Radiofrequency Catheter Ablation Therapy Research Articles

Safety and Effectiveness of Exercise-Based Cardiac Rehabilitation for Patients With Atrial Fibrillation Following Radiofrequency Catheter Ablation Therapy: A Systematic Review and Meta-Analysis

Safety and Effectiveness of Exercise-Based Cardiac Rehabilitation for Patients With Atrial Fibrillation Following Radiofrequency Catheter Ablation Therapy: A Systematic Review and Meta-Analysis

Exploring interpretability in deep learning prediction of successful ablation therapy for atrial fibrillation.

Background: Radiofrequency catheter ablation (RFCA) therapy is the first-line treatment for atrial fibrillation (AF), the most common type of cardiac arrhythmia globally. However, the procedure currently has low success rates in dealing with persistent AF, with a reoccurrence rate of ∼50% post-ablation. Therefore, deep learning (DL) has increasingly been applied to improve RFCA treatment for AF. However, for a clinician to trust the prediction of a DL model, its decision process needs to be interpretable and have biomedical relevance. Aim: This study explores interpretability in DL prediction of successful RFCA therapy for AF and evaluates if pro-arrhythmogenic regions in the left atrium (LA) were used in its decision process. Methods: AF and its termination by RFCA have been simulated in MRI-derived 2D LA tissue models with segmented fibrotic regions (n = 187). Three ablation strategies were applied for each LA model: pulmonary vein isolation (PVI), fibrosis-based ablation (FIBRO) and a rotor-based ablation (ROTOR). The DL model was trained to predict the success of each RFCA strategy for each LA model. Three feature attribution (FA) map methods were then used to investigate interpretability of the DL model: GradCAM, Occlusions and LIME. Results: The developed DL model had an AUC (area under the receiver operating characteristic curve) of 0.78 ± 0.04 for predicting the success of the PVI strategy, 0.92 ± 0.02 for FIBRO and 0.77 ± 0.02 for ROTOR. GradCAM had the highest percentage of informative regions in the FA maps (62% for FIBRO and 71% for ROTOR) that coincided with the successful RFCA lesions known from the 2D LA simulations, but unseen by the DL model. Moreover, GradCAM had the smallest coincidence of informative regions of the FA maps with non-arrhythmogenic regions (25% for FIBRO and 27% for ROTOR). Conclusion: The most informative regions of the FA maps coincided with pro-arrhythmogenic regions, suggesting that the DL model leveraged structural features of MRI images to identify such regions and make its prediction. In the future, this technique could provide a clinician with a trustworthy decision support tool.

Overcoming High Impedance in the Transitional Area of the Distal Great Cardiac Vein during Radiofrequency Catheter Ablation of Ventricular Arrhythmia.

(1) Background: Radiofrequency catheter ablation (RFCA) is an essential treatment for ventricular arrhythmia (VA). However, high impedance in the transitional area of the distal great cardiac vein (TAODGCV) often leads to ablation failure. This study aimed to explore the factors influencing impedance and identify effective ways to reduce impedance. (2) Methods: A total of 156 patients with VA arising from the TAODGCV received RFCA therapy at our center from October 2009 to August 2021 and were retrospectively analyzed. Local impedance variation during RFCA was monitored, recorded, and analyzed. (3) Results: The impedance increased from the proximal to distal portions of the TAODGCV and decreased by increasing the saline flow rate at the same site. To overcome high impedance, we implemented the following strategies: (1) Reset the upper limit impedance to 300 Ω and accelerate the saline flow rate to 60 mL/min (effective in 118 of 144 patients); (2) turn off the upper limit impedance (effective in eleven of 21 patients); (3) use high-flow-rate irrigation devices (effective in five of 15 patients); and (4) increase the upper limit temperature (effective in six of ten patients). (4) Conclusions: In the TAODGCV, local impedance is mainly influenced by the target site location and saline flow rate. We concluded several methods to overcome the high impedance and contribute to a successful ablation.

Recovery of mental health parameters after ablation in patients with premature ventricular complex induced cardiomyopathy.

