Initial results of using a novel irrigated multielectrode mapping and ablation catheter for pulmonary vein isolation Dong-In Shin, MD, Kiriakos Kirmanoglou, MD, Christian Eickholt, MD, Jan Schmidt, MD, Lukas Clasen, MD, Britta Butzbach, MD, Tienush Rassaf, MD, Marc Merx, MD, Malte Kelm, MD, Christian Meyer, MD From the Division of Cardiology, Pulmology and Vascular Medicine, University Hospital, Duesseldorf, Germany. BACKGROUND Pulmonary vein isolation (PVI) as a cornerstone for catheter ablation of atrial fibrillation (AF) remains a complex and time-consuming procedure. OBJECTIVE To assess feasibility, safety, and acute efficacy of a novel irrigated multielectrode ablation catheter guided by an electroanatomic mapping system for PVI in patients with paroxysmal AF. METHODS Twenty-five consecutive patients (60 ⫾ 10 years) with paroxysmal AF underwent PVI by using a novel decapolar mapping and ablation catheter (nMARQ catheter, Biosense Webster Inc, Diamond Bar, CA). Ablation was guided by electroanatomic mapping allowing radiofrequency (RF) energy delivery in the antral region of pulmonary veins (PVs) from 10 irrigated electrodes simultaneously. The day after ablation, cardiac magnetic resonance imaging was performed routinely in order to assess for potential acute PV stenosis. RESULTS Overall, 97 of 97 (100%) targeted PVs could be isolated with a mean of 27 ⫾ 11 RF applications and a mean total burning time of 15 ⫾ 6 minutes per patient. The total procedure time from femoral vein access to catheter withdrawal was 110 ⫾ 31 minutes, including a mean total fluoroscopy time of 23 ⫾ 9 minutes. On average, 6 ⫾ 3 RF impulses with a maximum of 25 W were applied
Introduction In treatment of symptomatic and drug refractory atrial fibrillation (AF), catheter-based pulmonary vein isolation (PVI) has been established as a standard procedure by using a single-tip ablation catheter for creating linear lesions around ipsilateral pulmonary veins (PVs).1 Alternatively, so-called single-shot devices that allow delivery of different energy forms by anatomically designed ablation tools aimed at the Address reprint requests and correspondence: Dr Dong-In Shin, Division of Cardiology, Pulmology and Vascular Medicine, University Hospital, Moorenstrasse 5, 40225 Duesseldorf, Germany. E-mail address: dong-in. [email protected].
1547-5271/$-see front matter B 2014 Heart Rhythm Society. All rights reserved.
per vein. After a short learning curve, procedure, fluoroscopy, and total burning times decreased to 94 ⫾ 16, 16 ⫾ 3, and 9 ⫾ 2 minutes, respectively (P o .05). Entrance and exit blocks could be verified by placing the ablation catheter into 90 of 97 (93%) PVs in 18 of 25 (72%) patients. No procedure-related complications were observed, especially no acute PV stenosis could be detected. CONCLUSIONS The use of a novel irrigated multielectrode ablation system for PVI is feasible and safe, resulting in acute isolation of all targeted PVs with no complications and short procedure times. Sustainability of these initial results has to be confirmed in longterm efficacy and follow-up trials. KEYWORDS Atrial fibrillation; Catheter ablation; Multielectrode ablation catheter ABBREVIATIONS 3D ¼ 3-dimensional; ACT ¼ active clotting time; AF ¼ atrial fibrillation; FAM ¼ fast anatomic mapping; INR ¼ international normalized ratio; MRI ¼ magnetic resonance imaging; PV ¼ pulmonary vein; PVAC ¼ pulmonary vein ablation catheter; PVI ¼ pulmonary vein isolation; RF ¼ radiofrequency; RIPV ¼ right inferior pulmonary vein (Heart Rhythm 2014;11:375–383) I 2014 Heart Rhythm Society. All rights reserved.
creation of linear lesions by only a few impulse applications have been developed.2,3 Furthermore, as a non–balloonbased concept, the pulmonary vein ablation catheter (PVAC) is the only multielectrode mapping and ablation catheter used for PVI on a routine basis that is associated with the disadvantages of lacking a 3-dimensional (3D) mapping and using nonirrigated energy delivery.4,5 Using an irrigated multielectrode electroanatomically guided mapping and ablation catheter might be advantageous over the currently available ablation systems. Therefore, this study describes our first clinical experiences with this novel ablation system by using a decapolar mapping and ablation catheter that provides both irrigation and electroanatomic mapping http://dx.doi.org/10.1016/j.hrthm.2013.12.008
376 features. The aim of this study was to assess feasibility, safety, and acute efficacy of this novel multielectrode ablation catheter for PVI in patients with paroxysmal AF.
Methods Patient population A total of 25 patients (mean age 60 ⫾ 10 years; 64% men) with symptomatic, drug refractory paroxysmal AF underwent PVI and were included in a prospective registry. AF was documented at least by 1 electrocardiogram. Informed consent was obtained from all patients, and the study protocol was approved by the institutional review board of the University Hospital Duesseldorf. Study design and data management were not influenced by Biosense Webster in any aspect.
nMARQ ablation system nMARQ catheter The nMARQ catheter (Biosense Webster Inc, Diamond Bar, CA) is an 8.4-F decapolar mapping and ablation catheter with an adjustable circular array of a diameter between 20 and 35 mm. Platinum electrodes are 3 mm long, with a spacing of 4 mm. Each of the electrodes possesses a thermocouple and holes for irrigation (Figure 1A). By a steering mechanism placed at the handle (Figure 1B), the catheter can be deflected unidirectionally, while the diameter of the loop can be varied in its diameter. The catheter with all
Heart Rhythm, Vol 11, No 3, March 2014 10 electrodes can be recognized by using the CARTO 3 system (Biosense Webster Inc), which allows a 3D anatomic mapping of the left atrium and the PVs. Intracardiac signals are acquired by 5 bipolar recordings through adjacent electrode pairs. At the time of the study, CE marking of the catheter was existent (“CE” originally stood for “Communauté Européenne”, French for “European Community”; The CE marking or formerly EC mark, is a mandatory conformity marking for certain products sold within the European Economic Area (EEA) since 1985). nMARQ generator The nMARQ generator ((Biosense Webster Inc; Figure 1C) is a multichannel RF generator capable of delivering independently unipolar or bipolar RF energy to a maximum of 10 electrodes simultaneously. During unipolar ablation, current flow is provided between the electrodes and an indifferent electrode attached to the patient’s leg, while in the bipolar energy mode, current flows between adjacent electrodes. RF energy is delivered in a temperature-controlled manner, while maximum energy level can be chosen from 1 to a maximum of 25 W in the unipolar mode and up to 15 W in the bipolar ablation mode. Temperature, impedance, and power levels are displayed during energy application for every single electrode on a separate screen. Each electrode can be turned on or off at any time of RF delivery individually on the touch screen monitor (Figure 1D). During
Figure 1 Irrigated multieletrode ablation system. Multielectrode ablation system consisting of the nMARQ catheter with 10 electrodes placed on a circular array (A), with a unidirectional steering mechanism (B), ablation generator (C), and touch screen monitor (D).
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ablation, a continuous flow of heparinized saline fluid is provided by a cooling pump (Cool Flow Pump, Biosense Webster Inc) with 60 mL/min for irrigation of all electrodes.
