Atrial myopathy, atriotomies, and fibrotic scars are the pathophysiological substrate of lines of conduction block, promoting atrial macroreentry. The aim of this study was to determine the acute and long-term outcome of radiofrequency catheter ablation (RFCA) for right atrial tachyarrhythmia (AT) in adults after cardiac surgery for congenital heart disease (CHD) and acquired heart disease (AHD) and predictors of these outcomes. Clinical records of adults after surgery for heart disease undergoing RFCA of right-sided AT were analyzed retrospectively. Multivariate analyses identified clinical and procedural factors predicting acute and long-term outcomes. A total of 372 patients (69% men; age 61 ± 15 years) after surgical repair of CHD (n = 111) or AHD (n = 261) were studied. Cavotricuspid isthmus–dependent atrial flutter (CTI-AFL) was observed in 300 patients and non-CTI-AFL in 72 patients. Ablation was successful in 349 cases (94%). During a mean follow-up of 51 ± 30 months, recurrences were observed in 24.5% of patients. Multivariate analysis showed that non-CTI-AFL (hazard ratio [HR] 1.78, 95% confidence interval [CI] 1.1 to 2.9) and CHD (HR 1.75, 95% CI 1.07 to 2.9) were independent predictors of long-term recurrences. Multivariate analysis showed that female gender (HR 2.29, 95% CI 1.6 to 3.3), surgery for AHD (HR 95% 2.31, 95% CI 1.5 to 3.7), and left atrial dilatation (HR 2.1, 95% CI 1.3 to 3.2) were independent predictors of long-term atrial fibrillation. In conclusion, RFCA of right-sided AT after cardiac surgery is associated with high acute success rates and significant long-term recurrences. Non–CTI-dependent AFL and surgery for CHD are at higher risk of recurrence. Atrial fibrillation is common during follow-up, particularly in patients with AHD and enlarged left atrium.
Atrial tachyarrhythmias (ATs) are a well-known complication of atrial incision during heart surgery. Atriotomies, implants of grafts, and fibrotic scars are the pathophysiological substrate for the creation of lines of block that promote atrial macroreentry. Supraventricular tachycardias are common in patients with congenital heart disease (CHD) and are associated with increased morbidity and mortality. Patients with acquired heart disease (AHD), treated with coronary artery bypass grafting (CABG) or valve surgery, also show a high incidence of supraventricular tachyarrhythmias. Radiofrequency catheter ablation (RFCA) can treat AT ; however, the arrhythmogenic substrate in patients with previous surgery is complex, and targeting these arrhythmias requires detailed mapping for successful ablation. Studies have described the success of RFCA in these substrates; however, long-term follow-up information is limited. Studies to date have reported rates of recurrence as high as 27% to 52%, but the characteristics of recurrences have not been adequately studied. Therefore, the aims of the present investigation were (1) to evaluate the effectiveness of the RFCA procedure of right atrial AT after the surgical repair of heart diseases and (2) to analyze the long-term outcome of such patients describing predictors of recurrences and of adverse events.
Methods
A survey of Electrophysiology Laboratories in Spain identified 372 patients from 9 centers who had been referred for ablation of postoperative AT from 1998 to 2011. Investigators from each participating center identified consecutive patients referred for RFCA of right AT after surgery for CHD or AHD. To recruit a sample with more homogeneous tachyarrhythmia mechanisms, only those arrhythmias originating in the right atrium were considered; those that originated in the left atrium were excluded because left atrial arrhythmias require a more complex approach and procedure. The study was approved by the local ethics committee from all centers.