The diagnosis of premature ventricular complex-induced cardiomyopathy (PVC-CMP) is based on the presence of common PVCs associated with cardiomyopathy without a reasonable etiology for the cardiomyopathy. The treatment strategies for PVCs include radiofrequency catheter ablation (RFCA) and drug therapy. In addition to physiological symptoms, PVCs also cause psychological symptoms. Impaired quality of life and sleep quality parameters have been observed in these patients. The aim of the study was to investigate the effects of RFCA treatment on cardiac function and psychiatric health parameters. A total of 60 consecutive patients undergoing catheter ablation for cardiomyopathy-associated idiopathic PVCs were included in this study. Each patient underwent a three-lead ECG recording over a 24-hour period during normal daily ambulatory activities at a screening visit before and 3 months after RFCA. The Beck Depression Inventory Index (BDI-I), Beck Anxiety Inventory Index (BAI-I), and Global Pittsburgh Sleep Quality Index (GPSQI) were assessed before and after RFCA. PVC frequency decreased from 21.99±6.10 to 1.2% after RFCA. Left ventricular ejection fraction (LVEF) increased from 0.41±0.05 to 0.50±0.06 after RFCA (p<0.001). GPSQI (4.90±1.99 to 3.80±1.75, p <0.001), BDI-I (14.12±7.05 to 8.67±5.13, p<0.001), BAI-I (15.12±6.89 to 9.40±5.11, p<0.001) values decreased after RFCA. We found a moderate negative correlation between GPSQI, BDI-I, BAI-I and LVEF (rs=-0.56; p <0.001, rs=-0.55; p<0.001 and rs=-0.62; p<0.001). In addition to the recovery of systolic and diastolic cardiac functions, mental and psychiatric health parameters also showed great improvement.

A Simple Logistic Regression Model for Predicting the Likelihood of Recurrence of Atrial Fibrillation Within 1 Year After Initial Radio-Frequency Catheter Ablation Therapy.

BackgroundThe clinical factors associated with the recurrence of atrial fibrillation (Af) in patients undergoing catheter ablation (CA) are still ambiguous to date.Purpose1. To recognize preoperative serologic factors and clinical features associated with Af recurrence after the first ablation treatment. 2. To Develop a Logical Regression Model for Predicting the Likelihood of Recurrence Within 1 Year After the Initial Radio-Frequency Catheter Ablation (RFCA) Therapy.MethodsAtrial fibrillation patients undergoing RFCA at our institution from January 2016 to June 2021 were included in the analysis (n = 246). A combined dataset of relevant parameters was collected from the participants (clinical characteristics, laboratory results, and time to recurrence) (n = 200). We performed the least absolute shrinkage and selection operator (Lasso) regression with 100 cycles, selecting variables present in all 100 cycles to identify factors associated with the first recurrence of atrial fibrillation. A logistic regression model for predicting whether Af would recur within a year was created using 70% of the data as a training set and the remaining data to validate the accuracy. The predictions were assessed using calibration plots, concordance index (C-index), and decision curve analysis.ResultsThe left atrial diameter, albumin, type of Af, whether other arrhythmias were combined, and the duration of Af attack time were associated with Af recurrence in this sample. Some clinically meaningful variables were selected and combined with recognized factors associated with recurrence to construct a logistic regression prediction model for 1-year Af recurrence. The receiver operating characteristic (ROC) curve for this model was 0.8695, and the established prediction model had a C-index of 0.83. The performance was superior to the extreme curve in the decision curve analysis.ConclusionOur study demonstrates that several clinical features and serological markers can predict the recurrence of Af in patients undergoing RFCA. This simple model can play a crucial role in guiding physicians in preoperative evaluation and clinical decision-making.

Correction: Effect of Exercise on Outcome after Ventricular Tachycardia Ablation in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy.

Competitive sports and intensive exercise are associated with adverse outcomes in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). This study aimed to assess the role of exercise on long-term results of radiofrequency catheter ablation (RFCA) therapy of ventricular tachycardia (VT) in patients with ARVD/C. Exercise participation was evaluated by telephone or in-person interviews in patients from our ARVD/C registry with previous VT ablation (38 patients, 26 males, age 52.6±14.1years). Of 38 patients, 30 were involved in sports activities before RFCA. Only the minority of our patient population (21.1%) had a sedentary lifestyle before RFCA; 42.1 and 36.8% reported recreational or competitive sports, respectively. During the follow-up period of 52.5±31.4 months, 23 of the total 38 patients with previous RFCA (60.5%) remained free from VT recurrence. In univariate and binary logistic regression analysis, only advanced age was significantly associated with VT recurrence, with a hazard ratio of 1.15, and 95% confidence interval 1.05–1.26 (p=0.004). The results of our observational study indicate that recreational sports do not impair long-term results after RFCA treatment compared with a sedentary lifestyle. Furthermore, the dynamic component of recreational exercise did not affect the outcome of VT ablation in our patient population. Recreational exercise at low to moderate intensity is not associated with an increased risk for VT recurrence after catheter ablation in patients with ARVD/C.