Mapping and ablation procedure All patients underwent ablation under continuous oral anticoagulation by phenprocoumon with an international normalized ratio (INR) ranging between 2 and 3. In cases of the preprocedural usage of dabigatran or rivaroxaban, anticoagulation was withheld on the morning of the ablation procedure and continued the next day, giving lowmolecular-weight heparin subcutaneously in a weightadjusted manner on the ablation day. All patients were treated under deep sedation with midazolam, propofol, and piritramide, while blood pressure and oxygenation were monitored continuously. Vascular access was obtained through a femoral vein. A quadripolar diagnostic catheter (Biosense Webster Inc) was placed in the right ventricular apex, while an octopolar catheter (Inquiry, St Jude Medical Inc, Minnetonka, MN) was positioned in the coronary sinus. Transseptal puncture was performed by using a long sheath (Lamp45, St Jude Medical Inc) and a Brockenbrough needle (BRK, St Jude Medical Inc) under fluoroscopic control. As soon as the left atrium was accessed, 80 IU heparin/kg were given intravenously, targeting an active clotting time (ACT) of 4300 seconds. A left atrial angiogram was performed through the application of approximately 25 mL of contrast medium over the fixed sheath under high ventricular pacing at a cycle length of 300 ms for about 20 seconds. By placing a wire in the left superior pulmonary vein, the fixed sheath was exchanged for a steerable sheath (8.5 F, Agilis,, small curl, St Jude Medical Inc, or 9.5 F, Channel, Bard, Lowell, MA) by using the Seldinger technique. Then, the nMARQ
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catheter was introduced into the steerable sheath under continuous flushing by the cool flow pump with 60 mL/ min. Inside the left atrium, the basal flow rate was adjusted to 4 mL/min, respiration gating function was activated, and a fast anatomic mapping (FAM) was started, beginning with the intubation of the left superior pulmonary vein. In correspondence to the left atrial angiogram, fluoroscopy, intracardiac signals from the nMARQ catheter, and anatomic mapping, the antral region of the atrium-PV conjunction was defined as the ablation target zone and marked with the snapshot function (Figure 2). This was repeated for each PV, while the left atrium was also mapped anatomically. Beginning at the right inferior pulmonary vein (RIPV), the nMARQ catheter was placed exactly over the acquired snapshot and high-energy (10 mV/2 ms) pacing from each electrode of the nMARQ catheter was performed at a cycle length of 500 ms to rule out phrenic nerve capture. Then, 1 unipolar RF impulse was applied with a maximum power of 25 W over a maximum period of 60 seconds. After oral communication and recently published appearance of a lethal atrioesophageal fistula by using the nMARQ catheter,6 we modified energy delivery characteristics to a maximum power of 20 W and a maximum duration of 45 seconds for safety reasons after the first 10 cases. Quite often, PV signals recorded preablationally by the nMARQ catheter diminished within 10 seconds of RF application (Figure 3). Therefore, energy delivery was stopped 5–8 seconds afterward, resulting in an impulse duration of 15–18 seconds, aiming for further risk reduction relating to possible thermal damage inferred on the esophagus. Afterward, the nMARQ catheter was turned clockwise between 90º and 120º for a second RF impulse delivery of the same magnitude. PV isolation was investigated by advancing the nMARQ catheter into the PV after adjusting it to the smallest possible diameter and
Figure 2 Fast anatomic map of the left atrium with pulmonary vein ostia. After anatomic mapping of the left atrium by the nMARQ catheter, ablation target zones were marked with the snapshot function (arrows) in a posterior-anterior (PA) and a left anterior oblique (LAO) view at the PV ostia. LIPV ¼ left inferior pulmonary vein; LSPV ¼ left superior pulmonary vein; RIPV ¼ right inferior pulmonary vein; RSPV ¼ right superior pulmonary vein.
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Figure 3 PV-signal registration with the nMARQ catheter. Intracardiac signals obtained by the nMARQ catheter showing atrial and PV signals (arrows) from the right superior vein before (A) and after (B) RF delivery.
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consecutive pacing from each electrode pair in order to observe exit block. If no exit block had been achieved, further RF applications were applied in the antral region until both exit and entrance blocks could be established. If the PV could not be intubated by the nMARQ catheter, a steerable multielectrode diagnostic catheter was placed into the proximal PV for differential pacing. During RF delivery, reduction of the atrial or PV signal was observed continuously and at the same time electrodes showing no heating over 361C or else reaching less than 15 W were turned off. In the case of lack of atrial signals on some of the 10 electrodes, those displaying no signals were excluded from subsequent energy delivery. After isolation of the last PV, exit and entrance blocks were reconfirmed for all PVs after a waiting period of 20 minutes.
Postablation management After withdrawal of all catheters, patients were monitored on an intermediate care unit overnight; oral anticoagulation was continued the same day for all patients and administered for at least 3 months and with no time limit in patients with a CHA2DS2-VASC score of 41. Twenty-four to 48 hours postprocedure, all patients underwent a cardiac magnetic resonance imaging (MRI) scan to rule out acute PV stenosis. Hereby, PV stenosis was defined as a 50% reduction of ostial PV diameter compared to radiographically assessed data by using left atrial angiogram during the ablation procedure. Antiarrhythmic drugs were discontinued immediately after ablation procedure and 4 weeks treatment with proton pump inhibitors was recommended for all patients. Patients were scheduled for follow-up examinations 3, 6, and 12 months after the initial treatment, and rhythm monitoring during the follow-up visits were performed by the clinical assessment of AF recurrence and a 7-day Holter monitoring.
Statistical analysis Continuous variables are presented as mean ⫾ SD and were compared by using a paired t test. A P value of o.05 indicated statistical significance.
Results Patient characteristics Twenty-five patients (64% men) with a mean age of 60 ⫾ 10 years underwent PVI by using the nMARQ ablation system. All patients suffered from paroxysmal AF who demonstrate an European Heart Rhythm Association (EHRA) EHRA score of ZIII and had been refractory to at least 1 antiarrhythmic drug previously. Mean left ventricular ejection fraction observed was 58% ⫾ 3%. Furthermore, no patient showed a left atrial dilatation of Z44 mm. Patient characteristics are summarized in Table 1. In 3 (12%) patients, a common ostium of the left-sided PVs could be detected by using left atrial angiogram and anatomic mapping by using the nMARQ catheter, which was reconfirmed by postprocedural cardiac MRI in all cases.
Table 1 Patient characteristics Age (y) Sex: male/female History of AF (mo) Prior antiarrhythmic drugs EHRA I/II/III/IV Left atrial size (mm) Hypertension Coronary artery disease LVEF (%) CHA2DS2-VASC score
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60 ⫾ 10 16/9 41 ⫾ 30 1.4 (range 1–4) 0/0/19/6 41 ⫾ 2 14 (56) 1 (4) 58 ⫾ 3 2 ⫾ 0.7
Data are presented as mean ⫾ SD and as n (%). AF ¼ atrial fibrillation; EHRA ¼ European Heart Rhythm Association; LVEF ¼ left ventricular ejection fraction.
