Follow-up of children or teenagers with paroxysmal supraventricular tachycardia, but without pre-excitation syndrome.

BACKGROUND: Paroxysmal supraventricular tachycardia (SVT) is considered benign in children if the electrocardiogram in sinus rhythm is normal, but causes anxiety in parents, children and doctors. AIMS: To report on the clinical and electrophysiological data from children with SVT, their follow-up and management. METHODS: Overall, 188 children/teenagers (mean age 15±2.8 years) with a normal electrocardiogram in sinus rhythm were studied for SVT, and followed for 2.3±4 years. RESULTS: SVT was poorly tolerated in 30/188 children (16.0%). SVT was related to atrioventricular nodal reentrant tachycardia (AVNRT) (n=133) or atrioventricular reentrant tachycardia (AVRT) over a concealed accessory pathway (n=55; 29.3%). Ablation of the slow pathway (n=66) or the accessory pathway (n=43) was performed without general anaesthesia, 2±3 years after initial evaluation. Failure or refusal to continue occurred in 18/109 (16.5%) children: 7/66 with AVNRT (10.6%), 11/43 with AVRT (25.6%) (P<0.001). Symptoms of SVT recurred in 20/91 children (22.0%) with apparently successful ablation: 6/91 (6.6%) had real SVT recurrence; 14/91 (15.4%) had only a sinus tachycardia, more frequent in AVNRT (11/59; 18.6%) than AVRT (3/32; 9.4%) (P<0.05). In 13 children treated with an antiarrhythmic drug (AAD), SVT recurred in four; two presented AAD-related syncope. In 66 untreated children, one death was noted after excessive AAD infusion to stop SVT; the others remained asymptomatic or had well-tolerated SVT. CONCLUSIONS: At the time of ablation, SVT management remains difficult in children. Indications for ablation are more common in AVRT than in AVNRT, but failures are frequent; 22.0% remained symptomatic after successful ablation, but false recurrences were frequent (15.4%). Without ablation, one third had a spontaneous favourable evolution.

Electrocardiogram: his bundle potentials can be recorded noninvasively beat by beat on surface electrocardiogram.

BACKGROUND: The micro waveform of His bundle potential can't be recorded beat-to-beat on surface electrocardiogram yet. We have found that the micro-wavelets before QRS complex may be related to atrioventricular conduction system potentials. This study is to explore the possibility of His bundle potential can be noninvasively recorded on surface electrocardiogram. METHODS: We randomized 65 patients undergoing radiofrequency catheter ablation of paroxysmal superventricular tachycardia (exclude overt Wolff-Parkinson-White syndrome) to receive "conventional electrocardiogram" and "new electrocardiogram" before the procedure. His bundle electrogram was collected during the procedure. Comparative analysis of PAs (PA interval recorded on surface electrocardiogram), AHs (AH interval recorded on surface electrocardiogram) and HVs (HV interval recorded on surface electrocardiogram) interval recorded on surface "new electrocardiogram" and PA, AH, HV interval recorded on His bundle electrogram was investigated. RESULTS: There was no difference (P > 0.05) between groups in HVs interval (49.63 ± 6.19 ms) and HV interval (49.35 ± 6.49 ms). Results of correlational analysis found that HVS interval was significantly positively associated with HV interval (r = 0.929; P < 0.01). CONCLUSIONS: His bundle potentials can be noninvasively recorded on surface electrocardiogram. Noninvasive His bundle potential tracing might represent a new method for locating the site of atrioventricular block and identifying the origin of a wide QRS complex.

Safety and efficacy of early radiofrequency catheter ablation in patients with paroxysmal atrial fibrillation complicated with amiodarone-induced thyrotoxicosis.