Effect of Exercise on Outcome after Ventricular Tachycardia Ablation in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy.

Competitive sports and intensive exercise are associated with adverse outcomes in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). This study aimed to assess the role of exercise on long-term results of radiofrequency catheter ablation (RFCA) therapy of ventricular tachycardia (VT) in patients with ARVD/C. Exercise participation was evaluated by telephone or in-person interviews in patients from our ARVD/C registry with previous VT ablation (38 patients, 26 males, age 52.6±14.1years). Of 38 patients, 30 were involved in sports activities before RFCA. Only the minority of our patient population (21.1%) had a sedentary lifestyle before RFCA; 42.1 and 36.8% reported recreational or competitive sports, respectively. During the follow-up period of 52.5±31.4 months, 23 of the total 38 patients with previous RFCA (60.5%) remained free from VT recurrence. In univariate and binary logistic regression analysis, only advanced age was significantly associated with VT recurrence, with a hazard ratio of 1.15, and 95% confidence interval 1.05-1.26 (p=0.004). The results of our observational study indicate that recreational sports do not impair long-term results after RFCA treatment compared with a sedentary lifestyle. Furthermore, the dynamic component of recreational exercise did not affect the outcome of VT ablation in our patient population. Recreational exercise at low to moderate intensity is not associated with an increased risk for VT recurrence after catheter ablation in patients with ARVD/C.

Combination of doxorubicin liposomes with left atrial appendage radiofrequency catheter ablation to reduce post-ablation recovery of electrical conduction.

AimsTo determine whether use of radiofrequency catheter ablation (RFCA) combined with intravenously administered liposomal doxorubicin (L-DOX) facilitates a reduction in the recovery of post-ablation electrical conduction.MethodsCircumferential ablation was performed on the epicardial surface of the left atrial appendage (LAA) in New Zealand White rabbits, and L-DOX was then administered intravenously. Fluorescence spectrophotometry was used to assess reagent bio-distribution, while Western blots and immunohistochemistry were used to assess the localization of the apoptotic markers Bcl-2, Bax, and cleaved CASP3 in the LAA. Liver, kidney, and cardiac functions were also measured to evaluate the safety of this approach.ResultsAt 1 week and 1 month after RFCA, a pacing electrocardiogram could not be detected in most of the rabbits that had received the combined RFCA and L-DOX therapy. L-DOX began to target the LAA on the second day after RFCA. L-DOX treatment increased the apoptosis of cardiomyocytes in the regions peripheral to the necrotic area induced by RFCA. Doxorubicin had some effect on liver and kidney function, but these effects were reversible and did not affect survival.ConclusionThe present results provide evidence that L-DOX treatment can reduce the recovery of electrical conduction after RFCA therapy owing to L-DOX-induced apoptosis of cardiomyocytes in the ablated area and the proximal transition zone of the LAA.

Value of cystatin C in predicting atrial fibrillation recurrence after radiofrequency catheter ablation.

BackgroudRecent studies have demonstrated that cystatin C is a valuable risk marker for cardiovascular disease morbidity and mortality. Therefore, we hypothesized that the pre-ablation cystatin C level was associated with post-ablation atrial fibrillation (AF) recurrence.Methods207 patients were enrolled and completed in this prospective observational study. Patients with AF scheduled for receive radiofrequency catheter ablation (RFCA) therapy were screened for the study. Before ablation therapy, electrocardiogram, 24 h holter monitor, transesophageal echocardiography, serum cystatin C, high-sensitivity C-reactive protein, creatinine levels, and routine blood examinations were examined. After ablation, patients were followed up every week for the first month, and then at 2, 3, 6, 9, and 12 months. Thereafter, patients came back to out-patient clinic every six months regularly. Electrocardiogram or 24 h holter monitor were repeated if the patient experienced palpitations or every six months. AF recurrence was defined as atrial fibrillation/atrial flutter or atrial tachycardia lasting ≥ 30 seconds within three months after therapy.ResultsCompared to patients with no AF recurrence, patients with recurrence had longer AF history (P = 0.007), more early recurrence (P = 0.000), a larger left atrium (P = 0.004), and higher pre-ablation cystatin C levels (P = 0.000). Multivariate regression analysis revealed that cystatin C and left atria (LA) diameter were risk factors for AF recurrence. After adjusting for LA diameter, the risk of AF recurrence increased 30% with every milligram cystatin C elevation (95% CI: 1.117–1.523).ConclusionsPre-ablation cystatin C levels were associated with AF recurrence after RFCA therapy, an optimal cut-off value of 1.190 mg/L (sensitivity = 0.576; specificity = 0.851).