Data regarding congenital defects and surgical history were obtained from hospital records. The clinical and electrophysiological features of the index tachycardia were reviewed, and number and characteristics of AT circuits targeted during the ablation procedure were noted. The patients were divided into 2 groups on the basis of the underlying heart disease: those operated on for CHD and those operated on for AHD. Patients from the CHD group were further divided into 2 subgroups: those operated for isolated ostium secundum atrial septal defect (OS-ASD), and those operated on for complex CHD which represent a heterogeneous population with more complex heart defects requiring more complex surgical interventions with a greater number of sutures and potential lines of block. Patients operated on for AHD were grouped into those who underwent surgery for pure coronary artery disease (referred for isolated CABG) or valvular related procedures (including valve surgery and mixed procedures). Data from echocardiograms were from the most recent examinations at the time of ablation. Left ventricular ejection fraction was determined with the Simpson method evaluated in the 4-chamber apical view. Left atrium dilatation was defined as >40 mm in the paraesternal long-axis view. Pulmonary hypertension was defined as systolic pulmonary artery pressure >40 mm Hg.
The electrophysiological study (EPS) and the ablation procedure were performed using multipolar electrode catheters that were inserted percutaneously into the femoral or internal jugular veins and were guided into the coronary sinus, high right atrium, and His bundle recording positions. Multielectrode catheters around the free wall, interatrial septum, and/or the tricuspid annulus were also used to help in the identification of the tachycardia circuit.
Entrainment mapping protocols aimed to delineate the tachycardia circuit and identify the protected zone of slow conduction. Briefly, concealed entrainment from the tricuspid isthmus was performed to confirm or exclude the cavotricuspid isthmus (CTI) as the protected zone of slow conduction. Bipolar activation and voltage maps were constructed using electroanatomic mapping systems during AT to (1) identify the underlying mechanism and (2) select target sites for ablation. In patients with non–CTI-dependent atrial flutter (AFL), the circuits were identified predominantly using 3-dimensional (3D) mapping systems and entrainment mapping maneuvers. On the basis of activation maps, 3 different types of AT were distinguished: (1) typical AFL: a single (counter) clockwise, CTI-dependent macroreentrant circuit; (2) non–CTI-dependent AFL: a macroreentrant tachycardia involving scar tissue, suture lines, or prosthetic materials, with the slow conduction zone located in areas of the right atrium different from the CTI; and (3) microreentry or focal AT: electrical activation originating from a small, circumscribed region from where it expands to the remainder of the atria.
For CTI-dependent AFL, linear ablation in the CTI was performed until termination of the tachycardia was achieved and bidirectional conduction block from the tricuspid annulus to the inferior vena cava was established. In patients with non–CTI-dependent AFL, RF energy was delivered to the narrowest and protected part of the AFL circuit (slow conduction zone), which typically involved a scar and the tricuspid annulus, the inferior vena cava, or the superior vena cava. Ablation was continued until complete block along these lines was achieved. Focal ATs were successfully ablated at the site of earliest activation. Success rates are reported for individual patients in relation to the clinical arrhythmias and not related to the overall number of induced tachyarrhythmias during the EP study.
After completion of the ablation procedure, all patients were followed by the electrophysiology team at each hospital. All centers carried out a thorough monitoring of adverse events, including tachyarrhythmia recurrence, onset of heart failure, development of atrial fibrillation (AF), and death. All data related to the clinical and electrophysiological characteristics of the recurrences and the reablation procedures were collected.
Quantitative variables are given as mean ± standard deviation and were compared using t tests. Variables that did not follow normal distributions were compared using the Mann–Whitney test. Categorical variables were summarized by the number of patients and percentage. Comparison of categorical variables was performed with the chi-square test (or Fisher’s exact when appropriate). Predictors of survival free of recurrences and survival free of AF were analyzed using the Cox proportional hazards model through a backward stepwise regression. Variables that were p <0.1 in the univariate analysis were included in the multivariate analysis. Multicollinearity tests of the model were performed to determine the presence of interaction between variables. For all tests, a value of statistical significance of p <0.05, 2-sided, was used. The data analysis was performed with SPSS 18.3 (SPSS Inc., Chicago, IL).
