- Email: [email protected]
Catheter ablation of atrial fibrillation in patients with persistent left superior vena cava is associated with major intraprocedural complications
Catheter ablation of atrial fibrillation in patients with persistent left superior vena cava is associated with major intraprocedural complications Erik Wissner, MD, Roland Tilz, MD, Melanie Konstantinidou, MD, Andreas Metzner, MD, Boris Schmidt, MD, KR Julian Chun, MD, Karl-Heinz Kuck, MD, FHRS, Feifan Ouyang, MD From the Department of Cardiology, Asklepios Klinik St. Georg, Hamburg, Germany. BACKGROUND A persistent left superior vena cava (PLSVC) is an uncommon cardiac anomaly. OBJECTIVE The purpose of this study was to assess the complication rate and procedural outcome in patients with PLSVC who were referred for catheter ablation of atrial fibrillation (AF). METHODS Between September 2006 and February 2009, seven patients referred for circumferential pulmonary vein (PV) isolation (PVI) demonstrated a PLSVC. PVI was confirmed by spiral catheter recording within the respective PVs. Ablation within the PLSVC was performed using an irrigated-tip catheter (energy settings 20 W, 43°C, flow rate 17 mL/min) or, alternatively, a cryoballoon catheter (28 mm balloon, 300-second energy application). Patients were analyzed according to procedural outcome and rate of complications. RESULTS Among seven patients (three female, mean age 57 ⫾ 8 years, two paroxysmal, five persistent AF, structural/congenital heart disease present in three patients, mean left atrial size 43 ⫾ 6 mm), 14 ablation procedures were performed. Two major complications (left phrenic nerve injury and cardiac tamponade) occurred in two of four patients undergoing PLSVC ablation. Of four of seven patients undergoing PLSVC ablation, two patients needed
Introduction Catheter ablation of atrial fibrillation (AF) is recommended in symptomatic patients refractory to antiarrhythmic drug therapy.1,2 The pulmonary vein (PV) musculature plays a critical role in the initiation of AF3; hence PV isolation (PVI) serves as a common procedural endpoint during AF ablation.1 Non-PV foci triggering AF have been described elsewhere.4 With an estimated prevalence of 0.3%– 0.5% in the general population, a persistent left superior vena cava (PLSVC) is an uncommon finding in patients referred for catheter ablation of AF.5 Embryologically, the left superior cardinal vein regresses to become the ligament of Marshall. A PLSVC results if regression fails. There are limited data describing catheter ablation of AF in patients with Address reprint requests and correspondence: Erik Wissner, Department of Cardiology, Asklepios Klinik St. Georg, Lohmühlenstrasse 5, 20099 Hamburg, Germany. E-mail address: [email protected]. (Received July 1, 2010; accepted August 6, 2010.)
one and one patient needed two redo PLSVC ablation procedures. The first-time procedural success rate was 29%, while the overall success rate reached 86% after a median follow-up period of 621 (339 –1,289) days. CONCLUSION In patients with ectopic activity from a PLSVC, the ablative strategy should include isolation of the PLSVC as a procedural endpoint, although multiple ablation procedures may be necessary to achieve stable sinus rhythm. Contrary to previous reports, complications are common if the PLSVC is targeted for ablation. KEYWORDS Atrial fibrillation; Catheter ablation; Persistent left superior vena cava; Congenital anomaly; Complication rate ABBREVIATIONS AF ⫽ atrial fibrillation; CFAE ⫽ complex fractionated atrial electrograms; CS ⫽ coronary sinus; LA ⫽ left atrial; LAA ⫽ left atrial appendage; LAT ⫽ left atrial tachycardia; PLSVC ⫽ persistent left superior vena cava; PV ⫽ pulmonary vein; PVI ⫽ pulmonary vein isolation; SR ⫽ sinus rhythm; RFC ⫽ radiofrequency current (Heart Rhythm 2010;7:1755–1760) © 2010 Heart Rhythm Society. All rights reserved.
PLSVC.6 – 8 This study sought to assess the procedural outcome and complication rate of catheter ablation of AF in patients with concomitant PLSVC.
Methods Between September 2006 and February 2009, seven patients with PLSVC underwent catheter ablation of drugrefractory paroxysmal (2/7; 29%) or persistent (5/7; 71%) AF. Patient characteristics are listed in Table 1. Congenital heart disease was present in two patients. In five patients, the presence of a PLSVC was unknown before admission to the hospital. All patients underwent preprocedural transesophageal echocardiography to rule out left atrial (LA) thrombus. In three of five patients, an enlarged coronary sinus (CS) was noted echocardiographically and selective CS angiography confirmed the presence of a PLSVC, while in the remaining two of five patients diagnosis was confirmed intraoperatively. No additional preprocedural imaging was performed.
