | 16 (59%) | 21 (78%) | 0.14 |
| All procedures (N = 54) | Coherence (N = 27) | No coherence (N = 27) | P-value | |
|---|---|---|---|---|
| Median age (IQR) (years) | 35 (30–48) | 35 (31–54) | 37 (29–48) | 0.76 |
| Median body weight (IQR) (kg) | 80 (66–93) | 80 (64–99) | 79 (67–92) | 0.67 |
| Number complex CHD (%) | 27 (50%) | 19 (70%) | 8 (30%) | 0.006 |
| Intracardial PM/ICD | 21 (39%) | 12 (44%) | 9 (33%) | 0.40 |
| AAM before ablation | 41 (75%) | 19 (70%) | 22 (81%) | 0.34 |
| Number of primary procedures | 42 (78%) | 22 (81%) | 20 (74%) | 0.37 |
| Median fluoroscopy time (IQR) (min) | 10 (5.2–14) | 12 (4–15) | 9 (7,3−0.3) | 0.84 |
| Median procedure duration (IQR) (min) | 180 (120–214) | 180 (150–240) | 150 (120–210) | 0.047 |
| Tachycardia mechanism | ||||
| ȃIART | 50 (78%) | 25 (86%) | 25 (71%) | 0.31a |
| ȃȃIART CTI dependent | ȃȃ21 (42%) | ȃȃ14 (56%) | ȃȃ7 (28%) | 0.12b |
| ȃȃIART non-CTI-dependent | ȃȃ29 (58%) | ȃȃ11 (44%) | ȃȃ18 (72%) | |
| ȃFAT | 14 (22%) | 4 (14%) | 10 (29%) | |
| Atrial fibrillation | 13 (24%) | 9 (33%) | 4 (15%) | 0.11 |
| Ablation | ||||
| ȃSVA only | 24 (44%) | 10 (37%) | 14 (58%) | 0.5 |
| ȃPVA only | 12 (22%) | 7 (26%) | 5 (19%) | |
| ȃSVA and PVA | 18 (33%) | 10 (37%) | 8 (30%) | |
| ȃCTI (SVA/PVA) | 30 (56%) | 18 (67%) | 12 (44%) | 0.1 |
| ȃPVI | 10 (19%) | 4 (15%) | 6 (22%) | 0.48 |
| Ablation time (IQR) (s) | 1035 (598–1936) | 1380 (600–1929) | 899 (591–1957) | 0.59 |
| Success | 47/54 (87%) | 27/27 (100%) | 20 (74%) | 0.01 |
| AAM after ablation | 37 (68%) | 16 (59%) | 21 (78%) | 0.14 |
AAM, antiarrhythmic medication; CHD, congenital heart defect; CTI, cavotricuspid isthmus; FAT, focal atrial tachycardia; IART, intraatrial re-entrant tachycardia; IQR, interquartile range; PVA, pulmonary venous atrium; PVI, pulmonary vein isolation; SVA, systemic venous atrium.
Comparison between IART and FAT.
Comparison between IART CTI dependent and IART non-CTI dependent.
The bold values are significant as statistical significance was given at a level of P < 0.05 as indicated in the section Statistical Analysis.
Procedural characteristics
The median procedure duration was 180 min (IQR 120–214; n = 54) and the median fluoroscopy time was 10 min (IQR 5.2–14; n = 54, Table 2). Procedure duration and fluoroscopy time were significantly longer in procedures with ablation within the PVA/LA than in procedures with ablation only in the SVA/RA [180 min (IQR 150–240) vs. 157 min (IQR 120–210), P = 0.019 and 12 min (IQR 10–17) vs. 8 min (IQR 2.7–11), P = 0.002, respectively]. Fluoroscopy time was significantly longer in procedures in patients with intracardiac PM or ICD [13 min (IQR 10–17) vs. 8 min (IQR 3.4–12), P = 0.004].
