Outcomes of atrial arrhythmia radiofrequency catheter ablation in patients with Ebstein’s anomaly

Outcomes of atrial arrhythmia radiofrequency catheter ablation in patients with Ebstein’s anomaly Abstract Aims Atrial arrhythmias are common in patients with Ebstein’s anomaly (EA) despite cardiac surgical repair and concomitant Maze procedures. We aimed to evaluate the outcome of radiofrequency catheter ablation in this group of patients. Methods and results All patients with EA and atrial arrhythmias who underwent catheter ablation for atrial arrhythmias between 1/1999 and 1/2016 were included. Atrial arrhythmia recurrence was identified as the primary outcome; secondary outcomes included repeat ablation, need for antiarrhythmic medications after ablation, and death. Predictors of recurrence were sought using univariate analysis. 22 patients (median age 42 years, 54.5% male) were included. Atrial flutter was the most common presenting arrhythmia (n = 14 patients, 63.5%), whereas focal atrial tachycardia (FAT) and atrial fibrillation were identified in 5 (22.7%) and 2 patients (9.1%), respectively, with both atrial flutter/fibrillation evident in a single patient 1 (4.5%). 8 patients (36.4%) had a history of right-sided maze procedures. Cavotricuspid isthmus atrial flutter (CTI-AFl) was the most commonly induced arrhythmia (n = 13, 59.1%), followed by incisional intra-atrial re-entrant tachycardia (IART; n = 4, 18.2%), and FAT (n = 4, 18.2%); 3 patients also underwent left-side ablation with concomitant pulmonary vein isolation (13.6%). 1-year and 5-year atrial arrhythmia recurrence rates were 10.0% and 41.2%, respectively. 7 patients (31.8%) underwent redo ablations, and anti-arrhythmic medication was utilized in 8 patients (36.4%) post-ablation. Neither ablation location nor echocardiographic parameters were found to be predictors of arrhythmia recurrence. Conclusion Catheter ablation of atrial arrhythmias in patients with EA has a favorable outcome overall with an acceptable recurrence and safety profile; left-sided ablations are rarely necessary. Despite prior Maze and catheter ablation procedures, CTI-AFl and IART recurrences predominate. Atrial arrhythmia, Ebstein’s anomaly, Catheter ablation, Outcome Introduction What’s new? Atrial arrhythmias occur commonly among patients with Ebstein’s anomaly (EA) despite prior invasive anti-arrhythmic procedures. In a cohort of 22 patients with EA and concomitant atrial arrhythmias, cavotricuspid isthmus dependent atrial flutter was the most common presenting rhythm. Most patients underwent exclusively right-sided ablation procedures 1-year, 3-year, and 5-year atrial arrhythmia recurrence rates were 10.0%, 21.7%, and 41.2%, respectively; no acute post-procedural complications were identified. No arrhythmia feature, ablation characteristic or cardiac structural parameter was identified as a predictor of arrhythmia recurrence on univariate analysis.Atrial arrhythmias are a common clinical issue in patients with Ebstein’s anomaly (EA), occurring in up to a third of this group.1,2 Tricuspid valve dysfunction with progressive right atrial enlargement, incisional scars following cardiac repair, as well as Maze and ablation procedures all contribute towards the creation of an ideal pro-arrhythmic substrate.3,4 Many of the arrhythmias identified are cavotricuspid isthmus-dependent atrial flutter (CTI-AFl) and incisional intra-atrial re-entrant tachycardia (IART); however, atrial fibrillation and focal atrial tachycardias (FATs) are also known to occur.5,6 Modified Maze procedures are commonly performed at the time of cardiac repair operations; anti-arrhythmic medications and radiofrequency catheter ablation (RFCA) are also employed to manage symptomatic arrhythmias for these patients.7–10 There is a paucity of data regarding atrial arrhythmia catheter ablation outcomes in patients with EA, and given the complex atrial anatomy and relative rarity, we therefore sought to describe our centre’s experience with catheter ablation in patients with EA and atrial arrhythmias. Methods The study was conducted with the approval of the Mayo Foundation Institutional Review Board and is compliance with the Declaration of Helsinski. All records for patients with EA who underwent catheter ablation at our institution between January 1999 and January 2016 were retrospectively reviewed. EA patients presenting with atrial arrhythmias (atrial tachycardia, atrial fibrillation, and atrial flutter) were included. Demographics and relevant clinical characteristics‒age at presentation, gender, cardiovascular surgical history, tricuspid valve type, catheter ablation history, and prior anti-arrhythmic medication use‒were recorded as well. Echocardiography The diagnosis of EA was confirmed through transthoracic echocardiogram. Echocardiographic parameters assessed at the time of ablation included right atrial (RA) size, left atrial (LA) size, right ventricular (RV) size and function, left ventricular (LV) size, and LV ejection fraction (LVEF). The degree of RV/LV dysfunction and enlargement were graded as: none, mild, moderate, moderate-to-severe, and severe. Arrhythmia recording and follow-up Atrial arrhythmias identified on electrophysiology study were recorded, as were the ablation procedures performed and immediate post-procedural complications. The primary outcome was time to atrial arrhythmia recurrence, where recurrence was defined as any atrial arrhythmia documented on electrocardiogram or 24-h Holter monitor after a 3-month blanking period. Other recorded outcomes included need for repeat ablation, stroke or transient ischemic attack, need for antiarrhythmic medications after ablation, and death. Invasive electrophysiological studies All antiarrhythmic drugs were discontinued 5 days prior to each procedure, except for amiodarone in 2 patients. Amiodarone was discontinued 4 weeks prior to ablation. Surface and intracardiac ECGs were digitally recorded and stored (Prucka CardioLab EP System, GE Healthcare). All patients underwent fluoroscopic, electrogram based mapping in addition to 3-dimensional electro-anatomic mapping using a CARTO (Biosense–Webster, Diamond Bar, CA) system. A reference duo-decapolar catheter was placed from the internal jugular into the coronary sinus in all patients (Orbiter, Boston Scientific). In addition, a second duodecapolar catheter (Crista Cath, Biosense–Webster) was inserted into the right atrium from the right or left femoral vein with the electrodes spanning the anterolateral, lateral or posterolateral right atrial free wall. Intracardiac electrograms were filtered from 30–500 Hz and measured with computer-assisted calipers at a sweep speed of 200 mm/s. Intracardiac echocardiography (ACUSON, Siemens) was utilized in all cases, being placed in the right atrium via groin access. Ablation was performed using an open-irrigated 3.5-mm-tip mapping and ablation catheter (ThermoCool, Biosense–Webster) and a steerable sheath (Agilis, St Jude Medical) was used in those patients with severe right atrial enlargement to provide better support and tissue contact. Tissue contact in the absence of atrial electrograms was confirmed with intracardiac echocardiography and pacing at 10 mA to identify excitability of the underlying muscle. Ablation lesions were delivered in a power controlled mode applying 15–30 Watts of power until the electrogram had fragmented, dissolved or reduced to at least 50% of the initial amplitude. The phrenic nerve was mapped using 10 and 20 mA output pacing, and labeled on the electroanatomical map. The ablation was undertaken in a consistent stepwise fashion starting with mapping of the presenting arrhythmia. If the patient was not in an atrial arrhythmia at the start of the case, pacing was performed using the following sequence for induction: (i) atrial decrement pacing to atrial ERP; (ii) atrial extrastimuli pacing with single and double extrastimuli (iii) burst pacing around atrial ERP (iv) burst pacing with concurrent isoproterenol infusion (using between 0.5–6 mcg/min). The presenting tachycardia and/or clinical atrial arrhythmia was initially ablated. Bidirectional block across all linear lesions was then confirmed before further inductions. Any subsequent