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doi:10.1016/j.hrthm.2010.08.005
1756 Table 1
Heart Rhythm, Vol 7, No 12, December 2010 Patients’ baseline demographic data, n ⫽ 7 (%)
Age Female gender Persistent AF LA diameter, mm Congenital heart disease Atrial septal defect repair Ventricular septal defect repair
57 ⫾ 8 3 (43) 5 (71) 43 ⫾ 6 2 (29) 1 (14) 1 (14)
PVI Electrical PVI was achieved by wide-area circumferential ablation using open-irrigated radiofrequency current (RFC). Along the posterior LA wall, maximal power was limited to 30 W, a flow rate of 17 mL/min, and a target temperature of 43°C, while a maximal power of 40 W and a flow rate of 25 mL/min were used when ablating along the anterior aspect of the LA wall. Ablation sites were tagged on a reconstructed CARTO (Biosense Webster, Diamond Bar, CA) three-dimensional LA map. Bilateral circumferential linear lesion sets were deployed around the ipsilateral PVs to achieve PVI as described elsewhere in detail9 (Figure 1). Irrigated RFC was applied for up to 30 seconds or until the maximal local electrogram amplitude decreased by 70% or double potentials were noted. The endpoint of PV ablation was defined as an absence of PV spikes registered on the spiral-mapping catheter (Lasso, Biosense Webster) positioned within the ipsilateral PV more than 30 minutes after the last RFC application.
open-irrigated 3.5-mm-tip ablation catheter limiting energy to 20 W with a maximal temperature of 43°C and a flow rate of 17 mL/min. Cryothermal energy ablation via a balloon catheter (Arctic Front, Cryocath, Montreal, Canada) was used in two patients who demonstrated a significantly enlarged proximal CS. A 28-mm cryoballoon catheter using a steerable sheath was advanced via the right femoral vein to the proximal CS. Each cryothermal energy application lasted 300 seconds targeting a temperature of ⫺80°C.
Postablation protocol and patient follow-up Routine transthoracic echocardiography and thoracic fluoroscopy were performed postoperatively to rule out pericardial effusion and pneumothorax, respectively. Patients were treated with intravenous unfractionated heparin targeting a partial thromboplastin time (PTT) of 50 –70 seconds starting 4 – 6 hours after the procedure, while oral anticoagulation was started 1 day postoperatively, targeting an international normalized ratio of 2.0 –3.0. Oral anticoagulation was continued for at least 3 months after ablation and maintained thereafter according to the individual patient’s risk score
Ablation of complex fractionated atrial electrograms The definition of complex fractionated atrial electrograms (CFAE) has been reported elsewhere in detail.10 Ablation of CFAEs was solely performed if electrical cardioversion failed after PVI.11 Target sites included the base of the LA appendage (LAA), anterior LA, LA septum, mitral annulus, within the CS, and eventually the right atrium. Outside the CS os, ablation was performed with a maximal power of 30 W, a flow rate of 17 mL/min, and a target temperature of 43°C.
Ablation targeting the PLSVC and CS The PLSVC and CS were targeted for ablation if the shortest AF cycle length was demonstrated within these structures (Figure 2). Before ablation, selective venography of the CS and PLSVC was performed (Figure 3). The proximal portion of the PLSVC originates from the distal CS, while its midportion runs along the left lateral ridge and anterior to the left PVs. The distal PLSVC extends beyond the left PVs. A spiral-mapping catheter (Lasso, Biosense Webster) positioned within the distal portion of the PLSVC was used to record local ectopic activity. Ablation of high-frequency signals targeting the midportion of the PLSVC was followed by catheter withdrawal to the proximal portion of the PLSVC and the CS until all local high-frequency signals were eliminated (Figure 4). RFC was applied using an
Figure 1 Three-dimensional CARTO map of the LA (green) and CS/ PLSVC (red) in a posterior-anterior projection during the initial procedure in patient no. 1. Circumferential linear lesion sets encircling the ipsilateral septal and lateral PVs (dark red dots). In addition, several lesion sets were deployed within the LA, CS, and PLSVC. Note the cumulative lesion sets at the midposterior level of the PLSVC. The yellow dot (arrow) indicates the site of isolation of the midportion of the PLSVC from the LA.
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Figure 2 Patient no. 3, first redo procedure. Compared with spiral-mapping catheter recordings from the LAA, local activity within the PLSVC demonstrates the shortest cycle length. The mapping catheter (map) is positioned within the PLSVC. Map ⫽ mapping catheter.
(CHADS2 score ⬎1) for stroke. Previously ineffective antiarrhythmic medication was continued for a minimum of 3 months. Follow-up was performed according to the Heart Rhythm Society/European Heart Rhythm Association/European Cardiac Arrhythmia Society expert consensus statement on catheter and surgical ablation of AF.1 All patients underwent 12-lead electrocardiogram and 24-hour Holter monitoring 1, 3, and 6 months after the procedure and at 6-month intervals thereafter. Patients were equipped with an event recorder in case of symptoms suggestive of arrhythmia recurrence. Any documented episode or symptoms sug-
gestive of atrial tachyarrhythmia lasting more than 30 seconds were considered a recurrent arrhythmic event. In addition, telephone interviews were used to assess clinical symptoms and current medication regimen.