Results
The study population included 372 patients, 111 of whom had undergone surgery for correction of CHD and 261 of whom had undergone surgery for AHD ( Figure 1 ). Table 1 provides the types of CHD and AHD and the surgical procedures that had been performed. The most common congenital disease was isolated OS-ASD (n = 47, 42% of patients with CHD). Six patients had undergone surgery for miscellaneous conditions but were included in the group of valvular-related procedures because surgical repair of these defects includes atriotomes and cannulations similar to those performed in valve-related interventions.
| Congenital Heart Disease (n = 111) | Surgical Procedure |
| Ostium secundum ASD (n=47) | Pericardial patch closure(n=8) Direct surgical closure (n= 39) |
| Sinus venosus ASD (n=2) | Surgical closure (n=2) |
| Ostium primum ASD (n=2) | Surgical closure (n=2) |
| ASD + pulmonary stenosis (n=4) | Surgical closure + infundibulectomy (n=4) |
| ASD + anomalous venous drainage (n=3) | Surgical closure + AVD correction (n=3) |
| Valvular (n=11) | Fontan Procedure (n=2) ; Valve replacement (n=3) Valvuloplasty (n=1) : Infundibulectomy (n=5) |
| Tetrallogy of Fallot (n=15) | Total correction (n=15) |
| Isolated anomalous venous drainage (n=5) | Anomalous venous drainage correction (n=5) |
| Transposition of the great arteries (n=7) | Mustard/Jatene Procedure(n=6) Rastelli Procedure (n=1) |
| Mixed procedures (n=3) | |
| Univentricular heart (n=6) | Modified Fontan Procedure (n=6) |
| Ventricular septal defect (n=4)) | Surgical closure (n=4) |
| Ebstein Anomaly (n=1) | Valve replacement (n=1) |
| Accessory pathway (n=1) | Surgical section (n=1) |
| Acquired Heart Disease (n = 261) | Surgical Procedure |
| Aortic valve disease (n=52) | Valve replacement (biological prosthesis) (n=11) Valve replacement (mechanical prosthesis) (n=39) Valve Repair (n=1) ; Ross Procedure (n=1) |
| Mitral valve disease (n=54) | Valve replacement (biological prosthesis) (n=3) Valve replacement (mechanical prosthesis) (n= 33) Valve Repair (n=17) |
| Mitral + Aortic valve disease (n=16) | Valve replacement (biological prosthesis) (n=2) Valve replacement (mechanical prosthesis) (n=13) Valve Repair (n=1) |
| Mitral + Tricuspid valve disease (n=4) | Valve replacement (mechanical prosthesis) (n=4) |
| Aortic valve disease + coronary artery disease (n=14) | Valve replacement (biological prosthesis) (n=6) + CABG Valve replacement (mechanical prosthesis) (n=8)+ CABG |
| Mitral valve disease + coronary artery disease (n=12) | Valve replacement (mechanical prosthesis) (n=9)+ CABG Valve Repair (n=3) + CABG |
| Mitral + Aortic valve disease + coronary artery disease (n=2) | Valve replacement (mechanical prosthesis) (n=2)+ CABG |
| Aortic, Mitral and Tricuspid valve disease + coronary artery disease (n=1) | Mitral and Aortic valve replacement + Tricuspid Anuloplasty (n=1) + CABG |
| Coronary artery disease (n=100) | Coronary artery bypass graft (n= 100) |
| Obstructive hypertrophic cardiomyopathy (n=2) | Miomectomy + Mitral Valve Replacement (n=2) |
| Post infarction ventricular septal defect (n=1) | Surgical closure (n=1) |
| Mixoma (n= 3) | Surgical resection (n= 4) |
The baseline characteristics of the sample are presented in Table 2 . Most patients were men, and the mean age at referral for ablation was 61 ± 15 years. Mean time from surgical procedure to ablation was 112 ± 108 months.