BACKGROUND: Amiodarone is an antiarrhythmic drug that is frequently used to control atrial fibrillation (AF). Many patients with AF are afraid of the risk of ablation and take amiodar-one, some patients develop amiodarone-induced thyrotoxicosis (AIT). The purpose of the study was to investigate the safety and efficacy of early radiofrequency catheter ablation in patients with paroxysmal AF complicated with AIT. METHODS: From the 146 consecutive patients with paroxysmal AF who had been treated with amiodarone and underwent 3-dimensional mapping system guided circumferential pulmonary vein isolation (PVI) at our center from January 2013 to June 2014, 20 had developed AIT. Thirty controls with normal thyroid function and matched for baseline characteristics were selected. RESULTS: Pulmonary vein isolation was completed in all patients without serious complications and with similar procedural (170.60 ± 14.80 vs. 158.18 ± 9.06 min; p = 0.062) and X-ray exposure (16.48 ± 2.15 vs. 15.36 ± 1.57 min; p = 0.058) time in AIT vs. control groups; however, upon coronary sinus catheter pacing (from 300 ms to 200 ms) after intrave-nous isoproterenol administration 30 min post PVI, rates of induction of AF (35% vs. 3.33%; p = 0.005) and of non-pulmonary vein-related atrial tachyarrhythmias (50% vs. 6.67%; p = 0.01) were higher, while those for atrial flutter (15% vs. 3.33%; p = 0.17) and atrial tachycardia (15% vs. 6.67%; p = 0.31) were similar, as was the recovery of conduction of pulmonary vein potential (15% vs. 30%; p = 0.191). In AIT vs. control group, atrial tachyarrhythmia recurrence rate was higher at 3 months (45% vs. 16.67%, p = 0.032) but not between 3 and 12 months (30% vs. 23.33%; p = 0.418) follow-up. CONCLUSIONS: Early catheter ablation for paroxysmal AF in patients with AIT appeared safe and effective albeit with higher atrial tachyarrhythmia recurrence rate up to 3 months but not beyond 12 months after PVI relative to controls.

Pulmonary Vein Antrum Isolation in Patients With Paroxysmal Atrial Fibrillation: More Than a Decade of Follow-Up.

BACKGROUND: We report the outcome of pulmonary vein (PV) antrum isolation in paroxysmal atrial fibrillation (AF) patients over more than a decade of follow-up. METHODS AND RESULTS: A total of 513 paroxysmal AF patients (age 54±11 years, 73% males) undergoing catheter ablation at our institutions were included in this analysis. PV antrum isolation extended to the posterior wall between PVs plus empirical isolation of the superior vena cava was performed in all. Non-PV triggers were targeted during repeat procedure(s). Follow-up was performed quarterly for the first year and every 6 to 9 months thereafter. The outcome of this study was freedom from recurrent AF/atrial tachycardia. At 12 years, single-procedure arrhythmia-free survival was achieved in 58.7% of patients. Overall, the rate of recurrent arrhythmia (AF/atrial tachycardia) was 21% at 1 year, 11% between 1 and 3 years, 4% between 3 and 6 years, and 5.3% between 6 and 12 years. Repeat procedure was performed in 74% of patients. Reconnection in the PV antrum was found in 31% of patients after a single procedure and in no patients after 2 procedures. Non-PV triggers were found and targeted in all patients presenting with recurrent arrhythmia after ≥2 procedures. At 12 years, after multiple procedures, freedom from recurrent AF/atrial tachycardia was achieved in 87%. CONCLUSIONS: In patients with paroxysmal AF undergoing extended PV antrum isolation, the rate of late recurrence is lower than what previously reported with segmental or less extensive antral isolation. However, over more than a decade of follow-up, nearly 14% of patients developed recurrence because of new non-PV triggers.

Importance of nonpulmonary vein foci in catheter ablation for paroxysmal atrial fibrillation.