Study endpoints The primary endpoint was defined as complications directly related to ablation within the CS and PLSVC. Secondary endpoints were defined as freedom from atrial tachyarrhythmias subsequent to the initial catheter ablation procedure and overall freedom from atrial tachyarrhythmias after multiple ablation procedures.
Figure 3 Selective venography of the PLSVC in the right anterior oblique 30° and left anterior oblique 40° projection. A spiral-mapping catheter is placed within the LSPV, while a second spiral-mapping catheter is positioned at the level of the mid-PLSVC.
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First catheter ablation procedure During the initial procedure, all patients underwent PVI using irrigated RFC. In two of seven (29%) patients with failed electrical cardioversion after PVI, additional ablation was performed targeting CFAEs within the right atrium and LA (patient nos. 1 and 5). In one patient with the shortest AF cycle length originating from the PLSVC, isolation of the mid-PLSVC was performed (patient no. 1).
Second catheter ablation procedure Owing to AF recurrence, four (57%) of seven patients underwent a second ablation procedure. During the second procedure, two patients underwent successful redo PVI (patient nos. 2 and 3). After confirmation of complete PVI, isolation of the mid-PLSVC was performed in three patients using RFC and cryothermal energy, respectively (patient nos. 3, 5, and 7).
Third catheter ablation procedure
Figure 4 Three-dimensional CARTO map of the LA (red) and CS/ PLSVC (green) in a posterior-anterior projection during the first redo procedure in patient no. 3. Multiple lesions were deployed within the CS and PLSVC (dark red dots). After isolation of the midportion (arrow) of the PLSVC, ablation along the proximal CS/PLSVC resulted in termination of AF (yellow dots).
Statistical analysis Mean ⫾ standard deviation was used to describe continuous variables with normal distribution. Otherwise, median and range were reported. For diagnostic parameters, the absolute and relative frequency were counted.
Results Type and number of ablation procedures performed in the patient cohort are summarized in Table 2. In four of seven patients, the PLSVC was deemed critical for the maintenance of AF and targeted for ablation. Initial attempts to isolate at the proximal CS-PLSVC level (Table 3) were unsuccessful and followed by targeting the midlevel of the PLSVC, where only half of its luminal circumference is surrounded by muscular LA-PLSVC connections. Table 2
A third ablation procedure was performed in two (29%) of seven patients. Both patients had undergone isolation of the mid-PLSVC during the second ablation procedure (patient nos. 3 and 7). During the third procedure, patient no. 3 underwent redo mid-PLSVC isolation using RFC. In addition, an LA tachycardia with its critical isthmus along the mitral valve annulus was successfully ablated. Finally, slow pathway ablation was performed owing to reproducible induction of atrioventricular nodal reentrant tachycardia. Patient no. 7 underwent redo isolation of the mid-PLSVC using RFC.
Fourth catheter ablation procedure A fourth procedure was performed in one (14%) of seven patients. Patient no. 7 needed a second redo isolation of the mid-PLSVC using RFC.
Primary endpoint Major complications occurred in two of four patients undergoing isolation of the midportion of the PLSVC. During the second ablation procedure, patient no. 3 developed cardiac tamponade while ablating within the PLSVC. No steam pop was audible. After emergent pericardiocentesis, the patient made a complete recovery and experienced no un-
Number and type of ablation procedures performed
Patient
1. Ablation
2. Ablation
3. Ablation
4. Ablation
1 2 3
PVI ⫹ CFAE ⫹ mid-PLSVC isolation PVI PVI PVI PVI ⫹ CFAE PVI PVI PVI (n ⫽ 7), CFAE (n ⫽ 2), mid-PLSVC isolation (n ⫽ 1)
— — Mid-PLSVC isolation ⫹ LAT ⫹ AVNRT — — — Mid-PLSVC isolation Mid-PLSVC isolation (n ⫽ 2), LAT (n ⫽ 1), AVNRT (n ⫽ 1)
— — —
4 5 6 7 Total
— Redo PVI Redo PVI ⫹ mid-PLSVC isolation — Mid PLSVC isolation — Mid-PLSVC isolation Redo PVI (n ⫽ 2), mid-PLSVC isolation (n ⫽ 3)
Note: AVNRT: atrioventricular nodal reentrant tachycardia; LAT: left atrial tachycardia.
— — — Mid-PLSVC isolation Mid-PLSVC isolation (n ⫽ 1)
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toward events during a third ablation procedure. Patient no. 7 developed left phrenic nerve palsy during the second ablation procedure while attempting isolation of the midportion of the PLSVC using a 28-mm cryoballoon catheter. Despite persistence of left diaphragmatic paralysis throughout the follow-up period, the patient remained asymptomatic.
