Summary
Background
Pulmonary vein isolation (PVI) takes longer when using a patent foramen ovale (PFO) compared with a transseptal puncture in paroxysmal atrial fibrillation (AF) with manual catheter ablation. To our knowledge, no data exist concerning the impact of a PFO on AF ablation procedure variables when using a remote magnetic navigation (RMN) system.
Aim
To assess the impact of a PFO when using an RMN system in patients requiring AF ablation.
Methods
Between December 2011 and December 2012, catheter ablation was performed remotely using the CARTO ® 3 system in 167 consecutive patients who underwent PVI for symptomatic drug-refractory AF. The radiofrequency generator was set to a fixed power ≤ 35 W. The primary endpoint was wide-area circumferential PVI confirmed by spiral catheter recording during ablation for all patients and including additional lesion lines (left atrial roof) or complex fractionated atrial electrograms for persistent AF. Secondary endpoints included procedural data.
Results
Mean age 58 ± 10 years; 18% women; 107 (64%) patients with symptomatic paroxysmal AF; 60 (36%) with persistent AF; CHA 2 DS 2 -VASc score 1.2 ± 1. The PFO presence was evidenced in 49/167 (29.3%) patients during the procedure but in only 26/167 (16%) by transoesophageal echocardiography. Median procedure time 2.5 ± 1 hours; median total X-ray exposure time 14 ± 7 minutes; transseptal puncture and catheter positioning time 7.5 ± 5 minutes; left atrium electroanatomical reconstruction time 3 ± 2.3 minutes; catheter ablation time 3 ± 3 minutes. No procedure time or X-ray exposure differences were observed between patients with or without a PFO during magnetic navigation catheter ablation. X-ray exposure time was significantly reduced using a PFO compared with double transseptal puncture access.
Conclusions
A PFO does not affect magnetic navigation during AF ablation; procedure times and X-ray exposure were similar. Septal catheter probing is mandatory to limit X-ray exposure and prevent potential complications.
Résumé
Contexte
Il a été démontré que la durée des procédures d’isolation des veines pulmonaires VPs était plus longue lors de l’utilisation d’un foramen ovale perméable (FOP) comparée à l’utilisation de la ponction transeptale dans le traitement par radiofréquence (RF) de la fibrillation atriale (FA) paroxystique par la technique d’ablation manuelle. Il n’y a pas, à notre connaissance, de données dans la littérature sur l’influence du FOP sur les temps ou les données opératoires lors de l’utilisation d’un robot magnétique (RM).
Objectif
Cette étude prospective a cherché à évaluer l’impact de l’utilisation d’un FOP avec un système de RM sur les procédures de RF de FA en comparaison avec la double ponction transeptale.
Méthodes
Entre décembre 2011 et décembre 2012, 167 patients consécutifs ont bénéficié d’un traitement par RF par technique du RM. L’objectif principal était l’isolement électrique des VPs confirmé par la technique du lassos et la réalisation de lignes complémentaires et/ou l’ablation de potentiels fractionnés en cas de FA persistante.
Résultats
Cent soixante sept patients ont été inclus (58 ± 10 ans ; 18 % de femmes), dont 107 FA paroxystiques (64 %) et 60 FA persistantes (36 %). Un FOP était présent chez 49/167 (29,3 %) au cours de la procédure mais seulement 26/167 (16 %) ont été détectés par échographie transoesophagienne. Le temps médian de procédure était de 2,5 ± 1 heures et la médiane d’exposition aux rayons X était de 14 ± 7 minutes (ponction transeptale et positionnement des cathéters 7,5 ± 5 min, reconstruction électro-anatomique de l’oreillette gauche 3 ± 2 min, et temps d’ablation robotisé 3 ± 2 min). Aucune différence de temps opératoire ou d’exposition aux rayons X n’a été observé entre les patients avec présence d’un FOP et les patients avec double ponction transeptale.
Conclusions
La présence et l’utilisation d’un FOP n’ont pas d’impact sur les temps opératoires et sur la durée d’exposition aux rayons X lors de l’utilisation de la technique par robot magnétique au cours des ablations de fibrillation atriale. La présence d’un FOP permet de réduire de manière significative le temps d’exposition aux rayons X en comparaison avec la double ponction transeptale.