Supraventricular arrhythmias in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy associate with long-term outcome after catheter ablation of ventricular tachycardias.

This study aimed to assess the impact of supraventricular tachycardia (SVT) on long-term results of radiofrequency catheter ablation therapy of ventricular tachycardia (VT) in a large cohort of patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). Supraventricular tachycardia occurrence has been studied in patients from our ARVD/C registry (70 patients, 48 male, age 53.2 ± 14.0, 45 patients (64.3%) with previous VT ablation). SVT were diagnosed in 26 of 70 patients (37.1%). Atrial fibrillation (AF) was the most frequent atrial arrhythmia, diagnosed in 17 patients (24.3%). In univariate analysis advanced age, clinical symptoms of heart failure, enlarged right atrium, diagnosis of significant tricuspid regurgitation (TR), and inappropriate implantable cardioverters-defibrillators therapy were associated with SVT. In binary logistic regression analysis only heart failure: hazard ratio (HR) 10.89, 95% confidence interval (95% CI) 1.08-109.96 (P = 0.043) and significant TR: HR 4.79, 95% CI 1.35-16.33 (P = 0.015) remained associated with SVT. In patients with previous VT ablation Cox multiple regression survival analysis revealed older age (≥53 years): HR 4.63, 95% CI 1.51-14.24 (P = 0.008) and SVT: HR 3.01, 95% CI 1.15-7.89 (P = 0.025) as predictors for VT recurrence during the follow-up. SVT and older age are associated with the recurrence of VT after catheter ablation in patients with ARVD/C.

Abstract 072: Impact of Chronic Diabetes on Periprocedural Outcomes Among Patient With Atrial Fibrillation and Flutter Who Underwent Radiofrequency Catheter Ablation Therapy (RFA). Report From the NIS 2014.

Background: Diabetes has been associated with complications and poor perioperative outcomes. In Radiofrequency catheter ablation - therapy of choice for drug refractory atrial fibrillation and flutter, association between diabetes and procedural complications are less documented. Objectives: To examine if there is a difference in perioperative complications in patients with chronic diabetes who underwent RFA for atrial fibrillation/flutter when compared with non-diabetics. Methods: We selected patients &gt; 45 years from the National Inpatient Survey data 2014. We identified 8356 patients (69.6 ± 9.1yrs) who underwent catheter ablation. Logistic regression analyses were performed to investigate the difference in perioperative complications (hemorrhage, cardiac perforation, cardiac complications, respiratory complications, peripheral vascular complications, stroke and in-hospital mortality) between diabetics and non-diabetics. All models were adjusted for age, gender, race, residential income, insurance, co-morbidities, hospital bed size, hospital location/teaching status, hospital region, length of stay and median household income. Results: Among our selected 8356 patients, 5777(69.1%) were non-diabetics, 2203(26.4%) had uncomplicated diabetes and 376 (4.5%) complicated diabetes. Overall there were 634 events (240 hemorrhages, 56 perforations, 163 cardiac complications, 43 respiratory complications, 12 strokes, 40 peripheral vascular complications and 80 in-hospital death. Rates of complications were the same among diabetes and non-diabetics. In the multivariate models, the odds of complications remain statistically non-significant across all the groups. However, among all the patients who underwent RFA, there is an increased odds of hemorrhage among patients with Medicare insurance versus private insurance (OR 1.73 95%CI 1.11-2.70), peripheral vascular complications among hospitals in the south (OR 3.35 95%CI 1.30-9.62), respiratory complications among patients with CHF (4.60 95%CI 1.68-12.60), death among patients with renal failure (OR 2.22 95%CI 1.32-3.73) and hospitals in the south (2.55 95% CI 1.08-6.0) and west (OR 3.23 95%CI 1.25-8.3) compared to the northeast. Odds of stroke were less among both urban non-teaching (OR 0.02 95%CI 0.01 - 0.34) and teaching hospital (OR 0.05 95%CI 0.01-0.36) when compared to rural hospital. Conclusions: RFA has a similar procedural safety in diabetics when compared to non-diabetic patients. It remains a safe procedure in diabetics with drug-refractory atrial fibrillation and flutter. Renal failure, CHF, type of Insurance, hospital location and teaching status are predictors of complications after RFA.