Secondary endpoint After the first ablation procedure, two (29%) of seven patients were in sinus rhythm (SR) after a median follow-up period of 411 (339 – 482) days. Overall, five (71%) of seven patients maintained SR during a median follow-up period of 621 (339 –1,289) days and a median of two (one to four) ablation procedures. One patient with asymptomatic recurrent AF after the first procedure declined a second ablation attempt.
Other major complications Patient no. 1 experienced left hemiplegia owing to embolic infarction involving the region of the right medial cerebral artery 3 days after the initial ablation procedure.
Discussion The current study assessing catheter ablation of AF in patients with concomitant PLSVC demonstrates that (1) isolation of the PLSVC was associated with major complications; (2) after first-time ablation, SR was maintained in merely two (29%) of seven patients after a median follow-up period of 411 (339 – 482) days; and (3) SR was maintained in five (71%) of seven patients after a median of two (one to four) ablation procedures if isolation of the mid-PLSVC was part of the procedural endpoint.
Complications related to PLSVC isolation No significant complications were reported in previous case series of patients with PLSVC undergoing AF ablation.6 – 8 Contrary to prior reports, this study found a high procedural complication rate if the PLSVC was targeted for ablation. Because of its luminal composition, a 28-mm cryoballoon catheter was used in two of four patients undergoing firsttime isolation of the PLSVC. Left phrenic nerve palsy as a major complication in the current study may be explained by the close anatomical proximity of the left phrenic nerve to the mid and distal portion of the PLSVC. Hence, cryothermal energy application via a balloon catheter should be critically evaluated when attempting to isolate the PLSVC. The second major complication, a cardiac tamponade, resulted from ablation within the PLSVC despite judicious use of RFC energy. Extensive RFC energy delivery within delicate structures such as the CS or PLSVC may increase the risk of cardiac perforation.
The importance of PLSVC isolation Previous case series in patients with concomitant PLSVC undergoing AF ablation reported a high first-time procedural success rate.6 – 8 By contrast, this study demonstrated that the first-time procedural success rate was poor and that
1759 only after an average of two catheter ablation procedures could maintenance of SR be accomplished in 57% of patients. In one patient a total of four ablation procedures were required to achieve SR. Ectopic activity from the PV musculature is the most common AF trigger.1 Accordingly, PVI should be the primary procedural endpoint in patients referred for catheter ablation of AF. In the current study, all patients underwent PVI as the first-line ablative strategy. This approach may suffice if the PLSVC represents a silent bystander. Ectopic beats from the CS or ligament of Marshall may trigger AF.4 Consequently, AF may be initiated by ectopic activity originating from a PLSVC. This study highlights the critical role of the PLSVC in the maintenance of AF (Figure 2). In patients with ectopic activity originating from a PLSVC, mere PVI may not serve as an adequate first-line treatment strategy; instead, isolation of the PLSVC should be part of the ablative endpoint. Isolation proved successful only if targeting the midportion of the PLSVC, while attempts at isolation of its proximal portion were futile. This may in part be explained by significant enlargement of the CS ostium and proximal PLSVC (up to 33 mm in diameter in our patient cohort), rendering circumferential isolation at this anatomical level an unattainable task. By contrast, isolation at midlevel of the PLSVC is feasible, since electrical connections between PLSVC and LA are typically present only along half of its circumference.6
Limitations This study did not routinely use isoproterenol to assess for ectopic activity from the PLSVC. Hence only patients with spontaneous activity were targeted for isolation of the PLSVC. Furthermore, cardiac computed tomography scanning or magnetic resonance imaging was not routinely performed before catheter ablation of AF. As a result, the true prevalence of a PLSVC in our patient cohort is unknown. Despite this limitation, the reported prevalence of 0.4% in the current study is in line with anatomical data in the Table 3 Overview detailing the number of patients undergoing ablation within the PLSVC, type of complications, and energy source used during ablation procedures Patient
PLSVC ablation
Complications
Energy
1 2 3 4 5
⫹ — ⫹ — —
Stroke — Tamponade — —
6 7
⫹ ⫹
Total
4
— Left phrenic nerve damage 3 (2)
RFC RFC RFC RFC RFC ⫹ cryoballoon RFC RFC ⫹ cryoballoon
Note: Bold highlights direct association with ablation within the PLSVC.
1760 general population. Thus, we consider routine screening for a PLSVC not cost-effective.
Conclusions Catheter ablation of AF in patients with PLSVC is feasible. In patients with ectopic activity from a PLSVC, the ablative strategy should include isolation of the PLSVC as a procedural endpoint, although multiple ablation procedures may be necessary to achieve stable SR. Contrary to previous reports, complications are common if the PLSVC is targeted for ablation.
References 1. Calkins H, Brugada J, Packer DL, et al. HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for personnel, policy, procedures and follow-up. A report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation developed in partnership with the European Heart Rhythm Association (EHRA) and the European Cardiac Arrhythmia Society (ECAS); in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), and the Society of Thoracic Surgeons (STS). Endorsed and approved by the governing bodies of the American College of Cardiology, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, and the Heart Rhythm Society. Europace 2007;9(6):335–379.