Procedural success and learning curve The overall procedure time from vascular access until removal of all catheters was 110 ⫾ 31 minutes (range 60– 180 minutes), while a mean fluoroscopy time of 23 ⫾ 9 minutes could be observed (Table 2A). All the 97 targeted PVs could be isolated by using the nMARQ catheter that was verified by entrance and exit blocks for each vein. The mean total burning time was 15 ⫾ 6 minutes per patient. An average number of 27 ⫾ 11 RF impulses per patient was needed to achieve isolation of all PVs, including a mean number of 2 ⫾ 1 energy deliveries due to reconnection after a waiting period of 20 minutes in 9 of 25 (36%) cases. Touchup ablation by using a single-tip ablation catheter did not have to be used in any of the cases. In spite of a flow rate of 60 mL/min during energy application and 4 mL/min during mapping, the total amount of fluid administered during the entire procedure reached a mean value of 900 mL and did not exceed 1.5 L, which was similar to that administered during single-tip ablation procedures. The deployment of the nMARQ catheter was successful in all left-sided PVs and all right-sided superior PVs. Deployment into the RIPV was not successful in 7 (28%) cases (see Table 2B), thus necessitating the placement of an octopolar diagnostic catheter into the RIPV for differential pacing. In those cases, the mean diameter of the respective RIPVs obtained by using MRI was 16.3 ⫾ 2.5 mm. A fast learning curve could be observed by comparing procedural data of the first and the last 5 cases of this series, resulting in a significant decrease in the procedure time from 150 ⫾ 27 to 94 ⫾ 16 minutes (P ¼ .0099) and fluoroscopy time from 33 ⫾ 11 to 16 ⫾ 3 minutes (P ¼ .0035), respectively. Furthermore, ablation strategy changed during the observed series, targeting a lower maximum energy of 20 W in unipolar ablation and constituting a signal-orientated RF impulse duration over a fixed one for safety reasons.
Follow-up data During the mean follow-up time of 4.1 ⫾ 1.6 months (range 2–7 months), no left atrial flutter or tachycardia occurred. After 3 months, sinus rhythm was stable off antiarrhythmic drugs in 17 of 21 (80.9%) patients.
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Table 2 Procedural and ablation data A: Procedural data Procedure time (min) Fluoroscopy time (min) Total burning time (min) Complications Access site complications Pericardial tamponade TIA/stroke PV stenosis Phrenic nerve palsy Atrioesophageal fistula Death B: Ablation data Procedures Total PV Common ostium Successful PV isolation with the nMARQ catheter Successful PV intubation with the nMARQ catheter Mean number of RF applications—total Mean number of RF applications—LSPV Mean number of RF applications—LIPV Mean number of RF applications—RSPV Mean number of RF applications—RIPV Charring of the nMARQ electrode
110 ⫾ 31 23 ⫾ 9 15 ⫾ 6 – – – – – – – – 25 97 3 97 of 97 (100) 90 of 97(93) 27 ⫾ 11 9⫾5 7⫾5 5⫾2 5⫾2 3 of 25 (12)
Data are presented as mean ⫾ SD and as n (%). LIPV ¼ left inferior pulmonary vein; LSPV ¼ left superior pulmonary vein; PV ¼ pulmonary vein; RIPV ¼ right inferior pulmonary vein; RF ¼ radiofrequency; RSPV ¼ right superior pulmonary vein; TIA ¼ transient ischemic attack.
MRI data The diameter of PV ostia was obtained both by FAM using the multielectrode ablation catheter and the CARTO system and postprocedural MRI, demonstrating smaller diameter values when measured by MRI compared to the nMARQ catheter method (see Table 3). A mechanical extension of the PV ostia by the circular array of the nMARQ catheter was suggested as a possible explanation for this observation.
Safety concerns Charring of the electrodes could be detected during the first 3 cases, especially on electrodes 1 and 10. We suggested an adjacent heating of overlapping electrodes when the diameter of the circular frame was adjusted to the minimum. Hence, we applied energy over all 10 electrodes only if a sufficient distance between electrodes 1 and 10 was observed. Electrode overlapping was easily noticeable not only by fluoroscopy and 3D catheter visualization of the Table 3 Vein diameter obtained by MRI in comparison to CARTO (mean ⫾ standard deviation)
Vein
Diameter measured by MRI (mm)
Diameter measured by CARTO (mm)
p-value
LSPV LSPV RSPV RIPV
19.9 ⫾ 18.4 ⫾ 18.6 ⫾ 17.6 ⫾
24.7 ⫾ 22.9 ⫾ 23.6 ⫾ 22.7 ⫾
0.001 0.003 0.003 0.001
2.5 4.1 4.9 3.9
3.1 2.9 2.9 2.4
CARTO system but also by resulting artifact signals recorded by affected electrodes, as shown in Figure 4. Furthermore, we stopped applying bipolar RF energy and since then no further charring was detected. No complications occurred during or after the ablation procedure, especially no clinically detectable cerebral thromboembolic event or phrenic nerve palsy could be observed. Furthermore, acute PV stenosis could be ruled out by cardiac MRI scan.
Discussion Acute efficacy The ablation of patients with paroxysmal AF by using a novel ablation system that provides a multielectrode 3D mapping and irrigated RF application resulted in an acute isolation of all addressed PVs. This acute success rate compares with published data by groups using a conventional, single-tip approach guided by a 3D mapping system.7,8 Since this standard approach is time-consuming and manually challenging, several single-shot devices have been introduced for a simplified PVI approach. Using the cryoballoon (Medtronic, Minneapolis, MN), which can be combined with a multipolar diagnostic catheter for achieving intracardiac electrograms during ablation, acute PVI in up to 98% of the treated PVs were observed.2,9 Comparably using a visually guided laser balloon catheter (Cardio Focus Inc, Marlborough, MA), acute PVI could be achieved in up to 99% of the targeted PVs,3,10 though requesting further mapping catheters since intracardiac signals are not available by this ablation tool. Furthermore, multielectrode ablation is also feasible by using the PVAC (Medtronic), which provides nonirrigated application of duty-cycled RF energy by up to 9 electrodes simultaneously. Investigators reported acute success rates of up to 99%.11,12
Procedure times Mean procedure time from skin to skin was 110 minutes, with a fluoroscopy time of 23 minutes. These data might even improve since the presented data included a steep learning curve, with a total procedure time of 94 minutes and fluoroscopy time of 16 minutes during the last 5 cases. In comparison, groups using the PVAC for PVI in paroxysmal AF report similar short procedure times (81–133 minutes) and fluoroscopy times (20–30 minutes).13–15 Furthermore, published data using a single-tip catheter referred to total procedure and fluoroscopy times varying between 148 and 165 minutes and between 16 and 28 minutes, respectively.2,16,17 Cryoballoon ablation requires mean procedure and fluoroscopy times between 135 and 170 minutes and between 21 and 40 minutes, respectively,9,18,19 whereas published data for the first 200 patients experience with laser balloon ablation demonstrate procedure and fluoroscopy times of 200 and 31 minutes, respectively.3 In summary, the nMARQ ablation system provides both short procedure and fluoroscopy times compared with other existing ablation systems (see Table 4).
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Figure 4 Effect of electrode overlapping during radiofrequency application. Overlapping of electrodes 1 and 10 in fluoroscopy (A, white arrow) and the corresponding one in the CARTO mapping (B, white arrow). During electrode overlapping, artifact signals are received by affected electrodes 1 and 10 (D, black arrows). The nMARQ catheter shows charring mainly on electrodes 9 and 10 (C, white arrows) after energy delivery with overlapping electrodes.
