- Email: [email protected]
Catheter Ablation of Atrial Fibrillation
JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY
VOL. 66, NO. 12, 2015
ª 2015 BY THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION
ISSN 0735-1097/$36.00
PUBLISHED BY ELSEVIER INC.
http://dx.doi.org/10.1016/j.jacc.2015.07.056
EDITORIAL COMMENT
Catheter Ablation of Atrial Fibrillation Advent of Second-Generation Technologies* Eric Buch, MD, Kalyanam Shivkumar, MD, PHD
“Vision is the art of seeing what is invisible to others.”
A
—Jonathan Swift (1) lthough the exact mechanisms by which pulmonary vein isolation (PVI) results in freedom from paroxysmal atrial fibrillation
(AF) are still the subject of inquiry and debate, this procedure is an effective alternative to drug therapy for rhythm control (2). The technique of catheterbased PVI has evolved through several stages, from focal ablation within the pulmonary vein (PV) (3), to segmental ostial isolation (4), and to antral circumferential and wide-area isolation (5), with or without additional lesion sets targeting non-PV foci (6) or modifying atrial substrate. All of these techniques initially used point-by-point ablation with radiofrequency (RF) ablation catheters. Single-procedure success rates for catheter ablation of paroxysmal AF are in the 60% to 80% range; however, the procedure is technically demanding, highly operator-dependent, and carries a substantial risk of complications. Moreover, regardless of acute procedural outcome or clinical success, late reconnection of PVs is common (7). Therefore, a variety of technologies have been developed with the goal of making the procedure shorter, safer, more predictable, and more durable. An evolutionary change has been the incorporation of contact force sensing into RF ablation catheters, allowing real-time assessment of catheter-tissue contact and potentially improving
efficacy and reducing complications, but still requiring a point-by-point lesion set. Another approach is to apply RF energy at multiple sites simultaneously around a circular catheter positioned outside of each PV ostium (8,9). This has the theoretical advantage of allowing circumferential energy delivery instead of requiring the operator to move the ablation catheter to each site around the vein, which might result in more rapid PVI. In addition, energy can be applied selectively to certain electrodes, allowing fine control over how much ablation occurs at different sites. However, in practice, maintaining adequate contact between PV antral tissue and each of the ablation electrodes simultaneously is not always possible. Another concern is that the level of PVI might be closer to the vein ostium than the wide-area pointby-point lesion set favored by many operators. Some of the technical issues that hampered early adoption of these catheters have been mitigated (10), but it remains to be seen whether they will become standard equipment for AF catheter ablation. Balloon-based technologies are another method of delivering energy around the PVs to achieve isolation. High-intensity focused ultrasound appeared promising as an energy source, with significant lesions created even in the absence of firm tissue-balloon contact. Unfortunately, ablation with this catheter (ProRhythm, Ronkonkoma, New York) caused collateral damage, including phrenic nerve injury and atrioesophageal fistula, and human trials were suspended. One possible explanation for these complications was the obligate circumferential energy delivery; the operator could not choose which part of the balloon
*Editorials published in the Journal of the American College of Cardiology
would deliver ablative energy or adjust the intensity of
reflect the views of the authors and do not necessarily represent the
tissue destruction around the balloon. As a result, the
views of JACC or the American College of Cardiology.
portion of the left atrium adjacent to the esophagus or
From the UCLA Cardiac Arrhythmia Center, UCLA Health System, David
phrenic nerve received the same energy as those areas
Geffen School of Medicine at UCLA, Los Angeles, California. Both authors have reported that they have no relationships relevant to the contents of this paper to disclose. Fred Morady, MD, served as Guest Editor for this paper.
where deeper lesions were desired. The most widely used balloon-based technology for PVI to date is the cryoballoon catheter, with over
1362
Buch and Shivkumar
JACC VOL. 66, NO. 12, 2015
Catheter Ablation of Atrial Fibrillation
SEPTEMBER 22, 2015:1361–3
100,000 cases performed worldwide (Arctic Front
we should also keep in mind that most of the laser
Advance, Medtronic, Minneapolis, Minnesota). The
balloon operators were inexperienced, and there was
catheter delivers nitrous oxide to an inner balloon,
a trend toward better results with increasing experi-
where it undergoes phase change from liquid to gas
ence. An obvious strength of this study, as opposed to
80 C. The balloon
those previously published on the laser balloon, was
catheter has a central lumen for a spiral mapping
the prospective, randomized treatment assignment,
catheter to guide balloon position, reduce perforation
which should minimize bias.