BACKGROUND: Pulmonary vein (PV) isolation is an established treatment strategy for paroxysmal atrial fibrillation (PAF). However, the recurrence rate of PAF is 8% to 37%, despite repeated procedures, and the catheter ablation strategy for PAF with non-PV foci is unclear. OBJECTIVE: The purpose of this study was to assess the PAF ablation strategy for non-PV foci. METHODS: The study included 304 consecutive patients undergoing PAF ablation (209 males, age 63.0 ± 10.4 years) divided into 3 groups: group 1 (245 patients) with no inducible non-PV foci; group 2 (34 patients) with atrial fibrillation (AF) originating from non-PV foci and all the foci successfully ablated; and group 3 (25 patients) with AF originating from non-PV triggers, but without all foci being ablated or with persistently inducible AF. RESULTS: Mean follow-up period was 26.9 ± 11.8 months, and AF recurrence rates since the last procedure were 9.8%, 8.8%, and 68.0% in groups 1, 2, and 3, respectively. There was no statistically significant difference in recurrence rate between groups 1 and 2 (P = .89); however, there were statistically significant differences between groups 3 and 1 (P <.0001) and groups 3 and 2 (P <.0001). The patients in group 2 had an AF-free outcome to equivalent to those who had PV foci in group 1 (P = .83). CONCLUSION: Success rates can be improved for PAF ablation if non-PV foci are detected and eliminated.

Electrophysiological studies in patients with paroxysmal supraventricular tachycardias but no electrocardiogram documentation: findings from a prospective registry.

AIMS: A significant proportion of patients presenting with paroxysmal supraventricular tachycardia (PSVT) has no electrocardiogram (ECG) documentation. In these patients an electrophysiological study (EPS) may be performed to facilitate the diagnosis. METHODS AND RESULTS: In a prospective registry we compared the prevalence of inducible arrhythmias and the clinical outcome in 525 patients with and without ECG documentation. Compared with patients with a documented PSVT a smaller but substantial proportion of patients (63.7%) without ECG documentation had inducible supraventricular tachycardias (SVT). Atrio-ventricular nodal reentrant tachycardia was the most common type in both groups. Patients with an inducible SVT and no documentation were significantly younger, had a shorter episode duration and a lower hospitalization rate, which may be the cause for the lacking documentation. Similar to patients with documented PSVTs most of these patients (90.0%) were asymptomatic or clinically improved after the EPS. Even 43% of patients without an inducible tachycardia improved clinically, probably due to a placebo effect of the EPS. In particular, patients between 31 and 60 years of age seemed to benefit from an EPS because they were more likely to have inducible SVTs that could be cured by radiofrequency ablation. CONCLUSION: Our data show that a substantial proportion of patients with suspected paroxysmal tachycardia, but without ECG documentation, have inducible SVTs and obtain a clear clinical benefit from an EPS. Thus, our data provide justification for using EPS for patients in this category. To the best of our knowledge, ours is the first prospective registry that supports this approach.

Selection for atrial fibrillation ablation: Importance of diastolic function grading.

BACKGROUND: Pulmonary vein isolation (PVI) has become an accepted therapy for patients with atrial fibrillation (AF) and the indications have widened to include non-paroxysmal AF-patients. Maintenance of sinus rhythm after PVI can be adversely affected by clinical or echocardiographic parameters, which should be clearly identified. METHODS AND RESULTS: After baseline clinical and echocardiographic evaluations, PVI was performed in patients with paroxysmal or non-paroxysmal AF. The follow-up strategy after PVI included: (1) clinical follow up, 12-lead electrocardiography (ECG) and 24-h ECG every 3 months, (2) trans-telephonic ECGs twice daily and when symptomatic (over 4 weeks) every 3 months, or (3) continuous monitoring via implanted devices. A recurrence was an atrial arrhythmia lasting >30s. All 340 PVI procedures of 229 patients were analyzed. On average, 1.5 PVI procedures per patient (range, 1-6 PVI) were performed. The mean age was 58±11 years (73% male) with 109 paroxysmal and 120 non-paroxysmal AF cases. Clinical follow-up with 12-lead ECGs, 24-h ECGs, trans-telephonic ECGs, and implanted devices was complete in 100%, 63%, 51%, and 16% of cases, respectively. The overall one-year recurrence rate of 59% (range, 24-82%) was dependent on grades of diastolic function (normal - dysfunction grade III) in a multivariable analysis model. Patients with normal diastolic function had the lowest recurrence rates of 24% and 49% after 1 and 3 years of follow-up, respectively (p<0.0001). CONCLUSION: Diastolic function could serve as a simple summary predictor for AF recurrence, and would facilitate clinical decision-making in AF treatment.