atrial arrhythmia was then mapped and ablated in a sequential fashion using the same electroanatomical technique. Substrate/voltage maps were created during the atrial arrhythmia mapping for all patients, or during sinus rhythm/constant atrial pacing if no atrial arrhythmia was inducible following presenting arrhythmia ablation. Areas of low voltage (<0.2 mV) and fragmented/fractionated atrial electrograms were then targeted, working on the premise that these devitalized areas can potentially provide a nidus for micro re-entry, macro re-entry and FATs in the future. The areas were homogenized and/or anchored to adjacent scar/inert structures such as tricuspid valve, IVC, SVC or patch, and all linear ablation was checked for bidirectional block. This was performed using the duodecapolar catheter, differential pacing or a new electroanatomical map with pacing either side of the line. Following right atrial ablation, if atrial fibrillation was still easily inducible or noted to be originating from the left atrium with isoproterenol infusion–the pulmonary veins were then isolated using a wide-are circumferential approach. For all pulmonary vein isolations (PVIs), entrance block was proven pacing from the coronary sinus or atria. Statistics Descriptive statistics for continuous data were presented using median and range and counts and percentages were used for dichotomous and categorical data. Comparison between two groups was tested for continuous and dichotomous variables using two-sample t-tests and χ2 tests, respectively. The cumulative probability of atrial arrhythmia recurrence was estimated using the Kaplan–Meier method. Predictors of atrial arrhythmia recurrence were evaluated using univariable Cox proportional hazards modeling. A probability value (P-value) of ≤ 0.05 was identified as a cut-off for statistical significance. Results A total of 978 patients with EA were evaluated at our institution; of these, 113 had a prior history of Maze procedure. 22 patients met the inclusion criteria for the present study. Table 1 summarizes the clinical characteristics of the cohort examined. The median age at presentation was 64 (range 12–71), with a slight male predominance (n = 12 patients, 54.5%). The presenting arrhythmia was atrial flutter in the majority of patients (n = 14, 63.6%), whereas FAT and atrial fibrillation were present in 5 (22.7%) and 2 patients (9.1%), respectively. Only one patient had both atrial fibrillation and flutter. All patients involved in the study had a prior history of cardiovascular surgery; most had undergone tricuspid valve replacement (n = 19, 86.4%). Right-sided Maze procedure was documented in 8 patients prior to the ablation (36.4%); of these, 5 were cryotherapy/RCFA while 3 underwent a cut-and-sew Maze. 10 patients (47.6%) had a prior history of catheter ablation, and 8 patients (36.4%) were on anti-arrhythmic medications on presentation. Table 1 Patient baseline characteristics and relevant arrhythmia/surgical histories Variables  Patients (N = 22)  Gender   Male  12 (54.5%)   Female  10 (45.5%)  Age at procedure  42 (10–63)  Arrhythmia   FAT  5 (22.7%)   Atrial flutter  14 (63.6%)   Atrial fibrillation  2 (9.1%)   Atrial fibrillation/flutter  1 (4.5%)  Tricuspid valve type   Porcine (Carpentier–Edwards)  16 (72.7%)   Native/annuloplasty  3 (13.6%)   Porcine (St. Jude)  2 (9.1%)   Porcine (Hancock II)  1 (4.5%)  Prior right-sided MAZE  8 (36.4%)  Prior ablation  10 (47.6%)  Prior cardiovascular surgery  22 (100%)  Anti-arrhythmic medication use  8 (36.4%)  Variables  Patients (N = 22)  Gender   Male  12 (54.5%)   Female  10 (45.5%)  Age at procedure  42 (10–63)  Arrhythmia   FAT  5 (22.7%)   Atrial flutter  14 (63.6%)   Atrial fibrillation  2 (9.1%)   Atrial fibrillation/flutter  1 (4.5%)  Tricuspid valve type   Porcine (Carpentier–Edwards)  16 (72.7%)   Native/annuloplasty  3 (13.6%)   Porcine (St. Jude)  2 (9.1%)   Porcine (Hancock II)  1 (4.5%)  Prior right-sided MAZE  8 (36.4%)  Prior ablation  10 (47.6%)  Prior cardiovascular surgery  22 (100%)  Anti-arrhythmic medication use  8 (36.4%)  Echocardiographic parameters for the study cohort are shown in Table 2. RA size was at least moderately enlarged in 17 patients (77.3%). In contrast, LA size was normal in most patients (n = 15, 68.2%). A large fraction of patients had severe RV enlargement (n = 10, 45.5%) and dysfunction (n = 6, 27.3%), whereas LV size was normal in most patients (18 patients, 81.8%); in addition, median LVEF (range 40–68%) was normal as well. LA size was normal in most patients (18 patients, 81.8%). Table 2 Echocardiographic parameters at the time of ablation Variables  Patients (N = 22)  Right atrial size   Normal  1 (4.5%)   Mild  3 (13.6%)   Mild to moderate  1 (4.5%)   Moderate  8 (36.4%)   Moderate to severe  3 (13.6%)   Severe  6 (27.3%)  Right ventricular size   Normal  1 (4.5%)   Mild  1 (4.5%)   Moderate  6 (27.3%)   Moderate to severe  4 (18.2%)   Severe  10 (45.5%)  Right ventricular systolic function   Mild dysfunction  4 (18.2%)   Mild to moderate dysfunction  1 (4.5%)   Moderate dysfunction  7 (31.8%)   Moderate to severe dysfunction  4 (18.2%)   Severe dysfunction  6 (27.3%)  Left ventricular size   Normal  18 (81.8%)   Enlarged  4 (18.2%)  Left ventricular ejection fraction (%)  58 (40–68)  Left atrial size   Normal  15 (68.2%)   Mild  1 (4.5%)   Mild to moderate  1 (4.5%)   Moderate  5 (22.7%)  Variables  Patients (N = 22)  Right atrial size   Normal  1 (4.5%)   Mild  3 (13.6%)   Mild to moderate  1 (4.5%)   Moderate  8 (36.4%)   Moderate to severe  3 (13.6%)   Severe  6 (27.3%)  Right ventricular size   Normal  1 (4.5%)   Mild  1 (4.5%)   Moderate  6 (27.3%)   Moderate to severe  4 (18.2%)   Severe  10 (45.5%)  Right ventricular systolic function   Mild dysfunction  4 (18.2%)   Mild to moderate dysfunction  1 (4.5%)   Moderate dysfunction  7 (31.8%)   Moderate to severe dysfunction  4 (18.2%)   Severe dysfunction  6 (27.3%)  Left ventricular size   Normal  18 (81.8%)   Enlarged  4 (18.2%)  Left ventricular ejection fraction (%)  58 (40–68)  Left atrial size   Normal  15 (68.2%)   Mild  1 (4.5%)   Mild to moderate  1 (4.5%)   Moderate  5 (22.7%)  Median (range) is presented for continuous variables. Electrophysiology study findings and ablations performed are described in Table 3. 3 patients (13.6%) underwent ablation of the clinical arrhythmia only, whereas 15 patients (68.2%) underwent ablation of the clinical arrhythmia plus arrhythmias induced during their studies. In addition to arrhythmia ablation, 4 patients (18.2%) also underwent additional substrate modification. Atrial flutter was found in 19 patients (86.4%), with the majority being CTI-AFl (Figure 1). Atrial fibrillation and FAT were noted in 3 (13.6%) and 4 (18.2%) patients, respectively. The vast majority of patients underwent right–sided ablation (21 patients, 95.5%), whereas only 3 patients (13.6%) underwent left sided ablation with concomitant PVIs. All patients left the electrophysiology lab in sinus rhythm, and at the completion of the procedure, all presenting/clinical atrial arrhythmias had been targeted successfully and could not be reinduced. There were no procedural or periprocedural complications including perforation, stroke, or myocardial infarction. CTI-AFl was identified in 4 patients with a prior right-sided Maze procedure, yet only a single patient had undergone a definitive CTI ablation with cryotherapy as part of the Maze. Table 3 Electrophysiologic study findings, ablations performed, and complications identified Variable  Patients (n = 22)  Electrophysiologic Study Findings   Atrial fibrillation  3 (13.6%)   Atrial flutter  19 (86.4%)    CTI-AFl  13 (59.1%)    IART  4 (18.2%)    Left-sided flutter  1 (4.5%)   FAT  4 (18.2%)  Ablation Aim   Ablate clinical arrhythmia  3 (13.6%)   Ablate clinical and induced arrhythmias  15 (68.2%)   Ablate clinical and induced arrhythmia plus substrate modification  4 (18.2%)  Ablation Performed   Right-sided ablation  21 (95.5%)   Left-sided ablation  3 (13.6%)   Length of ablation (minutes)  338 (192–517)   PV isolation  3 (13.6%)   Septal ablation  1 (4.5%)   SVC isolation  3 (12%)   Procedural non-inducibility following ablation  20 (90.9%)  Post-Procedural Complications  0 (0%)   MI  0 (0%)   Perforation  0 (0%)   Stroke  0 (0%)  Variable  Patients (n = 22)  Electrophysiologic Study Findings   Atrial fibrillation  3 (13.6%)   Atrial flutter  19 (86.4%)    CTI-AFl  13 (59.1%)    IART  4 (18.2%)    Left-sided flutter  1 (4.5%)   FAT  4 (18.2%)  Ablation Aim   Ablate clinical arrhythmia  3 (13.6%)   Ablate clinical and induced arrhythmias  15 (68.2%)   Ablate clinical and induced arrhythmia plus substrate modification  4 (18.2%)  Ablation Performed   Right-sided ablation  21 (95.5%)   Left-sided ablation  3 (13.6%)   Length of ablation (minutes)  338 (192–517)   PV isolation  3 (13.6%)   Septal ablation  1 (4.5%)   SVC isolation  3 (12%)   Procedural non-inducibility following ablation  20 (90.9%)  Post-Procedural Complications  0 (0%)   MI  0 (0%)   Perforation  0 (0%)   Stroke  0 (0%)  Median (range) is presented for continuous variables. The 1-year, 3-year, and 5-year atrial arrhythmia recurrence rates were 10.0%, 21.7%, and 41.2%, respectively (Figure 2). Among the 10 patients who experienced a recurrence, the majority had atrial flutter, atrial fibrillation, or a combination of the two (Table 4); 5 patients experienced a recurrence of the index arrhythmia, whereas the other 5 patients experienced another atrial arrhythmia. 8 patients (36.4%) were on anti-arrhythmic medications following catheter ablation. 1 patient underwent an AV nodal ablation procedure. 7 patients (31.8%) underwent redo ablation procedures. On univariate analysis, there was no arrhythmia feature, ablation characteristic or cardiac structural parameter that was found to be a significant predictor of recurrence (Table 5). Table 4 Summary of atrial arrhythmia recurrence types, anti-arrhythmia medication use, and AV nodal and redo ablation procedures following catheter ablation therapy Variable  Patients (N = 22)  Recurrence type   Atrial flutter  4 (40.0%)   Atrial fibrillation  3 (30.0%)   EAT  2 (20.0%)   Atrial fibrillation/flutter  1 (10.0%)  Anti-arrhythmic medications after ablation   None  14 (63.6%)   Amiodarone  2 (9.1%)   Propafenone  2 (9.1%)   Sotalol  1 (4.5%)   Dronedarone  2 (9.1%)   Flecainide  1 (4.5%)   Dofetilide  0 (0%)  AV node ablation  1 (4.5%)  Redo ablation   No  15 (68.2%)   Once  3 (13.6%)   Twice  4 (18.2%)  Variable  Patients (N = 22)  Recurrence type   Atrial flutter  4 (40.0%)   Atrial fibrillation  3 (30.0%)   EAT  2 (20.0%)   Atrial fibrillation/flutter  1 (10.0%)  Anti-arrhythmic medications after ablation   None  14 (63.6%)   Amiodarone  2 (9.1%)   Propafenone  2 (9.1%)   Sotalol  1 (4.5%)   Dronedarone  2 (9.1%)   Flecainide  1 (4.5%)   Dofetilide  0 (0%)  AV node ablation  1 (4.5%)  Redo ablation   No  15 (68.2%)   Once  3 (13.6%)   Twice  4 (18.2%)  Table 5 Univariate analysis for identifying potential predictors of atrial arrhythmia recurrence Variable  Hazard ratio (95% CI)  P-value  Length of procedure (min)  1.00 (0.99, 1.01)  0.80  Age at procedure  0.96 (0.92, 1.01)  0.079  Right-sided ablation  0.80 (0.10, 6.57)  0.84  Left-sided ablation  0.46 (0.06, 3.76)  0.47  Atrial fibrillation  0.60 (0.08, 4.83)  0.63  Atrial flutter (all types)  0.55 (0.11, 2.72)  0.46  CTI-AFl  1.85 (0.50, 6.87)  0.36  IART  0.90 (0.25, 3.27)  0.87  Left-sided flutter  1.25 (0.15, 10.28)  0.84  FAT  2.02 (0.40, 10.17)  0.40  Severe RA size  0.48 (0.10, 2.27)  0.35  Severe RV size  1.72 (0.48, 6.18)  0.40  Severe RV dysfunction  1.42 (0.39, 5.12)  0.59  Variable  Hazard ratio (95% CI)  P-value  Length of procedure (min)  1.00 (0.99, 1.01)  0.80  Age at procedure  0.96 (0.92, 1.01)  0.079  Right-sided ablation  0.80 (0.10, 6.57)  0.84  Left-sided ablation  0.46 (0.06, 3.76)  0.47  Atrial fibrillation  0.60 (0.08, 4.83)  0.63  Atrial flutter (all types)  0.55 (0.11, 2.72)  0.46  CTI-AFl  1.85 (0.50, 6.87)  0.36  IART  0.90 (0.25, 3.27)  0.87  Left-sided flutter  1.25 (0.15, 10.28)  0.84  FAT  2.02 (0.40, 10.17)  0.40  Severe RA size  0.48 (0.10, 2.27)  0.35  Severe RV size  1.72 (0.48, 6.18)  0.40  Severe RV dysfunction  1.42 (0.39, 5.12)  0.59  Figure 1 View largeDownload slide Illustration of the atrium (letter "a"; drawn as incised and peeled back for clarity) with catheter ablation lines performed in the setting of EA. The ablation lesions depicted by the dark maroon lines reflect the current right-sided maze procedure lesions performed at our institution. A linear lesion extends from the inferior tricuspid annulus to the inferior vena cava, and a more lateral linear lesion from the same valve to the lateral/posterolateral atriotomy site. This latter lesion is extended in a cranial and caudal direction so that a complete intercaval lesion is created. The right atrial appendage is amputated and this is then used as an anchoring lesion for a linear lesion down to the tricuspid valve. Variably, a linear lesion is extended from the fossa ovalis/patent foramen ovale/secundum atrial septal defect repair site to the superior vena cava. The ellipses identify the most common sources for atrial arrhythmias, with CTI-AFl being the most common; IART and FAT both equally account for the majority of the remainder. Figure 1 View largeDownload slide Illustration of the atrium (letter "a"; drawn as incised and peeled back for clarity) with catheter ablation lines performed in the setting of EA. The ablation lesions depicted by the dark maroon lines reflect the current right-sided maze procedure lesions performed at our institution. A linear lesion extends from the inferior tricuspid annulus to the inferior vena cava, and a more lateral linear lesion from the same valve to the lateral/posterolateral atriotomy site. This latter lesion is extended in a cranial and caudal direction so that a complete intercaval lesion is created. The right atrial appendage is amputated and this is then used as an anchoring lesion for a linear lesion down to the tricuspid valve. Variably, a linear lesion is extended from the fossa ovalis/patent foramen ovale/secundum atrial septal defect repair site to the superior vena cava. The ellipses identify the most common sources for atrial arrhythmias, with CTI-AFl being the most common; IART and FAT both equally account for the majority of the remainder. Figure 2 View largeDownload slide Kaplan–Meier Curve demonstrating arrhythmia recurrence following atrial arrhythmia ablation (dotted lines represent 95% confidence intervals). Figure 2 View largeDownload slide Kaplan–Meier Curve demonstrating arrhythmia recurrence following atrial arrhythmia ablation (dotted lines represent 95% confidence intervals). Three patients died throughout the course of the study. 2 patients sustained likely cardiovascular deaths (one died from sudden death 3 months after the ablation while the other one died 11.5 years after) and the third patient death was non-cardiac. Discussion This report characterizes the medium and long-term outcomes in patients with EA who have undergone catheter-based ablation procedures to manage their symptomatic atrial arrhythmias. The results demonstrate very acceptable success rates, and are comparable with other ablation results in patients with complex congenital heart disease.11,12 Right-sided ablations constitute the majority of the procedures performed, with left-sided ablations rarely needed. Consistent with longitudinal follow-up studies in this group–multiple cardiac operations are not uncommon in these patients’ lifetime.13 Re-do tricuspid valve repair and replacement is necessary in almost a fifth of patients with this disease; a milieu associated with continued disease progression with regards to atrial stretch and dilatation. Through this mechanism, myocardial fibrosis and slower myocardial conduction times engender a more pro-arrhythmic environment. The necessity for redo procedures for these patients is an important element to discuss preemptively, yet it does not appear that it poses any higher risk to the patients. The procedures are almost exclusively right-sided and complications are very low. The electrophysiological findings also provide insight into the role of prior Maze surgery in the arrhythmia management of these patients. This intervention was present in more than a third of the study cohort. This does not reflect on the anti-arrhythmic efficacy of Maze surgeries, given