Heart Rhythm, Vol 7, No 12, December 2010 2. Natale A, Raviele A, Arentz T, et al. Venice Chart international consensus document on atrial fibrillation ablation. J Cardiovasc Electrophysiol 2007;18(5): 560 –580. 3. Haissaguerre M, Jais P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. New Eng J Med 1998;339(10):659 – 666. 4. Lin WS, Tai CT, Hsieh MH, et al. Catheter ablation of paroxysmal atrial fibrillation initiated by non-pulmonary vein ectopy. Circulation 2003;107:3176 – 3183. 5. Abbott M. Atlas of congenital heart disease. New York: American Heart Association, 1936. 6. Hsu LF, Jais P, Keane D, et al. Atrial fibrillation originating from persistent left superior vena cava. Circulation 2004;109:828 – 832. 7. Elayi CS, Fahmy TS, Wazni OM, Patel D, Saliba W, Natale A. Left superior vena cava isolation in patients undergoing pulmonary vein antrum isolation: impact on atrial fibrillation recurrence. Heart Rhythm 2006;3:1019 –1023. 8. Liu H, Lim KT, Murray C, Weerasooriya R. Electrogram-guided isolation of the left superior vena cava for treatment of atrial fibrillation. Europace 2007;9:775– 780. 9. 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. 10. Nademanee K, McKenzie J, Kosar E, et al. A new approach for catheter ablation of atrial fibrillation: mapping of the electrophysiologic substrate. J Am Coll Cardiol 2004;43:2044 –2053. 11. Tilz RR, Chun KR, Schmidt B, et al. Catheter ablation of long-standing persistent atrial fibrillation: a lesson from circumferential pulmonary vein isolation. J Cardiovasc Electrophysiol 2010;21:1085–1093.
Introduction Catheter ablation of atrial fibrillation (AF) is recommended in symptomatic patients refractory to antiarrhythmic drug therapy.1,2 The pulmonary vein (PV) musculature plays a critical role in the initiation of AF3; hence PV isolation (PVI) serves as a common procedural endpoint during AF ablation.1 Non-PV foci triggering AF have been described elsewhere.4 With an estimated prevalence of 0.3%– 0.5% in the general population, a persistent left superior vena cava (PLSVC) is an uncommon finding in patients referred for catheter ablation of AF.5 Embryologically, the left superior cardinal vein regresses to become the ligament of Marshall. A PLSVC results if regression fails. There are limited data describing catheter ablation of AF in patients with Address reprint requests and correspondence: Erik Wissner, Department of Cardiology, Asklepios Klinik St. Georg, Lohmühlenstrasse 5, 20099 Hamburg, Germany. E-mail address: [email protected]. (Received July 1, 2010; accepted August 6, 2010.)
one and one patient needed two redo PLSVC ablation procedures. The first-time procedural success rate was 29%, while the overall success rate reached 86% after a median follow-up period of 621 (339 –1,289) days. CONCLUSION In patients with ectopic activity from a PLSVC, the ablative strategy should include isolation of the PLSVC as a procedural endpoint, although multiple ablation procedures may be necessary to achieve stable sinus rhythm. Contrary to previous reports, complications are common if the PLSVC is targeted for ablation. KEYWORDS Atrial fibrillation; Catheter ablation; Persistent left superior vena cava; Congenital anomaly; Complication rate ABBREVIATIONS AF ⫽ atrial fibrillation; CFAE ⫽ complex fractionated atrial electrograms; CS ⫽ coronary sinus; LA ⫽ left atrial; LAA ⫽ left atrial appendage; LAT ⫽ left atrial tachycardia; PLSVC ⫽ persistent left superior vena cava; PV ⫽ pulmonary vein; PVI ⫽ pulmonary vein isolation; SR ⫽ sinus rhythm; RFC ⫽ radiofrequency current (Heart Rhythm 2010;7:1755–1760) © 2010 Heart Rhythm Society. All rights reserved.
PLSVC.6 – 8 This study sought to assess the procedural outcome and complication rate of catheter ablation of AF in patients with concomitant PLSVC.
Methods Between September 2006 and February 2009, seven patients with PLSVC underwent catheter ablation of drugrefractory paroxysmal (2/7; 29%) or persistent (5/7; 71%) AF. Patient characteristics are listed in Table 1. Congenital heart disease was present in two patients. In five patients, the presence of a PLSVC was unknown before admission to the hospital. All patients underwent preprocedural transesophageal echocardiography to rule out left atrial (LA) thrombus. In three of five patients, an enlarged coronary sinus (CS) was noted echocardiographically and selective CS angiography confirmed the presence of a PLSVC, while in the remaining two of five patients diagnosis was confirmed intraoperatively. No additional preprocedural imaging was performed.