Background
Over the last few years, radiofrequency (RF) therapy has played a decisive role in the treatment of complex arrhythmias and, more particularly, atrial fibrillation (AF) . This technology requires experienced operators, but X-ray exposure and complications remain too high . The current trend favors technology that is similar to or more effective than manual RF techniques, but safer. The remote magnetic navigation (RMN) system appears to be an innovative technology with a very favorable benefit/risk ratio for both the patient and operator, in combination with three-dimensional non-fluoroscopic navigation . During manual paroxysmal AF RF, pulmonary vein isolation (PVI) appeared to take longer when using a patent foramen ovale (PFO) compared with a transseptal puncture, but procedural variables were not influenced by the PFO presence during linear left atrial (LA) RF . The use of a flexible magnetic catheter has increased the safety of complex procedures such as RF ablation considerably; the risk of perforation was shown to be almost zero and was more due to the softness of the catheter than to the constant force applied to the tissue, which did not exceed 15–20 g . However, the softness of the catheter and the PFO orientation could be inconvenient compared with manual transseptal puncture. To our knowledge, no data exist concerning the impact of a PFO on AF ablation procedures when using a remote magnetic navigation (RMN) system.
This prospective study aimed to assess the impact of PFO on AF ablation procedures when using a RMN system.
Methods
Catheter ablation was performed remotely using the Niobe ® II RMN system (Stereotaxis Inc., St. Louis, MO, USA) combined with a new three-dimensional non-fluoroscopic navigation system (CARTO ® 3 system; Biosense Webster, CA, USA) in 167 consecutive patients who underwent pulmonary vein (PV) disconnection for symptomatic drug-refractory AF.
Detection of a patent foramen ovale
Transoesophageal echocardiography (TEE) was performed in all patients within the 48 hours before the ablation procedure to rule out the presence of an atrial thrombus and to detect the presence of a PFO. Briefly, the TEE transverse four-chamber and longitudinal cavae views were used to detect the presence of a PFO. Doppler color flow was used first. Right-sided contrast injections using 10 mL of manually agitated saline solution or dextrose solution were then rapidly injected into a peripheral brachial vein to generate echogenic microbubbles. In the presence of a PFO, these microbubbles crossed the interatrial septum from the right atrium to the left atrium (LA). Transient elevations of right atrial pressure produced by coughing or Valsalva manoeuvres were used to facilitate the passage of microbubbles. During the ablation procedure, catheter manipulation in the region of the septum was systematically used to probe for a PFO before transseptal puncture in all cases.
Electrophysiological procedures
All patients received anticoagulation therapy with vitamin K antagonists for at least 2 months prior to the procedure (target international normalized ratio, 2:3) and therapeutic anticoagulation was maintained with intravenous or low-molecular-weight heparin following vitamin K antagonist discontinuation starting 3 days before the intervention. TEE was performed within the 48 hours before the procedure to exclude LA thrombus. Vitamin K antagonists were resumed the day after the procedure and effective anticoagulation was maintained with heparin until the international normalized ratio was > 2.0. Surface electrocardiograms and bipolar endocardial electrograms (filtered from 30 to 500 Hz) were continuously monitored and stored on a computer-based digital amplifier/recorder system. A deflectable quadripolar catheter (5 mm interelectrode spacing; Xtrem ® ; ELA Medical, Montrouge, France) was positioned in the coronary sinus for pacing and recording. The LA was accessed by a PFO, when present, or by transseptal double puncture. A guidewire was introduced into the LA using an 8 F long sheath. The sheath was perfused during the procedure with heparinized solution (3000 U of heparin in 500 mL of sodium chloride 0.9% at a rate of 150 mL/hour). A multipolar deflectable catheter (LASSO ® ; Biosense Webster, Diamond Bar, CA, USA) was inserted through the long sheath to map the PV ostia for all ablation procedures.
RF ablation was performed using a 3.5 mm open irrigated-tip magnetic ablation catheter (NAVISTAR ® RMT THERMOCOOL ® ; Biosense Webster, Diamond Bar, CA, USA). The catheter was advanced into the LA through a second transseptal puncture or the same PFO. The venous sheath was then withdrawn in the right atrium and continuously perfused. Following transseptal puncture, intravenous unfractionated heparin was administered as a bolus (7500 U), and additional boluses were given throughout the procedure to maintain an activated clotting time of at least 300 seconds. Activated clotting time was determined 30 minutes after the transseptal puncture and every 30 minutes thereafter. When the activated clotting time was < 300 seconds, an additional bolus of 2500 U was administered. Deep sedation was achieved using intravenous nalbuphine and midalzolam.
Radiofrequency catheter ablation procedures
Regardless of the study group, the ablation endpoints were PVI, defined as complete elimination or dissociation of pulmonary potentials validated with a circumferential mapping catheter in all cases (paroxysmal and persistent AF), as well as the creation of linear lesions interconnecting the upper PV ostia (roofline).