resulting in a temperature near
risk, and record PV potentials during ablation. A
Overall, acute procedural results were similar in the
steerable sheath (FlexCath, Medtronic) facilitates
laser balloon and control groups. Procedures were
positioning of the balloon at each PV antrum. Ablation
longer and required more fluoroscopy with the laser
with this technology has been proven more efficacious
balloon, but both resulted in complete PVI in > 95% of
than antiarrhythmic drug therapy in the multicenter,
patients. Although the adverse event rate seems quite
randomized STOP AF (North American Arctic Front)
high in both groups (11.8% in laser balloon, 14.5% in
trial (11), with an acceptable safety profile, although
RF), this was largely driven by cardioversion, a Food
11.2% of patients had transient or persistent phrenic
and Drug Administration–mandated primary adverse
nerve injury. A large, randomized comparison of
event. Adverse events besides cardioversion totaled
RF catheter ablation and cryoballoon has finished
5.9% in the laser balloon arm and 6.4% in the control
recruiting patients, and results are expected soon (12).
arm. The most concerning complications with the laser balloon were a 3.5% risk of persistent diaphragmatic
SEE PAGE 1350
paralysis and 1.2% risk of stroke, but these estimates
Given this rapidly expanding array of technologies
are necessarily imprecise due to the small number of
for PV isolation, do we really need another balloon-
patients and events. In clinical follow-up, the
based ablation catheter? In this issue of the Journal,
recurrence-free survival curves were superimposable,
Dukkipati et al. (13) report the results of a large ran-
with both groups showing nearly 40% AF recurrence
domized trial comparing point-by-point RF catheter
rate, somewhat higher than that seen in contemporary
ablation (without contact force sensing) to visually-
studies on paroxysmal AF ablation.
guided ablation using a laser balloon (HeartLight,
These initial randomized results are not yet
CardioFocus, Marlborough, Massachusetts). In theory,
compelling enough to predict that the laser will
this technology has distinct advantages over both
become a major energy source in catheter ablation of
point-by-point ablation and the cryoballoon catheter.
AF, but the early experience is promising and is
It offers stable catheter position and contiguous
another piece of evidence that the days of point-by-
lesions like other balloon-based technologies, along
point ablation for PVI are numbered. One day we
with an ability to selectively titrate energy to each
might routinely visualize changes in tissue as we
part of the circumferential lesion set like point-by-
perform catheter ablation, allowing us to see what
point RF ablation. In addition, the laser balloon
has so far been invisible. The advent of second-
diameter can be changed dynamically to suit each PV
generation technologies for catheter ablation also
antrum, and this is the first ablation technology to
provides a moment to focus on the fact that we still
allow the operator to directly visualize tissue changes
need a better understanding of the mechanisms of
during ablation. However, theoretical advantages
this devastating arrhythmia to improve therapeutics.
notwithstanding, the value of any ablation technolREPRINT REQUESTS AND CORRESPONDENCE: Dr.
ogy derives from its clinical results. Before examining those results, we should em-
Kalyanam Shivkumar, UCLA Cardiac Arrhythmia Cen-
phasize that RF ablation catheters have improved
ter, David Geffen School of Medicine at UCLA, 100
since this study was initiated, especially with the
UCLA Medical Plaza, Suite 660, Los Angeles, California
introduction of contact force sensing (14). However,
90095-1679. E-mail: [email protected].
REFERENCES 1. BrainyQuote. Jonathan Swift quotes. Available at: http://www.brainyquote.com/quotes/quotes/j/jona thansw122246.html. Accessed August 3, 2015.
Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol 2014; 64:e1–76.
4. Haissaguerre M, Shah DC, Jais P, et al. Electrophysiological breakthroughs from the left atrium to the pulmonary veins. Circulation 2000;
2. January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS guideline for the management of
3. Haissaguerre M, Jais P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic
102:2463–5.
patients with atrial fibrillation: a report of the American College of Cardiology/American Heart
beats originating in the pulmonary veins. N Engl J Med 1998;339:659–66.
ential pulmonary-vein ablation for chronic atrial fibrillation. N Engl J Med 2006;354:934–41.