Unroofed coronary sinus detected by 2D/3D echocardiography in a patient referred to catheter ablation for atrial fibrillation

A 67-year-old female visited our echo lab for a preoperative screening exam before radiofrequency catheter ablation for atrial fibrillation. Transthoracic echocardiography revealed abnormal color flow signal in the right atrium, and following 2D/3D transesophageal echocardiography proved partial type of unroofed coronary sinus. Absence of associated congenital abnormalities was ruled out by Doppler and contrast echo examinations. Surgical findings confirmed exactly the same anatomical abnormalities as preoperative 2D/3D echocardiography. Echocardiography plays an important role in finding unexpected underlying cardiac diseases in patients who are referred to arrhythmia clinics. In the present case with atrial fibrillation, we could accurately diagnose an unroofed coronary sinus syndrome during preoperative transthoracic and transesophageal echocardiography prior to planned radiofrequency catheter ablation.<Learning objective: Radiofrequency catheter ablation therapy for atrial fibrillation has been greatly developed in recent years. Echocardiography plays an important role in the diagnosis of underlying cardiac diseases in patients who are referred to arrhythmia clinics. We could clearly visualize partial type of unroofed coronary sinus by 2D/3D echocardiography in a patient who was planned to undergo radiofrequency catheter ablation, and then could contribute to the proper therapeutic management for the rare congenital heart disease.>

Decrease in B-Type Natriuretic Peptide Levels and Successful Catheter Ablation for Atrial Fibrillation in Patients with Heart Failure.

Little is known about the association between B-type natriuretic peptide (BNP) levels and catheter ablation of atrial fibrillation (AF) in patients with heart failure. This study aimed to examine the impact of elimination of AF by catheter ablation on BNP levels in patients with left ventricular systolic dysfunction. Fifty-four AF patients with left ventricular ejection fraction (LVEF) ≤ 50%, who underwent radiofrequency catheter ablation therapy of AF, were included. BNP sampling was performed at baseline, 3 days, and 1 month after ablation. After a follow-up period of 6 months, the BNP levels decreased significantly in the nonrecurrence group (n = 35; median 126.3 [interquartile 57.2-206.5] pg/mL, 63.5 [23.9-180.2] pg/mL, and 45.9 [21.9-160.3] pg/mL, P < 0.001, respectively), but not in the recurrence group (n = 19; 144.7 [87.1-217.3] pg/mL, 88.8 [12.9-213.2] pg/mL, and 118.5 [51.6-298.2] pg/mL, P = 0.368, respectively). The patients in the nonrecurrence group had a higher percentage relative reduction in BNP levels from baseline to 1 month after ablation than those in the recurrence group (56.5 [-9.0-77.4]% vs -2.4 [-47.1-60.9]%, P = 0.027). Additionally, a relative reduction in BNP levels significantly correlated with an increase in LVEF after ablation (r = 0.486, P < 0.001). Plasma BNP levels decreased significantly with successful catheter ablation of AF in patients with impaired LVEF. The decrease in BNP levels might be associated with early recovery of cardiac function and subsequent maintenance of sinus rhythm at follow-up.

A Case of Esophageal Thermal Injury Following Radiofrequency Catheter Ablation Therapy