that successful Maze procedures would not have presented with recurrence and consideration of catheter ablation. It is, nevertheless, important to recognize that a large fraction of patients required ablation of a CTI-AFl–a region of the right atrium that is not typically addressed by most modern modified right-sided Maze procedures. This common atrial flutter should be prevented by complete transmural lesions between lateral atriotomy and the tricuspid valve. Anatomically, the isthmus is grossly abnormal in these patients, related in part to the displacement of the tricuspid valvular apparatus, and also affected in part by the adjacent annular dilatation that accompanies the right ventricular abnormality and the tricuspid regurgitation. This constellation of findings suggests that an empiric cavotricuspid linear lesion should likely be considered standard at the time of cardiac repair. Given that this region can be excluded by implantation of a bioprosthetic valve, preemptive ablation or discussion with the cardiac surgeon to ensure this atrial flutter is addressed appears to be imperative.14 Furthermore, this does bring up for discussion whether all other right-sided modified Maze lesions are useful in preventing incisional/atriotomy flutters, yet this study was not powered to address this question. CTI-AFl was present in almost 60% of patients with a prior right-sided Maze procedure; hence, further investigation into the types of Maze procedures to prevent this occurrence should be considered. In principle, the incisional/atriotomy flutters should be prevented by a single, transmural, and continuous inter-caval line.15 Unfortunately, the sheer length of this lesion lends itself to inconsistencies in the presence and durability of bidirectional block unless a cut & sew approach is employed. Current Maze techniques utilize cryo-energy or radiofrequency for the majority of cases,16 and cut & sew techniques (even though associated with better longer term results), are also associated with more bleeding and longer bypass/operation times.17 Simply anchoring to the inferior vena cava from the atriotomy site as a single lesion set has not been evaluated, but conceptually this may reduce flutter with less pro-arrhythmia related to a shorter lesion set.15 Half of the cohort had undergone a procedure elsewhere, and we do not have enough data to surmise whether the ablations at our institution were to address primary arrhythmias that were inadequately treated, or whether new rhythm abnormalities developed de novo as a corollary to disease progression. With an average procedural time of 338 min, these procedures are more complex and challenging to perform; and consistent with the PACES/HRS Expert Consensus Statement on the use of catheter ablation in patients with congenital heart disease, this intervention should likely be undertaken at centres with experience in congenital heart disease management and complex arrhythmia ablation.18 A significant proportion of the patients studied experienced atrial fibrillation in addition to atrial flutter, and yet the atrial fibrillation was rendered non-inducible by an isolated right-sided procedure. This data does suggest that in addition to reentrant atrial arrhythmia, AF is not an uncommon occurrence in this patient population and left-sided ablations may, therefore, be warranted. In this subset of patients, atrial flutter may degenerate into atrial fibrillation in the context of abnormal myocardium with variable conduction velocity and anisotropy. This data provides insight into the mechanisms of atrial fibrillation in EA patients, which in turn gives direction regarding the ideal lesion set to be undertaken at the time of Maze surgery. Based on our findings, a right-sided Maze procedure may be effective in preventing arrhythmia recurrence, and a concomitant left-sided Maze may not be necessary in most patients. It does appear that to gain complete control of these substrate-based atrial arrhythmias adjunctive anti-arrhythmic medication remains necessary in a minority of patients. This highlights the utility of this procedure for the young patient, who can potentially avoid life-long anti-arrhythmics with their associated pro-arrhythmic risk. A third of patients, however, do require some anti-arrhythmic medication–speaking to the progressive nature of the disease, and the fact that patients continue to develop tricuspid valve regurgitation despite surgery–with around half of this patient group requiring re-operation within the 10–15 year time frame.19 This study represents the largest investigation of catheter-based ablation outcomes of atrial arrhythmias in EA patients. That being said, it is difficult to draw firm conclusions from the univariate analysis given the relatively small numbers. In essence, however, there is likely sufficient support for the claim that the presence of RV size and function, RA size, and prior Maze surgery are not strong predictors of arrhythmia recurrence. Hence, this procedural intervention can be considered in almost all patients with EA who have symptomatic atrial arrhythmias. Conclusions The present study provides novel data for guiding interventional anti-arrhythmic strategies in patients with EA and concomitant atrial arrhythmias. Peri-tricuspid reentrant atrial tachycardia remains a fundamental problem even after Maze procedures in this patient group. The study’s findings should be helpful in guiding preemptive anti-arrhythmic strategies in this patient group for pediatric and adult invasive electrophysiologists alike. Conflict of interest: Dr. Packer reports royalties from St. Jude Medical to the Mayo Clinic relevant to the topic of this study. He reports serving as an unpaid consultant or as a member of the advisory board relevant to this topic for Biosense Webster and St. Jude Medical. No conflicts of interest to disclose among the other authors. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. 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Electroanatomic characterization of conduction barriers in sinus/atrially paced rhythm and association with intra-atrial reentrant tachycardia circuits following congenital heart disease surgery. J Cardiovasc Electrophysiol  2001; 12: 17– 25. Google Scholar CrossRef Search ADS PubMed  6 Moore JP. Arrhythmia management for the adult patient with congenital heart disease: an update and analytical review. Minerva Pediatr  2014; 66: 415– 39. Google Scholar PubMed  7 Cappato R, Schluter M, Weiss C, Antz M, Koschyk DH, Hofmann T et al.   Radiofrequency current catheter ablation of accessory atrioventricular pathways in Ebstein's anomaly. Circulation  1996; 94: 376– 83. Google Scholar CrossRef Search ADS PubMed  8 Hebe J, Hansen P, Ouyang F, Volkmer M, Kuck KH. Radiofrequency catheter ablation of tachycardia in patients with congenital heart disease. Pediatr Cardiol  2000; 21: 557– 75. Google Scholar CrossRef Search ADS PubMed  9 Khairy P, Van Hare GF, Balaji S, Berul CI, Cecchin F, Cohen MI et al.   PACES/HRS expert consensus statement on the recognition and management of arrhythmias in adult congenital heart disease: developed in partnership between the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS). Endorsed by the governing bodies of PACES, HRS, the American College of Cardiology (ACC), the American Heart Association (AHA), the European Heart Rhythm Association (EHRA), the Canadian Heart Rhythm Society (CHRS), and the International Society for Adult Congenital Heart Disease (ISACHD). Heart Rhythm  2014; 11: e102– 65. Google Scholar CrossRef Search ADS PubMed  10 Brugada J, Blom N, Sarquella-Brugada G, Blomstrom-Lundqvist C, Deanfield J, Janousek J et al. Pharmacological and non-pharmacological therapy for arrhythmias in the pediatric population: EHRA and AEPC-Arrhythmia Working Group joint consensus statement. Europace 2013;15:1337-82. 11 Kumar S, Tedrow UB, Triedman JK. Arrhythmias in adult congenital heart disease: diagnosis and management. Cardiol Clin  2015; 33: 571– 88, viii. Google Scholar CrossRef Search ADS PubMed  12 Sherwin ED, Triedman JK, Walsh EP. Update on interventional electrophysiology in congenital heart disease: evolving solutions for complex hearts. Circ Arrhythm Electrophysiol  2013; 6: 1032– 40. Google Scholar CrossRef Search ADS PubMed  13 Brown ML, Dearani JA, Danielson GK, Cetta F, Connolly HM, Warnes CA et al.   