RF was applied using an open irrigated-tip catheter with a power output ≤ 35 W close to the PV ostia and 30 W for the roofline or while creating coronary sinus disconnection. Irrigation with sodium chloride 0.9% at a rate of 20–35 mL/min was employed to maintain a tip temperature of < 43 °C.
Remote magnetic navigation system and CARTO ® 3 system features
The RMN system (Niobe II; Stereotaxis Inc., St. Louis, MO, USA) is a technological platform that uses a steerable magnetic field to remotely guide a supple catheter inside the heart . The CARTO ® 3 system used allows for real-time Advanced Catheter Location™ and visualization of both ablation and circular mapping catheters (NAVISTAR and LASSO catheters). The catheter location display is identical to that of the fluoroscopic view. The CARTO ® 3 system combines electromagnetic technology (as in the CARTO ® XP system) with new advanced catheter location technology that enables visualization of multiple catheters without fluoroscopy. Both technologies have been described fully elsewhere .
Measurements: procedural and fluoroscopy variables
The following variables were recorded for all patients and compared within study groups: total procedure duration (skin to skin; minutes); total X-ray exposure (minutes and Gy/cm 2 ), from needle insertion to ultimate catheter removal; skin to catheter positioning X-ray exposure (minutes and Gy/cm 2 ), from femoral access to the end of catheter positioning in the LA, including double transseptal access; LA electroanatomical mapping X-ray exposure (minutes and Gy/cm 2 ), from catheter positioning in the LA to the creation of a satisfactory electroanatomical reconstruction compared with the LA computed tomography scan; ablation X-ray exposure (minutes and Gy/cm 2 ), from the first to the last RF delivery.
Endpoints
The primary endpoint was wide-area circumferential PVI, confirmed by spiral catheter recording during ablation in all patients. PVI was defined as abolition or dissociation of activities in all of the PVs. PV potentials and far-field potentials were distinguished with pacing technique from the LA, LA appendage or coronary sinus, using the ablation or the quadripolar catheter. An additional lesion line (LA roof) or coronary sinus defragmentation or complex fractionated electrogram lesions for persistent AF could be performed. Secondary endpoints included procedural data, complications and freedom from atrial tachycardia/AF.
Follow-up
Patients were routinely hospitalized for 3 days postprocedure and a blanking period of 2 months was applied. The blanking period was defined as a period during which early recurrences were considered a transient phenomenon rather than a procedure failure. Antiarrhythmic medication was maintained for 6 months and then discontinued in patients with paroxysmal AF, but maintained in those with persistent AF. Vitamin K antagonists were continued, with consideration for the Congestive heart failure, Hypertension, Age > 75 years [2 points], Diabetes mellitus, Stroke or transient ischaemic attack [2 points], Vascular disease, Age 65–74 years and Sex category [female] score (CHA 2 DS 2 -VASc). Success was defined as the absence of any documented arrhythmia or symptoms suggestive of arrhythmia recurrences. Twenty-four-hour Holter monitoring was performed each time the patient experienced palpitations. Patients were followed every 6 months by means of a clinical interview. A redo procedure was permitted > 6 months after the index procedure, if the patient so wished.
Statistical analysis
All clinical variables were assessed at the time of the hospitalization and procedure. Continuous variables are presented as mean ± standard deviation or median with interquartile, as appropriate. Categorical variables are expressed as percentages. Statistical significance was assessed using the unpaired Student’s t test or the Mann–Whitney test, if necessary. Categorical variables, expressed as numbers or percentages, were analyzed with the chi-square test or Fisher’s exact test. All tests were two-tailed and a P value < 0.05 was considered statistically significant. Cumulative event rates (i.e. the occurrence of subsequent arrhythmia) were calculated according to the Kaplan–Meier method. All analyses were performed using StatView ® 5.0 software (Abacus Concept, Berkeley, CA, USA).
Results
Baseline population characteristics
Baseline clinical data are summarized in Table 1 . In total, 167 patients were prospectively included, with the following patient characteristics: mean age 58 ± 10 years; 18% women; 107 (64%) with symptomatic paroxysmal AF; 60 (36%) with persistent AF; CHA 2 DS 2 -VASc score 1.2 ± 1; mean LA diameter 43 ± 0.7 mm; 27.5% with structural heart disease. The percentage of circumferential PVI, confirmed by spiral catheter recording during ablation, was 97%.