Impact of biatrial defragmentation in patients with paroxysmal atrial fibrillation: results from a randomized prospective study.

BACKGROUND: Single procedure success rates of pulmonary vein isolation (PVI) in patients with paroxysmal atrial fibrillation (PAF) are still unsatisfactory. In patients with persistent atrial fibrillation (AF), ablation of complex fractionated atrial electrograms (CFAEs) after PVI results in improved outcomes. OBJECTIVE: We aimed to investigate if PAF-patients with intraprocedurally sustained AF after PVI might benefit from additional CFAE ablation. METHODS: A total of 1134 consecutive patients underwent a first catheter ablation procedure of PAF between June 2008 and December 2012. In most patients, AF was either not inducible or terminated during PVI. In 68 patients (6%), AF sustained after successful PVI. These patients were randomized to either cardioversion (PVI-alone group; n = 33) or additional CFAE ablation (PVI+CFAE group; n = 35) and followed up every 1-3 months and serial Holter recordings were also obtained. The primary end point was the recurrence of AF/atrial tachycardia (AT) after a blanking period of 3 months. RESULTS: Procedure duration (127 ± 6 minutes vs 174 ± 10 minutes), radiofrequency application time (44 ± 3 minutes vs 74 ± 5 minutes), and fluoroscopy time (26 ± 2 minutes vs 41 ± 3 minutes) were longer in the PVI+CFAE group (all P < .001). In 30 of 35 patients (86%) in the PVI+CFAE group, ablation terminated AF. There was no significant group difference with respect to freedom from AF/AT (22 of 33 [67%] vs 22 of 35 [63%]; P = .66). Subsequently, 10 of 11 patients in the PVI-alone group (91%) and 11 of 13 patients in PVI+CFAE group (85%) underwent repeat ablation (P = 1.00). Overall, 29 of 33 [88%] vs 30 of 35 [86%] patients (P = 1.00) were free from AF/AT after 1.4 ± 0.1 vs 1.4 ± 0.2 (P = .87) procedures. CONCLUSION: Patients with sustained AF after PVI in a PAF cohort are rare. Regarding AF/AT recurrence, these patients did not benefit from further CFAE ablation compared to PVI alone, but are exposed to longer procedure duration, fluoroscopy time, and radiofrequency application time.

Radiofrequency ablation annotation algorithm reduces the incidence of linear gaps and reconnection after pulmonary vein isolation.

BACKGROUND: A common mechanism of atrial fibrillation recurrence after catheter ablation is resumption of pulmonary vein (PV) conduction due to gaps in the ablation line. These gaps may go unrecognized owing to inadequate ablation lesion annotation. OBJECTIVE: To examine the utility of an automated radiofrequency (RF) ablation annotation algorithm for the detection and treatment of ablation gaps during pulmonary vein isolation (PVI). METHODS: Eighty-four patients with paroxysmal atrial fibrillation underwent PVI. In 42 patients (group A), RF ablation was guided by an automated algorithm with predefined criteria of catheter stability range of motion ≤2 mm and impedance decrease ≥5% for individual ablation applications. In 42 control patients (group B), ablation was guided by the operator. Successful PVI, conduction recovery, and dormant conduction with adenosine were compared between the groups. RESULTS: Ipsilateral PVI at the completion of the initial anatomical line was obtained in 90.5% of group A patients (76 of 84 ipsilateral pairs of PVs) but only in 66.7% of group B patients (56 of 84 ipsilateral pairs of PVs) (P = .0001). Ineffective energy delivery was detected in 23% (1005 of 4362) of group A applications but only in 9% (368 of 4071) of group B applications (P = .0001). The frequency of conduction recovery was lower in group A than in group B (5.9% vs 25%; P = .001). Arrhythmia-free survival at 6 months trended higher in group A (38 of 42 [90%]) than in group B (32 of 42 [76%]; P = .07). CONCLUSION: Automated ablation lesion annotation provides real-time feedback of RF ablation that may improve effective energy delivery.

The COR trial: a randomized study with continuous rhythm monitoring to compare the efficacy of cryoenergy and radiofrequency for pulmonary vein isolation.