Introduction: Radiofrequency ablation (RFA) is a catheter based ablation technique used in patients with atrial fibrillation(AF) to achieve rhythm control.There is risk of esophageal thermal injury during RFA to the posterior left atrium given its close proximity to the anterior esophagus.We describe a case of thermal injury to the esophagus following RFA therapy to the left atrium. Case Report: A 69-year-old female with a history of hypertension, AF was seen with a two day history of melena.The patient's melenic stools began one day following RFA therapy.The patient reported a “gassy feeling” in her stomach but denied abdominal pain,nausea,vomiting,chest pain,heartburn,dysphagia,o dynophagia,fever/chills.No history of GI bleed or change in stool consistency/color were reported in the past.On exam patient was afebrile,hypertensive(178/78) with heart rate of 80. Abdomen was soft/nontender/nondistended with normoactive bowel sounds, no abdominal masses, organomegaly. Lungs were clear to ausculation as no abnormal heart sounds were noted. Lab results demonstrated Potassium 3.5mmol/L,Sodium 142mmol/L,Chloride 102mmol/L,hemoglobin 13.9 g/dL,platelet count 219 10(3)/mcl,PT 15.6, INR 1.4,PTT 31.5.Liver enzymes were normal.An EGD demonstrated a 6-7 mm healing ulcer in the mid esophagus with no evidence of active bleeding.The submucosa was not seen and no evidence of perforation was noted.She was discharged home with pantoprazole 40mg twice daily,sucralfate 1g four times daily and instructions to follow up in the GI clinic. Discusion: Esophageal injury is one complication of RFA therapy.This is due to the close anatomical proximity between the esophagus and the posterior LA wall which is estimated to be ≤ 5 mm in 40% of the population.The intestinal tissue is also far more susceptible to radiofrequency induced thermal injury than the muscular tissue of the heart. Therefore,direct contact of a probe is not required for thermal injury, as convection heat generated within the LA is enough energy to cause esophageal injury.Early diagnosis is vital to prevent fatal outcomes from complication such as perforation and fistula formation. Atrial fibrillation is projected to surge 2.5-fold in the near future due to the aging demographic leading to an increase use of RFA therapy. This may result in a higher incident of RFA related thermal esophageal injury.Further research is needed to identify risk factors,preventive strategies and optimal treatment for esophageal thermal injury related to left atrial RFA.Figure 1

Radiofrequency catheter ablation therapy used in 123 children with drug-refractory tachycardia arrhythmias

Objective To evaluate the safety and efficacy of radiofrequency catheter ablation (RFCA) in children with tachycardia arrhythmias. Methods One hundred and twenty-three children under 3 years old with drug-refractory tachycardia underwent an interventional electrophysiology procedure and RFCA in Medical Center of Tsinghua University from April 1994 to December 2014, including 98 male and 25 female, and their average age was (22.9±9.6) months(2-35 months) and body weight was (13.64±2.80) kg(4.66-19.40 kg). The mechanism, RFCA methods, the success rate, recurrence rate and complication rate of the different types of tachycardia were investigated. Results Among these children, interventional electrophysiological study confirmed 94 cases (76.4%, 94/123 cases) with atrioventricular reentrant tachycardia (AVRT), 7 cases(5.7%, 7/123 cases) with atrioventricular nodal reentrant tachycardia (AVNRT), 3 cases (2.4%, 3/123 cases) with focal atrial tachycardia (FAT), 8 cases (6.5%, 8/123 cases) with atrial flutter (AF), 5 cases (4.1%, 5/123 cases) with idiopathic left ventricular tachycardia (ILVT), 6 cases (4.8%, 6/123 cases) arrhythmia was not induced.RFCA was performed in 109 cases (88.6%, 109/123 cases). The success rate of RFCA was 94.5%(103/109 cases) and the recurrence rate was 6.8% (7/103 cases). In 88 cases of AVRT, the success rate was 96.6%(85/88 cases), and the recurrence rate was 8.2%(7/85 cases). In 5 cases of AVNRT, the success rate was 100.0%(5/5 cases). In 3 cases of FAT, the success rate was 33.3%(1/3 cases). In 8 cases of AF, the success rate was 87.5%(7/8 cases). In 5 cases of ILVT, the success rate was 100.0%(5/5 cases), and there was no recurrence.The complication of RFCA was puncture vascular occlusion in 2 cases (1.6%, 2/123 cases), without other serious complications and death cases.In this group of children, the fluoroscopy exposure time was (11.2±5.8) min(5.7-18.2 min) and dose area product(DAP) exposure was (954.5±117.4) mGy×cm2(707-2 201 mGy×cm2). Compared with the elder children (379 cases over 3 years old) of the exposure fluoroscopy time(10.8±6.4) min(3.9-20.5 min) and DAP exposure (927.5±193.4) mGy×cm2(439-3 201 mGy×cm2), there was no statistically significant difference(t=0.616, 1.463, all P>0.05). Conclusions AVRT was the most common type of arrhythmia in infants and a higher incidence of multiple accessory pathways was found in infants.Application of radiofrequency ablation to children with tachycardia arrhythmias can be relatively safe and effective to the infants with drug-resistant tachycardia. Key words: Tachycardia arrhythmia; Radiofrequency catheter ablation; Infant

Development of a novel shock wave catheter ablation system--the first feasibility study in pigs.