| Variable | Total ( n=372 ) | Congenital Heart Disease ( n=111 ) | Acquired Heart Disease ( n= 261 ) | p |
|---|---|---|---|---|
| Female gender | 116 (31 %) | 51 (46 %) | 65 (25 %) | <0.001 |
| Age at Surgery (years) | 49 ± 22 | 26 ± 20 | 59 ± 13 | <0.001 |
| Age at Ablation (years) | 61 ± 15 | 47 ± 15 | 67 ± 10 | <0.001 |
| Left ventricular ejection fraction (%) | 54 ± 12 | 57 ± 11 | 53 ± 13 | 0.005 |
| Left atrium (mm) | 44 ± 6 | 43 ± 7 | 45 ± 6 | 0.04 |
| Pulmonary hypertension | 123 (33 %) | 39 (35 %) | 84 (32 %) | 0.33 |
| Clinical Presentation | ||||
| Palpitation | 194 (52 %) | 71 (64 %) | 123 (47 %) | 0.003 |
| Heart Failure | 30 (8 %) | 5 (4,5 %) | 25 (9,5 %) | 0.14 |
| Syncope | 14 (4 %) | 5 (4,5 %) | 9 (3,5 %) | 0.34 |
| Dyspnea | 103 (28 %) | 23 (21 %) | 80 (30 %) | 0.06 |
| Time Surgery-Ablation (months) | 112 ± 108 | 192 ± 130 | 77 ± 70 | <0.001 |
Results of EPS are presented in Table 3 . At the time of ablation, 48% (n = 178) of patients had used and failed on at least 1 antiarrhythmic drug. Mean tachycardia CL was 270 ± 50 ms, and it was longer in patients with CHD compared to patients with AHD. This resulted in higher 1:1 conduction and higher heart rate in patients with CHD compared to patients with AHD (19% vs 3%, p <0.001, and 125 vs 111 beats/min, p = 0.002, respectively). The EP study before the ablation showed that the clinical arrhythmia was macroreentry around tricuspid annulus (CTI-dependent AFL) in 300 patients (mean cycle length 264 ± 47 ms) and non–CTI-dependent AFL in 68 patients (cycle length 288 ± 55 ms). As described, the vast majority of the AT were macroreentrant tachycardias; only 4 cases (1%) were focal AT. Because of the limited number of focal atrial tachycardias, these were included in the non–CTI-dependent AFL group.
| Variable | Total (n=372) | Congenital Heart Disease (n=111) | Acquired Heart Disease (n=261) | p |
|---|---|---|---|---|
| Typical atrial flutter | 289 (77 %) | 63 (57 %) | 226 (87 %) | <0.001 |
| Heart rate (bpm) | 116 ± 35 | 125 ± 33 | 111 ± 34 | 0.002 |
| 1:1 Conduction | 29 (8 %) | 21 (19 %) | 8 (3 %) | < 0.001 |
| Cycle Length (ms) | 270 ± 50 | 285 ± 58 | 261 ± 43 | <0.001 |
| Slow Conduction zone | ||||
| CTI | 300 (81 %) | 61 (55 %) | 239 (92 %) | <0.001 |
| Counterclockwise | 254 (85 %) | 40 (70 %) | 214 (92 %) | 0.001 |
| Non-CTI atrial flutter | 72 (19 %) | 50 (45 %) | 22 (8 %) | <0.001 |
| Anterior | 8 (11 %) | 5 (10 %) | 3 (14 %) | 0.87 |
| Lateral | 43 (60 %) | 32 (64%) | 11 (50%) | 0.4 |
| Posterior | 6 (8 %) | 3 (14 %) | 3 (14 %) | 0.99 |
| Septal | 15 (21%) | 10 (20%) | 5 (23%) | 0.8 |
| Type of catheter | ||||
| 8-mm tip | 204 (55%) | 45 (41%) | 152 (58%) | 0.002 |
| Irrigated-tip | 122 (33%) | 37 (34%) | 85 (33%) | 0.95 |
| > 1 circuit identified | 58 (16 %) | 40 (37 %) | 18 (7 %) | 0.001 |
| > 1 circuit ablated | 42 (11 %) | 32 (29 %) | 10 (3,8 %) | 0.001 |
| Procedure Duration (min) | 130 ± 89 | 195 ± 107 | 102 ± 62 | <0.001 |
| Fluoroscopy time (min) | 30 ± 23 | 39 ± 29 | 25 ± 18 | <0.001 |
| Electroanatomic mapping system | 124 (33 %) | 70 (63 %) | 54 (21 %) | <0.001 |
| Success rate | 349 (94 %) | 98 (88 %) | 251 (96 %) | 0.008 |
| Complications rate | 13 (3,5 %) | 6 (5,4 %) | 7 (2,7 %) | 0.2 |