BACKGROUND: Results from randomized trials designed to compare cryoenergy with radiofrequency for pulmonary vein (PV) isolation are lacking. OBJECTIVE: To compare the efficacy of a simplified strategy for PV cryoablation (group C) vs PV isolation with open-irrigated radiofrequency catheters (group R). METHODS: Fifty patients with paroxysmal atrial fibrillation (AF) and 4 independent PVs received a Reveal XT implantable cardiac monitor and were randomized to group C or group R. In group C, PV ablation was done with a single Arctic Front balloon (23 or 28 mm) per patient and two 300-second applications per PV. No further applications were delivered to close residual conduction gaps. In group R, bidirectional PV conduction block was pursued with Lasso and Navistar ThermoCool catheters and the CARTO system. The primary end point was the proportion of patients remaining free from AF recurrences ≥2 minutes without taking antiarrhythmic drugs 12 months after ablation. RESULTS: The primary end point was met by 12 (48%) patients in group C and 25 (68%) patients in group R (odds ratio 0.43; P = .05). This difference disappeared after adjustment for acute procedural outcome. In patients for whom all 4 PVs were blocked at the end of the procedure, there was no difference between group C and group R in the primary end point (67% vs 68%; P = .94). CONCLUSIONS: The efficacy of the simplified strategy for PV cryoablation tested in this study is inferior to PV isolation using open-irrigated radiofrequency catheters with electrophysiological and electroanatomical guidance. Complete PV conduction block is critical to the success of AF ablation.

Unipolar signal modification as a guide for lesion creation during radiofrequency application in the left atrium: prospective study in humans in the setting of paroxysmal atrial fibrillation catheter ablation.

BACKGROUND: In patients treated for paroxysmal atrial fibrillation, the pulmonary vein (PV) reconnection rate is substantial and may be related to the lack of transmurality achievement while performing PV isolation (PVI). It has been experimentally demonstrated that positive unipolar atrial electrogram completion, when applying radiofrequency energy, was associated with transmural lesions. In this regard, we seek to determine whether the unipolar signal modification may be an appropriate end point for point-by-point radiofrequency application and find out whether it could improve the paroxysmal atrial fibrillation ablation results in humans. METHODS AND RESULTS: Fifty consecutive patients (61±8 years old, 41 men) with paroxysmal atrial fibrillation underwent PVI using Carto and Lasso. Each radiofrequency application lasted until development of a completely positive unipolar electrogram. Fifty patients (63±9 years old, 40 men), who previously underwent PVI following the standard approach of our institution, corresponded to the control group. All PVs were isolated in all patients of both groups. However, the procedural and ablation times were significantly lower in the unipolar group compared with those of the control group, whereas the PV reconnection rate, after 30 minutes of waiting time, was not significantly different. Overall, 21±4 months after 1 PVI session, the sinus rhythm maintenance rate without antiarrhythmic drugs was significantly higher (P=0.027) in the unipolar group (88%) compared with that of the control group (70%). CONCLUSIONS: Unipolar signal modification is a useful end point for radiofrequency energy delivery in patients with paroxysmal atrial fibrillation who undergo PVI and leads to a substantial midterm sinus rhythm maintenance rate.

Autonomic denervation added to pulmonary vein isolation for paroxysmal atrial fibrillation: a randomized clinical trial.