Ablation strategy
diameter of the circular array and deployed the catheter into the PV by using it like a decapolar circular diagnostic catheter (eg, Lasso, Biosense Webster Inc). By starting the FAM, 3D reconstruction of the intubated PV could be generated easily and the PV ostium was defined by local electrogram interpretation and fluoroscopic control showing a “hopping” movement, like a short jump out of the vein during continuous pulling of the catheter back to the left atrium. By starting with the left superior pulmonary vein,
Since no data referred to ablation strategy using the nMARQ system are published, we aimed for the most pragmatic and straightforward approach. In contrast to the PVAC, the nMARQ catheter cannot be placed over a wire but has to address the target zone directly. Therefore, we used a steerable sheath in all cases to optimize catheter placement, especially for the lower PVs, although this is not our regular approach while using a single-tip catheter. We minimized the Table 4
Comparison of procedural data in different ablation technologies used for PVI in treatment of paroxysmal atrial fibrillation
Technology 2
Conventional RF ablation Cryoballoon ablation2 Visually guided laserablation3 PVAC15 nMARQ catheter
Acute success (%)
Procedure time (min)
Fluoroscopy time (min)
n
97.6 97.5 98.8 100 100
165 160 200 133 110
24 34 31 30 23
2870 905 200 89 25
Data are presented as mean values. PVAC ¼ pulmonary vein ablation catheter; PVI ¼ pulmonary vein isolation; RF ¼ radiofrequency.
382 which could be intubated in all cases with the nMARQ catheter, the same mapping and tagging was done for the left inferior pulmonary vein, the right superior pulmonary vein, and the RIPV. We declined to obtain a left atrial imaging study before the procedure since left atrial angiogram and FAM provided sufficient information of the target regions during the ablation procedure. Depending on the individual anatomy and the localization of the transseptal puncture side, addressing the RIPV by the nMARQ catheter was hampered frequently. As soon as we established the correct placement of the nMARQ catheter at the RIPV, we started isolating those veins first, since flexion abilities of the nMARQ catheter change during ongoing procedure owing to warming of the catheter material by the blood, thus reducing subsequent placement attempts. In recognition of its adjustable diameter size, precaution must be taken not to deliver RF energy inside the PV; therefore, we deliberately enlarged the diameter of the catheter in the antral region. The use of intracardiac echocardiography might have been useful to further confirm the avoidance of energy delivery within the PVs at the same time, giving an additional indication of existence of sufficient tissue contact. Furthermore, we avoided overlapping of electrodes during RF application by enlarging the diameter. By using the nMARQ catheter as a Lasso mapping catheter for proving exit and entrance blocks, we declined to use a separate multielectrode diagnostic catheter as in conventional single-tip approaches. Thus, no data can be given related to differences of electrogram characteristics obtained by the nMARQ catheter and the Lasso catheter, respectively. We like to point out that the interpretation of electrograms obtained by the nMARQ catheter during energy application was reasonable in contrast to the use of the PVAC in which electrogram analysis during ablation is not possible owing to artifacts. However, the nMARQ catheter appeared to be less flexible owing to its stiffer catheter shaft compared to the Lasso catheter, requiring more cautious movements for placing it inside the PVs. In the case of unsuccessful intubation by the nMARQ catheter, we introduced an octopolar diagnostic catheter into the PV for differential pacing.
Safety No procedure-related complications could be observed in this study. No access site–related bleeding complications, cardiac tamponade, or phrenic nerve palsy occurred. No acute PV stenosis appeared while MRI scan showed no narrowing of the examined PV ostia; however, the development of such stenosis might occur delayed after several months or weeks,20 which cannot be excluded by our present set of data. In consideration of published data suggesting a causal connection between multielectrode ablation and observed esophageal lesions by passive heating of an intraluminal temperature probe,21 we declined to perform esophageal temperature monitoring. Therefore, power management
Heart Rhythm, Vol 11, No 3, March 2014 during ablation along the posterior wall contained a maximum energy level of 20 W and a maximum impulse duration of 30 seconds. Since no clinical signs for esophageal damage appeared, no endoscopy was performed. Thus, no data can be given for possible thermal esophageal lesions by ablation. No patient showed symptoms related to cerebral thromboembolism. Although there was an absence of clinically noticeable cerebral thromboembolic injuries, we cannot exclude or quantify possible asymptomatic cerebral events, which have been described extensively in several publications that are associated with all available ablation techniques used for PVI,22,23 because no cerebral MRI scan has been performed. Charring was documented in 3 of 25 (12%) patients who were all anticoagulated by phenprocoumon and showed a mean INR of 2.5 ⫾ 0.3 and a mean ACT during ablation procedure of 387 ⫾ 36 seconds. In cases with no charring, a mean INR of 2.4 ⫾ 0.3 and a mean ACT of 346 ⫾ 87 seconds could be observed, showing no significant difference. Furthermore, this group included 8 patients treated with dabigatran or rivaroxaban instead of phenprocoumon. Bipolar energy delivery was used only in the charring group, whereas the total number of bipolar impulses was low (1 per case). The overlapping of electrodes 1 and 10 during energy application was allowed only in the first 3 cases when charring occurred. In our opinion, a distance of 4 mm between electrode 1 and electrode 10 should be established, resembling the spacing distance of adjacent electrodes 1–10.
Study limitations Several limitations of our study have to be addressed. First of all, our study provides a small patient number and a short follow-up time of 4.1 months; thus, the effect of given follow-up data is of limited value to determine long-term success. However, the aim of the study was not long-term follow-up but its capabilities to reach PV isolation as an end point. Long-term efficacy is addressed by ongoing clinical trials (EVOLUTION and reMARQable), and data analysis is expected for 2014 and 2018, respectively. Furthermore, we changed ablation strategy concerning maximum power and duration of energy delivery after the first 10 cases related to safety reasons, which might have affected the learning curve results. Moreover, we declined to administer adenosine at the end of the procedure, which might have affected the rate of observed acute PV reconnection. Finally, we did not provide data referring to a possible asymptomatic cerebral event; thus, cerebral MRI should be considered for future studies in order to assess a possible effect on the safety of this new technology.
Conclusions Pulmonary vein isolation using an irrigated multielectrode mapping and ablation system appears to be feasible and safe. Long-term clinical efficacy has to be evaluated in further studies.
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383 and clinical outcome after PVAC ablation. J Cardiovasc Electrophysiol 2013;24: 290–296. Wieczorek M, Hoeltgen R, Brueck M, Bandorski D, Akin E, Salili AR. Pulmonary vein isolation by duty-cycled bipolar and unipolar antrum ablation using a novel multielectrode ablation catheter system: first clinical results. J Interv Card Electrophysiol 2010;27:23–31. Fredersdorf S, Weber S, Jilek C, et al. Safe and rapid isolation of pulmonary veins using a novel circular ablation catheter and duty-cycled RF generator. J Cardiovasc Electrophysiol 2009;20:1097–1101. Beukema RJ, Elvan A, Smit JJ, Delnoy PP, Misier AR, Reddy V. Pulmonary vein isolation to treat paroxysmal atrial fibrillation: conventional versus multielectrode radiofrequency ablation. J Interv Card Electrophysiol 2012;34: 143–152. Stabile G, Scaglione M, del GM, et al. Reduced fluoroscopy exposure during ablation of atrial fibrillation using a novel electroanatomical navigation system: a multicentre experience. Europace 2012;14:60–65. Pappone C, Oreto G, Rosanio S, et al. Atrial electroanatomic remodeling after circumferential radiofrequency pulmonary vein ablation: efficacy of an anatomic approach in a large cohort of patients with atrial fibrillation. Circulation 2001;104:2539–2544. Bordignon S, Chun KJ, Gunawardene M, et al. Comparison of balloon catheter ablation technologies for pulmonary vein isolation: the laser versus cryo study. J Cardiovasc Electrophysiol 2013;24:987–994. Klein G, Oswald H, Gardiwal A, et al. Efficacy of pulmonary vein isolation by cryoballoon ablation in patients with paroxysmal atrial fibrillation. Heart Rhythm 2008;5:802–806. von BC, Weber S, Dornia C, et al. Evaluation of pulmonary vein stenosis after pulmonary vein isolation using a novel circular mapping and ablation catheter (PVAC). Circ Arrhythm Electrophysiol 2011;4:630–636. Deneke T, Bunz K, Bastian A, et al. Utility of esophageal temperature monitoring during pulmonary vein isolation for atrial fibrillation using duty-cycled phased radiofrequency ablation. J Cardiovasc Electrophysiol 2011;22:255–261. Wissner E, Metzner A, Neuzil P, et al. Asymptomatic brain lesions following laserballoon-based pulmonary vein isolation. Europace 2013; Aug 9. Epub ahead of print. Herrera SC, Deneke T, Hocini M, et al. Incidence of asymptomatic intracranial embolic events after pulmonary vein isolation: comparison of different atrial fibrillation ablation technologies in a multicenter study. J Am Coll Cardiol 2011;58:681–688.