1547-5271/$ -see front matter © 2010 Heart Rhythm Society. All rights reserved.
doi:10.1016/j.hrthm.2010.08.005
1756 Table 1
Heart Rhythm, Vol 7, No 12, December 2010 Patients’ baseline demographic data, n ⫽ 7 (%)
Age Female gender Persistent AF LA diameter, mm Congenital heart disease Atrial septal defect repair Ventricular septal defect repair
57 ⫾ 8 3 (43) 5 (71) 43 ⫾ 6 2 (29) 1 (14) 1 (14)
PVI Electrical PVI was achieved by wide-area circumferential ablation using open-irrigated radiofrequency current (RFC). Along the posterior LA wall, maximal power was limited to 30 W, a flow rate of 17 mL/min, and a target temperature of 43°C, while a maximal power of 40 W and a flow rate of 25 mL/min were used when ablating along the anterior aspect of the LA wall. Ablation sites were tagged on a reconstructed CARTO (Biosense Webster, Diamond Bar, CA) three-dimensional LA map. Bilateral circumferential linear lesion sets were deployed around the ipsilateral PVs to achieve PVI as described elsewhere in detail9 (Figure 1). Irrigated RFC was applied for up to 30 seconds or until the maximal local electrogram amplitude decreased by 70% or double potentials were noted. The endpoint of PV ablation was defined as an absence of PV spikes registered on the spiral-mapping catheter (Lasso, Biosense Webster) positioned within the ipsilateral PV more than 30 minutes after the last RFC application.
open-irrigated 3.5-mm-tip ablation catheter limiting energy to 20 W with a maximal temperature of 43°C and a flow rate of 17 mL/min. Cryothermal energy ablation via a balloon catheter (Arctic Front, Cryocath, Montreal, Canada) was used in two patients who demonstrated a significantly enlarged proximal CS. A 28-mm cryoballoon catheter using a steerable sheath was advanced via the right femoral vein to the proximal CS. Each cryothermal energy application lasted 300 seconds targeting a temperature of ⫺80°C.
Postablation protocol and patient follow-up Routine transthoracic echocardiography and thoracic fluoroscopy were performed postoperatively to rule out pericardial effusion and pneumothorax, respectively. Patients were treated with intravenous unfractionated heparin targeting a partial thromboplastin time (PTT) of 50 –70 seconds starting 4 – 6 hours after the procedure, while oral anticoagulation was started 1 day postoperatively, targeting an international normalized ratio of 2.0 –3.0. Oral anticoagulation was continued for at least 3 months after ablation and maintained thereafter according to the individual patient’s risk score
Ablation of complex fractionated atrial electrograms The definition of complex fractionated atrial electrograms (CFAE) has been reported elsewhere in detail.10 Ablation of CFAEs was solely performed if electrical cardioversion failed after PVI.11 Target sites included the base of the LA appendage (LAA), anterior LA, LA septum, mitral annulus, within the CS, and eventually the right atrium. Outside the CS os, ablation was performed with a maximal power of 30 W, a flow rate of 17 mL/min, and a target temperature of 43°C.
Ablation targeting the PLSVC and CS The PLSVC and CS were targeted for ablation if the shortest AF cycle length was demonstrated within these structures (Figure 2). Before ablation, selective venography of the CS and PLSVC was performed (Figure 3). The proximal portion of the PLSVC originates from the distal CS, while its midportion runs along the left lateral ridge and anterior to the left PVs. The distal PLSVC extends beyond the left PVs. A spiral-mapping catheter (Lasso, Biosense Webster) positioned within the distal portion of the PLSVC was used to record local ectopic activity. Ablation of high-frequency signals targeting the midportion of the PLSVC was followed by catheter withdrawal to the proximal portion of the PLSVC and the CS until all local high-frequency signals were eliminated (Figure 4). RFC was applied using an
Figure 1 Three-dimensional CARTO map of the LA (green) and CS/ PLSVC (red) in a posterior-anterior projection during the initial procedure in patient no. 1. Circumferential linear lesion sets encircling the ipsilateral septal and lateral PVs (dark red dots). In addition, several lesion sets were deployed within the LA, CS, and PLSVC. Note the cumulative lesion sets at the midposterior level of the PLSVC. The yellow dot (arrow) indicates the site of isolation of the midportion of the PLSVC from the LA.
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Figure 2 Patient no. 3, first redo procedure. Compared with spiral-mapping catheter recordings from the LAA, local activity within the PLSVC demonstrates the shortest cycle length. The mapping catheter (map) is positioned within the PLSVC. Map ⫽ mapping catheter.