The outcomes of operations for 539 patients with Ebstein anomaly. J Thorac Cardiovasc Surg  2008; 135: 1120– 36, 36 e1–7. Google Scholar CrossRef Search ADS PubMed  14 El Yaman MM, Asirvatham SJ, Kapa S, Barrett RA, Packer DL, Porter CB. Methods to access the surgically excluded cavotricuspid isthmus for complete ablation of typical atrial flutter in patients with congenital heart defects. Heart Rhythm  2009; 6: 949– 56. Google Scholar CrossRef Search ADS PubMed  15 Akar JG, Kok LC, Haines DE, DiMarco JP, Mounsey JP. Coexistence of type I atrial flutter and intra-atrial re-entrant tachycardia in patients with surgically corrected congenital heart disease. J Am Coll Cardiol  2001; 38: 377– 84. Google Scholar CrossRef Search ADS PubMed  16 Abo-Salem E, Lockwood D, Boersma L, Deneke T, Pison L, Paone RF et al.   Surgical treatment of atrial fibrillation. J Cardiovasc Electrophysiol  2015; 26( 9): 1027– 1037. Google Scholar CrossRef Search ADS   17 Stulak JM, Dearani JA, Puga FJ, Zehr KJ, Schaff HV, Danielson GK. Right-sided Maze procedure for atrial tachyarrhythmias in congenital heart disease. Ann Thorac Surg  2006; 81: 1780– 4;discussion 4-5. Google Scholar CrossRef Search ADS PubMed  18 Saul JP, Kanter RJ, COMMITTEE W, Abrams D, Asirvatham S, Bar-Cohen Y et al.   PACES/HRS expert consensus statement on the use of catheter ablation in children and patients with congenital heart disease: Developed in partnership with the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS). Endorsed by the governing bodies of PACES, HRS, the American Academy of Pediatrics (AAP), and the American Heart Association (AHA). Heart Rhythm  2016; 13: e252. 19 Brown ML, Dearani JA, Danielson GK, Cetta F, Connolly HM, Warnes CA et al.   Functional status after operation for Ebstein anomaly: the Mayo Clinic experience. J Am Coll Cardiol  2008; 52: 460– 6. Google Scholar CrossRef Search ADS PubMed  Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. 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Outcomes of atrial arrhythmia radiofrequency catheter ablation in patients with Ebstein’s anomaly

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Abstract

Abstract Aims Atrial arrhythmias are common in patients with Ebstein’s anomaly (EA) despite cardiac surgical repair and concomitant Maze procedures. We aimed to evaluate the outcome of radiofrequency catheter ablation in this group of patients. Methods and results All patients with EA and atrial arrhythmias who underwent catheter ablation for atrial arrhythmias between 1/1999 and 1/2016 were included. Atrial arrhythmia recurrence was identified as the primary outcome; secondary outcomes included repeat ablation, need for antiarrhythmic medications after ablation, and death. Predictors of recurrence were sought using univariate analysis. 22 patients (median age 42 years, 54.5% male) were included. Atrial flutter was the most common presenting arrhythmia (n = 14 patients, 63.5%), whereas focal atrial tachycardia (FAT) and atrial fibrillation were identified in 5 (22.7%) and 2 patients (9.1%), respectively, with both atrial flutter/fibrillation evident in a single patient 1 (4.5%). 8 patients (36.4%) had a history of right-sided maze procedures. Cavotricuspid isthmus atrial flutter (CTI-AFl) was the most commonly induced arrhythmia (n = 13, 59.1%), followed by incisional intra-atrial re-entrant tachycardia (IART; n = 4, 18.2%), and FAT (n = 4, 18.2%); 3 patients also underwent left-side ablation with concomitant pulmonary vein isolation (13.6%). 1-year and 5-year atrial arrhythmia recurrence rates were 10.0% and 41.2%, respectively. 7 patients (31.8%) underwent redo ablations, and anti-arrhythmic medication was utilized in 8 patients (36.4%) post-ablation. Neither ablation location nor echocardiographic parameters were found to be predictors of arrhythmia recurrence. Conclusion Catheter ablation of atrial arrhythmias in patients with EA has a favorable outcome overall with an acceptable recurrence and safety profile; left-sided ablations are rarely necessary. Despite prior Maze and catheter ablation procedures, CTI-AFl and IART recurrences predominate. Atrial arrhythmia, Ebstein’s anomaly, Catheter ablation, Outcome Introduction What’s new? Atrial arrhythmias occur commonly among patients with Ebstein’s anomaly (EA) despite prior invasive anti-arrhythmic procedures. In a cohort of 22 patients with EA and concomitant atrial arrhythmias, cavotricuspid isthmus dependent atrial flutter was the most common presenting rhythm. Most patients underwent exclusively right-sided ablation procedures 1-year, 3-year, and 5-year atrial arrhythmia recurrence rates were 10.0%, 21.7%, and 41.2%, respectively; no acute post-procedural complications were identified. No arrhythmia feature, ablation characteristic or cardiac structural parameter was identified as a predictor of arrhythmia recurrence on univariate analysis.Atrial arrhythmias are a common clinical issue in patients with Ebstein’s anomaly (EA), occurring in up to a third of this group.1,2 Tricuspid valve dysfunction with progressive right atrial enlargement, incisional scars following cardiac repair, as well as Maze and ablation procedures all contribute towards the creation of an ideal pro-arrhythmic substrate.3,4 Many of the arrhythmias identified are cavotricuspid isthmus-dependent atrial flutter (CTI-AFl) and incisional intra-atrial re-entrant tachycardia (IART); however, atrial fibrillation and focal atrial tachycardias (FATs) are also known to occur.5,6 Modified Maze procedures are commonly performed at the time of cardiac repair operations; anti-arrhythmic medications and radiofrequency catheter ablation (RFCA) are also employed to manage symptomatic arrhythmias for these patients.7–10 There is a paucity of data regarding atrial arrhythmia catheter ablation outcomes in patients with EA, and given the complex atrial anatomy and relative rarity, we therefore sought to describe our centre’s experience with catheter ablation in patients with EA and atrial arrhythmias. Methods The study was conducted with the approval of the Mayo Foundation Institutional Review Board and is compliance with the Declaration of Helsinski. All records for patients with EA who underwent catheter ablation at our institution between January 1999 and January 2016 were retrospectively reviewed. EA patients presenting with atrial arrhythmias (atrial tachycardia, atrial fibrillation, and atrial flutter) were included. Demographics and relevant clinical characteristics‒age at presentation, gender, cardiovascular surgical history, tricuspid valve type, catheter ablation history, and prior anti-arrhythmic medication use‒were recorded as well. Echocardiography The diagnosis of EA was confirmed through transthoracic echocardiogram. Echocardiographic parameters assessed at the time of ablation included right atrial (RA) size, left atrial (LA) size, right ventricular (RV) size and function, left ventricular (LV) size, and LV ejection fraction (LVEF). The degree of RV/LV dysfunction and enlargement were graded as: none, mild, moderate, moderate-to-severe, and severe. Arrhythmia recording and follow-up Atrial arrhythmias identified on electrophysiology study were recorded, as were the ablation procedures performed and immediate post-procedural complications. The primary outcome was time to atrial arrhythmia recurrence, where recurrence was defined as any atrial arrhythmia documented on electrocardiogram or 24-h Holter monitor after a 3-month blanking period. Other recorded outcomes included need for repeat ablation, stroke or transient ischemic attack, need for antiarrhythmic medications after ablation, and death. Invasive electrophysiological studies All antiarrhythmic drugs were discontinued 5 days prior to each procedure, except for amiodarone in 2 patients. Amiodarone was discontinued 4 weeks prior to ablation. Surface and intracardiac ECGs were digitally recorded and stored (Prucka CardioLab EP System, GE Healthcare). All patients underwent fluoroscopic, electrogram based mapping in addition to 3-dimensional electro-anatomic mapping