Introduction In treatment of symptomatic and drug refractory atrial fibrillation (AF), catheter-based pulmonary vein isolation (PVI) has been established as a standard procedure by using a single-tip ablation catheter for creating linear lesions around ipsilateral pulmonary veins (PVs).1 Alternatively, so-called single-shot devices that allow delivery of different energy forms by anatomically designed ablation tools aimed at the Address reprint requests and correspondence: Dr Dong-In Shin, Division of Cardiology, Pulmology and Vascular Medicine, University Hospital, Moorenstrasse 5, 40225 Duesseldorf, Germany. E-mail address: dong-in. [email protected].
1547-5271/$-see front matter B 2014 Heart Rhythm Society. All rights reserved.
per vein. After a short learning curve, procedure, fluoroscopy, and total burning times decreased to 94 ⫾ 16, 16 ⫾ 3, and 9 ⫾ 2 minutes, respectively (P o .05). Entrance and exit blocks could be verified by placing the ablation catheter into 90 of 97 (93%) PVs in 18 of 25 (72%) patients. No procedure-related complications were observed, especially no acute PV stenosis could be detected. CONCLUSIONS The use of a novel irrigated multielectrode ablation system for PVI is feasible and safe, resulting in acute isolation of all targeted PVs with no complications and short procedure times. Sustainability of these initial results has to be confirmed in longterm efficacy and follow-up trials. KEYWORDS Atrial fibrillation; Catheter ablation; Multielectrode ablation catheter ABBREVIATIONS 3D ¼ 3-dimensional; ACT ¼ active clotting time; AF ¼ atrial fibrillation; FAM ¼ fast anatomic mapping; INR ¼ international normalized ratio; MRI ¼ magnetic resonance imaging; PV ¼ pulmonary vein; PVAC ¼ pulmonary vein ablation catheter; PVI ¼ pulmonary vein isolation; RF ¼ radiofrequency; RIPV ¼ right inferior pulmonary vein (Heart Rhythm 2014;11:375–383) I 2014 Heart Rhythm Society. All rights reserved.
creation of linear lesions by only a few impulse applications have been developed.2,3 Furthermore, as a non–balloonbased concept, the pulmonary vein ablation catheter (PVAC) is the only multielectrode mapping and ablation catheter used for PVI on a routine basis that is associated with the disadvantages of lacking a 3-dimensional (3D) mapping and using nonirrigated energy delivery.4,5 Using an irrigated multielectrode electroanatomically guided mapping and ablation catheter might be advantageous over the currently available ablation systems. Therefore, this study describes our first clinical experiences with this novel ablation system by using a decapolar mapping and ablation catheter that provides both irrigation and electroanatomic mapping http://dx.doi.org/10.1016/j.hrthm.2013.12.008
376 features. The aim of this study was to assess feasibility, safety, and acute efficacy of this novel multielectrode ablation catheter for PVI in patients with paroxysmal AF.
Methods Patient population A total of 25 patients (mean age 60 ⫾ 10 years; 64% men) with symptomatic, drug refractory paroxysmal AF underwent PVI and were included in a prospective registry. AF was documented at least by 1 electrocardiogram. Informed consent was obtained from all patients, and the study protocol was approved by the institutional review board of the University Hospital Duesseldorf. Study design and data management were not influenced by Biosense Webster in any aspect.
nMARQ ablation system nMARQ catheter The nMARQ catheter (Biosense Webster Inc, Diamond Bar, CA) is an 8.4-F decapolar mapping and ablation catheter with an adjustable circular array of a diameter between 20 and 35 mm. Platinum electrodes are 3 mm long, with a spacing of 4 mm. Each of the electrodes possesses a thermocouple and holes for irrigation (Figure 1A). By a steering mechanism placed at the handle (Figure 1B), the catheter can be deflected unidirectionally, while the diameter of the loop can be varied in its diameter. The catheter with all
Heart Rhythm, Vol 11, No 3, March 2014 10 electrodes can be recognized by using the CARTO 3 system (Biosense Webster Inc), which allows a 3D anatomic mapping of the left atrium and the PVs. Intracardiac signals are acquired by 5 bipolar recordings through adjacent electrode pairs. At the time of the study, CE marking of the catheter was existent (“CE” originally stood for “Communauté Européenne”, French for “European Community”; The CE marking or formerly EC mark, is a mandatory conformity marking for certain products sold within the European Economic Area (EEA) since 1985). nMARQ generator The nMARQ generator ((Biosense Webster Inc; Figure 1C) is a multichannel RF generator capable of delivering independently unipolar or bipolar RF energy to a maximum of 10 electrodes simultaneously. During unipolar ablation, current flow is provided between the electrodes and an indifferent electrode attached to the patient’s leg, while in the bipolar energy mode, current flows between adjacent electrodes. RF energy is delivered in a temperature-controlled manner, while maximum energy level can be chosen from 1 to a maximum of 25 W in the unipolar mode and up to 15 W in the bipolar ablation mode. Temperature, impedance, and power levels are displayed during energy application for every single electrode on a separate screen. Each electrode can be turned on or off at any time of RF delivery individually on the touch screen monitor (Figure 1D). During
Figure 1 Irrigated multieletrode ablation system. Multielectrode ablation system consisting of the nMARQ catheter with 10 electrodes placed on a circular array (A), with a unidirectional steering mechanism (B), ablation generator (C), and touch screen monitor (D).
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ablation, a continuous flow of heparinized saline fluid is provided by a cooling pump (Cool Flow Pump, Biosense Webster Inc) with 60 mL/min for irrigation of all electrodes.