IntroductionRadio-frequency catheter ablation (RFCA) using Joule heat has two fundamental weaknesses: the limited depth of treatment and the risk of thrombus formation. In contrast, focused shock wave (SW) therapy could damage tissues at arbitrary depths without heat generation. Thus, we aimed to develop a SW catheter ablation (SWCA) system that could compensate for the weaknesses of RFCA therapy.Methods and ResultsWe developed a SWCA system where the SW generated by a Q-switched Holmium: yttrium aluminum garnet (YAG) laser beam was reflected by a reflector attached to 14-Fr catheter tip and then was converged onto the focus. We examined the feasibility of our system on pigs in vivo. When applied using the epicardial approach, the SWCA caused persistent spheroidal lesions with mild superficial injury than the RFCA. The lesions were created to a depth based on the focal length (2.0 mm) [2.36 ± 0.45 (SD) mm immediately after procedure, n = 16]. When applied to the atrioventricular (AV) node using the endocardial approach, the SWCA caused junctional escape rhythms in 2 pigs and AV block in 12 pigs (complete AV block in 9) in acute phase (n = 14). Nine of the 14 pigs survived with pacemakers for the long-term study, and the AV block persisted for 12.6 ± 3.9 (SD) days in all surviving pigs. Histological examination showed AV nodal cell body atrophy in the acute phase and fibrotic lesions in the chronic phase. Importantly, no acute or chronic fatal complications were noted.ConclusionsOur novel SWCA system could be a promising modality as a non-thermal ablation method to compensate for the weaknesses of RFCA therapy. However, further research and development will be necessary as the current prototype still exhibited the presence of micro-thrombus formation in the animal studies.

Radiofrequency catheter ablation of idiopathic left anterior fascicular ventricular tachycardia in children.

Idiopathic ventricular tachycardia of left anterior fascicular origin (IVT-LAF) is a rare condition, and radiofrequency catheter ablation (RFCA) therapy has not been reported in children. This study aimed to evaluate the procedures and outcomes of RFCA for pediatric IVT-LAF. Pediatric IVT-LAF cases for which RFCA was performed between June 2006 and May 2012 at our hospital were reviewed. Of 537 pediatric cases of RFCA, 6 had IVT-LAF; 4 had anterior fascicular involvement only, while 2 had both anterior and posterior fascicular involvement. All 6 of them underwent RFCA at the median age of 8.8 years (range 4.3-14.3 years). RFCA was successful in all patients, but 4 had recurrence and underwent 1-3 additional sessions of RFCA. In a total of 10 RFCA sessions, the overall recurrence rate was 50%. The site of RFCA was determined on the basis of detection of diastolic potential during ventricular tachycardia (7 sessions) or isolated delayed potential during sinus rhythm (1) or by pace mapping (2). During the median follow-up period of 33 months, no further recurrence was reported except for 1 patient, who had a recurrence and was scheduled for additional session at the time of this report. Major complications included 1 case of complete atrioventricular block and 1 case of complete left bundle branch block. Despite a high recurrence rate and a few complications, RFCA of the site of isolated delayed potential or diastolic potential, if applied cautiously, is a possible treatment of choice for pediatric IVT-LAF.

Catheter ablation versus antiarrhythmic medication as first line therapy in paroxysmal atrial fibrillation: on treatment analysis of the MANTRA-PAF data