using a CARTO (Biosense–Webster, Diamond Bar, CA) system. A reference duo-decapolar catheter was placed from the internal jugular into the coronary sinus in all patients (Orbiter, Boston Scientific). In addition, a second duodecapolar catheter (Crista Cath, Biosense–Webster) was inserted into the right atrium from the right or left femoral vein with the electrodes spanning the anterolateral, lateral or posterolateral right atrial free wall. Intracardiac electrograms were filtered from 30–500 Hz and measured with computer-assisted calipers at a sweep speed of 200 mm/s. Intracardiac echocardiography (ACUSON, Siemens) was utilized in all cases, being placed in the right atrium via groin access. Ablation was performed using an open-irrigated 3.5-mm-tip mapping and ablation catheter (ThermoCool, Biosense–Webster) and a steerable sheath (Agilis, St Jude Medical) was used in those patients with severe right atrial enlargement to provide better support and tissue contact. Tissue contact in the absence of atrial electrograms was confirmed with intracardiac echocardiography and pacing at 10 mA to identify excitability of the underlying muscle. Ablation lesions were delivered in a power controlled mode applying 15–30 Watts of power until the electrogram had fragmented, dissolved or reduced to at least 50% of the initial amplitude. The phrenic nerve was mapped using 10 and 20 mA output pacing, and labeled on the electroanatomical map. The ablation was undertaken in a consistent stepwise fashion starting with mapping of the presenting arrhythmia. If the patient was not in an atrial arrhythmia at the start of the case, pacing was performed using the following sequence for induction: (i) atrial decrement pacing to atrial ERP; (ii) atrial extrastimuli pacing with single and double extrastimuli (iii) burst pacing around atrial ERP (iv) burst pacing with concurrent isoproterenol infusion (using between 0.5–6 mcg/min). The presenting tachycardia and/or clinical atrial arrhythmia was initially ablated. Bidirectional block across all linear lesions was then confirmed before further inductions. Any subsequent atrial arrhythmia was then mapped and ablated in a sequential fashion using the same electroanatomical technique. Substrate/voltage maps were created during the atrial arrhythmia mapping for all patients, or during sinus rhythm/constant atrial pacing if no atrial arrhythmia was inducible following presenting arrhythmia ablation. Areas of low voltage (<0.2 mV) and fragmented/fractionated atrial electrograms were then targeted, working on the premise that these devitalized areas can potentially provide a nidus for micro re-entry, macro re-entry and FATs in the future. The areas were homogenized and/or anchored to adjacent scar/inert structures such as tricuspid valve, IVC, SVC or patch, and all linear ablation was checked for bidirectional block. This was performed using the duodecapolar catheter, differential pacing or a new electroanatomical map with pacing either side of the line. Following right atrial ablation, if atrial fibrillation was still easily inducible or noted to be originating from the left atrium with isoproterenol infusion–the pulmonary veins were then isolated using a wide-are circumferential approach. For all pulmonary vein isolations (PVIs), entrance block was proven pacing from the coronary sinus or atria. Statistics Descriptive statistics for continuous data were presented using median and range and counts and percentages were used for dichotomous and categorical data. Comparison between two groups was tested for continuous and dichotomous variables using two-sample t-tests and χ2 tests, respectively. The cumulative probability of atrial arrhythmia recurrence was estimated using the Kaplan–Meier method. Predictors of atrial arrhythmia recurrence were evaluated using univariable Cox proportional hazards modeling. A probability value (P-value) of ≤ 0.05 was identified as a cut-off for statistical significance. Results A total of 978 patients with EA were evaluated at our institution; of these, 113 had a prior history of Maze procedure. 22 patients met the inclusion criteria for the present study. Table 1 summarizes the clinical characteristics of the cohort examined. The median age at presentation was 64 (range 12–71), with a slight male predominance (n = 12 patients, 54.5%). The presenting arrhythmia was atrial flutter in the majority of patients (n = 14, 63.6%), whereas FAT and atrial fibrillation were present in 5 (22.7%) and 2 patients (9.1%), respectively. Only one patient had both atrial fibrillation and flutter. All patients involved in the study had a prior history of cardiovascular surgery; most had undergone tricuspid valve replacement (n = 19, 86.4%). Right-sided Maze procedure was documented in 8 patients prior to the ablation (36.4%); of these, 5 were cryotherapy/RCFA while 3 underwent a cut-and-sew Maze. 10 patients (47.6%) had a prior history of catheter ablation, and 8 patients (36.4%) were on anti-arrhythmic medications on presentation. Table 1 Patient baseline characteristics and relevant arrhythmia/surgical histories Variables  Patients (N = 22)  Gender   Male  12 (54.5%)   Female  10 (45.5%)  Age at procedure  42 (10–63)  Arrhythmia   FAT  5 (22.7%)   Atrial flutter  14 (63.6%)   Atrial fibrillation  2 (9.1%)   Atrial fibrillation/flutter  1 (4.5%)  Tricuspid valve type   Porcine (Carpentier–Edwards)  16 (72.7%)   Native/annuloplasty  3 (13.6%)   Porcine (St. Jude)  2 (9.1%)   Porcine (Hancock II)  1 (4.5%)  Prior right-sided MAZE  8 (36.4%)  Prior ablation  10 (47.6%)  Prior cardiovascular surgery  22 (100%)  Anti-arrhythmic medication use  8 (36.4%)  Variables  Patients (N = 22)  Gender   Male  12 (54.5%)   Female  10 (45.5%)  Age at procedure  42 (10–63)  Arrhythmia   FAT  5 (22.7%)   Atrial flutter  14 (63.6%)   Atrial fibrillation  2 (9.1%)   Atrial fibrillation/flutter  1 (4.5%)  Tricuspid valve type   Porcine (Carpentier–Edwards)  16 (72.7%)   Native/annuloplasty  3 (13.6%)   Porcine (St. Jude)  2 (9.1%)   Porcine (Hancock II)  1 (4.5%)  Prior right-sided MAZE  8 (36.4%)  Prior ablation  10 (47.6%)  Prior cardiovascular surgery  22 (100%)  Anti-arrhythmic medication use  8 (36.4%)  Echocardiographic parameters for the study cohort are shown in Table 2. RA size was at least moderately enlarged in 17 patients (77.3%). In contrast, LA size was normal in most patients (n = 15, 68.2%). A large fraction of patients had severe RV enlargement (n = 10, 45.5%) and dysfunction (n = 6, 27.3%), whereas LV size was normal in most patients (18 patients, 81.8%); in addition, median LVEF (range 40–68%) was normal as well. LA size was normal in most patients (18 patients, 81.8%). Table 2 Echocardiographic parameters at the time of ablation Variables  Patients (N = 22)  Right atrial size   Normal  1 (4.5%)   Mild  3 (13.6%)   Mild to moderate  1 (4.5%)   Moderate  8 (36.4%)   Moderate to severe  3 (13.6%)   Severe  6 (27.3%)  Right ventricular size   Normal  1 (4.5%)   Mild  1 (4.5%)   Moderate  6 (27.3%)   Moderate to severe  4 (18.2%)   Severe  10 (45.5%)  Right ventricular systolic function   Mild dysfunction  4 (18.2%)   Mild to moderate dysfunction  1 (4.5%)   Moderate dysfunction  7 (31.8%)   Moderate to severe dysfunction  4 (18.2%)   Severe dysfunction  6 (27.3%)  Left ventricular size   Normal  18 (81.8%)   Enlarged  4 (18.2%)  Left ventricular ejection fraction (%)  58 (40–68)  Left atrial size   Normal  15 (68.2%)   Mild  1 (4.5%)   Mild to moderate  1 (4.5%)   Moderate  5 (22.7%)  Variables  Patients (N = 22)  Right atrial size   Normal  1 (4.5%)   Mild  3 (13.6%)   Mild to moderate  1 (4.5%)   Moderate  8 (36.4%)   Moderate to severe  3 (13.6%)   Severe  6 (27.3%)  Right ventricular size   Normal  1 (4.5%)   Mild  1 (4.5%)   Moderate  6 (27.3%)   Moderate to severe  4 (18.2%)   Severe  10 (45.5%)  Right ventricular systolic function   Mild dysfunction  4 (18.2%)   Mild to moderate dysfunction  1 (4.5%)   Moderate dysfunction  7 (31.8%)   Moderate to severe dysfunction  4 (18.2%)   Severe dysfunction  6 (27.3%)  Left ventricular size   Normal  18 (81.8%)   Enlarged  4 (18.2%)  Left ventricular ejection fraction (%)  58 (40–68)  Left atrial size   Normal  15 (68.2%)   Mild  1 (4.5%)   Mild to moderate  1 (4.5%)   Moderate  5 (22.7%)  Median (range) is presented for continuous variables. Electrophysiology study findings and ablations performed are described in Table 3. 