5. Oral H, Pappone C, Chugh A, et al. Circumfer-
JACC VOL. 66, NO. 12, 2015
Buch and Shivkumar
SEPTEMBER 22, 2015:1361–3
Catheter Ablation of Atrial Fibrillation
6. Corrado A, Bonso A, Madalosso M, et al. Impact of systematic isolation of superior vena cava in addition to pulmonary vein antrum isolation on the outcome of paroxysmal, persistent, and permanent atrial fibrillation ablation: results from a randomized study. J Cardiovasc Electrophysiol 2010;21:1–5. 7. Jiang RH, Po SS, Tung R, et al. Incidence of pulmonary vein conduction recovery in patients without clinical recurrence after ablation of paroxysmal atrial fibrillation: mechanistic implications. Heart Rhythm 2014;11:969–76. 8. Boersma LV, Wijffels MC, Oral H, et al. Pulmonary vein isolation by duty-cycled bipolar and unipolar
radiofrequency ablation catheter for pulmonary vein isolation. J Cardiovasc Electrophysiol 2014; 25:339–45.
cryoballoon versus radiofrequency ablation with 3D-reconstruction. J Cardiovasc Electrophysiol 2014; 25:1314–20.
10. Wieczorek M, Hoeltgen R, Brueck M. Does the number of simultaneously activated electrodes during phased RF multielectrode ablation of atrial
13. Dukkipati SR, Cuoco F, Kutinsky I, et al., for the HeartLight Study Investigators. Pulmonary vein isolation using the visually guided laser balloon: a
fibrillation influence the incidence of silent cerebral microembolism? Heart Rhythm 2013;10:953–9.
prospective, multicenter, and randomized comparison to standard radiofrequency ablation. J Am Coll Cardiol 2015;66:1350–60.
11. Packer DL, Kowal RC, Wheelan KR, et al., for the STOP AF Cryoablation Investigators. Cryoballoon ablation of pulmonary veins for paroxysmal atrial fibrillation: first results of the North American Arctic Front (STOP AF) pivotal trial. J Am Coll Cardiol 2013;61:1713–23.
radiofrequency energy with a multielectrode ablation catheter. Heart Rhythm 2008;5:1635–42.
12. Furnkranz A, Brugada J, Albenque JP, et al. Rationale and Design of FIRE AND ICE: a mul-
9. Deneke T, Schade A, Muller P, et al. Acute safety and efficacy of a novel multipolar irrigated
ticenter randomized trial comparing efficacy and safety of pulmonary vein isolation using a
14. Afzal MR, Chatta J, Samanta A, et al. Use of contact force sensing technology during radiofrequency ablation reduces recurrence of atrial fibrillation: a systematic review and meta-analysis. Heart Rhythm 2015;12:1990–6.
KEY WORDS paroxysmal atrial fibrillation, pulmonary vein isolation, rhythm control
1363
VOL. 66, NO. 12, 2015
ª 2015 BY THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION
ISSN 0735-1097/$36.00
PUBLISHED BY ELSEVIER INC.
http://dx.doi.org/10.1016/j.jacc.2015.07.056
EDITORIAL COMMENT
Catheter Ablation of Atrial Fibrillation Advent of Second-Generation Technologies* Eric Buch, MD, Kalyanam Shivkumar, MD, PHD
“Vision is the art of seeing what is invisible to others.”
A
—Jonathan Swift (1) lthough the exact mechanisms by which pulmonary vein isolation (PVI) results in freedom from paroxysmal atrial fibrillation
(AF) are still the subject of inquiry and debate, this procedure is an effective alternative to drug therapy for rhythm control (2). The technique of catheterbased PVI has evolved through several stages, from focal ablation within the pulmonary vein (PV) (3), to segmental ostial isolation (4), and to antral circumferential and wide-area isolation (5), with or without additional lesion sets targeting non-PV foci (6) or modifying atrial substrate. All of these techniques initially used point-by-point ablation with radiofrequency (RF) ablation catheters. Single-procedure success rates for catheter ablation of paroxysmal AF are in the 60% to 80% range; however, the procedure is technically demanding, highly operator-dependent, and carries a substantial risk of complications. Moreover, regardless of acute procedural outcome or clinical success, late reconnection of PVs is common (7). Therefore, a variety of technologies have been developed with the goal of making the procedure shorter, safer, more predictable, and more durable. An evolutionary change has been the incorporation of contact force sensing into RF ablation catheters, allowing real-time assessment of catheter-tissue contact and potentially improving
efficacy and reducing complications, but still requiring a point-by-point lesion set. Another approach is to apply RF energy at multiple sites simultaneously around a circular catheter positioned outside of each PV ostium (8,9). This has the theoretical advantage of allowing circumferential energy delivery instead of requiring the operator to move the ablation catheter to each site around the vein, which might result in more rapid PVI. In addition, energy can be applied selectively to certain electrodes, allowing fine control over how much ablation occurs at different sites. However, in practice, maintaining adequate contact between PV antral tissue and each of the ablation electrodes simultaneously is not always possible. Another concern is that the level of PVI might be closer to the vein ostium than the wide-area pointby-point lesion set favored by many operators. Some of the technical issues that hampered early adoption of these catheters have been mitigated (10), but it remains to be seen whether they will become standard equipment for AF catheter ablation. Balloon-based technologies are another method of delivering energy around the PVs to achieve isolation. High-intensity focused ultrasound appeared promising as an energy source, with significant lesions created even in the absence of firm tissue-balloon contact. Unfortunately, ablation with this catheter (ProRhythm, Ronkonkoma, New York) caused collateral damage, including phrenic nerve injury and atrioesophageal fistula, and human trials were suspended. One possible explanation for these complications was the obligate circumferential energy delivery; the operator could not choose which part of the balloon
*Editorials published in the Journal of the American College of Cardiology
would deliver ablative energy or adjust the intensity of
reflect the views of the authors and do not necessarily represent the
tissue destruction around the balloon. As a result, the
views of JACC or the American College of Cardiology.