(CHADS2 score ⬎1) for stroke. Previously ineffective antiarrhythmic medication was continued for a minimum of 3 months. Follow-up was performed according to the Heart Rhythm Society/European Heart Rhythm Association/European Cardiac Arrhythmia Society expert consensus statement on catheter and surgical ablation of AF.1 All patients underwent 12-lead electrocardiogram and 24-hour Holter monitoring 1, 3, and 6 months after the procedure and at 6-month intervals thereafter. Patients were equipped with an event recorder in case of symptoms suggestive of arrhythmia recurrence. Any documented episode or symptoms sug-
gestive of atrial tachyarrhythmia lasting more than 30 seconds were considered a recurrent arrhythmic event. In addition, telephone interviews were used to assess clinical symptoms and current medication regimen.
Study endpoints The primary endpoint was defined as complications directly related to ablation within the CS and PLSVC. Secondary endpoints were defined as freedom from atrial tachyarrhythmias subsequent to the initial catheter ablation procedure and overall freedom from atrial tachyarrhythmias after multiple ablation procedures.
Figure 3 Selective venography of the PLSVC in the right anterior oblique 30° and left anterior oblique 40° projection. A spiral-mapping catheter is placed within the LSPV, while a second spiral-mapping catheter is positioned at the level of the mid-PLSVC.
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First catheter ablation procedure During the initial procedure, all patients underwent PVI using irrigated RFC. In two of seven (29%) patients with failed electrical cardioversion after PVI, additional ablation was performed targeting CFAEs within the right atrium and LA (patient nos. 1 and 5). In one patient with the shortest AF cycle length originating from the PLSVC, isolation of the mid-PLSVC was performed (patient no. 1).
Second catheter ablation procedure Owing to AF recurrence, four (57%) of seven patients underwent a second ablation procedure. During the second procedure, two patients underwent successful redo PVI (patient nos. 2 and 3). After confirmation of complete PVI, isolation of the mid-PLSVC was performed in three patients using RFC and cryothermal energy, respectively (patient nos. 3, 5, and 7).
Third catheter ablation procedure
Figure 4 Three-dimensional CARTO map of the LA (red) and CS/ PLSVC (green) in a posterior-anterior projection during the first redo procedure in patient no. 3. Multiple lesions were deployed within the CS and PLSVC (dark red dots). After isolation of the midportion (arrow) of the PLSVC, ablation along the proximal CS/PLSVC resulted in termination of AF (yellow dots).
Statistical analysis Mean ⫾ standard deviation was used to describe continuous variables with normal distribution. Otherwise, median and range were reported. For diagnostic parameters, the absolute and relative frequency were counted.
Results Type and number of ablation procedures performed in the patient cohort are summarized in Table 2. In four of seven patients, the PLSVC was deemed critical for the maintenance of AF and targeted for ablation. Initial attempts to isolate at the proximal CS-PLSVC level (Table 3) were unsuccessful and followed by targeting the midlevel of the PLSVC, where only half of its luminal circumference is surrounded by muscular LA-PLSVC connections. Table 2
A third ablation procedure was performed in two (29%) of seven patients. Both patients had undergone isolation of the mid-PLSVC during the second ablation procedure (patient nos. 3 and 7). During the third procedure, patient no. 3 underwent redo mid-PLSVC isolation using RFC. In addition, an LA tachycardia with its critical isthmus along the mitral valve annulus was successfully ablated. Finally, slow pathway ablation was performed owing to reproducible induction of atrioventricular nodal reentrant tachycardia. Patient no. 7 underwent redo isolation of the mid-PLSVC using RFC.
Fourth catheter ablation procedure A fourth procedure was performed in one (14%) of seven patients. Patient no. 7 needed a second redo isolation of the mid-PLSVC using RFC.
Primary endpoint Major complications occurred in two of four patients undergoing isolation of the midportion of the PLSVC. During the second ablation procedure, patient no. 3 developed cardiac tamponade while ablating within the PLSVC. No steam pop was audible. After emergent pericardiocentesis, the patient made a complete recovery and experienced no un-
Number and type of ablation procedures performed
Patient
1. Ablation
2. Ablation
3. Ablation
4. Ablation
1 2 3
PVI ⫹ CFAE ⫹ mid-PLSVC isolation PVI PVI PVI PVI ⫹ CFAE PVI PVI PVI (n ⫽ 7), CFAE (n ⫽ 2), mid-PLSVC isolation (n ⫽ 1)
— — Mid-PLSVC isolation ⫹ LAT ⫹ AVNRT — — — Mid-PLSVC isolation Mid-PLSVC isolation (n ⫽ 2), LAT (n ⫽ 1), AVNRT (n ⫽ 1)
— — —
4 5 6 7 Total
— Redo PVI Redo PVI ⫹ mid-PLSVC isolation — Mid PLSVC isolation — Mid-PLSVC isolation Redo PVI (n ⫽ 2), mid-PLSVC isolation (n ⫽ 3)
Note: AVNRT: atrioventricular nodal reentrant tachycardia; LAT: left atrial tachycardia.
— — — Mid-PLSVC isolation Mid-PLSVC isolation (n ⫽ 1)
Wissner et al
AF Ablation and Persistent Left SVC
toward events during a third ablation procedure. Patient no. 7 developed left phrenic nerve palsy during the second ablation procedure while attempting isolation of the midportion of the PLSVC using a 28-mm cryoballoon catheter. Despite persistence of left diaphragmatic paralysis throughout the follow-up period, the patient remained asymptomatic.