Most patients with AHD had typical CTI-dependent AFL compared to patients with CHD (92% vs 55%, p <0.001). In contrast, non–CTI-dependent AFL was more common in patients with CHD compared to patients with AHD (45% vs 8%, p <0.0001). In patients with non–CTI-dependent AFL, the most frequent area of slow conduction was the anterolateral RA, followed by the septal region ( Table 3 ). Additional tachycardia circuits were identified in 58 patients (16%). Overall, 460 circuits were mapped in 372 patients. In the group of CHD, presence of more than one circuit responsible for the tachycardia was observed more frequently than in patients with AHD (37% vs 7%, p <0.001), and therefore, a greater number of circuits were targeted during the ablation procedure (mean 1.3 vs 1.04, p <0.001). In patients with CTI-dependent AFL, 23 patients (8%) presented with additional tachycardia circuits. In contrast, in patients presenting with non–CTI-dependent AFL, more than 2 tachyarrhythmia circuits were mapped in 35 patients (48%; p <0.001).
The characteristics of the RFCA procedure are also presented in Table 3 . Mean success rate for the overall population of patients was 94%. The success rate was higher in patients operated for AHD compared to patients operated for CHD (96% vs 88%, p = 0.008), and a trend was observed for higher efficacy of ablation in CTI-dependent AFL compared to non–CTI-dependent AFL (95% vs 89%, p = 0.09). Successful RFCA was obtained in 93% of patients with isolated OS-ASD, 84% of patients operated on for complex CHD, (p = 0.2), and 97% of patients treated with isolated CABG, compared to 96% in patients who underwent valvular-related procedure, p = 0.6.
During a mean follow-up of 51 ± 30 months, 91 patients (24.5%) presented with at least one recurrence ( Table 4 ); of these, 51 (56%) occurred during the first year, with a mean time to recurrence of 17 ± 5 months. In 46 cases (51% of recurrences), reablation was performed and the same substrate was found in recurrent arrhythmia in 54% of cases. The reablation was effective in 94% of cases. Figure 2 shows multivariate analysis with a Cox proportional hazards model of predictors of AT recurrence after RFCA. Three variables were identified as independent predictors of recurrences: surgery for CHD, non–CTI-dependent AFL, and fluoroscopy time. Figure 3 shows survival free of recurrences according to underlying heart disease (congenital vs acquired). Figure 4 shows survival free of recurrences according to type of macroreentry (CTI-dependent AFL compared to non–CTI-dependent AFL).
| Variable | Total (n=372) | Congenital Heart Disease (n=111) | Acquired Heart Disease (n=261) | P |
|---|---|---|---|---|
| Follow-up (months) | 51 ± 30 | 57 ± 46 | 48 ± 34 | 0.37 |
| Recurrence | 91 (24,5 %) | 46 (41 %) | 45 (17 %) | <0.001 |
| Time to Recurrence (months) | 17 ± 5 | 15 ± 23 | 20 ± 28 | 0.42 |
| Multiple Recurrences | 28 (31 %) | 18 (39 %) | 10 (22 %) | 0.11 |
| Re-Ablation | 46 (51 %) | 25 (54 %) | 21 (47 %) | 0.53 |
| Time to Re-ablation (months) | 16 ± 23 | 21 ± 28 | 11 ± 13 | 0.56 |
| Re ablation Success rate | 94 % | 94 % | 93 % | 0.99 |
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