Mapping and ablation procedure All patients underwent ablation under continuous oral anticoagulation by phenprocoumon with an international normalized ratio (INR) ranging between 2 and 3. In cases of the preprocedural usage of dabigatran or rivaroxaban, anticoagulation was withheld on the morning of the ablation procedure and continued the next day, giving lowmolecular-weight heparin subcutaneously in a weightadjusted manner on the ablation day. All patients were treated under deep sedation with midazolam, propofol, and piritramide, while blood pressure and oxygenation were monitored continuously. Vascular access was obtained through a femoral vein. A quadripolar diagnostic catheter (Biosense Webster Inc) was placed in the right ventricular apex, while an octopolar catheter (Inquiry, St Jude Medical Inc, Minnetonka, MN) was positioned in the coronary sinus. Transseptal puncture was performed by using a long sheath (Lamp45, St Jude Medical Inc) and a Brockenbrough needle (BRK, St Jude Medical Inc) under fluoroscopic control. As soon as the left atrium was accessed, 80 IU heparin/kg were given intravenously, targeting an active clotting time (ACT) of 4300 seconds. A left atrial angiogram was performed through the application of approximately 25 mL of contrast medium over the fixed sheath under high ventricular pacing at a cycle length of 300 ms for about 20 seconds. By placing a wire in the left superior pulmonary vein, the fixed sheath was exchanged for a steerable sheath (8.5 F, Agilis,, small curl, St Jude Medical Inc, or 9.5 F, Channel, Bard, Lowell, MA) by using the Seldinger technique. Then, the nMARQ
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catheter was introduced into the steerable sheath under continuous flushing by the cool flow pump with 60 mL/ min. Inside the left atrium, the basal flow rate was adjusted to 4 mL/min, respiration gating function was activated, and a fast anatomic mapping (FAM) was started, beginning with the intubation of the left superior pulmonary vein. In correspondence to the left atrial angiogram, fluoroscopy, intracardiac signals from the nMARQ catheter, and anatomic mapping, the antral region of the atrium-PV conjunction was defined as the ablation target zone and marked with the snapshot function (Figure 2). This was repeated for each PV, while the left atrium was also mapped anatomically. Beginning at the right inferior pulmonary vein (RIPV), the nMARQ catheter was placed exactly over the acquired snapshot and high-energy (10 mV/2 ms) pacing from each electrode of the nMARQ catheter was performed at a cycle length of 500 ms to rule out phrenic nerve capture. Then, 1 unipolar RF impulse was applied with a maximum power of 25 W over a maximum period of 60 seconds. After oral communication and recently published appearance of a lethal atrioesophageal fistula by using the nMARQ catheter,6 we modified energy delivery characteristics to a maximum power of 20 W and a maximum duration of 45 seconds for safety reasons after the first 10 cases. Quite often, PV signals recorded preablationally by the nMARQ catheter diminished within 10 seconds of RF application (Figure 3). Therefore, energy delivery was stopped 5–8 seconds afterward, resulting in an impulse duration of 15–18 seconds, aiming for further risk reduction relating to possible thermal damage inferred on the esophagus. Afterward, the nMARQ catheter was turned clockwise between 90º and 120º for a second RF impulse delivery of the same magnitude. PV isolation was investigated by advancing the nMARQ catheter into the PV after adjusting it to the smallest possible diameter and
Figure 2 Fast anatomic map of the left atrium with pulmonary vein ostia. After anatomic mapping of the left atrium by the nMARQ catheter, ablation target zones were marked with the snapshot function (arrows) in a posterior-anterior (PA) and a left anterior oblique (LAO) view at the PV ostia. LIPV ¼ left inferior pulmonary vein; LSPV ¼ left superior pulmonary vein; RIPV ¼ right inferior pulmonary vein; RSPV ¼ right superior pulmonary vein.
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Figure 3 PV-signal registration with the nMARQ catheter. Intracardiac signals obtained by the nMARQ catheter showing atrial and PV signals (arrows) from the right superior vein before (A) and after (B) RF delivery.
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consecutive pacing from each electrode pair in order to observe exit block. If no exit block had been achieved, further RF applications were applied in the antral region until both exit and entrance blocks could be established. If the PV could not be intubated by the nMARQ catheter, a steerable multielectrode diagnostic catheter was placed into the proximal PV for differential pacing. During RF delivery, reduction of the atrial or PV signal was observed continuously and at the same time electrodes showing no heating over 361C or else reaching less than 15 W were turned off. In the case of lack of atrial signals on some of the 10 electrodes, those displaying no signals were excluded from subsequent energy delivery. After isolation of the last PV, exit and entrance blocks were reconfirmed for all PVs after a waiting period of 20 minutes.
Postablation management After withdrawal of all catheters, patients were monitored on an intermediate care unit overnight; oral anticoagulation was continued the same day for all patients and administered for at least 3 months and with no time limit in patients with a CHA2DS2-VASC score of 41. Twenty-four to 48 hours postprocedure, all patients underwent a cardiac magnetic resonance imaging (MRI) scan to rule out acute PV stenosis. Hereby, PV stenosis was defined as a 50% reduction of ostial PV diameter compared to radiographically assessed data by using left atrial angiogram during the ablation procedure. Antiarrhythmic drugs were discontinued immediately after ablation procedure and 4 weeks treatment with proton pump inhibitors was recommended for all patients. Patients were scheduled for follow-up examinations 3, 6, and 12 months after the initial treatment, and rhythm monitoring during the follow-up visits were performed by the clinical assessment of AF recurrence and a 7-day Holter monitoring.
Statistical analysis Continuous variables are presented as mean ⫾ SD and were compared by using a paired t test. A P value of o.05 indicated statistical significance.
Results Patient characteristics Twenty-five patients (64% men) with a mean age of 60 ⫾ 10 years underwent PVI by using the nMARQ ablation system. All patients suffered from paroxysmal AF who demonstrate an European Heart Rhythm Association (EHRA) EHRA score of ZIII and had been refractory to at least 1 antiarrhythmic drug previously. Mean left ventricular ejection fraction observed was 58% ⫾ 3%. Furthermore, no patient showed a left atrial dilatation of Z44 mm. Patient characteristics are summarized in Table 1. In 3 (12%) patients, a common ostium of the left-sided PVs could be detected by using left atrial angiogram and anatomic mapping by using the nMARQ catheter, which was reconfirmed by postprocedural cardiac MRI in all cases.
Table 1 Patient characteristics Age (y) Sex: male/female History of AF (mo) Prior antiarrhythmic drugs EHRA I/II/III/IV Left atrial size (mm) Hypertension Coronary artery disease LVEF (%) CHA2DS2-VASC score
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60 ⫾ 10 16/9 41 ⫾ 30 1.4 (range 1–4) 0/0/19/6 41 ⫾ 2 14 (56) 1 (4) 58 ⫾ 3 2 ⫾ 0.7
Data are presented as mean ⫾ SD and as n (%). AF ¼ atrial fibrillation; EHRA ¼ European Heart Rhythm Association; LVEF ¼ left ventricular ejection fraction.
Procedural success and learning curve The overall procedure time from vascular access until removal of all catheters was 110 ⫾ 31 minutes (range 60– 180 minutes), while a mean fluoroscopy time of 23 ⫾ 9 minutes could be observed (Table 2A). All the 97 targeted PVs could be isolated by using the nMARQ catheter that was verified by entrance and exit blocks for each vein. The mean total burning time was 15 ⫾ 6 minutes per patient. An average number of 27 ⫾ 11 RF impulses per patient was needed to achieve isolation of all PVs, including a mean number of 2 ⫾ 1 energy deliveries due to reconnection after a waiting period of 20 minutes in 9 of 25 (36%) cases. Touchup ablation by using a single-tip ablation catheter did not have to be used in any of the cases. In spite of a flow rate of 60 mL/min during energy application and 4 mL/min during mapping, the total amount of fluid administered during the entire procedure reached a mean value of 900 mL and did not exceed 1.5 L, which was similar to that administered during single-tip ablation procedures. The deployment of the nMARQ catheter was successful in all left-sided PVs and all right-sided superior PVs. Deployment into the RIPV was not successful in 7 (28%) cases (see Table 2B), thus necessitating the placement of an octopolar diagnostic catheter into the RIPV for differential pacing. In those cases, the mean diameter of the respective RIPVs obtained by using MRI was 16.3 ⫾ 2.5 mm. A fast learning curve could be observed by comparing procedural data of the first and the last 5 cases of this series, resulting in a significant decrease in the procedure time from 150 ⫾ 27 to 94 ⫾ 16 minutes (P ¼ .0099) and fluoroscopy time from 33 ⫾ 11 to 16 ⫾ 3 minutes (P ¼ .0035), respectively. Furthermore, ablation strategy changed during the observed series, targeting a lower maximum energy of 20 W in unipolar ablation and constituting a signal-orientated RF impulse duration over a fixed one for safety reasons.