portion of the left atrium adjacent to the esophagus or
From the UCLA Cardiac Arrhythmia Center, UCLA Health System, David
phrenic nerve received the same energy as those areas
Geffen School of Medicine at UCLA, Los Angeles, California. Both authors have reported that they have no relationships relevant to the contents of this paper to disclose. Fred Morady, MD, served as Guest Editor for this paper.
where deeper lesions were desired. The most widely used balloon-based technology for PVI to date is the cryoballoon catheter, with over
1362
Buch and Shivkumar
JACC VOL. 66, NO. 12, 2015
Catheter Ablation of Atrial Fibrillation
SEPTEMBER 22, 2015:1361–3
100,000 cases performed worldwide (Arctic Front
we should also keep in mind that most of the laser
Advance, Medtronic, Minneapolis, Minnesota). The
balloon operators were inexperienced, and there was
catheter delivers nitrous oxide to an inner balloon,
a trend toward better results with increasing experi-
where it undergoes phase change from liquid to gas
ence. An obvious strength of this study, as opposed to
80 C. The balloon
those previously published on the laser balloon, was
catheter has a central lumen for a spiral mapping
the prospective, randomized treatment assignment,
catheter to guide balloon position, reduce perforation
which should minimize bias.
resulting in a temperature near
risk, and record PV potentials during ablation. A
Overall, acute procedural results were similar in the
steerable sheath (FlexCath, Medtronic) facilitates
laser balloon and control groups. Procedures were
positioning of the balloon at each PV antrum. Ablation
longer and required more fluoroscopy with the laser
with this technology has been proven more efficacious
balloon, but both resulted in complete PVI in > 95% of
than antiarrhythmic drug therapy in the multicenter,
patients. Although the adverse event rate seems quite
randomized STOP AF (North American Arctic Front)
high in both groups (11.8% in laser balloon, 14.5% in
trial (11), with an acceptable safety profile, although
RF), this was largely driven by cardioversion, a Food
11.2% of patients had transient or persistent phrenic
and Drug Administration–mandated primary adverse
nerve injury. A large, randomized comparison of
event. Adverse events besides cardioversion totaled
RF catheter ablation and cryoballoon has finished
5.9% in the laser balloon arm and 6.4% in the control
recruiting patients, and results are expected soon (12).
arm. The most concerning complications with the laser balloon were a 3.5% risk of persistent diaphragmatic
SEE PAGE 1350
paralysis and 1.2% risk of stroke, but these estimates
Given this rapidly expanding array of technologies
are necessarily imprecise due to the small number of
for PV isolation, do we really need another balloon-
patients and events. In clinical follow-up, the
based ablation catheter? In this issue of the Journal,
recurrence-free survival curves were superimposable,
Dukkipati et al. (13) report the results of a large ran-
with both groups showing nearly 40% AF recurrence
domized trial comparing point-by-point RF catheter
rate, somewhat higher than that seen in contemporary
ablation (without contact force sensing) to visually-
studies on paroxysmal AF ablation.
guided ablation using a laser balloon (HeartLight,
These initial randomized results are not yet
CardioFocus, Marlborough, Massachusetts). In theory,
compelling enough to predict that the laser will
this technology has distinct advantages over both
become a major energy source in catheter ablation of
point-by-point ablation and the cryoballoon catheter.