Mapping and arrhythmia substrates
During the 54 procedures, 64 AT were mapped, thereof 50 IART (78%) and 14 FAT (22%). Of the 50 IART, 42% of IART (21/50) were CTI dependent and 58% (n = 29/50) were non-CTI dependent. In 45 procedures 1 AT was induced and mapped and in 9 procedures 2 different AT were induced and mapped. The distribution of tachycardia mechanisms was not different between the two groups (Table 2). Atrial fibrillation occurred in 24% (n = 13/54) of the procedures. Pulmonary vein isolation was performed in 10 of 54 procedures (19%). Tachycardia substrates were in the SVA only in 24 procedures (44%), in the PVA only in 12 procedures (22%) and in both atria in 18 procedures (33%). In 30 procedures (56%), the CTI (located in the SVA and/or PVA) was the critical isthmus. The median ablation time was 1035 s (IQR 598–1936) and was not different between the two groups.
Procedural success
Overall procedural success was 87% (47/54 procedures). Procedural success was significantly higher in the Coherence group (100%; 27/27 procedures) than in the non-Coherence group (74%; 20/27 procedures; P = 0.01). Procedural success was not different depending on the severity of CHD [simple CHD 1/1 procedure, moderate CHD 21/26 procedures (81%) and complex CHD 25/27 procedures (93%), P = 0.35] or the ablation site [SVA only: 19/24 procedures (79%), PVA only 11/12 (92%) SVA and PVA 17/18 (94%), P = 0.39].
Complications
Three minor procedural complications occurred: In one patient with a history of multiple VSD closures, transient hypokinesia of the right diaphragm after an ablation line between the posterior intraatrial septum and the inferior vena cava occurred. In one patient with hypoplastic left heart syndrome and total cavopulmonary connection, epinephrine infusion was required due to prolonged systemic hypotension. In one patient who underwent PVI, oesophagoscopy revealed evidence of thermal lesions, which healed after 1 week. No complications related to the PENTARAY™ catheter were observed.
Follow-up
During a median follow-up of 26 months (IQR 12–45), recurrences occurred in 28 of 54 (52%) patients. Of those 28 patients, 15 patients underwent a repeat procedure. Kaplan–Meier analysis of freedom from AT recurrence showed no difference between the two groups (Figure 4A, log-rank P = 0.29). Also when comparing only patients with complex CHD Kaplan–Meier analysis showed no significant difference between the two groups (Figure 4B, log-rank P = 0.22). In our study cohort 12 of 54 procedures (22%) were repeat procedures, 10 of the 12 patients (83%) had the same tachycardia (same substrate). Antiarrhythmic medication was administered in 37 patients (68%) after ablation. One patient after Senning procedure for d-TGA died suddenly from unclear aetiology 2.5 weeks after ablation of the CTI. No angiographies of the coronary arteries were taken after ablation, but the patient had no electrocardiogram changings and was asymptomatic until this sudden event. Echocardiography was performed the day of ablation and the day after to rule out an effusion. The pacemaker could not be interrogated post-mortem and an autopsy was declined.
Kaplan–Meier curve of freedom from AT recurrence for procedures with mapping of AT using the high-density mapping and the Coherence algorithm or without Coherence (A) for all procedures (n = 27 in both groups), (B) for procedures of patients with complex CHD (n = 8 without Coherence, n = 19 with Coherence). Log-rank test showed no significant difference between the two groups (A: P = 0.29; B: P = 0.22). 0, without Coherence; 1, with Coherence. AT, atrial tachycardias, CHD, congenital heart disease.