Follow-up data During the mean follow-up time of 4.1 ⫾ 1.6 months (range 2–7 months), no left atrial flutter or tachycardia occurred. After 3 months, sinus rhythm was stable off antiarrhythmic drugs in 17 of 21 (80.9%) patients.
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Table 2 Procedural and ablation data A: Procedural data Procedure time (min) Fluoroscopy time (min) Total burning time (min) Complications Access site complications Pericardial tamponade TIA/stroke PV stenosis Phrenic nerve palsy Atrioesophageal fistula Death B: Ablation data Procedures Total PV Common ostium Successful PV isolation with the nMARQ catheter Successful PV intubation with the nMARQ catheter Mean number of RF applications—total Mean number of RF applications—LSPV Mean number of RF applications—LIPV Mean number of RF applications—RSPV Mean number of RF applications—RIPV Charring of the nMARQ electrode
110 ⫾ 31 23 ⫾ 9 15 ⫾ 6 – – – – – – – – 25 97 3 97 of 97 (100) 90 of 97(93) 27 ⫾ 11 9⫾5 7⫾5 5⫾2 5⫾2 3 of 25 (12)
Data are presented as mean ⫾ SD and as n (%). LIPV ¼ left inferior pulmonary vein; LSPV ¼ left superior pulmonary vein; PV ¼ pulmonary vein; RIPV ¼ right inferior pulmonary vein; RF ¼ radiofrequency; RSPV ¼ right superior pulmonary vein; TIA ¼ transient ischemic attack.
MRI data The diameter of PV ostia was obtained both by FAM using the multielectrode ablation catheter and the CARTO system and postprocedural MRI, demonstrating smaller diameter values when measured by MRI compared to the nMARQ catheter method (see Table 3). A mechanical extension of the PV ostia by the circular array of the nMARQ catheter was suggested as a possible explanation for this observation.
Safety concerns Charring of the electrodes could be detected during the first 3 cases, especially on electrodes 1 and 10. We suggested an adjacent heating of overlapping electrodes when the diameter of the circular frame was adjusted to the minimum. Hence, we applied energy over all 10 electrodes only if a sufficient distance between electrodes 1 and 10 was observed. Electrode overlapping was easily noticeable not only by fluoroscopy and 3D catheter visualization of the Table 3 Vein diameter obtained by MRI in comparison to CARTO (mean ⫾ standard deviation)
Vein
Diameter measured by MRI (mm)
Diameter measured by CARTO (mm)
p-value
LSPV LSPV RSPV RIPV
19.9 ⫾ 18.4 ⫾ 18.6 ⫾ 17.6 ⫾
24.7 ⫾ 22.9 ⫾ 23.6 ⫾ 22.7 ⫾
0.001 0.003 0.003 0.001
2.5 4.1 4.9 3.9
3.1 2.9 2.9 2.4
CARTO system but also by resulting artifact signals recorded by affected electrodes, as shown in Figure 4. Furthermore, we stopped applying bipolar RF energy and since then no further charring was detected. No complications occurred during or after the ablation procedure, especially no clinically detectable cerebral thromboembolic event or phrenic nerve palsy could be observed. Furthermore, acute PV stenosis could be ruled out by cardiac MRI scan.
Discussion Acute efficacy The ablation of patients with paroxysmal AF by using a novel ablation system that provides a multielectrode 3D mapping and irrigated RF application resulted in an acute isolation of all addressed PVs. This acute success rate compares with published data by groups using a conventional, single-tip approach guided by a 3D mapping system.7,8 Since this standard approach is time-consuming and manually challenging, several single-shot devices have been introduced for a simplified PVI approach. Using the cryoballoon (Medtronic, Minneapolis, MN), which can be combined with a multipolar diagnostic catheter for achieving intracardiac electrograms during ablation, acute PVI in up to 98% of the treated PVs were observed.2,9 Comparably using a visually guided laser balloon catheter (Cardio Focus Inc, Marlborough, MA), acute PVI could be achieved in up to 99% of the targeted PVs,3,10 though requesting further mapping catheters since intracardiac signals are not available by this ablation tool. Furthermore, multielectrode ablation is also feasible by using the PVAC (Medtronic), which provides nonirrigated application of duty-cycled RF energy by up to 9 electrodes simultaneously. Investigators reported acute success rates of up to 99%.11,12
Procedure times Mean procedure time from skin to skin was 110 minutes, with a fluoroscopy time of 23 minutes. These data might even improve since the presented data included a steep learning curve, with a total procedure time of 94 minutes and fluoroscopy time of 16 minutes during the last 5 cases. In comparison, groups using the PVAC for PVI in paroxysmal AF report similar short procedure times (81–133 minutes) and fluoroscopy times (20–30 minutes).13–15 Furthermore, published data using a single-tip catheter referred to total procedure and fluoroscopy times varying between 148 and 165 minutes and between 16 and 28 minutes, respectively.2,16,17 Cryoballoon ablation requires mean procedure and fluoroscopy times between 135 and 170 minutes and between 21 and 40 minutes, respectively,9,18,19 whereas published data for the first 200 patients experience with laser balloon ablation demonstrate procedure and fluoroscopy times of 200 and 31 minutes, respectively.3 In summary, the nMARQ ablation system provides both short procedure and fluoroscopy times compared with other existing ablation systems (see Table 4).
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Figure 4 Effect of electrode overlapping during radiofrequency application. Overlapping of electrodes 1 and 10 in fluoroscopy (A, white arrow) and the corresponding one in the CARTO mapping (B, white arrow). During electrode overlapping, artifact signals are received by affected electrodes 1 and 10 (D, black arrows). The nMARQ catheter shows charring mainly on electrodes 9 and 10 (C, white arrows) after energy delivery with overlapping electrodes.
Ablation strategy
diameter of the circular array and deployed the catheter into the PV by using it like a decapolar circular diagnostic catheter (eg, Lasso, Biosense Webster Inc). By starting the FAM, 3D reconstruction of the intubated PV could be generated easily and the PV ostium was defined by local electrogram interpretation and fluoroscopic control showing a “hopping” movement, like a short jump out of the vein during continuous pulling of the catheter back to the left atrium. By starting with the left superior pulmonary vein,
Since no data referred to ablation strategy using the nMARQ system are published, we aimed for the most pragmatic and straightforward approach. In contrast to the PVAC, the nMARQ catheter cannot be placed over a wire but has to address the target zone directly. Therefore, we used a steerable sheath in all cases to optimize catheter placement, especially for the lower PVs, although this is not our regular approach while using a single-tip catheter. We minimized the Table 4
Comparison of procedural data in different ablation technologies used for PVI in treatment of paroxysmal atrial fibrillation
Technology 2
Conventional RF ablation Cryoballoon ablation2 Visually guided laserablation3 PVAC15 nMARQ catheter
Acute success (%)
Procedure time (min)
Fluoroscopy time (min)
n
97.6 97.5 98.8 100 100
165 160 200 133 110
24 34 31 30 23
2870 905 200 89 25
Data are presented as mean values. PVAC ¼ pulmonary vein ablation catheter; PVI ¼ pulmonary vein isolation; RF ¼ radiofrequency.