AF, but the early experience is promising and is
It offers stable catheter position and contiguous
another piece of evidence that the days of point-by-
lesions like other balloon-based technologies, along
point ablation for PVI are numbered. One day we
with an ability to selectively titrate energy to each
might routinely visualize changes in tissue as we
part of the circumferential lesion set like point-by-
perform catheter ablation, allowing us to see what
point RF ablation. In addition, the laser balloon
has so far been invisible. The advent of second-
diameter can be changed dynamically to suit each PV
generation technologies for catheter ablation also
antrum, and this is the first ablation technology to
provides a moment to focus on the fact that we still
allow the operator to directly visualize tissue changes
need a better understanding of the mechanisms of
during ablation. However, theoretical advantages
this devastating arrhythmia to improve therapeutics.
notwithstanding, the value of any ablation technolREPRINT REQUESTS AND CORRESPONDENCE: Dr.
ogy derives from its clinical results. Before examining those results, we should em-
Kalyanam Shivkumar, UCLA Cardiac Arrhythmia Cen-
phasize that RF ablation catheters have improved
ter, David Geffen School of Medicine at UCLA, 100
since this study was initiated, especially with the
UCLA Medical Plaza, Suite 660, Los Angeles, California
introduction of contact force sensing (14). However,
90095-1679. E-mail: [email protected].
REFERENCES 1. BrainyQuote. Jonathan Swift quotes. Available at: http://www.brainyquote.com/quotes/quotes/j/jona thansw122246.html. Accessed August 3, 2015.
Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol 2014; 64:e1–76.
4. Haissaguerre M, Shah DC, Jais P, et al. Electrophysiological breakthroughs from the left atrium to the pulmonary veins. Circulation 2000;
2. January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS guideline for the management of
3. Haissaguerre M, Jais P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic
102:2463–5.
patients with atrial fibrillation: a report of the American College of Cardiology/American Heart
beats originating in the pulmonary veins. N Engl J Med 1998;339:659–66.
ential pulmonary-vein ablation for chronic atrial fibrillation. N Engl J Med 2006;354:934–41.
5. Oral H, Pappone C, Chugh A, et al. Circumfer-
JACC VOL. 66, NO. 12, 2015
Buch and Shivkumar
SEPTEMBER 22, 2015:1361–3
Catheter Ablation of Atrial Fibrillation
6. Corrado A, Bonso A, Madalosso M, et al. Impact of systematic isolation of superior vena cava in addition to pulmonary vein antrum isolation on the outcome of paroxysmal, persistent, and permanent atrial fibrillation ablation: results from a randomized study. J Cardiovasc Electrophysiol 2010;21:1–5. 7. Jiang RH, Po SS, Tung R, et al. Incidence of pulmonary vein conduction recovery in patients without clinical recurrence after ablation of paroxysmal atrial fibrillation: mechanistic implications. Heart Rhythm 2014;11:969–76. 8. Boersma LV, Wijffels MC, Oral H, et al. Pulmonary vein isolation by duty-cycled bipolar and unipolar
radiofrequency ablation catheter for pulmonary vein isolation. J Cardiovasc Electrophysiol 2014; 25:339–45.
cryoballoon versus radiofrequency ablation with 3D-reconstruction. J Cardiovasc Electrophysiol 2014; 25:1314–20.
10. Wieczorek M, Hoeltgen R, Brueck M. Does the number of simultaneously activated electrodes during phased RF multielectrode ablation of atrial
13. Dukkipati SR, Cuoco F, Kutinsky I, et al., for the HeartLight Study Investigators. Pulmonary vein isolation using the visually guided laser balloon: a
fibrillation influence the incidence of silent cerebral microembolism? Heart Rhythm 2013;10:953–9.
prospective, multicenter, and randomized comparison to standard radiofrequency ablation. J Am Coll Cardiol 2015;66:1350–60.
11. Packer DL, Kowal RC, Wheelan KR, et al., for the STOP AF Cryoablation Investigators. Cryoballoon ablation of pulmonary veins for paroxysmal atrial fibrillation: first results of the North American Arctic Front (STOP AF) pivotal trial. J Am Coll Cardiol 2013;61:1713–23.
radiofrequency energy with a multielectrode ablation catheter. Heart Rhythm 2008;5:1635–42.
12. Furnkranz A, Brugada J, Albenque JP, et al. Rationale and Design of FIRE AND ICE: a mul-
9. Deneke T, Schade A, Muller P, et al. Acute safety and efficacy of a novel multipolar irrigated
ticenter randomized trial comparing efficacy and safety of pulmonary vein isolation using a
14. Afzal MR, Chatta J, Samanta A, et al. Use of contact force sensing technology during radiofrequency ablation reduces recurrence of atrial fibrillation: a systematic review and meta-analysis. Heart Rhythm 2015;12:1990–6.
KEY WORDS paroxysmal atrial fibrillation, pulmonary vein isolation, rhythm control
1363