3 patients (13.6%) underwent ablation of the clinical arrhythmia only, whereas 15 patients (68.2%) underwent ablation of the clinical arrhythmia plus arrhythmias induced during their studies. In addition to arrhythmia ablation, 4 patients (18.2%) also underwent additional substrate modification. Atrial flutter was found in 19 patients (86.4%), with the majority being CTI-AFl (Figure 1). Atrial fibrillation and FAT were noted in 3 (13.6%) and 4 (18.2%) patients, respectively. The vast majority of patients underwent right–sided ablation (21 patients, 95.5%), whereas only 3 patients (13.6%) underwent left sided ablation with concomitant PVIs. All patients left the electrophysiology lab in sinus rhythm, and at the completion of the procedure, all presenting/clinical atrial arrhythmias had been targeted successfully and could not be reinduced. There were no procedural or periprocedural complications including perforation, stroke, or myocardial infarction. CTI-AFl was identified in 4 patients with a prior right-sided Maze procedure, yet only a single patient had undergone a definitive CTI ablation with cryotherapy as part of the Maze. Table 3 Electrophysiologic study findings, ablations performed, and complications identified Variable  Patients (n = 22)  Electrophysiologic Study Findings   Atrial fibrillation  3 (13.6%)   Atrial flutter  19 (86.4%)    CTI-AFl  13 (59.1%)    IART  4 (18.2%)    Left-sided flutter  1 (4.5%)   FAT  4 (18.2%)  Ablation Aim   Ablate clinical arrhythmia  3 (13.6%)   Ablate clinical and induced arrhythmias  15 (68.2%)   Ablate clinical and induced arrhythmia plus substrate modification  4 (18.2%)  Ablation Performed   Right-sided ablation  21 (95.5%)   Left-sided ablation  3 (13.6%)   Length of ablation (minutes)  338 (192–517)   PV isolation  3 (13.6%)   Septal ablation  1 (4.5%)   SVC isolation  3 (12%)   Procedural non-inducibility following ablation  20 (90.9%)  Post-Procedural Complications  0 (0%)   MI  0 (0%)   Perforation  0 (0%)   Stroke  0 (0%)  Variable  Patients (n = 22)  Electrophysiologic Study Findings   Atrial fibrillation  3 (13.6%)   Atrial flutter  19 (86.4%)    CTI-AFl  13 (59.1%)    IART  4 (18.2%)    Left-sided flutter  1 (4.5%)   FAT  4 (18.2%)  Ablation Aim   Ablate clinical arrhythmia  3 (13.6%)   Ablate clinical and induced arrhythmias  15 (68.2%)   Ablate clinical and induced arrhythmia plus substrate modification  4 (18.2%)  Ablation Performed   Right-sided ablation  21 (95.5%)   Left-sided ablation  3 (13.6%)   Length of ablation (minutes)  338 (192–517)   PV isolation  3 (13.6%)   Septal ablation  1 (4.5%)   SVC isolation  3 (12%)   Procedural non-inducibility following ablation  20 (90.9%)  Post-Procedural Complications  0 (0%)   MI  0 (0%)   Perforation  0 (0%)   Stroke  0 (0%)  Median (range) is presented for continuous variables. The 1-year, 3-year, and 5-year atrial arrhythmia recurrence rates were 10.0%, 21.7%, and 41.2%, respectively (Figure 2). Among the 10 patients who experienced a recurrence, the majority had atrial flutter, atrial fibrillation, or a combination of the two (Table 4); 5 patients experienced a recurrence of the index arrhythmia, whereas the other 5 patients experienced another atrial arrhythmia. 8 patients (36.4%) were on anti-arrhythmic medications following catheter ablation. 1 patient underwent an AV nodal ablation procedure. 7 patients (31.8%) underwent redo ablation procedures. On univariate analysis, there was no arrhythmia feature, ablation characteristic or cardiac structural parameter that was found to be a significant predictor of recurrence (Table 5). Table 4 Summary of atrial arrhythmia recurrence types, anti-arrhythmia medication use, and AV nodal and redo ablation procedures following catheter ablation therapy Variable  Patients (N = 22)  Recurrence type   Atrial flutter  4 (40.0%)   Atrial fibrillation  3 (30.0%)   EAT  2 (20.0%)   Atrial fibrillation/flutter  1 (10.0%)  Anti-arrhythmic medications after ablation   None  14 (63.6%)   Amiodarone  2 (9.1%)   Propafenone  2 (9.1%)   Sotalol  1 (4.5%)   Dronedarone  2 (9.1%)   Flecainide  1 (4.5%)   Dofetilide  0 (0%)  AV node ablation  1 (4.5%)  Redo ablation   No  15 (68.2%)   Once  3 (13.6%)   Twice  4 (18.2%)  Variable  Patients (N = 22)  Recurrence type   Atrial flutter  4 (40.0%)   Atrial fibrillation  3 (30.0%)   EAT  2 (20.0%)   Atrial fibrillation/flutter  1 (10.0%)  Anti-arrhythmic medications after ablation   None  14 (63.6%)   Amiodarone  2 (9.1%)   Propafenone  2 (9.1%)   Sotalol  1 (4.5%)   Dronedarone  2 (9.1%)   Flecainide  1 (4.5%)   Dofetilide  0 (0%)  AV node ablation  1 (4.5%)  Redo ablation   No  15 (68.2%)   Once  3 (13.6%)   Twice  4 (18.2%)  Table 5 Univariate analysis for identifying potential predictors of atrial arrhythmia recurrence Variable  Hazard ratio (95% CI)  P-value  Length of procedure (min)  1.00 (0.99, 1.01)  0.80  Age at procedure  0.96 (0.92, 1.01)  0.079  Right-sided ablation  0.80 (0.10, 6.57)  0.84  Left-sided ablation  0.46 (0.06, 3.76)  0.47  Atrial fibrillation  0.60 (0.08, 4.83)  0.63  Atrial flutter (all types)  0.55 (0.11, 2.72)  0.46  CTI-AFl  1.85 (0.50, 6.87)  0.36  IART  0.90 (0.25, 3.27)  0.87  Left-sided flutter  1.25 (0.15, 10.28)  0.84  FAT  2.02 (0.40, 10.17)  0.40  Severe RA size  0.48 (0.10, 2.27)  0.35  Severe RV size  1.72 (0.48, 6.18)  0.40  Severe RV dysfunction  1.42 (0.39, 5.12)  0.59  Variable  Hazard ratio (95% CI)  P-value  Length of procedure (min)  1.00 (0.99, 1.01)  0.80  Age at procedure  0.96 (0.92, 1.01)  0.079  Right-sided ablation  0.80 (0.10, 6.57)  0.84  Left-sided ablation  0.46 (0.06, 3.76)  0.47  Atrial fibrillation  0.60 (0.08, 4.83)  0.63  Atrial flutter (all types)  0.55 (0.11, 2.72)  0.46  CTI-AFl  1.85 (0.50, 6.87)  0.36  IART  0.90 (0.25, 3.27)  0.87  Left-sided flutter  1.25 (0.15, 10.28)  0.84  FAT  2.02 (0.40, 10.17)  0.40  Severe RA size  0.48 (0.10, 2.27)  0.35  Severe RV size  1.72 (0.48, 6.18)  0.40  Severe RV dysfunction  1.42 (0.39, 5.12)  0.59  Figure 1 View largeDownload slide Illustration of the atrium (letter "a"; drawn as incised and peeled back for clarity) with catheter ablation lines performed in the setting of EA. The ablation lesions depicted by the dark maroon lines reflect the current right-sided maze procedure lesions performed at our institution. A linear lesion extends from the inferior tricuspid annulus to the inferior vena cava, and a more lateral linear lesion from the same valve to the lateral/posterolateral atriotomy site. This latter lesion is extended in a cranial and caudal direction so that a complete intercaval lesion is created. The right atrial appendage is amputated and this is then used as an anchoring lesion for a linear lesion down to the tricuspid valve. Variably, a linear lesion is extended from the fossa ovalis/patent foramen ovale/secundum atrial septal defect repair site to the superior vena cava. The ellipses identify the most common sources for atrial arrhythmias, with CTI-AFl being the most common; IART and FAT both equally account for the majority of the remainder. Figure 1 View largeDownload slide Illustration of the atrium (letter "a"; drawn as incised and peeled back for clarity) with catheter ablation lines performed in the setting of EA. The ablation lesions depicted by the dark maroon lines reflect the current right-sided maze procedure lesions performed at our institution. A linear lesion extends from the inferior tricuspid annulus to the inferior vena cava, and a more lateral linear lesion from the same valve to the lateral/posterolateral atriotomy site. This latter lesion is extended in a cranial and caudal direction so that a complete intercaval lesion is created. The right atrial appendage is amputated and this is then used as an anchoring lesion for a linear lesion down to the tricuspid valve. Variably, a linear lesion is extended from the fossa ovalis/patent foramen ovale/secundum atrial septal defect repair site to the superior vena cava. The ellipses identify the most common sources for atrial arrhythmias, with CTI-AFl being the most common; IART and FAT both equally account for the majority of the remainder. Figure 2 View largeDownload slide Kaplan–Meier Curve demonstrating arrhythmia recurrence following atrial arrhythmia ablation (dotted lines represent 95% confidence intervals). Figure 2 View largeDownload slide Kaplan–Meier Curve demonstrating arrhythmia recurrence following atrial arrhythmia ablation (dotted lines represent 95% confidence intervals). Three patients died throughout the course of the study. 