Background: MANTRA-PAF is a large randomized multicenter trial comparing radiofrequency catheter ablation (RFA) and antiarrhythmic drug (AAD) therapy as first line treatment of paroxysmal atrial fibrillation (PAF). Intention-to-treat analysis showed no significant difference in cumulative AF burden, but at 24 months AF burden was significantly lower in the RFA than in the AAD group. In the present on-treatment analysis we compared three groups of patients: those who received only the prescribed treatment (pure RFA and pure AAD groups) and those treated with combination of RFA and AAD (cross-over group). Methods: A total of 294 AAD naive patients with PAF were randomly assigned to RFA (146 patients) or class IC/III AAD therapy (148 patients). Cumulative and per-visit AF burden (i.e., percentage of time in AF) was evaluated from 7-day Holter recordings at baseline and after 3, 6, 12, 18, and 24 months. The patients were considered free from AF if no AF episodes longer than 60 s were detected. In the AAD group, 54 patients (36%) underwent supplementary ablation and in the RFA group 30 patients (21%) received antiarrhythmic medication after the 3 months blanking period (at 24 months 9% were on AAD). Eight patients were excluded from the analysis because they did not receive the index treatment. Results: At 24 months, AF burden was significantly lower in the pure RFA group (n=110) than in the pure AAD (n=92) and the cross-over (n=84) groups (90th percentile 1% vs. 10% vs. 19%, P=0.007), and more patients in the RFA than in the other groups were free from any AF (89% vs. 73% vs. 74%, P =0.006). The cumulative AF burden was significantly lower in the pure RFA and AAD groups than in the cross-over group (90th percentile 10% vs. 6% vs. 24%, P<0.001). During the 2 year follow-up period 63%, 59% and 21% (P<0.001) of the patients in the pure RFA, pure AAD and the cross-over group had no AF episodes in any Holter recording, respectively. There was no significant difference in the number of severe complications between the groups. Conclusions: These data indicate that RFA is superior to AAD as first line treatment in a large subset of patients with highly symptomatic PAF. The results are pertinent among relatively young and healthy subjects and should not be extrapolated to elderly patients or to those with comorbidities.

Does atrial fibrillation ablation really reduce stroke rates?

less frequently than those treated with antiarrhythmic medications (14 of 589 [2.4%] vs 49 of 582 [8.4%]). However, that was a nonrandomized study from a single center and may have had a lot of confounders and selection bias. In this issue of HeartRhythm, Bunch et al 14 report that patients undergoing AF ablation have lower stroke rates during a long-term follow-up of more than 3 years than do patients who do not undergo AF ablation and the risk is similar to that of patients without a history of AF. Their results had 3 key implications. Their data were obtained from a large system-wide study derived from a prospectively collected registry and, therefore, may reflect a real-world cohort more adequately than did the data from other trials. In fact, the stroke rate at 1 year in their study is 3.5% in patients with AF who did not undergo ablation, which is well in line with the stroke rates of 2%–6% in patients treated mostly with anticoagulants and who had a mild to moderate risk in large-scale trials. 6,13,15,16 In addition, their patient groups were matched by age and sex, and although there was a small difference in the baseline risk between groups, the reduction in the stroke rate in the AF ablation group persisted after a multivariate adjustment for the confounding variables. Two recent studies from a large age- and sex-matched 15 or propensity-matched community sample 16 also showed comparative results in which the stroke rate in the ablation group with an ablation strategy was associated with a lower stroke rate as compared to patients treated with antiarrhythmic medications and who had no difference from that of the general population. Taken together, this suggests that the maintenance of sinus rhythm after ablation may be significantly more reduced than after antiarrhythmic medications

Presence of left atrial diverticula, accessory appendages, and normal variant pulmonary venous anatomy diagnosed using MDCT and adverse outcomes following radiofrequency catheter ablation therapy in patients with drug-refractory atrial fibrillation: An exploratory study

To determine the frequency of normal variation left atrial anatomy (NVLAA) (diverticula, accessory appendages) and normal variation pulmonary venous anatomy (NVPVA) in patients with atrial fibrillation (AF), and to determine whether the presence of these entities is associated with an increased recurrence of atrial arrhythmias following radiofrequency catheter ablation (RFCA). All cardiac MDCT images performed prior to RFCA between November 2009 and May 2011 in patients with drug-refractory AF were retrospectively evaluated. The presence, type, and location of NVLAA and NVPVA, and outcome of RFCA were recorded. Success was defined as restoration of sinus rhythm. Forty-six consecutive patients with a mean age of 59.8 (±9.7) years (76.1% male) underwent cardiac MDCT for anatomical planning prior to RFCA procedures. Fourteen (30.4%) patients had NVLAA, 35% of patients had NVPVA. Thirty (65%) patients had successful RFCA: 57% of these had a NVLAA, 67% had NVPVA. Sixteen (35%) patients had unsuccessful RFCA: 63% of these had a NVLAA, 56% had NVPVA. There was no significant association between the presence of NVLAA (p = 0.699), NVPVA (p = 0.197), or "NVLAA in the presence of normal pulmonary venous anatomy" (p = 0.589) and the outcome of RFCA. The presence of NVLAA and NVPVA appears unrelated to adverse outcome in patients undergoing RFCA for the treatment of drug-refractory AF.