382 which could be intubated in all cases with the nMARQ catheter, the same mapping and tagging was done for the left inferior pulmonary vein, the right superior pulmonary vein, and the RIPV. We declined to obtain a left atrial imaging study before the procedure since left atrial angiogram and FAM provided sufficient information of the target regions during the ablation procedure. Depending on the individual anatomy and the localization of the transseptal puncture side, addressing the RIPV by the nMARQ catheter was hampered frequently. As soon as we established the correct placement of the nMARQ catheter at the RIPV, we started isolating those veins first, since flexion abilities of the nMARQ catheter change during ongoing procedure owing to warming of the catheter material by the blood, thus reducing subsequent placement attempts. In recognition of its adjustable diameter size, precaution must be taken not to deliver RF energy inside the PV; therefore, we deliberately enlarged the diameter of the catheter in the antral region. The use of intracardiac echocardiography might have been useful to further confirm the avoidance of energy delivery within the PVs at the same time, giving an additional indication of existence of sufficient tissue contact. Furthermore, we avoided overlapping of electrodes during RF application by enlarging the diameter. By using the nMARQ catheter as a Lasso mapping catheter for proving exit and entrance blocks, we declined to use a separate multielectrode diagnostic catheter as in conventional single-tip approaches. Thus, no data can be given related to differences of electrogram characteristics obtained by the nMARQ catheter and the Lasso catheter, respectively. We like to point out that the interpretation of electrograms obtained by the nMARQ catheter during energy application was reasonable in contrast to the use of the PVAC in which electrogram analysis during ablation is not possible owing to artifacts. However, the nMARQ catheter appeared to be less flexible owing to its stiffer catheter shaft compared to the Lasso catheter, requiring more cautious movements for placing it inside the PVs. In the case of unsuccessful intubation by the nMARQ catheter, we introduced an octopolar diagnostic catheter into the PV for differential pacing.
Safety No procedure-related complications could be observed in this study. No access site–related bleeding complications, cardiac tamponade, or phrenic nerve palsy occurred. No acute PV stenosis appeared while MRI scan showed no narrowing of the examined PV ostia; however, the development of such stenosis might occur delayed after several months or weeks,20 which cannot be excluded by our present set of data. In consideration of published data suggesting a causal connection between multielectrode ablation and observed esophageal lesions by passive heating of an intraluminal temperature probe,21 we declined to perform esophageal temperature monitoring. Therefore, power management
Heart Rhythm, Vol 11, No 3, March 2014 during ablation along the posterior wall contained a maximum energy level of 20 W and a maximum impulse duration of 30 seconds. Since no clinical signs for esophageal damage appeared, no endoscopy was performed. Thus, no data can be given for possible thermal esophageal lesions by ablation. No patient showed symptoms related to cerebral thromboembolism. Although there was an absence of clinically noticeable cerebral thromboembolic injuries, we cannot exclude or quantify possible asymptomatic cerebral events, which have been described extensively in several publications that are associated with all available ablation techniques used for PVI,22,23 because no cerebral MRI scan has been performed. Charring was documented in 3 of 25 (12%) patients who were all anticoagulated by phenprocoumon and showed a mean INR of 2.5 ⫾ 0.3 and a mean ACT during ablation procedure of 387 ⫾ 36 seconds. In cases with no charring, a mean INR of 2.4 ⫾ 0.3 and a mean ACT of 346 ⫾ 87 seconds could be observed, showing no significant difference. Furthermore, this group included 8 patients treated with dabigatran or rivaroxaban instead of phenprocoumon. Bipolar energy delivery was used only in the charring group, whereas the total number of bipolar impulses was low (1 per case). The overlapping of electrodes 1 and 10 during energy application was allowed only in the first 3 cases when charring occurred. In our opinion, a distance of 4 mm between electrode 1 and electrode 10 should be established, resembling the spacing distance of adjacent electrodes 1–10.
Study limitations Several limitations of our study have to be addressed. First of all, our study provides a small patient number and a short follow-up time of 4.1 months; thus, the effect of given follow-up data is of limited value to determine long-term success. However, the aim of the study was not long-term follow-up but its capabilities to reach PV isolation as an end point. Long-term efficacy is addressed by ongoing clinical trials (EVOLUTION and reMARQable), and data analysis is expected for 2014 and 2018, respectively. Furthermore, we changed ablation strategy concerning maximum power and duration of energy delivery after the first 10 cases related to safety reasons, which might have affected the learning curve results. Moreover, we declined to administer adenosine at the end of the procedure, which might have affected the rate of observed acute PV reconnection. Finally, we did not provide data referring to a possible asymptomatic cerebral event; thus, cerebral MRI should be considered for future studies in order to assess a possible effect on the safety of this new technology.
Conclusions Pulmonary vein isolation using an irrigated multielectrode mapping and ablation system appears to be feasible and safe. Long-term clinical efficacy has to be evaluated in further studies.
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References 1. Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation. Heart Rhythm 2012;9:632–696. 2. Schmidt M, Dorwarth U, Andresen D, et al. Cryoballoon versus RF ablation in paroxysmal atrial fibrillation: results from the German Ablation Registry. J Cardiovasc Electrophysiol 2014;25(1):1–7. 3. Dukkipati SR, Kuck KH, Neuzil P, et al. Pulmonary vein isolation using a visually guided laser balloon catheter: the first 200-patient multicenter clinical experience. Circ Arrhythm Electrophysiol 2013;6:467–472. 4. Deneke T, Mugge A, Balta O, Horlitz M, Grewe PH, Shin DI. Treatment of persistent atrial fibrillation using phased radiofrequency ablation technology. Expert Rev Cardiovasc Ther 2011;9:1041–1049. 5. Deneke T, de Groot JR, Horlitz M, et al. Pulmonary vein isolation using a novel decapolar over-the-wire mapping and ablation catheter. Expert Rev Cardiovasc Ther 2009;7:1341–1347. 6. Deneke T, Schade A, Diegeler A, Nentwich K. Esophago-pericardial fistula complicating atrial fibrillation ablation using a novel irrigated radiofrequency multipolar ablation catheter. J Cardiovasc Electrophysiol 2013http://dx.doi.org/; doi: 10.1111/jce.12308. [Epub ahead of print] No abstract available. 7. Andrade JG, Macle L, Khairy P, et al. Incidence and significance of early recurrences associated with different ablation strategies for AF: a STAR-AF substudy. J Cardiovasc Electrophysiol 2012;23:1295–1301. 8. Ouyang F, Bansch D, Ernst S, et al. Complete isolation of left atrium surrounding the pulmonary veins: new insights from the double-Lasso technique in paroxysmal atrial fibrillation. Circulation 2004;110:2090–2096. 9. Neumann T, Vogt J, Schumacher B, et al. Circumferential pulmonary vein isolation with the cryoballoon technique results from a prospective 3-center study. J Am Coll Cardiol 2008;52:273–278. 10. Schmidt B, Gunawardene M, Urban V, et al. Visually guided sequential pulmonary vein isolation: insights into techniques and predictors of acute success. J Cardiovasc Electrophysiol 2012;23:576–582. 11. Wieczorek M, Hoeltgen R, Akin E, Salili AR, Oral H, Morady F. Results of shortterm and long-term pulmonary vein isolation for paroxysmal atrial fibrillation using duty-cycled bipolar and unipolar radiofrequency energy. J Cardiovasc Electrophysiol 2010;21:399–405. 12. De GY, Tavernier R, Schwagten B, De KG, Stockman D, Duytschaever M. Impact of radiofrequency characteristics on acute pulmonary vein reconnection
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