Secondary endpoint After the first ablation procedure, two (29%) of seven patients were in sinus rhythm (SR) after a median follow-up period of 411 (339 – 482) days. Overall, five (71%) of seven patients maintained SR during a median follow-up period of 621 (339 –1,289) days and a median of two (one to four) ablation procedures. One patient with asymptomatic recurrent AF after the first procedure declined a second ablation attempt.
Other major complications Patient no. 1 experienced left hemiplegia owing to embolic infarction involving the region of the right medial cerebral artery 3 days after the initial ablation procedure.
Discussion The current study assessing catheter ablation of AF in patients with concomitant PLSVC demonstrates that (1) isolation of the PLSVC was associated with major complications; (2) after first-time ablation, SR was maintained in merely two (29%) of seven patients after a median follow-up period of 411 (339 – 482) days; and (3) SR was maintained in five (71%) of seven patients after a median of two (one to four) ablation procedures if isolation of the mid-PLSVC was part of the procedural endpoint.
Complications related to PLSVC isolation No significant complications were reported in previous case series of patients with PLSVC undergoing AF ablation.6 – 8 Contrary to prior reports, this study found a high procedural complication rate if the PLSVC was targeted for ablation. Because of its luminal composition, a 28-mm cryoballoon catheter was used in two of four patients undergoing firsttime isolation of the PLSVC. Left phrenic nerve palsy as a major complication in the current study may be explained by the close anatomical proximity of the left phrenic nerve to the mid and distal portion of the PLSVC. Hence, cryothermal energy application via a balloon catheter should be critically evaluated when attempting to isolate the PLSVC. The second major complication, a cardiac tamponade, resulted from ablation within the PLSVC despite judicious use of RFC energy. Extensive RFC energy delivery within delicate structures such as the CS or PLSVC may increase the risk of cardiac perforation.
The importance of PLSVC isolation Previous case series in patients with concomitant PLSVC undergoing AF ablation reported a high first-time procedural success rate.6 – 8 By contrast, this study demonstrated that the first-time procedural success rate was poor and that
1759 only after an average of two catheter ablation procedures could maintenance of SR be accomplished in 57% of patients. In one patient a total of four ablation procedures were required to achieve SR. Ectopic activity from the PV musculature is the most common AF trigger.1 Accordingly, PVI should be the primary procedural endpoint in patients referred for catheter ablation of AF. In the current study, all patients underwent PVI as the first-line ablative strategy. This approach may suffice if the PLSVC represents a silent bystander. Ectopic beats from the CS or ligament of Marshall may trigger AF.4 Consequently, AF may be initiated by ectopic activity originating from a PLSVC. This study highlights the critical role of the PLSVC in the maintenance of AF (Figure 2). In patients with ectopic activity originating from a PLSVC, mere PVI may not serve as an adequate first-line treatment strategy; instead, isolation of the PLSVC should be part of the ablative endpoint. Isolation proved successful only if targeting the midportion of the PLSVC, while attempts at isolation of its proximal portion were futile. This may in part be explained by significant enlargement of the CS ostium and proximal PLSVC (up to 33 mm in diameter in our patient cohort), rendering circumferential isolation at this anatomical level an unattainable task. By contrast, isolation at midlevel of the PLSVC is feasible, since electrical connections between PLSVC and LA are typically present only along half of its circumference.6
Limitations This study did not routinely use isoproterenol to assess for ectopic activity from the PLSVC. Hence only patients with spontaneous activity were targeted for isolation of the PLSVC. Furthermore, cardiac computed tomography scanning or magnetic resonance imaging was not routinely performed before catheter ablation of AF. As a result, the true prevalence of a PLSVC in our patient cohort is unknown. Despite this limitation, the reported prevalence of 0.4% in the current study is in line with anatomical data in the Table 3 Overview detailing the number of patients undergoing ablation within the PLSVC, type of complications, and energy source used during ablation procedures Patient
PLSVC ablation
Complications
Energy
1 2 3 4 5
⫹ — ⫹ — —
Stroke — Tamponade — —
6 7
⫹ ⫹
Total
4
— Left phrenic nerve damage 3 (2)
RFC RFC RFC RFC RFC ⫹ cryoballoon RFC RFC ⫹ cryoballoon
Note: Bold highlights direct association with ablation within the PLSVC.
1760 general population. Thus, we consider routine screening for a PLSVC not cost-effective.
Conclusions Catheter ablation of AF in patients with PLSVC is feasible. In patients with ectopic activity from a PLSVC, the ablative strategy should include isolation of the PLSVC as a procedural endpoint, although multiple ablation procedures may be necessary to achieve stable SR. Contrary to previous reports, complications are common if the PLSVC is targeted for ablation.
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