2 patients sustained likely cardiovascular deaths (one died from sudden death 3 months after the ablation while the other one died 11.5 years after) and the third patient death was non-cardiac. Discussion This report characterizes the medium and long-term outcomes in patients with EA who have undergone catheter-based ablation procedures to manage their symptomatic atrial arrhythmias. The results demonstrate very acceptable success rates, and are comparable with other ablation results in patients with complex congenital heart disease.11,12 Right-sided ablations constitute the majority of the procedures performed, with left-sided ablations rarely needed. Consistent with longitudinal follow-up studies in this group–multiple cardiac operations are not uncommon in these patients’ lifetime.13 Re-do tricuspid valve repair and replacement is necessary in almost a fifth of patients with this disease; a milieu associated with continued disease progression with regards to atrial stretch and dilatation. Through this mechanism, myocardial fibrosis and slower myocardial conduction times engender a more pro-arrhythmic environment. The necessity for redo procedures for these patients is an important element to discuss preemptively, yet it does not appear that it poses any higher risk to the patients. The procedures are almost exclusively right-sided and complications are very low. The electrophysiological findings also provide insight into the role of prior Maze surgery in the arrhythmia management of these patients. This intervention was present in more than a third of the study cohort. This does not reflect on the anti-arrhythmic efficacy of Maze surgeries, given that successful Maze procedures would not have presented with recurrence and consideration of catheter ablation. It is, nevertheless, important to recognize that a large fraction of patients required ablation of a CTI-AFl–a region of the right atrium that is not typically addressed by most modern modified right-sided Maze procedures. This common atrial flutter should be prevented by complete transmural lesions between lateral atriotomy and the tricuspid valve. Anatomically, the isthmus is grossly abnormal in these patients, related in part to the displacement of the tricuspid valvular apparatus, and also affected in part by the adjacent annular dilatation that accompanies the right ventricular abnormality and the tricuspid regurgitation. This constellation of findings suggests that an empiric cavotricuspid linear lesion should likely be considered standard at the time of cardiac repair. Given that this region can be excluded by implantation of a bioprosthetic valve, preemptive ablation or discussion with the cardiac surgeon to ensure this atrial flutter is addressed appears to be imperative.14 Furthermore, this does bring up for discussion whether all other right-sided modified Maze lesions are useful in preventing incisional/atriotomy flutters, yet this study was not powered to address this question. CTI-AFl was present in almost 60% of patients with a prior right-sided Maze procedure; hence, further investigation into the types of Maze procedures to prevent this occurrence should be considered. In principle, the incisional/atriotomy flutters should be prevented by a single, transmural, and continuous inter-caval line.15 Unfortunately, the sheer length of this lesion lends itself to inconsistencies in the presence and durability of bidirectional block unless a cut & sew approach is employed. Current Maze techniques utilize cryo-energy or radiofrequency for the majority of cases,16 and cut & sew techniques (even though associated with better longer term results), are also associated with more bleeding and longer bypass/operation times.17 Simply anchoring to the inferior vena cava from the atriotomy site as a single lesion set has not been evaluated, but conceptually this may reduce flutter with less pro-arrhythmia related to a shorter lesion set.15 Half of the cohort had undergone a procedure elsewhere, and we do not have enough data to surmise whether the ablations at our institution were to address primary arrhythmias that were inadequately treated, or whether new rhythm abnormalities developed de novo as a corollary to disease progression. With an average procedural time of 338 min, these procedures are more complex and challenging to perform; and consistent with the PACES/HRS Expert Consensus Statement on the use of catheter ablation in patients with congenital heart disease, this intervention should likely be undertaken at centres with experience in congenital heart disease management and complex arrhythmia ablation.18 A significant proportion of the patients studied experienced atrial fibrillation in addition to atrial flutter, and yet the atrial fibrillation was rendered non-inducible by an isolated right-sided procedure. This data does suggest that in addition to reentrant atrial arrhythmia, AF is not an uncommon occurrence in this patient population and left-sided ablations may, therefore, be warranted. In this subset of patients, atrial flutter may degenerate into atrial fibrillation in the context of abnormal myocardium with variable conduction velocity and anisotropy. This data provides insight into the mechanisms of atrial fibrillation in EA patients, which in turn gives direction regarding the ideal lesion set to be undertaken at the time of Maze surgery. Based on our findings, a right-sided Maze procedure may be effective in preventing arrhythmia recurrence, and a concomitant left-sided Maze may not be necessary in most patients. It does appear that to gain complete control of these substrate-based atrial arrhythmias adjunctive anti-arrhythmic medication remains necessary in a minority of patients. This highlights the utility of this procedure for the young patient, who can potentially avoid life-long anti-arrhythmics with their associated pro-arrhythmic risk. A third of patients, however, do require some anti-arrhythmic medication–speaking to the progressive nature of the disease, and the fact that patients continue to develop tricuspid valve regurgitation despite surgery–with around half of this patient group requiring re-operation within the 10–15 year time frame.19 This study represents the largest investigation of catheter-based ablation outcomes of atrial arrhythmias in EA patients. That being said, it is difficult to draw firm conclusions from the univariate analysis given the relatively small numbers. In essence, however, there is likely sufficient support for the claim that the presence of RV size and function, RA size, and prior Maze surgery are not strong predictors of arrhythmia recurrence. Hence, this procedural intervention can be considered in almost all patients with EA who have symptomatic atrial arrhythmias. Conclusions The present study provides novel data for guiding interventional anti-arrhythmic strategies in patients with EA and concomitant atrial arrhythmias. Peri-tricuspid reentrant atrial tachycardia remains a fundamental problem even after Maze procedures in this patient group. The study’s findings should be helpful in guiding preemptive anti-arrhythmic strategies in this patient group for pediatric and adult invasive electrophysiologists alike. Conflict of interest: Dr. Packer reports royalties from St. Jude Medical to the Mayo Clinic relevant to the topic of this study. He reports serving as an unpaid consultant or as a member of the advisory board relevant to this topic for Biosense Webster and St. Jude Medical. No conflicts of interest to disclose among the other authors. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. 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EuropaceOxford University Press

Published: Mar 1, 2018

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