OBJECTIVES: The aim of this study was to investigate whether the combination of conventional pulmonary vein isolation (PVI) by circumferential antral ablation with ganglionated plexi (GP) modification in a single ablation procedure, yields higher success rates than PVI or GP ablation alone, in patients with paroxysmal atrial fibrillation (PAF). BACKGROUND: Conventional PVI transects the major left atrial GP, and it is possible that autonomic denervation by inadvertent GP ablation plays a central role in the efficacy of PVI. METHODS: A total of 242 patients with symptomatic PAF were recruited and randomized as follows: 1) circumferential PVI (n = 78); 2) anatomic ablation of the main left atrial GP (n = 82); or 3) circumferential PVI followed by anatomic ablation of the main left atrial GP (n = 82). The primary endpoint was freedom from atrial fibrillation (AF) or other sustained atrial tachycardia (AT), verified by monthly visits, ambulatory electrocardiographic monitoring, and implantable loop recorders, during a 2-year follow-up period. RESULTS: Freedom from AF or AT was achieved in 44 (56%), 39 (48%), and 61 (74%) patients in the PVI, GP, and PVI+GP groups, respectively (p = 0.004 by log-rank test). PVI+GP ablation strategy compared with PVI alone yielded a hazard ratio of 0.53 (95% confidence interval: 0.31 to 0.91; p = 0.022) for recurrence of AF or AT. Fluoroscopy duration was 16 ± 3 min, 20 ± 5 min, and 23 ± 5 min for PVI, GP, and PVI+GP groups, respectively (p < 0.001). Post-ablation atrial flutter did not differ between groups: 5.1% in PVI, 4.9% in GP, and 6.1% in PVI+GP. No serious adverse procedure-related events were encountered. CONCLUSIONS: Addition of GP ablation to PVI confers a significantly higher success rate compared with either PVI or GP alone in patients with PAF.

Left septal atrial tachycardias: electrocardiographic and electrophysiologic characterization of a paraseptal focus.

OBJECTIVE: The objective was to characterize the electrocardiographic and electrophysiological features of focal atrial tachycardia (FAT) originating from the left septum (LS). BACKGROUND: FAT is recognized to occur at predefined anatomic locations rather than randomly throughout the atria. We describe the ECG and EP features of ATs originating from the LS as an important site for apparent perinodal tachycardias. METHODS: Nine patients presenting with LS FAT from a consecutive series of 384 underwent EP/RFA for symptomatic FAT. RESULTS: The mean age was 56 ± 12 years; 7 female with symptoms for 36 ± 28 months. P wave morphology (PWM) was negative/positive in lead V1 and across the precordial leads and negative or negative/positive in inferior leads in all patients. Tachycardia was incessant in 6 out of 9 patients with a mean tachycardia cycle length 421 ± 56 milliseconds. His A was ahead of P wave in all patients (mean -15 ± 5 milliseconds) and earlier than CS proximal (mean 4 ± 9 milliseconds). Successful acute focal ablation achieved at a mean of 31 ± 12 milliseconds ahead of P wave with no recurrences at a mean follow-up of 30 ± 28 months. CONCLUSION: Although the left septum is an uncommon site for focal AT an awareness of this location for harboring foci is particularly important when mapping apparently right-sided septal tachycardias.

A new method for induction of atrioventricular nodal reentrant tachycardia in non-inducible cases.

AIM: In some patients with clinical paroxysmal supraventricular tachycardia (PSVT), who are candidates for radiofrequency (RF) catheter ablation, attempts for the induction of arrhythmia during the electrophysiological study (EPS) fail despite different stimulation protocols even during the isoproterenol infusion and atropine injection. The presence of an atrial-His interval (AH) jump during decremental pre-mature atrial stimulation is the only clue for slow pathway ablation in these patients; in occasional patients, however, the AH jump is an accidental finding and the real arrhythmia is not atrioventricularnodal reentrant tachycardia (AVNRT). We aimed to introduce a new method for the induction of AVNRT in these patients. METHODS AND RESULTS: Ten patients (50% male, mean age=44.40 ± 12.80 years) with clinical PSVT who were referred to our department for the EPS and RF catheter ablation were selected. These patients had documented clinical PSVT with non-inducible arrhythmia during the EPS with different stimulation protocols even during the isoproterenol infusion and atropine injection but they only showed an AH jump. To induce AVNRT, low-watt (15-20), low-temperature (40-45°C) RF currents were delivered into the slow pathway area for a maximum of 40 s. Atrioventricularnodal reentrant tachycardia was inducible in five cases (50%, three male, mean age=45.80 ± 9.65 years). Induction of AVNRT occurred either during the RF current application after the occurrence of junctional ectopic beats or after another stimulation protocol. CONCLUSION: A low-watt, low-temperature RF current application into the slow pathway area can be a provocative method for the induction of AVNRT probably by AV-junction warming and conduction-velocity augmentation.