Discussion
To our knowledge, this is the first study analysing a significant number of patients with CHD, in whom AT mapping and ablation were performed, using the PENTARAY™ catheter for high-density mapping and the CM algorithm. Mapping with this new technology led to an excellent acute success rate of 100%. This success rate was significantly higher than in the control group without Coherence. Improvement of acute success using high-density mapping systems has been described before in cohorts with CHD7,10,12 and without CHD.8 Additionally to high-density mapping, we also used the CM algorithm. This algorithm has been shown to better identify conduction isthmuses than conventional mapping in patients with scar-related ATs without CHD.13 Also in our population of patients with high complexity of CHD (70%) and complexity of AT with necessity of mapping in both atria in 37%, CM helped identifying the critical isthmus or focal origin of AT in 100% leading to excellent acute success rates. The aim of our study was to analyse the effect of CM. However, because our control group is a historical control group other influence factors like the learning curve of the operators or advancement in ablation like contact force may add to this excellent acute success rate. In our population, we encountered no problems with mapping of the entire arrhythmia because of enlarged chambers or arrhythmogenicity of the catheter as described with the mini-basket catheter.14 We were not able to analyse time for mapping itself, but CM did not improve fluoroscopy time or total procedure duration in our population in comparison to the non-Coherence group. Due to the higher number of complex CHD in the Coherence group (70 vs. 30%), mapping and ablation in the PVA were necessary more often (63 vs. 49%), leading to slightly longer procedure duration and comparable fluoroscopy time in this group. Fluoroscopy time and procedure duration were in the range of previous studies with different high-density mapping systems.7,14 Concerning the tachycardia mechanism, IART was the most induced mechanism (78%), thereof 42% CTI dependent, in comparison with FAT (22%), as has been described often before in the CHD population.5,15 Atrial fibrillation is a growing challenge in the CHD population, as patients grow older and AT often precedes atrial fibrillation.16 In our study, atrial fibrillation occurred in 13 patients (24%) and 10 of these patients underwent PVI. Although mapping with the Coherent algorithm led to a great improvement in acute success, differences in recurrence of AT did not reach statistical significance, possibly due to the small number of patients (see Figure 4). Our recurrence rate of 52% with a median follow-up of 26 months is not satisfying, but comparable with other studies and centres.2 Acute success is one important predictor for recurrence, but progressive fibrosis of atrial tissue due to atrial pressure and volume overload may lead to new AT, even if the procedure itself was successful.17 Especially in patients after atrial switch—or Fontan procedure (55% of patients in the Coherence group) multiple re-procedures might be necessary also after initially successful ablations.4 As described before, almost half of the patients with recurrences did not require further catheter ablation until the end of follow-up. Final scar formation and additional antiarrhythmic therapy may lead to sinus rhythm/atrial paced rhythm even after early recurrence.4,18 Complication rate was low and no complications related to the PENTARAY™ catheter were observed.
Limitations
This study is limited by its retrospective, single-centre design. Heterogeneity of underlying CHD and the difference in complexity of CHD in the two different groups make the interpretation of the data challenging. The focus of the study was to compare Coherence mapping with non-Coherence mapping. Because of the low number of procedures with high-density mapping without Coherence mapping (n = 3), it was not possible to compare two groups with high-density mapping with and without Coherence. The influence of high-density mapping itself without Coherence can therefore not be analysed. However, other influence factors (like primary vs. repeat procedures, complexity of CHD, number of induced tachycardias, and use of different EAMs before June 2019) on acute and mid-term-success were not analysed, an effect on results cannot be ruled out.
Conclusions
Mapping of AT in patients with CHD using the PENTARAY™ mapping catheter and the Coherence mapping algorithm led to excellent acute success. All ATs were possible to map and no complications related to the PENTARAY™ mapping catheter were observed. Thus, the use of the Coherence mapping algorithm represents a promising tool in patients with CHD and complex AT.
Supplementary material
Supplementary material is available at Europace online.
Funding
The authors received funding for Open Access Publishing by the Leipzig Heart Institute and the Open Access Publishing Fund of Leipzig University supported by the German Research Foundation within the program Open Access Publication Funding.
Data availability
All data are available in the text.
References
Author notes
Conflict of interest: None declared.
